Notes on: Barad, K. (2007).  Meeting the Universe Halfway: quantum physics and the entanglement of matter and meaning.  London: Duke University Press

Dave Harris

[A very fashionable text in some quarters, although my guess is that it is not that thoroughly read.  Develops a fashionable post humanism, but, more important, seeks to justify a more ethical stance towards nature and other people by developing arguments about entanglement originally found in quantum physics.  This is not to be developed through simple analogy, however, but through an ontology. Böhr is the particular source for this suitable ontology, although she admits that hers is a controversial reading, and Böhr does seem to invite controversy by referring to the basic units as 'phenomena'.  Barad runs into further interesting problems: she argues that the apparatus is intimately bound up with the ontology that results in quantum physics experiments, and then tries to generalize the notion of 'apparatus'to refer to most forms of human intervention.  However, she is light on the activities of consciousness, perception and affect, and recognizes that there is an infinite regress lurking here: the apparatus in the physics lab can itself be taken as an object constructed by some other apparatus in the history of science, and then we get back to the history of thought and so on forever.  The regress might be limited by a notion of objectivity that really turns on agreement on Popper's basic statements', but infinite regress still awaits if we consider the psychological and sociological factors that produce such agreement.  Barad also wants feminist politics to limit the infinite regress.

There is an ethical infinite regress in the last chapter, addressed primarily to scientists. Since we are linked to everything, in the tight sense that we co-constitute everything ( even brittlefish) we must be responsible in how we respond to everything. Everything. It is a techno-buddhist stance. If only liberals could see how undomesticated animals treat each other, and how they would constitute us as their dinner if they had to.

Starting the book with nuclear physics is revealing. It implies some hierarchy so that particle physics is the royal road to grasping 'nature' and once indeterminacy is found there the game is up for social life too. Indeterminacy has been a feature of social science for years of course,including the interference of measurement with the object etc. Entanglement is not really new? Inter and intra-interactions and their links are well known? 'Diffraction' is only discussing where approaches agree and disagree? [NB while we are here that 'reflexivity' has a special meaning for Barad, referring to an approach in in Science Studies that sees the knower as a mediator between reality and theory]. For social scientists to read this is a bit ironic -- we are getting reflected back to us what we have always known? The only reason for this approach is the claim that matter is itself active.

There's a lot of assertion and repetition of the basic arguments, which can be rather unsatisfactory.  For example she constantly asserts that matter itself is 'agential', but never explains what this agency might be – the will of god?  Some imminent force as in creative evolution in Bergson?  Some autopoietic tendencies in matter itself, as in DeLanda's stuff on the tendency of atoms to combine into molecules?  As these questions implied, I think Deleuze is a better ontologist [eg his multiplicity is her 'topological manifold' --she largely ignores the virtual in her discussion of possibility? Or sees it as only an outcome of actual reactions?].  As with many general arguments, there is a danger that human distinctiveness is going to be lost by reducing it to material interactions: I am not yet sure how far down this goes—whether or not she sees human emotions as a merely molecular reactions in brains or whatever.

Sometimes there is contradiction in the repetition -- Böhr's notion of objectivity is criticized as too dependent on human consensus in C4, and is abandoned in favour of Einsteinian separability, but it reappears uncritically in C5.  The ambiguity is also exploited for political reasons, and this is perhaps closest in C5 with the debates about maternal responsibility for the fetus: note here that everything is responsible for the fetus, such an extension of factors that in practice 'accountability' is so diluted that it disappears

The detail of the science examples is interesting but they leave us in her hands, and doubtless the inverse for scientists when discussing femninism -- just like the detail in Bourdieu and Foucualt, says DeCerteau.

Thinking of parallels with Actor Network Theory (ANT) reminded me of a debate about the 'agency' of machines there.  Machines can sometimes do things that surprise us, that are beyond what we thought they could do , and sometimes this is delightfully benevolent.  I have a brief example about the capacity of climbing gear which can surprise rock climbers and make it look as if they have been 'saved' by the gear.  This certainly reminds them that climbing machinery is a very important aspect of human action, but this is not to say that climbing gear possesses some conscious agency.  Instead, it has an extra capacity, engineered in, which exceeds what it is that climbers know about the capacities of the rope or the spikes.  Engineers apparently call this  'affordance'.  It seems quite likely that this affordance exceeds human knowledge, for, after all, very few of us know about the precise capacities of machines and how they have been designed.  I have myself been surprised and grateful for the excess capacity built into Yamaha motorcycles that stop them sliding on wet greasy roads even though they have exceeded my own expectations considerably and I was predicting doom.

I had growing doubts about the argument as I read through.  There's a lot of assertion, repetition and circularity, so that the concepts sequentially developed prop each other up—agential realism is explained in chapter four, and it justifies all the earlier argument about complementarity and so on, but the argument could easily run back the other way with agential realism explained first and all the other concepts being entailed.  This more than a suspicion that it is straw men who are being critiqued, and this comes at best in chapter six, where the approach is finally used to discuss something of which I have independent knowledge.  Major claims are made throughout about the implications for just about all classical analysis, causality, ontology and epistemology and so on, and in chapter six, this is turned against Marxism.  However, disappointingly, it is a straw man economic determinist Marx who is then criticized on the usual grounds that he ignores complexity, or diffraction as she insists on calling it, especially the affects of gender.  One single study on workplace determinants of consciousness is quoted in support.  Determinism is flirted with as well, but the whole thing badly needs Althusser and Poulantzas, not to mention some of the early work on images of class and how they are affected by local work conditions.

In fact the discussion needs sociology and discussion of the social relation more generally -- for Barad there are only causal or voluntarist relations . The problematic is set by feminist concerns about bodies, nature and culture?

I have just sidelined a few issues as I have read through:]

 Introduction

Böhr disagreed with Heisenberg about the uncertainty that both had detected after some famous early work in quantum physics [including the two slit experiment]. Heisenberg thought that we thought that we cannot know the position and momentum of a particle simultaneously because the experiment itself disturbed the properties in question [because shining a light beam on matter bombarded with photons and thus disturbs it—clearly important if we are observing electrons].  Böhr extended that into an ontological position: 'particles do not have determinate values of position and momentum simultaneously' (19).  This leads him to suggest there are no individual objects with complete sets of properties, but that measurement itself makes some properties determinate and excludes others—complementary sets of variables which are 'reciprocally determinable'.  Objectivity now can only mean intersubjective agreement on some visible results, accountability [basic statements].  All sorts of implications follow, including the blurring of ontology and epistemology, and also rethinking the role of psychic [things that go on in the mind] phenomena, including whether they are also traceable to isolated individuals.  There are moral implications as well.  We need a much more detailed analysis of the 'network of human and nonhuman agents involved'(23).  Causality will also have to be rethought since there are no easily drawn boundaries between objects.

However, we must not extend these arguments into other fields using only analogies.  Böhr's philosophy needs explication instead, to challenge our metaphysical notions.  In particular, we will be unable to theorize hitherto separated things as connected, including the social and the natural, matter and meaning.  However, we should not force these issues together, 'collapsing important differences between them'.  Instead, any collective issues will emerge rather than us predetermining them [surely a bit naive here thinking that we can do without presuppositions?].

Exploring Böhr's 'philosophy - physics' leads us to realize that 'we are a part of that nature that we seek to understand'(26), that science involves interactions between different parts of nature, and that acts of knowledge making are 'social-material enactments that contributes to, and are a part of, the phenomena we describe'.  There are some obvious similarities with post structuralism, which question the subject and the object and which tend to be anti humanist, but there may still be 'anthropocentrist and representationalist assumptions', and these 'unwanted remnants' can be removed by reading Böhr [what she calls 'reading...insights through one another']

Diffraction is 'an apt overarching trope for this book'(29), offering a suitable figuration of interaction rather than reflection, offering 'patterns of difference'—this argument like others is indebted to Haraway].  It will help us understand 'the full display of...intricate patterns and reverberations' (30). We also get the first mention of 'entanglement', referring originally to the inextricable link between apparatuses and their effects, for example in constructing boundaries: this helps oppose binary thinking.  Diffraction means we look at the relationship between the natural and the social without dividing one against the other or assuming a priority.  We can draw on our best scientific theories and practices to grasp 'the nature of nature', and our best social theories to grasp the nature of scientific theories. 

Eventually we will get to 'agential realism'. Böhr is only partly helpful here, because he did not focus sufficiently on ontology, and this needs to be extracted and made consistent.  We do this by emphasizing the performative dimensions of his account first.  We reject 'representationalism' that first separates words from things, and this is partly lead to a difference between discourse and material nature of practices.  Instead, the emphasis is on the 'practices for making meaning' and 'the conditions for the possibility of intelligibility and the co constitution of an excluded [separated out] domain'(31).  Instead, knowledge making practices are material enactments and thus are a parts of the phenomena been described.  Agential realism links epistemological ontological and ethical issues and sees them as integral.  It is post humanist, wishing to include practices that do not include humans, a refusal to distinguish the human and nonhuman as fixed: instead we should see how the dichotomy between nature and culture was produced.

There are no isolated separable objects, but rather 'phenomena' for Böhr, which Barad defines as indicating 'the ontological inseparability of the agential intra acting components' (33).  Intra action refers to 'the mutual constitution of entangled agencies' rather than thinking of interaction between original separate individual agencies.  Such agencies actually emerge from intra action, as does their separation, which makes distinctiveness relational not absolute.  We need to rethink the notion of causality together with other core philosophical concepts.  There is an extended notion of performative action to include not just social practices to materialize bodies, and not just human bodies: discursive practice ease and material phenomena are joined in a different way.

Chapter one

The development of the scanning tunneling microscope helps us actually see atoms grouped in structures, once we have set up the apparatus extremely carefully.  This might seem to challenge the idea that scientific knowledge about atoms, originally only theoretical knowledge, is not so much constructed but is based on empirical adequacy.  Observing atoms helps us realize that there are both cultural and natural dimensions to knowledge, rather than taking the view that science mirrors reality or culture.  Realism used to imply that the world has to be discovered, that it existed independently of any scientific practices, although this was subsequently refined into a realism about theories and a realism about entities, with the latter favoring experimental activity.  Experimentalists tend to count something as real if it offers effective experiments [and several positions in the history of science are reviewed, including Latour, 41, which connect with issues of the stability of science—Haraway likes to stress instability especially of boundaries, and also has an extended agentialism, as in the stuff on cyborgs].  For culture analysts, including discourse theorists, the emphasis is often on criticizing scientific discourse, but there can also be a notion of the need for consistency, a partial acknowledgement of the constraints of reality outside—see Foucault's wrigglings here].  Much more work is needed [conveyed by a list of rhetorical questions].

Barad herself offers a 'realist tenor' (43), despite the philosophical critiques, including political ones [useful background here, 43].  She wants to counter the tendencies towards playful theory.  Realism implies that we can access the ontology of the world.  This is not to reject any role for linguistics.  She draws upon feminist science to oppose full relativism ,although there are dangers in realism and in using the concept 'nature', as we shall see.  She thinks the new notion of realism will overcome many of the old oppositions and problems—agential realism breaks away from the old notion of links between words and things as a correspondence of some kind, and insists that we move away from thinking of representations towards thinking of discursive practices including scientific ones, designed to account  for 'the material nature of practices and how they come to matter'(45) [first of several deliberately?  ambiguous uses of terms like material and matter].

Notions of the natural have been central to a number of political positions, especially feminism. Beauvoir for example sees women as social beings, as 'transcendental human subjects, constrained, but not determined, by their natures'.  This might be essentialist about the category of woman, and humanist in that it presupposes a free subject after the analysis of constraints has preceded.  Structuralism in particular would argue that this subject is itself produced by structures inevitably and is an effect.  Post structuralists have challenged the idea of unitary structures and have rethought the debates about structure and free will [there's also a mention of the 'geometrical of conception of subjectivity', which implies that there are  internal and external dimensions].  Foucault, for example, argues that subjects are produced by systems of power, including the subjects of feminism, meaning that political intervention has to be carefully thought out [more Butler below].

Representationalism [which is the name for those practices] is criticized in science as well, especially in science studies.  Scientific representations are seen as clearly produced by scientific practices.  Hacking and Rouse represent the clearest critique of representationalism (48).  It is a position that underpins the usual alternatives of scientific realism or social constructivism: both positions still assume that scientific knowledge offers adequate representations of the material world, whether these be concepts or photographic images, and disagree only over the referent of scientific knowledge [nature or culture].  The approach might have begun with the Greeks who originally imagined that what was real was something that could be recognized in a likeness, so that the issue then became one of judging representations in terms of their representational adequacy.  Descartes is also involved with his line between internal [subject] and external [reality], between word and world, with the latter somehow privileged.  Hacking argues that subjective sense or thought is no more accessible to language than is external reality.  Our faith in representations as a crucial element of description is simply a 'a Cartesian habit of mind' (49).

Performative understandings do better.  There are no differences between representations and apparently ontologically separate entities: knowing involves 'a direct material engagement with the world' [just as problematic I would've thought, to guarantee that it is direct and not mediated through representations].  It is not just humans who do these performative enactments.  We have a break not only with representationalism but other concepts of ontology as well.  Performativity appears in science studies and in social and political theory, and can be profitably compared.

Hacking argues that we decide what is real on the basis of our effective interventions.  He also quotes Marx in saying that it is important politically to change the world not just understand it.  Effective intervention does not necessarily imply realism: electrons are real because they enable us to intervene.  It is not enough just to inspect or reflect.  This helps justify experimental approaches to science as well.  We can see the effects of the approach when we consider what is required to actually see through a microscope [again I'm not sure that we do away with representations here, since we have to manage images. Also, distinctions between noise and signal, for example, are based on theoretical approaches not just pragmatic ones].  If different practices lead to the same results, Hacking says we can be confident that we are on the right tracks.  [This implies some scientific community to share results and arbitrate on them of course].  Hacking apparently thinks that experimentation is not theory laden, but involves contacts with real entities

Techniques like the tunneling microscope can undermine optical representationalism [and there is an aside about how geometrical reflection is challenged by ordinary microscope use].  The representations of the tunneling microscope arise from touch rather than vision.  Incidentally tunneling itself is a quantum phenomenom where electrons cross the barrier between the surface of the sample and the microscope tip.  [but the data has to be turned into an image, which looks like representationalism again?].  Classic representationalism minimizes the practices which produce representations, and examples like the tunneling microscope show us that the visual representations are not immediately adequate or privileged.

Böhr can be read as offering a 'proto - performative account' (54), invoking the need to set up specific physical arrangements as complicit with concepts [if we are to avoid theory as a spectator sport or as play].  Scientific practice is still intervention.  Another historian of science is cited as indicating the importance of the context of developing practical instruments and technological solutions [including clocks], which played an important part in the development of Einstein's approach, having encountered ingenious gadgets in the patent office.

Practices include technical apparatuses, but also social and political ones, turning on the contexts for the development of technology such as democracy or colonialism.  [The start of an infinite regress?]. Practical necessity and developments of the 'cultural imaginary' drove progress.  Theories are never pure ideas, but are material practices themselves [this assumes a positivism, or at least the connection of science and technology?].  We arrive at complex entanglement of theory and experiment rather than simple representations which linked to separated fields.

Even people like Hacking seem to have assumed that the world is composed of individual identities, things, just like representationalism.  This introduces a note of essentialism, an 'individualist metaphysics' (56).  We can break with this by thinking not of things but of phenomena, 'entangled material agencies', seeing scientific work as a dynamic practice that can help constitute 'objects and subjects and matter and meaning'.  Part of the story has been developed by actor network theory, which emphasizes scientific practices which produce networks of humans and non humans [she even uses the term 'assemblages'], but the tendency to see the world as composed of things is widespread.  But at the same time, there is no need to overemphasize the role of language or discourse.

Turning back to Butler, 'gender is not an attribute of individuals' (57) but of doing, a matter of gendering, which produces gendered subjects by applying repeated norms.  This would agree with ANT [although Latour once flirted with ethnomethodology].  It is not just a matter of adding gender in.  Phenomena are produced by 'knowledge - discourse - power practices'.  What is excluded is also important.  Different practices ['intra-actions'] produce different phenomena.  We have to take ethical responsibility for exclusions and be accountable for their effects [to whom?] [This is the basis of the claim that epistemology, ontology and ethics are all somehow joined in the approach].  Certainly, inclusion or exclusion of gender is political and advocates should be heard in science studies.  Nor should this politics be representational [another deliberate ambiguity?]—The issue is power, including a power to work with difference.  Metaphysical individualism will come back otherwise.  Post structuralism therefore offers the best alternative to representationalism [but it is not widespread in science studies?].

Butler also attacks social constructivism that sees only gender as a cultural construction, with sex as a natural state.  This ignores the agency of biological matter itself.  Butler draws on Foucault to show that sex itself is culturally variable, even to the extent of naming particular parts of the body as sexual.  Sexual difference has never been explained in terms of biological constitution: on the contrary, cultural assumptions about gender drove such work, so that gender actually produces sexual divisions and not the other way around.  But is there nothing natural or material?  Matter itself needs to be examined, at least as a constraint on what can be constructed culturally, sometimes expressed in binary or causal arguments.  If we take a performative approach, we can see gender as 'becoming or activity'(62), not just a theatrical performance under the control of the subject, not a singular act at all, but a process that creates individual subjects at the same time as social ones [shades of Lacan or other Freudians here? Or good old Cooley and hte 'looking glass self'?] The subject emerges inside gender relations: those relations constitute but do not determine the subject, as in Foucault on discursive practices.

Foucault himself can be related between hermeneutics and structuralism [to cite the famous book], so that subjects are not just affects of social systems, and nor do they produce reality from their consciousness.  Subjectivity emerges in particular historical conditions.  Power is not external to subjects but is 'an immanent set of force relations that constitutes (but does not fully determine) the subject' (63).  He also discusses the materiality of the body, affected by material conditions of various kinds in disciplinary practices.  However, there is no clear link between the discursive and these non discursive practices, except through the notorious notion of 'dispositif, usually translated as apparatus'[another useful ambiguity?], referring to heterogeneous ensembles of discourses, laws, statements and architectural forms.  This is not positive/active enough for Barad.

Butler sees repeated regulatory practices as materializing bodies specifically, as sexed and gendered.  Performativity covers both.  She also urges a new attention to matter as a process of materialization of bodies with boundaries and surfaces [actualization in Deleuze's terms?]  This involves a possibility for change.  We also need to see what is necessarily excluded by these processes, 'outside' discourse.  This 'constitutive outside' leads to a notion of agency [recovering what is excluded and thus breaking with the objective illusion?].  However there is still a gap between discourse and materialization, which might suggest that one could completely engulf the other.  Matter has to be seen as dynamic, so that the material forces of the body, including anatomy and physiology, and its relation to nonhuman forces can actively intervene.  Foucault denies that he is ignoring the materiality of the body, but fails to explain it and its relation to biology and history.  The issue is particularly relevant given Haraway's reminder of the merger of the body and technology.

Power operates materially as well as socially, including ways in which the atoms that make up the biological body affect it, and the nonhuman world that surrounds it.  All make 'agential contributions' (66).  This will produce a posthumanist notion of performativity.  We will also need to think of causality in a new way.  Agential realism will not only offer 'a unified theory of cultural and natural forces' but help us see how they have been differentiated in the first place.

Böhr is therefore a suitable place to start, and his questions extend beyond quantum physics.  We can now see that 'we are a part of that nature that we seek to understand'(67).  We need to pursue further his examination of measurements and how measurement itself constructs knowledge, as a further example of performance.  We have to be careful that quantum theory is not misused in rhetoric, seen as a path to eastern mysticism, something' less eurocentric, more feminine, more postmodern, and generally less regressive'.  It has also led to atomic weapons and 'scientific reductionism'.  Nor should we develop suspect analogies between the quantum world and social situations that interest us [although her video suggests there is an affinity with queer theory?]

The debate focuses instead on philosophical issues which run across different fields.  Philosophy is integral to physics as well as to the cultural world, and Böhr's contribution was not just a practical one.  His framework needs to be rounded out and developed into ontology.  There is a big debate about how to interpret him, and Barad says she is going to develop an ontology that is consistent with these views even though he himself might not necessarily have held it.  She is interested in coherence rather than what Böhr was actually thinking.  It will lead to agential realism which might then be applied elsewhere through 'widely applicable epistemological and ontological issues', and which raises questions about background assumptions in different fields.

Chapter two

Diffraction is used here as 'an apt overarching trope' (71).  It means  'reading insights through one another in attending to and responding to the details and specificities of relations of difference and how they matter' [she's going to see how the different approaches agree and disagree?].  It is a way of breaking with the notion of reflection [as in correspondences between theory and matter, not as in critical analysis].  Haraway uses the term and argues that reflection indicates mirroring, 'geometries of sameness', while diffraction recognizes difference—[of the nice kind, not involving exclusion].

Diffraction represent something real in the world of physics as well, and indicates 'patterns of difference that make a difference' as the 'fundamental constituents that make up the world' (72), as will become apparent.  When used in physics and quantum physics, diffraction patterns can be seen as 'the entangled structure of the changing and contingent ontology of the world, including the ontology of knowing'.  The apparatus of diffraction helps us investigate reality, but is also itself 'an object of investigation' (73), although it cannot be both of the same time.  We can use insights from both stances to tune our instruments [as in abduction?]. 

The main aim here is to explore entanglements, in their specificity.  Entanglements do not change against a stable background of space, time or matter, since these do not exist 'prior to the intra actions that reconstitute entanglements' (74).  Entanglements can exist between entities that do not appear to be connected by space and time at all.  We will have to develop these points in later chapters, but, for now, diffraction can be seen in the combination of waves,say of water or sound.  Diffraction patterns of light are particularly interesting, because they produce patterns of light and dark rather than sharp boundaries [example of the shadow of a razorblade on 76].  We have to remember that waves are disturbances in a medium and so they can overlap in space.  Amplitudes can either combine or cancel each other in superposition.  If we shine a light through two slits, we get a diffraction pattern, bands of brighter and dark areas according to whether waves add or cancel.  This produces anomalies such as bright areas inside shadows.  [Lots more examples ensue, including the rainbow effect on the surface of a CD].  This occurs with any wave. Using diffraction as a metaphor in methodology helps us break with the notion of reflection and geometrical optics.

Diffraction has had an important role in quantum theory, as in the two slit experiment showing that particles also behave like waves, whether we're talking about electrons, neutrons or atoms of other substances.  It should be noted that other experiments confirm that light can show particle behaviour in different circumstances.  Diffraction patterns led to considerable implications for conventional epistemology and ontology, because they lie at the heart of '"quantum weirdness"'(83).  We can also use diffraction techniques to analyze substances, since we can work back from diffraction patterns to deduce features of a distraction grating, including their molecular structure, as in x ray crystallography to get at the structure of DNA.

There were implications for classical optics and the need for quantum optics.  The former used geometrical optics to understand phenomena such as reflection, and physical optics to grasp diffraction.  Geometrical optics involves examining where light travels, and it is conventional to see the light simply as a 'ray', ignoring its possible characteristics.  With physical optics, the nature of light becomes more important as in studying diffraction.  Geometrical optics work well enough if the wavelength of light is small compared to the objects it is interacting with.  It's possible to draw analogies between geometrical optics and classical mechanics, but physical objects connect better with quantum mechanics.  The former are usually understood these days as 'approximation schemes that are useful under some circumstances' (85), while quantum mechanics is accepted as the full theory which can explain phenomena at any scale.

Optical metaphors have influenced methodology in other fields: the notion of reflection has underpinned a 'representationalism—the belief that words, concepts, ideas, and the like accurately reflect or mirror the things to which they refer' (86).  Reflexivity in this sense assumes that knowledge arises from a relationship between objects, representations and knowers.  It is still used in science studies, to critique social realism [which involves 'the reification of important categories of the social'], as in the sociology of scientific knowledge, although approaches like ANT and feminism do not see the social as totally determinant.

Feminist science studies have some early critiques of both relativism and reflexivity, especially those who were trained in science and were thus committed to 'take nature, objectivity, and the efficacy of science seriously' (87).  For them, reflexivity is insufficient, especially if it takes social variables such as gender as 'preformed' rather than as '"gender - in - the - making"'[which goes on through technoscientific practices as well].  Beneath this, there is a debate about the whole nature-culture dichotomy and its effects.

Reflexivity is founded on representationalism, so that theories reflect the social or natural realities and have no independent effect themselves on the objects.  The subject is uninvestigated, even when it is reflexive [in the sense of self critical], since the basic reflexivity remains unchallenged.  Diffraction seems more productive.  However this is not simply to follow an analogy, but to disrupt optical metaphors and the underlying assumption that separate entities can be understood through homology: instead, we are interested in 'specific material entanglements'(88) [then there is a substantial table, 89-90 to show the differences between diffraction and reflection—and lots of things like performativity rather than representationalism, entanglement, interaction, agential separability and several other terms that feature in later discussion.  I thought some of the categories, especially under reflection, represented straw men—eg the claim that words mirror things, which seems to naive for any serious reflectionist].

There are other advantages.  Haraway says that diffraction leads to critical practice 'for making a difference in the world', since it stresses differences and how they matter.  This is emphasized by the performative understandings implied, and it is a component of agential realism [we have one end of a circular argument here, since diffraction gains particular importance in agential realism, but when we come to discuss that, we find that the insights of diffraction are already assumed].  We do not just describe things, but rather draw attention to knowledge practices which have consequences and which are themselves material engagements, 'reconfiguring the world'(91).  This does not mean that knowledge is only subjective, rather that a new notion of objectivity is required which involves 'being accountable to the specific materializations  of which we are a part'.  It also shows us 'the extraordinary liveliness of the world'[I don't think this is explained very well, certainly not in the next few chapters—is this liveliness down to god, vitalism as in Bergson, or immanence and autopoiesis?  What is the energy that provides it, and is it prior to matter?].

We become aware of fine details, such as the actual patterns inside shadows.  We are also aware of the affects of apparatus on phenomena, for example the different sorts of diffraction gratings.  We can follow implications, for example in the analysis of spectra.  [interestingly, different atoms have different energy states, and electrons can leap from higher to lower energy levels—when they do so they emit light of a particular wavelength].  This technique has progressed to enable us to see really fine structures, and this has led to some extraordinary arguments which posit the existence of some prior state 'in which everything that can possibly exist exists in some potential form'(92) [the same as virtual reality in Deleuze?].  This potentiality produces really tiny shifts in energy that can be said to be 'the effects of unrealized possibilities': apparently, the experiments produced 'empirical confirmations of this seething potentiality'.

Her diffractive methodology leads her to look at say physics and poststructuralist theories against each other, rather than from setting up some hierarchy between them, as many do, when asserting the greater value of natural sciences, for example.  Instead there is a dynamic relationality focusing on the drawing of boundaries, exclusions and issues of accountability and responsibility for reconfiguration.  This resembles in some way existing transdisciplinary approaches, if these call into question the very boundaries of knowledge and their effects.  However, the fine details of difference between disciplines are also important, leading to 'respectful engagements' (93).  We will be examining the persistence of light spots in shadows, the 'relation of "exteriority within"'.  We'll eschew all reflectionist metaphors including those that relate macro to micro, or which see analogies, say between special relativity and cubism.  We will go for the deeper philosophical issues, including how technoscience interferes [as in interference patterns] with ordinary life and human bodies.  We will go on to discuss subjectivity and measurement, causality and identity.  In particular we will argue that quantum mechanics can be interpreted via a broader focus of agential realism, and that implications follow for things such as feminist theory and science studies.  We will focus on the 'specific material linkages' between different subject matters.

Chapter three

Representationalism sees language as a transparent medium, representing reality and presenting it to the knowing mind.  In Newtonian physics, observation is similarly a transparent process to gain knowledge and reveal properties.  Böhr is one of those who argued against, knowing that this would shake the foundations of epistemology and conventional physics.

The issue was what was the ontological nature of light.  Newton thought it was a matter of corpuscles or particles, but the two slit experiment raised problems.  The way in which one theory replaced another was a matter of a change in theoretical canons however [and Kuhn is very useful on this].  Experimental practice also changed, including the development of new mathematical elements and a different sort of reporting status.  A conceptual change was also available, from rays to waves, and there was an understandable reluctance to be seen to criticize Newton.  Eventually, light was accepted to be a wave.  Maxwell's unified field theory also enabled us to predict the wave nature of light.  However, there was still inconsistency, and also a generalization off the crisis in that matter itself was both wave and particle—'wave - particle duality' (100).  A seismic shift in the whole view of nature was threatened, especially since particles were seen as distinct localized entities with exclusive characteristics.

A series of thought experiments or gedanken pursued the issue.  The two slit thought experiment was developed by Böhr to prevent electrons seeming to interfere with each other—electrons could be sent through one at a time, but this also produced a wave pattern from a large number of repetitions.  There was also an attempt to develop a '"which-path"'variant that tested with the electrons were traveling through one of two parallel slits [diagram 105]: the results showed that electrons in this case were behaving as particles.  It eventually, it became possible to actually perform such an experiment in the lab, explained in chapter seven.

Böhr was to argue that this ambiguous behaviour was produced by the actual experimental apparatus itself—one apparatus produced one result [actual behavior for Böhr], and another another in a mutually exclusive way.  Both ways and particle behaviors are therefore 'complementary' and mutually exclusive—we can either find out the path traveled by the electron in the which path apparatus, or we can obtain a wave pattern, but not both at once.  Revolutionary implications followed in ascribing the apparatus as a crucial element in ontology, despite classical physics.  Clearly, objects did not exist with determinant properties independent of our investigations, and thus 'objectivism' had to be rejected, together with Newtonian physics.  In other words, underlying representationalism proved inadequate, together with all its assumptions about individual entities with proper boundaries, the possibility to separate knower and known and so on.

Strict determinism had to be modified too, as in predicting positions and momentum of particles using the laws of mechanics.  Attempts to measure these qualities produced paradox again.  Any attempt to shine a light on an object in order to observe of measure it necessarily disturbs the object, and this is clear if we are talking about subatomic particles: normally such disturbance can be ignored.  Newtonian physics held out hope that this disturbance could be measured and allowed for in calculations of momentum, but quantum physics had already discovered that measurement interactions are not continuous: there is a quantum jump, referring to 'the smallest quantity or discrete amount that exists'(108) [this gives a necessarily lumpy quality to matter, and a jerky quality to momentum, despite assumptions that both are smooth and continuous?].  Planck confirmed that energy is exchanged in discrete packets or quanta. This causes problems for Newtonian physics, since disturbances from the impact of lights can never be reduced to zero—even one photon will cause a disturbance.  We will have to actually establish the effects of measurement.

However Böhr saw a problem.  Measurement and description entail each other, 'theoretical concepts... are specific physical arrangements' (109) [I think this is saying that concepts like position and momentum are always embodied, and they will turn out to be complementary as above].  If we try to measure position, it seems straightforward to measure it, and again the problems occur at every scale, although they are particularly noticeable at the atomic scale—Planck's constant is universal, and can never be reduced to zero.  We might use a fixed flash camera in a dark room with a photographic plate to record the position of the object once we have illuminated it.  In this case, position means something recorded on a fixed photographic plate.  Measuring momentum is different, and requires a movable plate so that we can gauge how far the platform has absorbed the momentum of the particle [we need to remember that momentum is not an intuitive concept, but refers to a product of mass and velocity.  I still don't see why we couldn't measure both mass and velocity in a static way, seeing velocity as distance traveled in a fixed time for example].  In this way, position and momentum appear in mutually exclusive experiments.

We could compare momentum of the photon before and after it bumps into the object to estimate the measurement interaction.  Once we know the change in the photon's momentum, we can calculate the momentum of the particle which will be equal and opposite.  However, we will still need to measure the momentum of the photon using a movable platform, but we cannot do this to measure the position of the photon [to make sure that it actually hits the particle?].  So the paradox reminds—we can measure things that we can never determine precisely the effects of this measurement, and thus we can never be sure what properties the particle itself has before it was measured.  Further, the indeterminability of the measurement interaction calls into question the assumption that the position of the particle is independent of measurement.

The implication for Böhr is that there can be no objective way to separate the [properties of the] object itself from what he called the '"agencies of observation"'(114).  Generalizing drastically, we can say that there is no clear way to separate objects and subjects either.  Indeed, in the experiment cited above, the photon becomes a part of the apparatus of observation when it is used to measure position, but a part of the object when it interacts with the particle.  Everything depends on how the apparatus is specifically arranged: only once we have specified this can we separate observation and the object—'the apparatus enacts a cut delineating the object from the agencies of observation'.  However this means that we have to treat the measuring device itself as an object when it goes about its work [so an infinite regress is threatened].  This notion of a cut will turn out to be something 'constructed, agentially enacted…  embodied…  contingent' (115).  In general, the apparatus is required to 'give meaning to a particular set of variables', excluding other variables with a particular and embodied cut.

Böhr and Heisenberg are compared 116f [more or less as above --Heisenberg saw a residual  uncertainty in measurement, an epistemological problem, but Böhr argued that this uncertainty can never be resolved because the concepts themselves have a material effect on what happens in physical reality, which is not just independent of observations while proving resistant to measurement: Heisenberg apparently agreed that Böhr was correct.  The attempt to observe actually produces a cut in reality].  The issue is indeterminacy not uncertainty [then an odd bit that this is a matter for both semantics and ontology, not epistemology—there seems to be some pragmatic underpinning of the semantic issues, where the meaning of concepts is derived from their use in apparatuses].  Property such as position and momentum are 'not simultaneously determinate...  It's is a question of what can be said to simultaneously exist' (118).

Böhr thought that 'quantum wholeness' referred to a unity of object and agencies of observation as the basic unit, at least at the quantum level, not independent entities, and he use the term phenomena to refer to these unities.  Phenomena refer to observations gained in specified circumstances.  He saw these as objective in the sense that individual observers were not crucial in the observation, so that '" objective means reproducible and unambiguously communicable—in the sense that permanence marks are left on bodies which define the experimental conditions"' (119) [which reminds me of Popper and the final role of the greed or unambiguous 'basic statements' in tests of theories].  We can therefore renounce both Newton and Descartes.

For Barad, the physical apparatus itself distinguishes subjects and objects, and combines them in 'a non dualistic whole'[so is it just a matter of convention whether we divide into subject and object or treat a phenomenon as a unity?  At least Husserl tried to ground his description of phenomena in the way in which human consciousness works.  He also saw a proper analysis of phenomena as a way of resolving the crises in science, of course]. She thinks this resolves  'the semantic-ontic indeterminacy' and leaves room for objectivity [by assertion really, refusing to take dualism as relevant.  The phenomenon is a synthesis of similar things or different things?].  She agrees that bodily signs of various kinds are central to objective scientific practice. There is still  an objective referent  for the value of the property measured, but not in the sense of having an independent object or measuring instrument.  We can only measure the properties of phenomena as defined above.  This referent in phenomena is a condition for objective knowledge [because it assumes we can all agree on how the apparatus has been combined with the object to produce the phenomenon in the first place?  Again this clearly places responsibility on the scientific community to regulate combinations?].

Thus waves and particles are classical concepts which can be now seen as given meaning only by referring to phenomena, and these will be mutually exclusive for that reason.  We can see both waves and particles in light, 'simultaneously, because mutually exclusive experimental arrangements are required' (121).  All sorts of new implications arise, based on this  'new interpretative framework'.  In particular, measurements must now be seen as a part of theorizing and cannot be split off as some practical activity [leading to a generalization which must have excited progressive teachers -- 'Böhr situates practice within theory' -- which is really colonizing practice by theory, however?].

Descriptive and interpretive processes must be fundamental to this account themselves, and may apply to Barad's account too [another glimpse of infinite regress.  Apparently, there may be a limit since phenomena are considered to be 'real, material'].  Barad justifies her presentation of Böhr in more familiar ways, though: (1) she has spent decades undergoing intensive study of his writings; (2) lots of other writers agree with her, although not always entirely, but she has closely read 'the primary texts'(122)—however, some critics see Böhr as anti realist in several ways, and he never spells out explicitly his ontology, and she knows she is in the minority, but Böhr is an important element of her own agential realism [so he must fit?]; (3) her aim is to present a consistent framework, not to offer comprehensive account of just Böhr.

It is problematic to see Böhr as a positivist.  He has denied an instrumental stance towards the behavior of light, refusing to accept simply the mathematical persuasiveness of some models, and demanding a 'solid conceptual foundation'.  So keen was he that he even wrote a paper with others suggesting that we should abandon the conservation of energy and momentum, and later had to abandon it.  He persisted in arguing that representationalism was flawed, however, and Barad thinks that concepts of complementarity show a commitment to realism.  At the same time, he did not see the atomic world as autonomous and independent.  He did not subscribe to a correspondence theory of truth which itself depends on an initial separation [followed by a correspondence]  between nature and culture, or objects and statements about them.  He even suggested that language could not be seen just as derivative, as a description of reality.  However, he was not fully clear on what he meant by reality.  He disagreed with Heisenberg about the existence of independent objects, and he also rejected classical causality.  He sketched out his ideas about reality in a discussion with Einstein, and in a crucial passage, he defines physical reality to include influences [of observation and measurement] upon apparently closed systems [a bit obscurely put—127].  As we have seen, the key unit of physical reality is the phenomenon.

Thus subjects do not exist separately and independently from each other, complementarity indicates the source of apparent semantic indeterminacy since it is an ontological indeterminacy not an epistemological one.  He never says this quite as explicitly as Barad does: she sees the measurement apparatus itself as 'the condition of possibility for determinate meaning, of the concept and for qualities of the object which are better understood as subsystems, 'determinately  bounded and propertied'[badly in need of the concept of multiplicity here again].  Phenomena are inseparable combinations of objects and apparatus at the ontological level [so where do the subsystems come from?].  Determinate entities emerge from intra- action [of this specific kind], while the term interaction 'relies on the metaphysics of individualism'[meaning specifically here 'the prior existence of separately determinate entities'—so far, no politics. In the social sphere, we have long known about the problems with the metaphysics of individualism of course].  Apparatus includes measuring agents, so Kantian noumena are denied.  All this apparently is 'consistent with recent experimental and theoretical developments in quantum physics'[argument from authority, apparently justified later in chapter seven].

So Böhr is a realist, as his paper arguing with Einstein shows.  Scientific theories describe physical phenomena [physical phenomena now, with no doubt or bracketing].  Correspondence between theories and phenomena is no longer a simple matter, because descriptions and theories are 'materially embodied in apparatuses that produce the phenomena'[especially clear with  gedanken, of course—do apparatuses ever have emergent qualities of their own, an agential element?].  His account is 'proto - performative'(129), as we shall see [scientific practice produces phenomena].  His interest in objectivity means he is not an idealist or a relativist, and nor are phenomena just activities in the mind—they are instead 'real physical entities or beings'[by assertion—his notion of objectivity does not lead only to this conclusion].

Classical causality, as 'strict determinism', has to be rejected, but there is no randomness or disorder.  Causality has to be preserved because it is indispensable to scientific knowledge.  The old dualism between determinism and freedom [straw man or liberal ideology] has to be rejected.  Instead we have to discuss agency in a way that goes beyond human agency, although this is implied rather than stated in Böhr.  More to follow, but for now, dualism has to be rejected [including dualism between active humans and inactive matter, it seems].  The concept of intra-action means human agency is not the only kind [but we have more or less defined intra-action, which has just been asserted, so that it implies this.  We could equally start with nonhuman agency and arrive at intra-action: the two are joined in a circle].

Chapter four

[This is the main chapter joining together some threads from the earlier commentaries.  It is badly in need of an editor!]

It is not just language that we should study, but matter itself [Barad warns us about the many puns on the term 'matter', which seem to allow it a role.  Unfortunately, she uses many such puns herself, as in saying that matter matters and so on]. 

There is a [modernist] view that we have direct access to language and culture and that we see matter as something passive and ahistorical, whose properties only emerge once we use language on it.  At its deepest, there's a belief that 'grammatical categories reflect the underlying structure of the world'(133) [criticized by Deleuze too], and this merges with representationalism and social constructivism.  We need instead of performative understanding of discourse as a form of engagement with the world.  This will contest the domination of language alone.  It should also help us realize that we have  'unexamined habits of mind' that see language and culture as dominant.

The humanist., individualist and representationalist viewpoint grants privilege to the human observer, able to distance themselves from the world.  Böhr contested this view.  Post structuralism also offers critique, but there are still residues, 'anthropocentric remainders' (135).  We need post humanist performativity , focused on 'practices, doings and action'.  Ontology needs to be restored, and the metaphor of reflection replaced with one of diffraction.  This will challenge notions of definite boundaries and absolute exteriority except as a result of enactments and 'constitutive exclusions' for which we should assume accountability.  Some of these ideas are found better developed in feminist theory.

It is not a matter of celebrating the postmodern eclipse of the individual.  Human beings are not just the effects of structures.  Humans are not treated as exceptional.  Culture is not the only source of change.  Nature itself has a sense of agency, so the boundary between nature and culture is something that is seen as 'actively configured and reconfigured'.  'Post humanism doesn't presume the separateness of any - "thing"'(136) [infinite regress].  However, separateness is not just an illusion.  Instead, 'difference cannot be taken for granted; it matters'.  Matter is not fixed but is both 'produced and productive'(137).  'Mattering is differentiating'[sounds very much like Bergson or Deleuze].  These differences can  'enact' a causal structure, and spacetime itself is 'an enactment of differentness, a way of making/marking here and now'.

Representational approaches separate the world into words and things, raising problems about their linkage, including whether signs are already found in objects [ Hjemslev?].  One consequence is that it is impossible to stand outside of language.  Similarly, 'atomistic metaphysics', originating with the Greeks, presuppose the existence of small, inseparable and bounded units.  The liberal version sees the same as occurring to human individuals [but how long have these views been uncontested?  This is a straw man].

Böhr rejected this view in quantum physics and went on to question the distinction between object and human subject as we saw.  However, there is to be no 'despair of nihilism or the dizziness of relativism', since he also believed [sic] in objective knowledge.  His philosophy was based on new empirical findings as much as philosophical reflection, but he did not spell out his insights.  Had he done so, he would've developed 'an agential realist ontology' (139).  This would see a new relationship between material reconfigurings of the world in discourse, and material phenomena themselves, which represent 'differentiating patterns of mattering'. There is a causal relationship between the apparatuses of bodily production and the phenomena produced—'agential intra-action'.  Theoretical concepts are better seen as physical arrangements [well they certainly imply them as an experimental procedures, especially in gedanken], and measurements are properties of phenomena.

Phenomena are not just entanglements of observer and observed, but of different agencies [the agency of matter is just announced].  Intra-action is entailed, and this is 'a profound conceptual shift'.  Such intra actions produce boundaries and properties of certain components of phenomena, and make them meaningful via concepts [happily, it all ends well, in meaning, but that's because concepts are never independent of the practices of observation and measurement, which seems to disqualify most mathematics?].  Intra-actions at the larger level serve to perform 'an agential cut' between subject and object, 'a resolution within the phenomenon of the inherent ontological (and semantic) indeterminacy' (140).  Relations within produce external data of relations, 'relata'.  Agential separability can therefore be assumed.  Agential cuts also 'enact a causal structure among components'[still in terms of the relation between measured objects and measured agencies], a new notion of causality.  [None of the traditional problems of causality are addressed here it seems—maybe they are all operationalized away? Deleuze does better].

Phenomena do not just arise from experimental activity, they simply 'are differential patterns of mattering ("diffraction patterns")'.  Relations among agents are complex and can be multiple.  'These causal intra actions need not involve humans': the boundary between human and nonhuman is also constituted by intra action.  Phenomena are 'constitutive of reality' [not just reality then?], rather than things in themselves, and there are no things behind phenomena [not energy or vitalism?].  The world itself is 'a dynamic process of intra activity and materialization'[but in what sense – Bergson's?  Deleuze's?].  The process means that one part of the world can become intelligible to another part, through the stabilization of things like causal structures and a general 'differential sense of being'.

'The world is an open process of mattering through which mattering itself acquires meaning and form through the realization of different agential possibilities' (141).  Time, space, and all the familiar relations then appear.  The dynamics is provided by 'the changing topologies of the world'[very much like Deleuze then—will there be any detail about these topologies?].  Overall, phenomena are 'dynamic topological reconfigurings/entanglements/relationalities/(re)articulations of the world'.  Words are not the primary semantic units: what is primary is 'material - discursive practices through which (ontic and semantic) boundaries are constituted'.  The world's dynamism is agency.  'The universe is agential intra- activity in its becoming'[more flirting with Deleuze?].  We can get to this through modifying Böhr, seeing linguistic representations as discursive practices, and seeing apparatuses as the result of a material discursive practice which also distinguishes social and scientific, nature and culture.

The apparatus is not just a set of instruments, and many usages of the term have been identified [including Althusser!].  There might also be seen as the dispositif in Foucault, or the performative in Butler [and lots of other ways—Deleuze on the virtual machine haunts the discussion too].  We can use all of these approaches seeing them as producing 'patterns of resonance and dissonance' (142).  They are not just assemblages, but are 'specific material reconfigurings of the world', that can themselves reconfigure spacetimematter [sic] 'as part of the ongoing dynamism of becoming'.  Böhr began the discussion, focusing on the relation between the object and the agencies of observation, although he needed to consider 'where the apparatus "ends"', instead of assuming it was obvious – for example is the person 'who reads the marks on the paper' part of the apparatus?  [They must be surely, but this would lead to infinite regress, via a deeper consideration of how our consciousness works—perception and the like, which she discusses a bit herself].  Böhr's answer follows from his concern for the possibility of objectivity, especially after acknowledging 'the fact that science works'(143) [which is where critique stops for Böhr and Barad?]

[There is a refinement on the earlier statement]—'only concepts defined by their specific embodiment as part of the material arrangement...  Are meaningful'.  Only then can we derive objective knowledge [via communal agreement on basic statements].  This assumes the knowing human, however, 'at the centre of all that is'.  Experimental practice is also far more complex [than gedanken]: his apparatuses are 'ideal' versions, sealed off from any outside influence [simplified magic for Adorno].  This ignores all the times that the experiment does not work, and the huge amount of adjustment and tinkering that is required to make them work. Böhr has therefore reduced subjective elements [she says he 'reifies' them, 145] to observation, and has imposed an external boundary around laboratories practice.  We need posthumanist understanding instead.

Other analysts have shown how sophisticated scientific practices actually are [like Latour or Woolgar].  We can even take Butler on performance here, although she is interested only in the production of human bodies, and draws a lot on Foucault.  Work on technoscientific practices and their 'profoundly productive effects', including on human bodies, need to be studied too.  Post humanist performativity will bring the two traditions together, via diffractive reading. Böhr will have to be revised too--the apparatus is not just the laboratory setup but a specific  'material - discursive' practice (146); they produce significant differences in the form of boundaries that 'are formative of matter and meaning'; they are material configurations or reconfigurations of the world; they are themselves phenomena; they are 'open-ended' rather than bounded; they are not just located in the world but are best seen as 'material configurations or reconfigurings' that produce space and time within which traditional dynamics takes place—they are not static structures and they do not just develop in space and over time.  [My question is whether there are any apparatuses that produce specific apparatuses, and again I thought of the difference between actual and virtual machines in Deleuze. Barad seems to be invoking some difference between the virtual and the actual but she is not spelling it out -- and rejects it when discussing possibility -- see below].

Discourse is meant in the Foucault sense as something that 'constraints and enables what can be said', what counts as a meaningful statement in 'a field of possibilities'.  This field of possibilities is 'a dynamic and contingent multiplicity' (147) [just what Deleuze says about Foucault].  They enable disciplinary knowledge practices.  They produce subjects and objects of these practices.  They develop from 'immanent and historical conditions'.  Connecting this with Böhr on the apparatus produces 'provocative resonances (and some fruitful dissonances)'. Böhr clearly sees concepts as connected to physical arrangements and practices, but he has a 'a much more intimate relationship between concepts and materiality' [in what sense?  Only because he has operationally squashed concepts down to what can be embodied in physical apparatus?].  However, using the term discursive practices can help us move away from human concepts and a static notion of apparatus.

We can extend the notion of discursive practices as well to acknowledge their 'intrinsically material nature'(148), and Böhr is useful here [can't see why].  We can use agential realism to demonstrate.  For Böhr, apparatuses actually enact what matters, show us the 'material conditions of possibility and impossibility of mattering' .  The apparatus is used to produce both ontic and semantic clarity and determinateness.  The boundaries they produce resolve these indeterminate possibilities [but only within the practice of science—scientists just get on with what the apparatus tells them?].

The meaning of something does not arise from grouping words together, nor from acquiring external references alone, but through material practices [compare with Deleuze in Logic of Sense, on uniting two series].  Discursive practices and meanings are not confined to humans though [as in Hjemslev?].  We need to look at how human discursive practices are constituted, and this will involve us in posthumanist analysis.  For agential realism, discursive practices reconfigure the world and enact boundaries, properties and meanings.  We must see these as involving intra-action with the nonhuman.  These enact causal structures, separating effects and causes [crucial to meaning in science of course, but controversial in social science].  Meaning is therefore a matter of performance 'of the world', leading to both intelligibility and unintelligibility, including impossibilities.  Human discourse arises from the boundary making practices.  Note that intelligibility is 'an ontological performance of the world in its ongoing articulation' (149), not something exclusively human, not even requiring intellect in the humanist sense.  What humans do is to respond differently to what already matters, and this is what makes agential realism 'go beyond' [transcend?] both humanist and anti humanist accounts [remembering that structuralism is anti humanism here].  Knowing does not depend on human perception, and even if aided by machines.  It involves specific practices to both articulate and account for the world, and nonhuman agents can partake in the engagement of the world in these practices [expression again?  Agency in the human sense?].  Knowledge is 'an ongoing performance of the world'[so infinite regress or arbitrary constraints?]. Discursive practices do not just refer just to speech and language.  We need 'a genealogical analysis' (150) of the emergence of humans and their speech, not as cause or just effect but as parts of the world, 'open-ended becoming'.  There are no simple words or things with definite boundaries.  Both are 'agentially enacted' [and then reified -- but by what?]

Butler critiques social constructivist accounts of the female body and urges a more material account, but sexual difference is not just prediscursive.  We cannot disentangle matter from discourses that already suggest uses.  Matter has to be materialized first, and Butler draws on Foucault and the notion of regulation.  However, there is still a tendency to see matter as produced by discursive practices 'rather than as an active agent participating in the very process of materialization' (151) [but as a full agent, no different from human agents?].  Butler is still anthropocentric.  Instead, we should see matter as 'substance in its intra active becoming—not a thing but a doing, a congealing of agency'[so agency is now some force prior to matter?  Compare with Bergson or Deleuze].  It is both stabilizing and destabilizing.  Phenomena are the smallest material units  [lots of repetitive assertion].  Matter emerges from material discourses, involving configuration of the world, the determination of boundaries and properties and so on, intra activity.  Matter must be 'an active "agent" in its ongoing materialization'[note the weaselly quote marks], 'implicated and enfolded in its iterative becoming'[so we have folding now, and it is going to play an important role, but it is not explained.  Is there some allusion to Leibniz or to Deleuze? It seems to be exhausted by iteration below].  In this way, materiality itself is discursive, inseparable from its apparatus of production, and we already know that discursive is material [so the two are reconciled, or 'mutually implicated in the dynamics of intra activity' (152).  The material dimensions of discourse are shown in the material aspects of regulatory practices in Foucault [but these are of course discourses that get implemented in political action].  So 'matter comes to matter' [irritating deliberate ambiguity].  Analyses that stress one side or the other are going to be flawed. Agential realism helps us take full account of material factors, but not in an empiricist way which assumes transparency or immediate givenness [well, sense data, or a psychology, according to Deleuze on Hume], and accepting that phenomena are the objective referents.

The full physicality of the body is important.  The humanness of the human body depends on one of these boundary distinctions, the result of intra activity.  These distinctions are prior to any subsequent effects produced by discourses or regulatory practices.  Such activity is 'always open to contestation' once it replaces the idea of strict determinism.  [I wonder where she stands on debates about the full materiality of the body, where electronic activity in the brain is responsible for everything human?].

Böhr accepts conventional boundaries and views of knowledge, and this helps him define objectivity as something intersubjective.  She acknowledges that this helps him manage 'the threat of infinite regress' (154).  He does not accept a rigid boundary between observer and observed, however and sees that as a matter of the practice embedded in apparatus.  It is still difficult to say whether we should see subjects as parts of observation, or as 'an outside observer that chooses the apparatus'.  Böhr resolves this by referring to specific combinations of human beings and instruments [the example is a blind person and a stick], where the instrument is part of the subject in one case, and an object in the other.  He does not pursue the matter into phenomenology.  Barad prefers to discuss the issues in terms of 'different material configurations of ontological bodies and boundaries'(155).

We know from physics that solids are not as they appear to our senses.  Their fixed boundaries are just a matter of habitual 'specific bodily performance'.  Boundaries have been challenged by many thinkers since, including 'cyborg theorists'.  [Examples from the optics of perception show that boundaries are conventional, 'that seeing is an achievement that results from specific bodily engagements with the world'(156). But what implications follow for observing marks etc as objective?].  We also know examples from the use of prosthetics by disabled people, where prosthetics change the idea of the body and its boundaries, and can become part of the self.  It is not just a matter of subjective experience, however: this tends to prioritize the notion of the body in able bodied people, as something normal.  We can examine prosthetics instead as showing 'the entangled nature of phenomena and the importance of the agential cut'(158), and the way in which the apparently able body is normalized.  Disabled people have more accurate perceptions.  This prevents them from being seen as fully other, and even valorises their experience [she goes on to argue that able bodied is a derivative category, and that able and disabled bodies are 'integrally entangled']. [More spectacular examples on pages 158 F, arising from meeting Stephen Hawking and realizing that his body included his prosthetics].  Haraway has long argued that it is a mistake to see bodies as ending at the skin, and goes on to see the gendered or racialized bodies as the result of practices that ascribe properties [a kind of conceptual prosthetic]. 

We can then extend the argument and say that all bodily boundaries are ontological and reveal stances towards reality, we need to look at how they are constituted as part of the world.  We can use the term entanglement—'I don't mean just any old kind of connection' (180) [we seem to have just either causes or entanglements] .  Agential realism is pursued, together with its ethical implications.  We begin back with Böhr and his limited notion of a boundary around the apparatus, and the difficulties with deciding what counts as a relevant feature of the experiment.  Infinite regress threatens in that an apparatus can become something observed by another larger apparatus in a larger phenomenon, and this would reduce the functions and characteristics of the first apparatus.  There are no intrinsic boundaries.  [Everything is connected to everything else?].  This point was subsequently investigated in a physics experiment [great example, 161f, where two scientists were trying to identify the tracks of subatomic particles on a recording plate, and found that they could do this only if one of them were present—the Stern-Gerlach experiment.  It turned out that the cheap cigar being smoked by one of them emitted enough sulfurous gases to make visible a beam of silver atoms being used to assess the position of electrons.  Other appalling difficulties with the practice of setting up the experiment also emerged.  Funding was crucial, as was the support of other scientists including Einstein.  The crucial role of the cheap cigar also implies matters of 'class, nationalism [one went on to support the Third Reich] , gender', all of which must become relevant parts of the apparatus].  We normally settle the boundary by preconceptions of what is obvious.  The experimenters were also able to rescue their views from apparently negative results [via ad hoc hypotheses], and the results were used as evidence for an alternative scientific project.

We can see the apparatuses as condensations or nodal points [black boxes] of all sorts of other factors.  We would be wrong to prioritize say gender or class, however.  It does show the difficulties of closing the system and excluding social values in particular [endless deferment of the political will result?] .  It shows that the world does not separate social and scientific realms: both are 'ongoing, open-ended, entangled material practices' (168).  We can only pick the relevant ones if they  particularly matter [!  And Barad thinks that gender does in this case].  The humans involved themselves have been co-constituted [by the cigar or the silver beam?].

Conventional physics has no place for the human, and there is still distaste for the role of human interventions including apparatus.  Poststructuralists see  the human subject as constituted by social practices, including relations of power.  Both are still anthropocentric—for example, Böhr's observer is a human subject, and there is a focus on the production of human bodies in Foucault.  Neither sees a role for the nonhuman in constituting the human.  Apparatuses are not just social technologies, but their role in natural science is unexamined, and vice versa for science studies.  Agential realism does not assume these divisions and can thus precede with 'a genealogical accounting of the material discursive practices' (169) which produce these divisions.

Apparatuses [in the most general sense now] are specific material configurations and reconfigurings which materialize bodies, 'practices of mattering' producing intelligibility.  Sometimes these apparatuses produce causal intra-actions as 'sedimented' or 'enfolded' forms of material becoming.  They articulate matter differently.  They reconfigure the whole field of possibilities and impossibilities [only apparatuses do this?  Or maybe the whole process of actualization is to be included in the term apparatus?  There are clear dangers of circularity here in defining apparatuses in terms of their supposedly independent properties].  As a results, apparatuses are best seen as 'open-ended practices'(170) [and then a dubious implication—'Matter's dynamism is inexhaustible, exuberant and prolific'.  The claim is that apparatuses are capable of prolific configurations, and that they are material, so matter itself is prolific—all of matter?  The flexibility of apparatuses comes from their matter? The whole argument is really one of showing what terms entail, and looping back from this section to later ones to prop bits up].

Matter is generative, bringing new things and to the world but also 'bringing forth new worlds, of engaging in an ongoing reconfiguring of the world'[these two are elided].  Bodies intra-act with their environments [human bodies do, so all bodies must?], and both dynamically reconfigure the world.  But at the same time, apparatuses are phenomena [that is they already have human components?].  They themselves are constitutive through practices, as we see when scientists have to get the instruments to work [only human agency here].  There are always possibilities of intra action with other apparatuses [is this the same kind of action?], and the resulting enfoldings can produce different materializations, say in subsequent iterations, with altered boundaries.

Some interactions may be causal and may not involve humans at all [DeLanda has some great examples of carbon molecules interacting with others].  We have to understand that for posthumanism, human subjects might be less involved in production than it is assumed.  They do not exist 'prior to their involvement in naturalcultural [sic] practices'(171), nor do they arise solely from discourse.  They are neither outside observers of apparatuses, nor independent actors upon apparatuses.  Humans play a role as part of larger material configurations.  Phenomena do not depend solely on human will or intentionality.  An apparatus is not just what is produced for a specific human project, and they are not limited by our choice of tools.  Specific intra-actions are important, not just assemblages [but Deleuzian assemblages do have affects].  Human bodies do not have fixed boundaries and properties outside of intra activity.  However humans do have responsibility for the outcomes of practices [why isn't this responsibility also produced by intra activity?].  We are not just 'pawns in the game of life' (172).  Humans are not the only agents, but they do have a role [for ethics? How come?].

Does this exclude objectivity as in science?  We need to understand objectivity differently.  In the debate with Einstein and others, Einstein wanted to reject entanglement and preserve spatial separability as a condition for objectivity [the ontological separation of the real from the observer].  For Böhr, apparently instant communication showed that both systems were part of the same phenomenon, and objectivity does not depend on separability, but depends on the 'unambiguous communication of the results of reproducible experiments'(174).  The apparatus produces permanent marks and therefore resolves indeterminacy etc, but this still depends on human beings.  Einstein can be developed to consider not just human, but 'agential separability'(175).  This separability is itself 'agentially enacted' within the phenomenon, however [infinite regress].  Apparently this breaks with metaphysics, at least with the metaphysics of individualism.  The agent cuts the phenomenon and separates the agents [!] As well as producing 'a local causal structure', all within the phenomenon itself.  We can change the apparatus and this will change the agential cut and open new possibilities and new phenomena [so 1 cut takes place within the phenomenon, but another will produce a new phenomenon—the ambiguities of 'lines of flight'!].  In this way, the apparatus provides the possibility of objective description [removing humans and giving the responsibility to the apparatus].

The notion of causality is changed from the conventional one.  It is no longer a matter of relations between isolated objects, since causal relations emerge only with specific material apparatuses which cuts so as to produce cause and effect.  However, the apparatus can also separate agencies of observation from the object [if we assume that the object causes observation, as she does].  Measurement assumes that the marks on the apparatus are the effects of the object itself, a 'causal intra action'(176), but we might prefer [sic] to see this more in terms of one parts of the universe making itself intelligible to another part.  We need to apply this to arguments that suggest that culture is an external force acting on nature, or maybe even producing of the natural, or vice versa. 

We need to separate these agents, and think of relations in terms of 'a dynamic and ever changing topology' (177) which will generate 'exteriority within phenomena'[a note on page 436 uses the term manifold and says that there are different forms of connectivity between points in a manifold].  Neither material nor discursive factors are to be seen as prior or part of a hierarchy.  We did to think instead of 'an ongoing topological dynamics of enfolding'[as in pinching and kneading].  This arises from  'matter's dynamism'.  It is folding and refolding that produces apparent separability within the same phenomenon.

Matter has an 'agentive role', which widens the notion of agency.  We can also abandon traditional notions of causality and the old issue of determinism vs. free will.  Intra-action always involves exclusions and thus possibilities.  Possibilities are produced by reconfigurings, but not everything is possible: there's constraint too.  However, overall, the 'vitality' of intra action can never be constrained, and 'the future is radically open at every turn'(178), inherently.  Agency is no longer just something humanist, more a feature of structures.  Performance as in Butler is no longer confined to the human.  It is not a matter of humanizing the nonhuman, but thinking about iterative reconfigurations of human, nonhuman and other forms [including cyborgs].

Agency is intra action, enactment, not something that belongs to a specific body.  It is not an attribute but a doing, a matter of 'iterative changes to particular practices' (178) [not one-directional as in duration?].  We need to remember it is not just a matter of gaining new knowledge but of 'the differential mattering of the world'.  Objectivity means 'being accountable'[ambiguity here too, implying ethically accountable] apparently it seems that 'we [sic] are responsible for the cuts that  we help enact', even though we do not choose these cuts: that is 'because we are an agential part of the material becoming of the universe'[a special part there nonetheless, one that does ethics].  It's is 'the larger material arrangement' that does the cutting, but we participate [so jail the guards but not the governor?].  In particular, we must not respond to others as something radically outside ourselves, it is the cuts that we help to enact that produce self and other: these are not enacted from the outside and nor are they once and for all.  [It seems to me that human agency is back in with a vengeance].

If we are interested in change, we need to study the dynamics of the system, the possibilities for change and the courses that might effect change.  Agential realism understands that the very notions of causality and agency have to be reworked [compared to conventional science—the clockwork universe of straw men].  'Intra actions are non arbitrary, non deterministic causal enactments' which fold matter as part of materialization.  It is not contained by space and measured by conventional time, since [conventional] time and space are also produced in the process, together with other boundaries [because of an interest in work says Bergson].  Exclusions are inherent.  Indeterminacy is never resolved finally.  Change is not just a mutation of what was or what might be, but 'the iterative differentiatings of spacetimemattering [sic]'.  (179).

To elaborate, time is not a matter of spaced moments, not just a relative matter, but a product of intra activity.  Materiality is never a simple product of practices but itself a factor in materialization [which is what iterative means for her?]: Specific material configurations make a difference to subsequent patterns, and thus 'matter is enfolded into itself'(180) [so iteration is what explains enfolding?].  This comes to matter [silly word play again].  We can see matter as segmented 'historiality'[a note explains that this is a term used by Derrida originally, and it implies that 'time as an operator, not a parameter'.  It can include recurrence as part of the differentiating of systems.  It is like the difference between iteration and repetition.  Moments are differentiated by more than just a 'a spatially extended duration' {not Bergson's notion which implies precisely that something is happening between moments} of duration because something happens in between moments.  There is also an application in thermodynamics where time is considered as an operator rather than just a number (438)].  Becoming involves not just an unfolding in time, but 'the inexhaustible dynamism of the enfolding of mattering'[Bergson was there first].  Time has a history which is not composed of evenly spaced moments.  Properties can come to matter in a more dynamic notion of time [compare Deleuze on intensive time, as when Albertine joined the group in Proust 'late' rather than at a particular time].

Nor is space a set of preexisting points prior to matter.  Intra actions enact boundaries including those between interior and exterior [just like Bergson again, but for him, space is a construction of work-oriented intelligence enabling manipulations of matter].  These are not abstract dimensions, but material configurations.  Space, time and matter are found in a manifold not a [Euclidian] geometrical structure, and they are folded together.  Changes to this manifold need not be continuous or follow a particular trajectory—'there are no trajectories' (181) [another unwarranted generalization like the one about endless possibilities].  The sedimentation apparent in time [tree rings are her example] also reflect differentials in mattering.  However, the past is not finished for ever, and nor is the future predictable as an extension of the present.  Both are 'enfolded participants in matter's iterative becoming'.  Nor is change continuous, and quantum theory has done much to introduce the notion of discontinuity which has disrupted conventional understandings [she realizes that not all discontinuities are disruptive in the form of a rhetorical question as usual: 'what is a discontinuous discontinuity?' (182)].  Some discontinuity 'queers [more deliberate ambiguity --philosophizing through word play] our presumptions of continuity'[that is, cannot be explained by an  additional correcting continuity].  Quantum leaps are indeterminate in a deeper sense, and we cannot know where and when they occur.  If we include discontinuity like this, we see that becoming itself is open-ended, that nature 'teeters on the cusp of stability and instability'.  [So a quantum leap is a definite line of flight from a multiplicity?].  Agency must therefore be extended to a much larger space of possibilities, although not everything is possible [a note takes on Deleuze here and says he trivializes the relationship between the real and the possible by seeing it as a matter of the relation between the virtual and the actual—and anyway he uses the terms differently so his 'critique is irrelevant'(437)].  Intra actions determine what is possible.  In addition [!], ethics are also a part of the world, the need to be responsible.  This is because 'each moment is alive with different possibilities for the world's becoming'[paranoia!].

The issue of the matter of the world has affected a number of scholars in different fields.  There is a drive to reclaim it, perhaps in the form of the body, against the self sufficiency of culture or mind.  We need to consider matter to identify the limits and constraints of discourse knowledge.  It is not just a matter of recognizing finitude.  Agential realism sees materiality is an active factor in materialization.  It is not culture alone that offers the potential for change.  The barrier between humans and non humans should not be incorporated, since that would limit 'the fullness of...historiality'(183), especially in feminism.  Performativity should be extended beyond discourse to the material aspects of practices, and the becoming of substance, which is 'a congealing of agency'(183-4) [classic Bergson]. Intra activity is what constitutes the material and the discursive and it can be iterative itself, for example in changing apparatuses of bodily production [feminist undertones again?].  Objectivity and agency must also include responsibility and accountability, deciding what matters and what must be excluded.

There is no external observation all point to observe nature, but there is agential separability, arising from the generation of exteriority within phenomena.  This means we're still part of the world and cannot develop a detached epistemology.  Feminists have to be careful here, because they do not wish to see the human as somehow are contained in nature or nature as providing some sort of essentialism.  The configuration of apparatus is is not arbitrary, nor determined by power structures.  Nor are they entirely under the control of human intentions, but materially configure the world themselves.  Humans have a part in this 'world - body space in its dynamic structuration' (185) [yet another term].  Knowing should be seen as a part of the world of becoming intelligible to another part, so knowing and being are implicated and we gain knowledge from being part of the world [rather like Bergson or Hegel here?].  Epistemology is not separate from ontology and we need 'onto-epistem-olgy'[another horrible compound word—if we make compound words, somehow we dissolve the differences between the components], 'knowing in being'.  While we are here let us add ethics—'ethico-onto-' etc], because knowing being and ethics are intertwined as new possibilities appear: 'the becoming of the world is a deeply ethical matter'[but only for us?  Unless human beings are somehow the spokesmen for the universe?].

Chapter five

Foucault's approach to the human body as showing the reception and subsequent transmission of force can be applied to machines, the piezoelectric crystal and the ultrasound scanner that it made possible.  The crystal expands or contracts according to the strengths and polarity of an electric signal applied to it.  It can be seen as the instrument of an observing apparatus, and it is also coupled to a number of discourses, including some about gender.

Butler discusses the material nature of the human body through a notion of performance, and this helps her to reinstall the importance of gender rather than sex in feminist theory.  She discusses the materialization of bodies, but only through culture and discourse, which produce significant material outcomes.  There are material dimensions in their own right though.  But that does provide a discussion of some of the discursive dimensions, however, including the issue of what is excluded.  Unfortunately, independent aspects of matter are excluded as well.

She talks about 'the medical interpellation of an infant at birth' (193), the emergence of a gendered human once ultrasound scans have been performed.  She should've investigated the development of ultrasound technology more rigorously.  It appeared in a specific context, including a set of power relations favoring medical personnel: as a result, many then began to hold pregnant women liable for the fate of the fetus, to blame them if they had an unsuitable lifestyle.  In this way, the machine maps 'geopolitical, economic and historical factors' as well as bodies (194) [hardly new, surely?].  Being able to identify the sex of the fetus also enables some people to precede to abort female infants.  The machine has had a definite effect [same as all medical technology?], and this needs to be examined as well.

Back to Böhr, 194 F.  The challenge to representationalism, the role of apparatus as an example of 'the interdependence of material and conceptual constraints and exclusions', the new view of causality and objectivity.  The challenge to the notion of continuous variables [Bergson is better].  The way the concepts are apparatus-dependent.  The role of quantum wholeness or inseparability in phenomena.  Cuts introduced by the apparatus—subject and object, complementary properties.  The importance of reproducing phenomena, and objectivity [more less direct repetition of the phrases here, 197], the role of permanent marks can be seen as an interest in bodies, the phenomena as the objective referent.  Intra action is defined here as 'the mutual constitution of objects and agencies of observation within phenomena'[so very specific definition limited to Böhr]: 'in particular, the different agencies ("distinct entities") remain entangled'[a note says that non humans may be involved, and that a phenomenon is not meant in the phenomenological sense 'but as particular material entanglements'(441)—so no phenomenological bracketing, but a simple assertion, made in order to preserve the cognitive superiority of science?].  Here, he also values 'the feeling of volition and the demand for causality [as] equally indispensable elements in the relation between subject and object'(198) [but does not investigate volition?].  This helps explain the wave/particle problem [and here she is back  supporting Böhr on objectivity, not modified Einstein as in the chapter above].

Foucault on observation as a disciplinary mechanism agrees with Böhr that observing instruments have an effect [we have always known this in social science, even though positivists try to forget it].  We can return to Böhr and the problem of where the apparatus ends [and here, 'the community of scientists' finally appears as having a role].  Bodies [material effects] play a role in the development of unambiguous communication, and this validates Böhr's recognition of the complexity of scientific practices.  Any analysis of apparatus should acknowledge this complexity [large parts of it will still be uninvestigated?].

Back to Foucault and the conditions for intelligibility producing apparatuses.  We can combine this with Böhr diffractively to extend both.  Foucault talks of various apparatuses of observation and discipline, as in the panopticon which changes the role of power to a more internalized form.  Power and knowledge are linked.  However, the nature of these links is not fully investigated, especially if we see materiality as dynamic and agential.  Modern technology in particular 'provides for much more intimate, pervasive, and profound reconfigurings of bodies, power, knowledge and their linkage' (200) than Foucault's bio power.  Haraway agrees on the much more extensive development of technology in '"technobiopower"'(201). Foucault should've seen that apparatuses, objects and subjects are already combined in phenomena.

Ultrasound technology provides a contemporary example.  The crystal itself makes and remakes boundaries, including those between living and  nonliving, nature and culture.  If we discuss it we can see the 'interface (intra-face)'between Foucault and Böhr.  Ultrasonic waves were first used in sonar, and then in medicine, especially obstetrics.  Producing the images is not simple, however, and misdiagnosis is common by non specialists.  The crystal transducer plays a key role as both source and receiver of ultrasound waves which are converted from and to electric signals.  Again there are complicating variables like the nature and thickness of the sample or how the element is actually mounted.

We can see how Böhr would fit this example, since observation and body are connected in the phenomenon through their intra action [at a pinch—it might be a matter of different components of the body appearing with different observational practices, but the components are not linked as a paradox or as a contradiction]  The fetus is not the objective referent, although there are both 'political and scientific reasons'(203) for claiming it is.  The crystal [I am tired of getting my voice recognition to spell  piezoelectric] apparatus itself has emerged from particular practices.  There is intra action with other apparatuses [example?  There are certainly connections with other uses as in sonar].  We should be accountable for the effects of our practices.  The apparatus is best understood itself as 'a material - discursive' phenomenon [so this neatly uses a definition to confirm what was argued before.  It is not at all clear how ultrasound specifically shows this, except in the general sense that everything is].

The transducer intra acts with lots of other practices [a long list, including social and organizational as wall as medical—infinite regress beckons again, 204].  We can include Foucault's apparatus is here as well.  At the same time, using ultrasound involves different local practices: Böhr suggests that these are more integrally related than Foucault might suggest, but we can use F on discourse to extend B's limited notion of linguistic concepts.  However, F focuses on the materialization of human bodies and takes nonhuman ones for granted, rather than examining how the boundaries are drawn.

Discussions of what is real must be undertaken, even though it risks the relevance.  We can still see it as political and ethical, if we take account of exclusions and boundaries.  B is not really explicit about his ontology, although we can suggest that it must refer to phenomena rather than things.  There is no being prior to signification, and both are related in agential realism.  For her, phenomena show 'an ontological inseparability of intra acting agencies'(206) [wasn't she arguing that they are separable and must be for objectivity?].  Phenomena show a [diffractive] pattern of 'matterings' independently of laboratory practices.  Apparatuses draw boundaries and offer material reconfigurations, and are themselves phenomena [we use these phenomena to analyze phenomena—infinite regress again].  There is an enfolding and reworking in these configurations.

This reveals that reality is not a fixed essence but an 'ongoing dynamic of intra activity'(206).  Human practices are not the only ones that matter, but they do intervene in the world.  They also configure and reconfigure, so 'they/we too are phenomena'.  We have no position outside the world.  Things like apparatuses that we construct are therefore neither arbitrary nor determined, and this extends to all our practices and concepts—'human practices are agentive participants in the world's intra active becoming' (207).  This means that 'we are responsible not only for the knowledge that we seek but, in part, for what exists'[a massive extension of human agency after all].

Thus discursive practices should be seen as 'intra- activity as part of nature'[the term intra activity just ducks the issue of what the relationship actually is with nature].  Realism depends on accurate descriptions of the reality of which we are a part.  Some of our practices are better than others in producing phenomena.  They must always take account of material constraints if they are to be empirically adequate.  Techno scientific practice can be understood as performance, producing materialization as well as human properties. 

We can use this to extend Butler [rambling structure!] to include science studies in feminism.  This might help us see 'how even the very atoms that make up the biological body come to matter'(208) [including the ones in the brain presumably].  There are 'mutually informative insights'to be pursued via agential realism [which is summarized on 208—there is an agential reality, no inherently vital properties of subjects or objects, practices constitute both, materialization proceeds from intra activity].  Butler talks about the social materialization of the body, but a fuller account might also help us escape from 'the workings of social norms' (209).  We can start to see how the boundaries between human and nonhuman, social and natural of drawing, how bodies of all kinds are produced by practices, how 'matter is substance in its intra active becoming—not a thing, but a doing, a congealing of agency' (210).

The power inherent in practices affects 'the [human?] enactment of the natural' as well.  We can understand regulatory practices as 'causal intra actions' [a significant shift permitting this link with science], at least as far as their material or physical components.  Bodies are intra actively produced and have physical presence [and only then are they subject to causal forces?  She repeats that her notion of cause is non determinist—so it can mean anything?].  So materialization  is a process common to all bodies.  It is not just that language and culture 'instantiate' physical elements like gesture or sound, because some of these are not 'efficacious'(211), showing no causal determinism [weak].

Butler [!] Suggest that different source of materiality correspond to different discursive practices—biological, hormonal, physiological and so on.  Barad thinks that all of these are entangled in practice, intra acting [what, somehow on their own?].  This shows there are no mysteries to the linkage between discursive practices and the material affects [since both are reduced to the other?]: there's a causal link between them, but one which preserves intra action.  We weaken materiality as a force if we reduce it to discourse, and omit material constraints and exclusions and the material dimensions of power.  Phenomena incorporate both.  This also helps us go beyond naive accounts of matter as just something beyond our control, as natural.  Nature and discourse are 'intra-twined'(212).

Going back to ultrasound [!], We can see that its specific context means it has a particular relationship with techno scientific political and other discourses.  It would not be suitable as 'an idealized surveillance technology' because it is not just a physical instrument with multiple uses [presumably because it requires specific medical practices to make it work?].  However, it has led to an increased focus on the fetus, sometimes to the extent of reducing the subjectivity of the pregnant woman.  These 'good' and 'bad' effects are inseparable [inevitable rather than the result of power in appropriation?].

[A final attempt to tidy up causality and agency] Foucault has a theory of power that is not strictly deterministic, partly because the objects of it can resist.  Nor is it just prohibitive.  Butler adds when bodies are materialized they do show the effects of power, but it is not just a discourse which is causing these effects.  Effects are constituted and formed instead.  Power has to be constantly reasserted or reiterated in a 'citational chain' (214).  A possibility of agency is apparent in the gap between bodies and norms.  There are also sometimes contradictory or ambivalent discursive demands.

Böhr also argues that there is no strict determinism nor unconstrained freedom, no simple chain between cause and effect: both emerge through intra actions.  In experiments, effects measure only some features of the objects, which might be said to cause them, but because there are always exclusions, there can be no strict determinism and there must be 'the condition of an open future'.  This means that agency in agential realism does not just depend on contradictory norms, but is itself an enactment, not belonging to either subjects or objects.  It becomes 'a matter of making iterative changes to particular practices through the dynamics of intra activity (including enfoldings and other topological reconfigurings)'[but who or what makes these iterative changes?  At least with Böhr there was an experimenter].  Agency also seems to imply the accountability for making boundaries and exclusions [so if we blame ourselves for something, we must be acting as an agent?]. There can be nonhuman forms of agency even though this 'may seem a bit queer'[ambiguity adds political significance again].  If agency involves enactment, it can cover nonhuman forms [if they also enact—and other words if they are agents!].  We can certainly see the world resisting experiments 'in a sense'(215).

Casper's critique of ANT says they accept nonhuman agency as a matter of principle but not as a matter of ontology, but this attribution is actually the result of a particular political practice.  We see this again with obstetrics and the way in which humanity is attributed to fetuses: again there are consequences in reducing the agency of the mother.  Casper eventually says that she simply 'wants'(215) nonhumans and animals to have agency, as a result of her own politics and deciding who she's accountable to [which includes her cats apparently].  Barad has some doubts with the example of fetal agency which can have good consequences, say in countries where girl babies are routinely aborted—another example of the political issues.

We might need to think more clearly about the object, in this case the fetus.  Medical practice and the law attributes subjectivity to it.  Scientists also sometimes feel they have an obligation to act as '"authorised ventriloquist for the object world"'[citing Haraway, 216].  The accountability of these practices and laws also need to be considered as part of the context that is wider than Casper acknowledges.  These practices have already constituted subjectivity, not just the agency of the medical scientists.  It is the attribution of subjectivity that is crucial.

Agential realism would see the fetus as a phenomenon, produced by intra action and including the apparatuses which have constituted it—the pregnant woman and her biology, her surroundings 'and much more' (217) [an infinite number of more things].  It is the material practices involved that have produced the cuts and distinctions within the phenomenon, not individual choice 'in the liberal humanist sense' [that is before sociology].  It is a specific practice that sees the fetus as self contained, and this is historically and culturally specific, with connections to the expansion of reproductive technologies.  'Environmental racism' has been denied, since these practices are mostly about white women: their bodies are already more than just maternal environments.

So both agents and apparatuses are found in phenomena as a result of specific intra actions.  Human ness is 'emergent and ever changing'(218).  Agency as a matter of liberal choice can be rejected [straw man again].  In this case [!] fetal resistance to medical technology, fetal enactments are not a sign of fetal subjectivity, since as a phenomenon it includes of the maternal body [going with legal definitions in this case] with which it intra acts.  We should hold to account not the mother but the whole construction of fetal subjectivity arising from various practices which can have differential effects on pregnant women.  Hear the factors include 'global neocolonialism, including the uneven distribution of wealth and poverty; and many other factors'. 

We can use this analysis for many political purposes including 'subversion, resistance, opposition, and revolution'.  Agential intra actions will both foster and limit possible changes since 'not all possibilities are open at each moment'.  We may have to distribute agency over nonhuman forms, and iteratively reconstitute humanness through a 'ongoing agential enactments'.  We must realize that we are not the only active beings, although we cannot deflect 'responsibility on to other entities'(219) [why should humans be uniquely responsible?].  Acts of subversion for example can involve 'subversive resignifications' to disrupt material configurations [new nationalism votes Brexit?].  We can change the economic conditions [!].  We should always be aware of material and discursive constraints, however.  Reproductive technology, for example might be used subversively in 'gynogenesis' which creates an embryo from two females: to critics who want to see this as unnatural, a certain E Sourbut says so is test-tube conception.  We can see the the relation between the genetic material, 'gene imprinting', as nonhuman agency [requiring human interventions still at this stage, though].  The form of this nonhuman agency might have additional potentials, unlocked by appropriate 'material discursive apparatuses'  and their intra actions. These acts are subversive and show 'the instability of hegemonic [sic—used for the first time] apparatuses' and may be met with 'hegemonic' attempts to contain contradictions and restabilized, so we should continually remind ourselves of accountability and responsibility.

Ultrasound is becoming  'enfolded' into new practices, as Computer Technology also develops: it is leading to three dimensional imaging, enhancing the already powerful status of the visual, and promising considerable 'epistemic earnings' as it extends to the whole body.  The images are lifelike enough to make it seem as if they are the object itself.  It works by storing planes which the computer then integrates, and this can include a solid looking surface to the body, making it more intelligible.  It has already become involved in abortion debates.  It has a general biological and surgical application.  We no need to change our understandings of bodies to include the relation between surface and volume, at the moment a significant boundary.  It also offers the possibility of making different cuts [sic] in the body and there may be implications for subjectivity [already foretold by poets and theologians who remind us that under the surface we're just blood and guts?].  Feminists should be involved—'there is a need to understand the laws of nature as well as the law of the father' (222), and we must intra act as well as understand.

Chapter six

[A controversial case study of shop floor conditions {Fernandes -- I have some notes of my own here} shows that the new insights are not terribly new, but there are also some clearer definitions of the key terms, and a claim that they all arise from the quantum discontinuity.  The stress on iteration certainly seems to come from quantum physics.  Much of this could easily be read as taking someone's discourse, someone feminist or Marxist, and installing the terms under your own discourse.  Human interactions {I am sick of writing intra actions} are just seen as part of general interactions, for example, the production of human bodies as part of the production of all material bodies.  Some of the key terms have to be diluted accordingly—enfolding seems to be able to cover any sort of combination of factors.  Agential realism turns out to be a colonizing discourse, and it is hard to see why anyone would bother.  The chapter ends with all sorts of revolutionary possibilities arising from an analysis of the possibilities in material configurations, but, just as with Deleuze, this is a philosophical politics not a real politics]

Apparently, notions like position, standpoint and locality are useful in feminist theory, but they seem to depend on a 'container model of space and a euclidean geometric imaginary' (223) and these are open to challenge from postmodern and cultural geographers.  Space is no longer a neutral background, something objective.  Instead 'space and society are mutually constituted, and...  space is an agent of change... it plays an active role in the unfolding of events' (224).  The same processes that construct bodies construct spaces as well, but these get reified [sic].  [Haraway is much cited here].  We need to add techno scientific and natural factors as well to show, among other things 'the iterative (re) materialization of the relations of production', using agential realism to understand entangled relations.  There is a useful ethnographic study of a workplace which shows the possibilities.

Once we break from the container notion of space, we can discuss 'a space of agency' (225) which will show both determinacy and indeterminacy.  [And then agential realism is summarized again 225f.  This time it is going to intervene in debates between post structuralism and Marxism, going beyond the usual notions of performance to include non humans and deteriorate constraints.  There are lots of rhetorical questions as usual.  We're going to explain the relation between economic forces, colonization, centers of production and the development of new technologies, and their impact on subjectivity.].  Marxism is strictly economic or strictly social.  A case study offers a corrective, seeing class as a dynamic variable, and it is to be subject to a diffractive reading.

Fernandes has studied a Calcutta jute mill using a variety of poststructuralist and Marxist concepts to understand the effect of technology on class relations at the workplace.  'Shop floor dynamics' (227) involve gender religion and ethnicity as well.  Apparently, an economic crisis led to an excessive displacement of women from the labor force.  Jute is worked using old technology and old social relations [which exclude things like immaterial labour or 'the rhizomic resistance of the multitudes'].  The work that goes on 'performatively produces relations of class and other forms of cultural identity'[there is much done on this already, including the work on images of class at the workplace level].  Difference is 'iteratively produced'[the word iterative is still not explained].  We can summarize it, rather unfortunately, as 'What differences do differences in production make for the production of different differences'[!].

There are 'contests over space, time, and movement'(228) in the factory producing gender and class relations.  These are revealed in the way in which women are positioned on the factory floor, which itself depends on existing notions of gender and community, so the space is gendered, and the combination produces 'particular kinds of class hierarchies between workers and managers and between male and female workers'[close to Parkin and closure theories here -- not mentioned in Ferrnandes].  Class is not being demoted here to something merely ideological or cultural, but nor is it an exceptional identity.  Class and gender are not seen as separate attributes that interact [we need something closer to Poulantzas and the many determinations of the concrete?].  There are important local variants rather than a universal class identity.  [And then an unfortunate analogy with a gear assemblage which work together although they are determined by the uneven distribution of forces acting on them—I prefer the CND badge variant of the capitalist mode of production].

We can see a link with Foucault and disciplinary regimes that similarly structure time, space and movement.  These structures are codified to produce stratifications of the work force, but the workforce is already stratified and materialized by gender and community.  The 'modes of representations and meanings' shape structures in turn (229).  [Class] structures are best seen as immanent forces.  They are themselves 'produced' through subject formation [ambiguity of 'produced' here—both brought into being and demonstrated?]. 

We can see this in terms of the 'intra action of "material discursive apparatuses of bodily production"' (230).  The apparatus is not external to the body, but is itself part of the phenomenon, a body itself produced by intra action.  [Fernandes has more conventional historical sequences of how crises develop] We have to think of the implications for conventional notions of 'causality, agency, space, time and matter'.  Agency is now a matter of changing some configurations of these elements, and thus altering the forces immanent in them.

We need to think out what a machine is, and how they are connected to political and social systems [Marx did this years ago—the water mill gives you the feudal lord, the steam engine gives you the capitalist and so on].  Machines also connect the production of surplus value and the development of engineering mechanics, since they are terms in both.  Sometimes this has led to a useful development, as when Kelvin began to see nature itself as machinic.  We can add in nonhuman and human agency as implications as well.

We cannot see machines just mediating between subjective action and objective nature as in the old binary embedded in Newton.  Machinic agency has developed discontinuously in the 20th century, and so has natural philosophy and political economy, which have intra acted and entangled.  We have to think about what Böhr said about apparatuses [I thought he was due an appearance], which will draw our attention to differentiating and boundary making.  We have already seen him being read diffractively with performance theorists.  We should ourselves 'build an apparatus that is attentive to the nature of specific entanglements'(233) [this seems essential if she's to demonstrate the superiority of her approach as more than just another game with words].

In particular, we need to consider dynamics as well as power.  The newtonian idea saw dynamics as offering continuous change, as in the calculus.  This led to a deterministic world because we could predict the future states of physical systems: trajectories could be calculated, effects predicted from causes.  This provided a universal viewpoint, vision as infallible, a split with culture.  The quantum interrupted all this with its discontinuities.  It did not lead to free will but rather to a new set of possibilities, and a new conception of dynamism as 'an iterative becoming of spacetimemattering' (234) [so iterative here means as in quantum physics, or in the calculations of destinations of quantum particles through iterative equations? Wikipedia has: 'applying a function repeatedly, using the output from one iteration as the input to the next'. Or: In Object-Oriented Programming, an iterator is an object that ensures iteration is executed in the same way for a range of different data structures, saving time and effort in later coding attempts' That still leaves the problem -- why is becoming iterative? Because it is aiming at some solution or goal?].  Intra actions are 'nonarbitrary nondeterministic causal enactments through which matter - in - the - process - of - becoming is iteratively enfolded into its ongoing differential materialiaztion'[it all looks highly definitional to me].  These produce conventional notions of time and space.

The quantum discontinuity [NB] means that the past and future are both enfolded in iterative becoming.  Becoming itself as a result of 'the inexhaustible dynamism of the enfolding of matter'.  There is no determinism since some possibilities are excluded each time [but are also made available by the configurations?].  We therefore have a notion of constraint but not determinism.  Possibilities are not limited by realization [as in Deleuze] but are released each time in a configuration.  This produces the 'vitality to intra activity...  A new sense of aliveness'(234-5) [so not the old vitality?].  Agency never ends.  It is no longer confined to human intentions or subjectivity.  Matter is itself agentive.  There is a greater openness than is suggested by cultural demands or possibilities alone.  However, we cannot just ascribe agency to the nonhuman at will [we never get any specific  rules or criteria of course. It depends on our politics or ethics?]

Agency should be seen as enactment, intra activity leading to particular practices best described as 'iterative reconfigurings of topological manifolds [equals multiplicities?] of spacetimematter relations'(235).  Agency means changing 'possibilities of change'[sic] in these reconfigurations, especially looking at boundaries and exclusions.  The possibility to do this is present 'at every moment' and we must look to our ethical obligations 'to intra act responsibly in the world's becoming'[green politics?].  Like Foucault, power is not external, but it operates not only with humans, since nonhuman bodies are also materialized by 'forces at work'[same as power?].  We can also understand power's productivity in terms of causal relations, because in agential realism, causality is intra activity [mutual support of terms]: the difference between causes and effects are 'intra actively demarcated through the specific production of marks on bodies'[generalizing through ambiguity of metaphors from Böhr's original limited claims].

EP Thompson appears, to argue that class itself emerges from relations [in his critique of Althusser].  Fernandes also offers possibilities by charting the different material constraints on workers, and denying a simple trajectory of power [class theoretic determination].  The constraints are not immutable and they are affected by discourse: precise material arrangements are contingent.  We can see her study of the shop floor as an example of more general views of the 'spatiality of capitalism' (237), in that the local practices maintain a more general hegemonic construction of class.  Gender too is not only reflected but performed, and the workers have their own exclusionary practices [Parkin!].  These practices are produced as iterative materializations [not just reproductions?].  The space that results shows enfolded aspects of class, gender and community [what happened to age and disability?] [so what Barad is doing is using her own terms to replace those of Fernandes—diffractive reading or symbolic violence?].  Thus the jute mill can be seen as 'an intra acting multiplicity of material - discursive apparatuses of bodily production' [no doubt—but why go to all that trouble?].  The apparatuses are phenomena produced by further intra actions [iterative ones of course] between the people, machines and other materials [and those people and machines reveal further intra-actions?].  There is no 'purified notion of the economic' [straw man], and production produces commodities and subjects and structures.

Production is the result of different forms of agency, human and nonhuman.  Sometimes a machine 'refuses to work' [!], and this can initiate subsequent events like conflict between the workers or accusations of mismanagement.  Crowding machines together can require extra disciplinary practices, and management sometimes introduces surveillance techniques because workers can also talk to each other.  Machines and humans produce and entanglement which helps constitute the components.  However possibilities for reworking are also revealed, like removing unsafe practices.

Back to the unhelpful analogy, we can now add that gears can also be 'remilled' through intra action, and there are different forms of enfolding them into an assemblage.  We'll need a genealogy of the assemblage to grasp these possibilities and their consequences.  This will offer us a better understanding of production processes, such as those [unspecified straw men] who see it as solely human.  The underlying dynamics are the same. Enfolding is iterative and is not arbitrary but agential.  It really constitutes the underlying topology with its boundaries and exclusions.  There are certainly no Althusserian apparatuses which are rigidified and social only [but also dynamic given his view of reproduction]. 

There is an underlying notion of machine [a virtual one?] which is topological.  It can configure relations such as those described as intersectionality, specifically gender and ethnicity.  This also should not be understood as a geometric combination but as a matter of changing topologies.  Identity formation in Fernandes is contingent and material and the result of intra action, including configurations of power.  So, for example, a dispute between two workers on the shop floor, one an operative and one a mechanic, was based partly on a caste distinction, which in turn led to different support from trade unions and managers, but which then generalized as a conflict between workers and managers.  Initially, class boundaries were connected to caste hierarchies, but the political process itself had an effect [just like Marxist polarization].  Community identity itself is a result of the 'dynamic of hegemony and resistance'(242).  The different identities materialize and are enfolded [which now means any combination?].  The precise nature of the folding depends on other materializations at work on the shop floor [all of these have equal weight?].

So Marxist analysis is still relevant, and the example of these old fashioned production methods shows that there is no easy progress for modern to postmodern forms, no conventional temporality.  However, the study focuses too locally on the factory and misses global effects on the topology, together with those intra actions that defined the local ones [our old friend infinite regress again].  However we need much more work to grasp the detail, not only an analysis of the apparatuses but an account of the dynamics.  There is also an ethical issue of accountability both for what we know for and for what exists [happily, this can be postponed indefinitely].

The material discursive forces at work are constantly reconfigured, so the notion of position is itself contingent, just like the property of being a worker is not fixed or unitary.  It is contested and disunified, but we can still see it as objective in the sense that refers to specific phenomena.  The spatial dimension of capitalism is not uniform but can be seen as a 'contested and ever changing topology'(243).  Class itself cannot be isolated from intra actions with other practices that define gender and community.  [Although Fernandes's conclusion seems a bit banal here—that there are status differences inside the category working class].  Gender is a structuring category, but it is also contested so that its precise effect emerges only in 'specific materializing structural relations' including the economic.  Gender, class and community are enfolded and 'produced through one another'[again no attempt to pin down the relative strength of these forces].  These aspects are all equally material as well as discursive.

Material conditions do not just support discourses.  Both are involved in materialization and enfolding [enfolding here seems to mean intra action].  No analysis should attempt to isolate separate effects—not only is this a misidentification of the object, but it also will 'elide important questions of responsibility' (244).  This will also help us break with empiricist assumptions about the givenness of the world, and move us beyond the banality that the world is mediated, an unhelpful metaphor that has prevented proper analysis, proper 'accounting of the empirical'.  We do still have to 'take the empirical world seriously once again in the construction and testing of theories', however, but we should refer to phenomena.  These conceptions also help us incorporate post structuralism and feminism.

We return again to the example of commerce taking place through the Net.  Old euclidean categories of distance and time will not help, and we require 'topological analysis' of things such as 'boundaries, connectivity, interiority and exteriority (topological concerns)'.  We need similar analysis of the 'multi dimensional multiply connected, heterogeneous' landscape (245).  It is not just a matter of altering some euclidean terms [such as compressing time and space?].  Responsibility is no longer a matter of positionality or social location.  The point is to look at the very process of construction and the way in which concepts like space are exclusionary.  For example, conventional notions of scale are exclusionary, in that they offer a property of space that connects with social processes and social connections.  It involves 'agential enfolding'[where global agents affect local ones?].  Categories of the local, national and global are 'intra actively produced through one another'. 

Boundary transgressions similarly involve a reconfiguration.  Information is not something that traverses all borders with equal ease, producing a level playing field.  It can actually increase the unevenness of the distribution of goods and adds to the constraints on everyday lives, since expanded opportunity can also mean diminished possibilities [a note refers to Marx on uneven development, 452].  The nation state need not be made obsolescent. 

We need a proper genealogy of the apparatuses of production that involve reconfigurations of 'the spacetimematter manifold'(246).  Phenomena can exist at different scales.  We can grapple injustice better if we realize that apparently distant events can make local places or events.  This will also help us link ethics and knowing.  Topological analysis can open up possibilities for change so we can reconfigure other possibilities: there are no limits to possibilities, and they might include quite different social locations and positions.  Material configurations are inexhaustibly lively and reveal 'the ongoing dance of agency immanent [in them]'.  The politics of identity and location can be extended into a broader 'politics of possibilities'.  [all promise and no delivery as usual].

Chapter seven

[Enormously long and poorly edited, going over many of the earlier arguments about quantum physics but in much more detail.  The arguments are interesting, but we have to take so much for granted with no independent access to the work of Böhr or Schrödinger—although there's a lot of stuff about the Schrödinger wave equation online.  The overall effect is to demonstrate that the quantum world is not at all like the macro world, which is long overdue.  I'm going to go for the conclusions of the argument with one or two details about them rather than a full summary]. [Since writing this, I have added some additional notes and details of crucial bits, like the quantum erasure experiment here]

[Barad claims an extra authority here because she actually practices science, unlike many of her colleagues in science studies.] She says that too many discussions of quantum physics are 'oversimplified, confused, and glossy eyed' (249), but serious persons should make a commitment to attempt to understand what is going on. 

Quantum theory began as a [mathematical] formalism, with the Schrödinger equation as a major component.  However, until recently, the interpretative issues were unresolved.  There's a lot of early debate between our heroes Böhr, Heisenberg, Schrödinger, and Einstein and his associates.  Böhr was to argue that the two approaches, one describing particles and the other describing waves were formally complementary, mathematically equivalent. 

Schrödinger's equation in particular provided [workable probabilities].  It established values for the wave function of a particle.  At the formal level, these can be imaginary [and there is an imaginary number, the square root of -1, in the equation].  This indicates not a direct relation to a physical process but a more complex relation.  Meanwhile, the wave function is useful even if there is some dispute about how to interpret it.  Calculations are based on a particular ' Copenhagen interpretation' which helps us interpret the probability that the particle will be found in a given position at a given time [apparently based on 'taking the (absolute square magnitude of the) wave function' (251)].  This is all we can expect to know, and it is useful in calculations, say of the set of energy states displayed by electrons, permitting spectroscopic data, and there are lots of other applications. As an interpretation, there are still problems.  We have 'a pastiche of different elements, a partially negotiated and indeterminate combination and superposition [sic] of contributions from leading physicists'(252), and the computational benefits have been pursued instead, at least until recently [empirical experiments to test some of the speculation are considered later, meaning we no longer have to rely on gedanken].

One of the main mysteries turns on the superposition of waves in the quantum world, revealed by the Schrödinger equation.  In the macro world waves can overlap to increase their amplitude or cancel them in a linear manner.  In the quantum world, there can sometimes be two solutions resulting from superposition [represented by the Greek letter psi].  At first, we can add these two together as before.  [For some reason] we can multiply each one by 'an arbitrary (complex) number'[to increase amplitudes?], and as long as they are 'normalized'[squaring each number and seeing if they add to 1 or 100%, that is, exhaust the possibilities], their sum will also be a solution to the wave equation.  The implication apparently is that superpositions of individual solutions are also viable wave functions, or 'the very existence of superpositions is a feature of the wave behaviour of matter'[I think this means that waves at the quantum level add together like waves at the macro level, at least when they have been normalized].

In a homely example, we might consider the case when a color property of a particle is either red or green—a two state system in this case.  There will be two solutions [to the Schrödinger equation] —eigenfuntions or eigenstates [Barad explains that the term eigen means characteristics].  The two states will have two solutions to the wave equation—psi r and psi g -- the eigenvalues.  We know from the above that the combination of psi in each case is permitted by the maths, and if normalized is 'a physically allowed state'(256).  Apparently, we can decide that this will also mean that the combination of the two is 'the most general solution' to the Schrödinger equation.  As long as the complex numbers, when squared, add to one, all is well.  There will be many possible complex numbers which will do this producing 'an infinite number of allowed or possible states'[I'm not at all sure why the available complex numbers will be infinite].  We can now see the separate psi values, red and green, as a special case of the general solution.

If we do some gedanken, we can ask what would happen if we could invent a box to sort particles by color, so that red particles came out through one slit, and green ones through the other.  We can test this by sending all those with psi r through first and seeing if they all come out of one slot.  This tests the apparatus and also confirms that the eigenstate, color, is a definite characteristic.  Then we send through a stream of particles where the square root of 1/4  of them have psi r and the square root of 3/4 them psi g.  This will be one of the physically allowed possibilities because we have multiplied the wave function by the square roots of 1/4 and ¾ respectively, so that, when we square them they do add to 1.  We should find that 25% of the particles come out of the the slit selecting for red, and 75% out of the slit selecting for green [so when we substitute percentages for fractions, we exhaust all the possibilities when we add the probabilities of red and green].

To take an actual case, particles can be selected according to their [more complex] characteristics of spin, up or down.  The same characteristics apply—a two state system, and two wave functions, psi u and psi d, and the same possibilities for multiplying them by complex numbers.  Spin has an additional complication in that it is normally thought of as a vector quantity, and it is possible in all three dimensions, X, Y, and Z, giving spinX (SX) et cetera.  The Stern-Gerlach apparatus discussed above [with its cheap cigar] measures spin along each of these three dimensions in turn, again by splitting a beam of particles and deflecting them to different slits by a magnetic field.  As before, if we are measuring the up spin in the Z dimension and 100% of the particles have it, they will all appear through one slit.  If we have a distribution with 1/2 of the particles with up spin and 1/2 with down, it will be 50:50, and we can test the apparatus by passing all the up particles into an up spin detector to confirm that they will come out of the same slit.

What happens if we take the half with an up spin and pass them into a second device which measures spin in the X direction [diagram page 260).  Let us imagine that a further half of the stream comes out of the up slit, and 1/2 out of the down slit.  Things get complex if we add a third spin measuring device, that also measures spin in the Z direction, and we add that onto the end of the first two, so that it will receive particles which all have up spin in the Z dimension, with half of them having up spin in the X dimension as well.  Common sense tells us that the third device should confirm that these are all particles with an up spin in Z, because they have already been selected by the first box.  But 'this intuition proves to be wrong'(260).  What actually happens is that the third box seems to sort the Z particles again in two equal numbers of up and down spin.  Somehow, measuring for spin in X has affected the results of the second measurement.  It seems that it is impossible to determine more than one of the components of spin.

We might explain this either in terms of uncertainty or indeterminacy: it is an epistemological problem (Heisenberg) meaning that our knowledge is necessarily limited to measurements in one dimension, and measurement itself disturbs the values, or is is an ontological one (Böhr) because of the values in each dimension are not 'simultaneously determinate'(261), and when we set up an apparatus we are in effect defining the concepts and the properties concerned, precluding complementary sets.  If it is measurement that disturbs the particle, we can still preserve some bits of Newton, while acknowledging that there are limits to what we can know, because measurement itself introduces disturbances.  But superpositions remain as a problem [I'm not at all sure why—maybe because they can only represent possibilities for what we can know, derived from the formal properties of mathematics?].

In yet another experiment, we might split the particles in terms of their spin in the Z dimension, then recombine them in a second linked apparatus measuring X spin, and then sort out spin in the Z dimension again in the third linked apparatus.  This time, despite the disturbance of recombining beams, all particles act according to their first selection -- they all come out of the same slot in the second detetctor as if nothing had happened. The second apparatus seems to have no effect and the third apparatus splits the particles in exactly the same way.  Since varying the disturbances does not seem to have an effect, the suspicion is that 'what is at issue is not a matter of disturbance after all' (263).

Having tested Heisenberg, we now look at what Böhr might say.  He would want to decompose the notion of spin, denying there is an overall vector sum, and seeing spin in each dimension as separately determinate, according to the apparatus used.  If the apparatus is not applied any more, the value becomes indeterminate.  It is the material arrangement of the sorting boxes, rather than a fallible human being, that provides a cut between the object being observed and the measuring device, and the affect of this cut is to make boundaries and properties determinate, and dimensions meaningful.  We can reinterpret the arrangement of sorting boxes accordingly—the second box, by measuring X components has effectively switched off the Z component introduced by the first box, and that is why the third box can start all over again to materialize the Z dimension.  [Böhr also explains the final experiment that I found mystifying, the one involving recombining.  Apparently Heisenberg cannot explain it—264.  I think what happens is that the  recombining switches off the X component which thus remains indeterminate, while the Z component is not affected]. It looks like the specific arrangement of the apparatuses what produces the puzzling effects.  We always find one of the characteristics, so there are limits to what varies.

The consequence is that superpositions offer something more than just mixtures.  Mixtures have ensembles of particles each with a determinate value for some property, and we can estimate the probability of the existence of particular particles.  But quantum indeterminacy is different, a matter of superposition, which produces 'ontologically indeterminate states'(265), and this indeterminacy is what produces the puzzling results.  Here calculations of probability are  'intrinsic to the nature of quantum phenomena'.  With superpositions, there are 'interference effects'. 

Returning to the classic two slit experiment, we have seen that the particles can behave like waves and produce an interference pattern even if they go through the apparatus one at a time.  The two slit experiment with a which-path detector led to Einstein arguing that we can assess the disturbance of the particle as it goes through the detector [and this will explain the subsequent wave pattern].  Böhr argued that the interference pattern would be destroyed [because it would somehow force the particle to act as a particle, and the result would be a scatter pattern not a wave]: we can either find out which path a particle takes or measure its interference pattern, but it will not do both.  If we set up an apparatus to detect which slit, we will only find particle behaviour, because the experimental arrangement itself has produced a specific cut and a determinate value.  Apparently the experiment was actually performed in the 1990s.

With a which slit apparatus, we will have a mixture of particles with different wave functions and they will be divided into coherent streams according to whether they go through the top or bottom slit: no interference patterns because no superposition.  Without the which slit, we will not only have a mixture of particles, we would also have no information about which slit the particle passes through: that information is 'not just unknown; it is ontologically indeterminate' (268), says Böhr.  This will produce superposition and thus an interference pattern.  Whenever we get an interference pattern, we must have a superposition, and we find superpositions 'are a fundamental feature of the quantum world', unlike classical physics where we only get mixtures.

Einstein, Podolsky and Rosen [I referred to them as Einstein and colleagues above] challenged quantum mechanics by pointing to an area where it was incomplete.  They said they had thought of the way to determine the position and momentum of a system simultaneously and without disturbing it by measurement.  This would be inexplicable by quantum theory.  We consider two systems that interact to such an extent that they become correlated with each other.  We then measure things in one system but do not disturb the other.  The two systems have to remain correlated with no additional changes.  The issue turns on the correlation and whether it is or is not entanglement.  Entangled states are special 'quantum mechanical correlations' (270) [found only in the quantum world then?], explored only after Einstein's death.  They are like superpositions 'uniquely quantum mechanical', with no equivalent in classical physics.  They can be seen as arising from 'a generalization of a superposition to the case of more than one particle'.

We get to entanglement if we consider individual particles each with a different spin eigenvalue, up or down.  [The spin value is apparently equivalent to the wave function, 271].  In an entangled state, we will find complex numbers of particles with different spin values—one up one down, plus one down one up [not both up or both down?]  It seems important that the systems are 'oppositely correlated'[—the whole argument only works when they are?].  The particles concerned can only be related in this way, forbidding other combinations such as seeing the system as a composite or a mixture with the particles remaining separate.  [Because of this opposite correlation], the state must be seen as a single entity [lots of supporting definitions here—entanglement is defined in effect as existing in relation where the components are oppositely related or interdependent].

Einstein and colleagues assumed an entanglement between their two systems, so that if we know the properties of one set of particles, we will know by inverse correlation the properties of the other set.  However, if we are to know more than one property, we have to assume a particular kind of entanglement, where there is opposite correlation what ever dimension is chosen—the 'singlet state'(272) [and it looks like we have to assume that the opposing pairs are present in equal proportions].  It seems like what is happening in a singlet state is that measurement of a pair along one axis 'instantaneously determines' the spin of the other pair as an opposite correlation, even though the systems are independent, even though they may be no longer interacting.  We can further test the properties of this state if we separate the systems of pairs and run them through a spin detector.  The two systems are now separated [unable to exchange information] and so the opposite correlation should not work, especially if we change the settings of the spin detectors before the systems run through them.  However, it seems that the spin values are always oppositely correlated.  It looks like those spin values were always there as determinate attributes in dependent of the measurement.  The alternative is to argue that the two systems communicated with each other in some strange way instantaneously, perhaps even faster than the speed of light, against relativity principles.  Einstein and colleagues went on to assume that there must be some hidden variable which explains both states of the systems, and if we discover it, we have found the secret of physical reality.

Böhr worked hard to respond, and suggested that there had been a disturbance after all, not a mechanical one, but a more subtle form of influence on the conditions which will affect the possibility of predictions.  It is all a matter of how ontological indeterminacy is managed to produce a distinction between object and agency of observation.  This happens only with particular experimental arrangements, and if we change those arrangements, we would change the distinction or cut and even the causal structure.  This will extend to the whole of physical reality for Böhr.  Einstein and his colleagues did not grasp the full implications of indeterminacy, they use different experimental arrangements and thus will introduce different cuts.  Physicists were attempted to agree with this from 'sheer pragmatism', since quantum theory had proved so valuable, while the philosophical issues could be simply left to one side as untestable—positivism triumphed.

Schrödinger intervened in the debate, with the cat experiment.  This is only a brief description initially designed 'to dramatize the difficulties of coming to an adequate understanding of the nature of measurement' (275).  He wanted to argue that the wave function implies a 'blurring' of all the variables concerned, at least in the microscopic domain.  The experiment is designed to raise questions about what would happen if blurring extended to macroscopic objects: this would be '"simply wrong"'.  The blurring at the microscopic level takes place only between measurements, but if it affected macro variables that would contradict the apparently sharp values of measurement at that level, which would be absurd—hence the cat experiment ['a cat is placed in a box with a radioactive source.  On the table is a Geiger counter…  If it detects a decay event, a relay trips a weight, which hits a flask which releases the poison which kills the cat' 277].  We only know whether the radioactive substance decays in the form of a probability.  If we tried to apply quantum theory and calculated a wave function for the entire system, we can assess the probability of whether the cat was alive or dead—the living and dead cat would be equally probable, with the value of its life 'blurred'.

This would only work if the overall wave function superposed alive and dead states of the cat, if the fate of the cat was strongly entangled with the microscopic decay of an atom.  It is not just that the cat can either be alive or dead and that we do not know which, nor that it is both alive and dead, since this would invalidate the notion of the values.  We have to understand that the cat is actually entangled with the source, such that if the atom is not decayed, the cat is alive, and the opposite possibilities are also correlated.  Since we only have the wave function to go on, not a precise measurement, we cannot decide which outcome prevails.  The entanglement means that we cannot use classical physics with classical calculations of probability. [The paradox arises because we are wrongly using quantum procedures?]

It is not simply that superpositions can only arise in the microscopic or quantum world, because that would imply two sets of physical laws, and 'no empirical evidence exists to support [this] assertion' (279).  However, quantum effects 'are not commonly evident in the realm of our everyday experience': (1) the mass of the object has an effect, and large objects have very small ratios between Planck constant and mass, so quantum affects take place, but they're usually 'too small to notice without special equipment'; (2) quantum effects are hard to separate from interactions with an erratically intervening environment which introduce mixtures instead of superpositions so that superpositions are randomized -- '"decoherence"'; (3) it is not all easy to identify entanglements, to find and measure correlations.  Nevertheless, quantum effects should be observable, and some useful ones have been observed, such as quantum tunneling and quantum coherence even at the macro level, and these have helped a useful technology develop.

Schrödinger's experiment rehearses an earlier discussion, that when we measure subatomic particles, we find them not directly as a superposition, but in one of the possible states.  In effect 'measurement resolves the indeterminacy' (280).  Measurement seems to collapse the wave function from superposition and entanglement, to one in which all the possibilities except one 'are set to zero'.  There is nothing in Schrödinger's wave equation to explain this.  Something happens during the process of measurement to effect the possible states, to reduce superposition to a mixture, just as when we find a cat either dead or alive.  There is only indeterminacy and wave function between measurements.  The formalistic model itself cannot describe what happens in the process of measurement, the abrupt change it brings.  Once more, it is not a matter of measurement acting upon reality independently. 

If we reject such [norma] realism, we cannot argue that variables have values before they are measured.  Does this mean that we can ascribe any old values?  It is rather that measurement must determine reality, produce real effects, and effects which can be repeated with the same measurement [my notes suggests that this is rather like using the reliability of assessment to claim its validity.  The whole debate is actually rather an old one in social science about observer effects].  Schrödinger was to argue that measurement intervenes in the wave function, changing expected predictions.  But there is an asymmetry here in that some older predictions will be deleted, but knowledge can not be lost [!].  This means that the object itself has changed.  Measurement has not changed the wave function, and discontinuous change is not like [experimental falsification]—knowledge is preserved which means that the object must change, and a whole set of new expectations must arise [because there's not only discontinuous change of the wave function, but unforeseen changes introduced as a result—this explains Barad's insistence that new sets of possibilities arise each time things are changed?  Even so, we are still only talking about the quantum level].  We may have a maximal knowledge but not total knowledge, for example with entangled states where we know that they once formed one system and we can find the traces left by the entanglement, or when wave functions assume superpositions [we can go back and find the functions for the separate waves?  Actually, I don't think this is the argument, since the separate waves are not factors to be multiplied.  Instead, I think we are left with common descriptions of two systems].

Schrödinger [gets close to Bergson] by arguing that a living subject reacting to a measurement resolves entanglement.  So if we put a device on the box with the cat that measured at intervals whether the cat was alive or not we would not be resolving the entanglement, but adding to it, since [if?] a recording device would be entangled with events inside the box. We need a [separated?] 'cognizing subject'if there is to be a definite value.  It is not that humans can effect events through mental action, but their engagement does change the wave function and reconstitute it, freeing it from entanglement with the objects in the box.  'Our knowledge' of the object becomes an entangling factor: we gain knowledge of the overall wave function, our knowledge adds to the possible predictions and thus to the maximal knowledge of the system.  [Odd argument - almost saying that we need a stance that protects existing knowledge and adds new stuff to it -- as in transcendence?] Note that it is knowledge that becomes entangled, so we are back to epistemology.

Schrödinger set the agenda for much subsequent discussion about measurement and the wave function, and the implications for entanglement.  He does not argue that the wave function collapses as much as it changes its state.  That is because measurement does not introduce a physical change in the system.  This is just as well because if wave functions collapsed, it could contaminate the whole of space [according to people cited on 285].  However, other physicists do talk in terms of the collapse of the wave function, and they then have a problem in explaining it on the basis of quantum theory as developed up until Schrödinger.  Other alternatives include seeing the wave function as offering information about a system rather than a description of the physical process.  [Apparently, some of the early examples show that we can predict measure of results from the Schrödinger equation in some circumstances—when initial states correspond to one of the predicted eigenstates {we can then predict that the opposite correlated eigenstate will appear?}]

Böhr has never discussed collapse of the way function and sees no need for it.  The continuing dissent shows the pastiche quality of quantum theory.  Several ingenious explanations have been advanced, involving consciousness, gravity, that measurement splits reality into many worlds, some hidden variables might be at work, and so on (287).  There may even be 'cognitive repression' at work that produces a reluctance to let go of classical physics.

[pause...]

There are now some experiments which have replaced gedanken—'experimental metaphysics'.  These test in particular whether or not there are hidden variables, or whether which path measurements destroy interference patterns, on whether measurement disturbs existing properties.  All this has taken place recently, after the death of Einstein and Böhr.

Bell for example claims to show that we can 'empirically differentiate between two different metaphysical positions'(289), in this case the ones between Einstein and colleagues and quantum mechanics.  He had to reformulate the Einstein argument to argue that hidden variables can explain any qualities in any case whatever, and then to test it against quantum mechanics.  We set up two entangled two state systems with opposite correlations, and measure their spin values simultaneously, along dimensions set each time by independent technicians.  The assumption is that a singlet entangled state will be examined.  If the technicians measure along the same dimension, they should get opposite results from the two pairs.  They can randomly choose their dimensions.  We should get in each case a net result 'the value that A obtained times the value that B obtained'(290) [can't see why].  We can then set the expectation value as the average value over a number of runs.  If there are hidden values, we should detect a certain inequality, whatever the values.  Quantum theory would suggest that there is no inequality [we are referred to a footnote].  It's an important exercise, but it was ignored for years as a result of neopositivist disinterest in philosophical matters.  Quantum theory emerged as a better predictor.  [Further explanation reveals that the so-called hidden values are the apparently inherent properties of individual objects, and there's an additional 'locality condition' which denies instantaneous communication between locations.  If quantum theory works better, one or both of these assumptions must be wrong.  Thus the consequences have led quantum theorists to reject either or both inherent properties and local conditions, a major rejection of classical physics]. 

In another 'theorem' by Bell and others complementarity is investigated.  Only variables that are mutually compatible or simultaneously determinable can appear in any one quantum state [and position and momentum are not in this group].  But even compatible variables are hard to specify, since the context of measurement matters there as well [and measurement can change the value of the variable], and the setup of an experiment can have an effect even with compatible variables.  This would obviously cause problems for classical physics, but it agrees with quantum mechanics in denying preexisting values.  The point is that the context, the experimental arrangements, affects all measurements [there is no detail of how they actually went ahead and tested this, but Barad says it is a useful step toward experimental metaphysics].

Back to which path experiments, with a summary of whether it is our knowledge which is uncertain, or reality which is indeterminate [then another summary of the differences over the wave - particle paradox, 295 F. ] This time, there is a formula to explain 'the relations of reciprocity', an apparently neutral term that does not take sides between Heisenberg and Böhr.  Böhr argued that theoretical concepts like space or time are really  'idealizations or abstractions'(296) which only take determinate meaning in particular experimental arrangements.  Complementarity is a quantum characteristic that explains apparent contradictory results.  We only get unambiguous, observable properties from the interaction with other systems {between objects and observation apparatus?}.  Thus particles and waves are complementary and there is no contradiction or inconsistency.  Böhr thought that the uncertainty described by Heisenberg had already been predicted by this account, so there is no independent disturbance produced by measurement.  Böhr sustain this view by noting both contrast and reciprocity between wave and particle characteristics, vibration and wavelength for one, and definite coordinates for the other.  However, empirical realization in both cases depends on superposition, which in effect combines these components, combining waves 'to form a wave packet localized in space' (298) [diagram of superposition on page 299, and some nice animated diagrams are available online].  Apparently, the spatial extent of the wave packet, which defines how it appears as a particle, is necessarily reciprocal to the spread of wavelengths which defines a wave.  There are two ['oppositely correlated? ] possibilities: there can be 'an infinitely narrow wave packet', wave number or wavelength is meaningless, or a single wave with a well defined wave number but no actual position. 

There can also be intermediate cases where both particle and wave characteristics appear and it is possible to understand the relation between these characteristics within certain limits [and in the form of an equation], which will give us 'a quantitative expression of complementarity'[I did not understand the maths page 300.  Further distinctions between Heisenberg and Böhr are developed 300f: the section is apparently designed to clarify the relationship for physics students where the two positions are often confused.] We have already seen in the debate between Böhr and Einstein and colleagues that Böhr interprets the which path experiment as interfering ontologically with the properties of the particles—the experiment has now been realized in the lab.

The main issue was whether or not it is fully possible to see which slit the particle travels through, leaving only approximate information.  The effects of such possibilities would be seen in the interference pattern, and would provide some intermediate states between complete scatter and complete wave pattern.  Two mathematicians discovered a continuum of possibilities like this, but argued that the results actually supported complementarity—because sources of ambiguity in the apparatus was correlated with changes in the interference pattern.  Overall, Böhr was right to say that there is 'a continuous trade off between particle and wave behaviors; the more it behaves like one, the less it behaves like the other' (303) [it seems that experimental attempts produce this problematic lack of sharpness in what was recorded on the screen?].

Barad wants to immediately squash any suggestion that Böhr only explains limit cases, and reworks his argument to show that intermediates behaviour has been allowed four when discussing definability in general, and that he has always seen that it is a trade off between determinate characteristics not a simple either/ or, while using the limit case is a pedagogic device.  What is new is that the two mathematicians can offer a 'precise quantitative relationship' for the trade off, and that the interference pattern persists in cases where we are almost certain which path the particle went through.  There has been subsequent experimental confirmation too, which suggest that fine measurements at least appear to make no difference in their own right: 'all that is required to degrade interference patterns is the possibility of distinguishing paths'(305)—the very possibility rather than any actual disturbance by measurement.  Further evidence is cited from subsequent findings, again confirming the importance of contextuality rather than actual measurement, supporting Böhr against Einstein and colleagues. 

Another ingenious experiment (Scully et al) obtains which path information without disturbance -- as  atoms are emitted they are 'excited' by lasers and enter 'micomaser cavities' instead of proceeding through which-path detetcors. There they all decay, with 100% certainty and emit a photon as a trace so we know which cavity they entered without disturbing their  'forward momentum' at all. Then they pass through double slits and proceed to the detecting screen ( diag p.307). Same results appear --with which path information, a scatter, without a wave. So a plus for Böhr -- Scully et al argue for 'correlations between the measuring apparatus and the systems' ( 308). Curiously, they still support Heisenberg though on the uncertainty issue -- the 'current episteme' (309)  is to blame

At bottom, complementarity implies that there can be no separation between the behavior of objects and their interaction with the measuring instruments: they are inseparable already.  Thus we get back to phenomena with agentially intra acting components which are also ontologically inseparable, entanglement in an ontological way rather than the way Schrödinger thought of it: the components are entangled, and this constitutes physical reality.  This is still misunderstood including by some of the more recent experimenters who confuse Böhr and Heisenberg.  We can see the effect of a paradigm [sic] here which has produced 'mistaken belief'(309) [this is her contribution to quantum physics then? Luckily, these limiting consequences of paradigms are specific to critics of Böhr]

There have been lots of supporting experimental tests, apparently, although we must accept that 'results and science are never incontrovertible, but rather are always open to question and to multiple interpretations and to the possibility of a reinterpretation' (310).  Nevertheless, Böhr is supported in his views of complementarity, entanglement/inseparability/contextuality, and the role of the specific experimental arrangements in determining onto-semantic issues, not just actual observations.

It might be possible to further test the issue by seeing what happens if we can somehow restore the original pattern by undoing or erasing the which path information.  If Böhr is right, this information has not so much been destroyed as redistributed to other parts of the entangled system.  It seems we actually can do this now, using the Scully apparatus above, where information was stored in micromaser cavities.  We can even do this after the whole experiment is over and all the atoms have passed through to the recording screen.  The cavities record photons that have been emitted after decay, and we can try to detect those 'with a photo detectector-shutter system' between the cavities  (311) which will absorb photons and thus erase the information provided by them.  Amazingly, if we do this even after all the atoms have gone through, we get an interference pattern on the screen, just as if we had no which path apparatus in the system at all, so Böhr is vindicated.  There is a bit of sleight of hand because we have to reexamine the pattern that has been left on the screen, which looks as if it is a wave at first.  The argument is that there is only a 50% probability that the photon will be absorbed, so that what we will get is in fact two scatter patterns on the screen, produced by the atoms going through either slit.  This requires that we can trace the path of individual atoms [which is possible apparently].  We then translate the wave pattern as really an overlapping double scatter pattern [diagram 314] [there is something dodgy about this, because this is the first time we're actually interpreting and decomposing the wave pattern on the screen.  Suddenly Barad says that 'generally speaking, the results don't simply announce themselves; rather, one has to analyze the data in some way' (312)].

For Böhr, what is happening is not that we have had some inverse disturbance from a second measurement, or that we have erased a measurement, but rather 'the conditions that define the possible types of prediction' have changed.  The entire apparatus has produced both sets of results, and some physicists agree.  The traveling atoms are not separate objects, and it is misleading to identify them as the only relevant abstract individuals, the objective referent.  What we have is quantum entanglement in the entire phenomenon, which includes the observing agencies.  The experimenter has not somehow magically changed the past, nor that the atoms have somehow communicated backwards.  Instead, 'the past was never simply there to begin with and the future is not simply what will enfold' [deterministically]. Both past and future states 'are iteratively reworked and enfolded', as parts of one phenomenon [repeated measurements produce iterations?].  Space and time are also produced in the materialization of phenomena.  The concept of the individual is 'ontologically and semantically indeterminate' until the apparatus is set up, which then goes on to resolve the indeterminacy.

Scully actually suggest that it is the memory of the passage through the cavities that has been erased, not that somehow the interference pattern has been recovered: it is a new interference pattern that is produced [with two curves as in the diagram]. Barad herself suggests that it is not a matter of erasing memory, but more that the memory remains, but is then made indeterminate again, and this is how past and future are 'iteratively reconfigured and enfolded through one another' (316).  Phenomena and their entanglements '"extend" across different spaces and times' (317), and measurement can actually extend these entanglements: the terminology of erasure or resolving is inaccurate.

[The next session runs over some of the arguments between Böhr and his colleagues that we have seen before].  Neither Einstein or Böhr can easily be said to be realists or anti realists, and that whole debate is mixed up with the issues of objectivity and subjectivism or even relativism.  However, there are different sorts of realism in science, such as 'entity realism' and 'theory realism'.  As we saw, objectivity has also been debated.  The point is to move away from representationalism.  The real issue between Einstein and Böhr turned on separability as we saw.  Thus some apparent challenges to Einstein such as the way in which apparently instant communication between atoms violates relativity theory [known as 'nonlocality'] can be explained away as above.  What we're talking about is better understood as '"outcome independence"' (318), and there is a special kind of '" quantum nonlocality"'which really involves nonseparability [there is even an argument that says it is an experimental artifact].  Separability therefore is the issue.  Einstein took a strong line and argued that if we give up the notion of independent existence, physics itself will be impossible, since it works by dividing up the world objectively.  Böhr responded, as we know, by saying that we should focus on phenomena as the objective referent, and that objectivity is reduced to agreement about what experimental results show: we also have to agree with the way in which the experiment cuts between the effects [for example measurement results] and causes.  As long as we do, we can achieve a 'reproducible and unambiguous measurement of one part of the phenomenon by another part'.  There has been much commentary and debate about the alternative positions ever since, including one that suggests that Einstein simply had to maintain a 'faith', 'conviction', or 'theoretical allegiance' (321), especially in the existence of an independent external real world, spatially separated.

Barad wants to maintain this notion of separability, while abandoning Böhr on intersubjectivity as we saw, through the agential realist notion that humans cannot be taken as privileged, some thing that can rise above reality to observe it from the outside, but instead that humanness itself can be accounted for in Böhrian terms as produced through a cut by apparatus.  She says we can even abandon philosophy and draw this conclusion from experimental evidence [by generalizing from the ones she's discussed, on the basis that there is no separation in principle between the quantum and the macro worlds, 'no theoretical basis or empirical evidence' for such a distrinction (324)].  Böhr has misleadingly talked about describing measurement in classical terms [cited in some of the literature in physics], but for different reasons—he is interested in the precise 'material embodiment'(325) of concepts. 

It is not that measuring agencies are always macroscopic, since they are a part of the object.  Again, intra action within the phenomenon is responsible for generating apparently macroscopic objects such as which path detectors.  The debate has much wider implications about the whole relation between the quantum and the macro world [I think the issue is that measuring instruments and their results are not taken as themselves subject to quantum indeterminacy].  There is no lingering ideological commitment for Böhr here, or if there is, 'it is one that is at least shared by many scientists, philosophers of science, and members of the general public' (327 - 8) [but Barad knows elsewhere that this is no ground for accepting an argument].  The argument is that the apparatus makes the cut between object and instrument, so there is no prior distinction, and no justification for seeing a prior separation between macroscopic and microscopic components.  Concepts become meaningful through embodiment in apparatus, for Böhr, and measurement involves simply a correlation between the behavior of the object and an instrument located in conventional space and time.  Beyond that, there is nothing general about measurement, because, for example, we know that it is not possible to measure position and momentum at the same time, therefore [!] 'The only well defined (unambiguous) concepts that one has available are particular concepts embodied in the specific experimental arrangements.  There are no others' (329) [so what of analogy or general applications of concepts?].

Objectivity is a matter of unambiguous communication for Böhr and this is a further requirement for the design of an experimental arrangement.  It also requires common understanding among scientists and hence classical concepts for Böhr, even though understanding is actually produced by the apparatus.  The result is an 'unfortunate' (330) ambiguity and he should've talked about embodied concepts instead of classical ones.  He also should have gone beyond epistemological definitions of objectivity to discuss an ontological notion of separability.  Epistemological issues and understandings still persist, however, as we have seen.

Post humanism to the rescue.  We can understand it as 'a thoroughgoing critical naturalism' (331), where humans and the activities of knowing, including scientific knowing, are natural processes of engagement with the world.  We can base it on scientific theory rather than 'philosophical preconceptions' (332) and we have to understand scientific practice as the investigation of 'causal intra actions'[in the general sense she develops above, in terms of anything that produces an effect is a cause].  In this case, it will help us provide a better interpretation of quantum theory [never short of ambition!].

We might start with approaches to quantum theory that offer relational ontology.  Particularism and individualism are rejected, in favour of phenomena and intra acting '" agencies"'(333) [note the quotes indicating doubt].  Phenomena are 'ontologically primitive relations' without preexisting 'relata' [things to be related, contents].  Agential intra actions set boundaries and properties of phenomena in a way that introduces determinacy and meaning.  A particular agential cut separates subject and object [still nothing inherent, not like Descartes].  In this way we move beyond Böhr and his anthropocentrism, which now includes his insistence on human-based concepts].  Apparatuses are not static but 'open-ended and dynamic material discursive practices through which specific "concepts" and "things" are articulated' (334).  This helps to see laboratory performance [as enactment].  It also helps us move beyond laboratory practice to follow much wider issues about nature and existence.  She thinks her agential realism is actually 'more consistent with the logic of Böhr's argument than his own formulation'.  At least Böhr offers some useful material approaches, which include the idea that concepts are material arrangements.  Barad draws from post structuralism the idea that linguistic concepts can also be seen as material and discursive.

Apparatuses are not just instruments constructed by humans, but 'specific material configurations' of the world (335).  They play a role in the production of phenomena and a part of the phenomena they produce.  This is because material practices 'causally produce specific material phenomena as part of the ongoing differential performance of the world'.  We are reminded that discursive practices are not just speech acts but configurings of the world which produce boundaries, properties and meanings,  the 'enactment of onto- semantic determinacy'.  Meaning is not based on human understandings, but is itself 'an ongoing performance of the world', which happens because the world has a 'differential intelligibility', shown in the performative articulation of what matters, 'differential becoming', different articulations of the world.  It is 'causal intra activity' that means that this intelligibility can be grasped by another part of the world, through boundary making practices.  This is where human concepts have a role to play—they are part of this material configuration.  The key shift is from things to phenomena, which suggests that matter is substance in the process of intra active becoming, 'a congealing of agency' which both stabilizes and destabilizes.  This is what makes phenomena matter [this unfortunate or clever ambiguity again—matter to us?].  Scientific practices are 'specific forms of engagement that make specific phenomena manifest'(336) [so sometimes they are latent?].

Schrodinger saw the human observer as essential to interpret the results of the measurement.  Others have pointed to other essentials in measurement such as a gravity field.  Böhr has insisted that measurement devices must be described in macroscopic terms, but he was interested primarily in making laboratory experiments work—he was not interested in philosophy as such..  The shift to agential realism offers a better discussion of ontology which will include what happens in the laboratory.  Thus measurement is not a simple physical matter of generating effects, but rather 'a correlation of the properties' of two systems [sounds a bit like Deleuze on how meaning is attached to events in Logic of Sense].  But it is not inherent properties that are correlated, since the systems are entangled, and it is only an agential cut that separates objects and measuring agents, following from a specific experimental arrangement.  It is one part of the phenomenon intra acting with another, including cases where the measuring device happens to be macroscopic.  Human concepts or practices are not foundational—some intra actions happen to involve humans.  In this sense, humans are not at the centre of measurement, nor do phenomena only exist in laboratories.  'Parts of the world are always intra acting with other parts of the world'(338), and this produces the differences in being, with boundaries and properties: these are 'enacted in the ongoing ebb and flow of agency' [Bergson on creative evolution!]  The only role of humans is to play a part in the constitution of particular phenomena. This goes beyond the humanism shared by Böhr and Einstein.  The issue is how humans emerged as special systems apparently separated from an actual processes. 

[Back to objectivity—I yearn for an editor].  Böhr and Einstein both have insights which can be combined, since intra actions also  'enact agential separability—the condition of exteriority - within – phenomena'(339).  There is no absolute separability.  There is no metaphysical underpinning either, since separability 'is disclosed by empirical findings that reveal its contingent nature'.  Thus observer and observed are simply two intra acting systems.  There is however a matter of 'accountability to marks on bodies'[the special ethical burden on humans?  Here accounting also mean something technical, almost like explaining how the apparatus works and why it is set up in the way that it is].  [So could she explain her own metaphysics in the same way?  A result of a special experimental apparatus somehow designed by the world to make it intelligible?]

Humans are part of the world's ongoing reconfiguring, parts of its dynamic structuring, knowing is a part of being so there is no separation between knower and known, rather, differently constituted relations.  Knowing is a practice rather than a matter of gaining ideas, a matter of practical engagement which we should be able to account for within scientific theory [so here 'accounting for' means acknowledging all the background factors as well?]. 

So measurement does not interfere with the world, such as causing wave forms to collapse.  It is more a matter of adequate practice.  However, scientific measurement still seems to deliver determinate values as a result of the 'superposition' [in the Schrodinger sense?]  of object and observing instrument.  We revert to the notion of a correlation between systems, and this must be read as an ontological entanglement, removing that special role for humans and human knowledge [it seems that human activity in gaining knowledge is what is responsible for the collapse of the wave function, because we can identify one value among the probabilities].  We can refer to those interesting experiments discussed above, like Scully.  Generalizing, we can suggest that measurements actually extend entanglements, certainly at least by introducing instruments and objects together.  But there must also be a possibility for further indeterminacy, something like a superposition.  Unsurprisingly, it is agential separability which resolves the indeterminacy. 

If we could somehow look inside a phenomenon, we would find the marks left by an object indicating a 'specific definite value' of a property.  We now have to see measurement as the equivalent of looking inside the phenomenon [seems horribly circular to me].  There can be no additional outside observations of the original phenomenon, except by really 'clever design' as in the Scully experiment.  Generally, though, pointers never indicate indeterminate values because measurement involves solving that indeterminacy [by entanglement between object and observing apparatus—handy how that always works though].  What this reveals is the need for a 'proper accounting of agential cuts'[a proper explanation of how they work in each particular case].

Back to Böhr [!].  All systems will reveal the operation of the Schrodinger equation, meaning that they are all open to the laws of quantum mechanics.  When he says we should use classical descriptions, what he means is that we should use descriptions that are appropriate for particular systems.  But actual systems are mixtures, combinations of individual states, not entangled ones, and the notion of mixture covers relations between objects and measuring apparatus.  We can continue to use terms appropriate for mixtures to describe quantum events.  What we are doing in effect is operating where'the degrees of freedom of the instruments are bracketed'(346) [very convenient and selective bracketing].  Otherwise, we must use quantum mechanics and the consequent indeterminacy to describe any property that is not affected by the experimental arrangement, and therefore not a mixture.  Whenever we use additional apparatus, we form some new phenomenon, so we have a new mixture [the argument seems to be that when we first use experimental apparatus we are entitled to see it as external and macroscopic even though we know that it is not except for the purposes of the experiment, but subsequent measures have to see the original apparatus as fully included in the phenomenon?].  This is a version, or example of agential separability [but it has been described entirely in human terms so far].   Again there is some empirical confirmation, or at least a supporting argument, suggesting that a pure state for a measuring instrument becomes a mixed one when we use it, as long as we ignore its degrees of freedom, and in effect, this is keeping it outside the phenomenon.

Agential separability is the issue, whether or not we see it as some external application of a measurement system, or as part of the phenomenon which we have artificially divided from the measurement system [it seems a repetition of the earlier point about how the measuring systems become phenomena when further measuring systems attempt to grasp the system.  She uses it as a way to explain that the full quantum behaviour does not show up in measurement because we cannot include the measurement device at the same time as using it.  The entanglement is not destroyed, but simply treated as a local mixture.  There is still really only one entity—the phenomenon].  We can place the agential cut differently by developing a different experimental arrangement—'it's all a matter of where we [NB] place the cut'(348).  All will be well as long as we fully acknowledge what we have done—how we account for the results.  We have to recognize how different cuts will produce 'differences that matter'.  She claims that the Scully work supports this view.

The Scully experiment shows the need to 'be clever enough to design an experiment'[why isn't this human agency?], and that we will not see quantum behaviour 'if we do the wrong experiment' (349).  It is not that we have used different macro measuring devices, but rather that we have discovered full quantum behaviour.  It is acknowledged to be very difficult to detect all the components of an entangled state, however [which seems to leave from the option of explaining any effects as the result of further components which have not been examined, not unlike the hidden local variable as above].  We can be consistent if we see the addition of extra measurement apparatuses as superposition.

We should be able to apply quantum theory to cosmology, as in the attempts to find a quantum theory of gravity, but this is proved difficult, and some people suggest an inconsistency between quantum and gravity.  It may just be the case that we cannot think of the measuring device outside the cosmos, and so we cannot apply the usual assumptions. Barad insists that there is no such thing as complete externality, and there can still be a separation between measurement and objects.  However there is a strong implication that the whole world can never be described, because intelligibility is always a relation between parts of it, and thus there must be an active and the passive part [or a subject and object].  Some cosmologists agree.

Overall, agential realism can incorporate the best of Böhr while extending his ontology and rejecting his humanism.  Böhr and Einstein do not define what they mean by human, which leaves room for conventional assumptions.  [If they tried to pin down the concept, they would see material components?].  Humanism also explains some of the apparently paradoxical elements of quantum theory such as Schrodinger and the cat paradox, and some measurement problems.  In agential realism, we should have to 'account for the intra active emergence of "humans" as a specifically differentiated phenomena [sic]' (352) [Bergson does].  Humans emerge from intra actions, and we are not just observers, but 'a natural phenomenon that needs to be accounted for'. 

Chapter eight

[Last one thank Christ.  A real mixture of gee whiz technology about new genetic engineering, with a bit of Levinas.  Ambiguities about things like responsibility and response are the things that link things together. Ludicrous anthropomorphism or the excessive generalization of terms like agency until they mean 'able to move' and then we can all have it]

Phenomena do not depend on humans, but we can  'bring forth the world and its specificity, including ourselves' (353), hence meeting the universe halfway. 

Our understanding of the atom has changed, certainly from Greek times—we know that they are not unbreakable objects, nor is the void which they inhabit a vacuum, empty: instead it is 'teaming with the full set of possibilities of what may come to be'(354).  This  'bubbling sea of possibilities' affects the very nature of subatomic particles.

Atoms are now seem to be actual bits of matter, real, partly because we can now rearrange them individually, and these practices are implicated in our understandings, as intra action.  [The example of rearranging individual atoms using stem tunneling microscopes is pursued 355f], and this has introduced the field of nanotechnology.  There is an immediate application in the field of electronics.  Interestingly, the ability to manipulate atoms arose as a possibility after the ST microscope was seen to leave streaks on the material it was being used to analyze: different currents can be used to image the surface or detach atoms from it, an example of [a good old binary] complementarity.  There is the same flirtation with the haptic as before.  Böhr can be used to extend this notion to break down barriers between objects and apparatus, object and subject.  The ability to manipulate atoms [one exercise involved recreating the IBM logo!] is a 'compelling emblem of the triumph of the scientific enterprise and its claims to scientific realism' (359-60).  However, we would be wrong to see this as a triumph for representationalist connections between words and things, because the atomic IBM logos are 'not snapshots of pre existing things', but 'condensations of multiple material practices across space and time'[and these include everything back to the role of the IBM Corp., and even that is only 'an abbreviated list': apparently it is a matter of what is '"relevantly interrelated"'{and who decides that?}].

For agential realism, the point is that what is disclosed is a result of intra action [empty formalism irrespective of content?].  Phenomena do not require human minds for their existence, and minds are themselves material phenomena.  What scientific practice does is to 'express ...the objective existence of particular material phenomena'(361).  Objectivity means accountability as argued before. 

There is now a gee whiz technology available to produce microscopic logical circuits, apparently using a cascade of molecules, where we intervene only to topple the first one through the st microscope.  This may be more metaphor than statement, but it does reveal a potential.  Just as Foucault suggest that power relations constitute specific bodies, so nanotechnology might be able to 'reconfigure the materiality about being all the way down to the very atoms of existence' (362): when this happens, we shall move beyond individualism and develop 'entanglements of becoming' between organic and inorganic, mind and body, and extend the notion of microphysics of power [still accepting Foucault's notions of domination?].

A lot of engineering goes on at these different scales, increasingly at the scale of life processes, and immense changes to life will soon be possible, it is assumed beneficial ones.  Apart from anything else, this will revalidate physics at the expense of biology.  However, 'ethical, legal, and social considerations' seem to be lagging behind, so we must reintroduce human terms like ethics and passion.

Considering an actual process like nanotechnology leads to a new technology of mimicking nature, 'biomimicry'.  A new postindustrial future is promised.  The dangers of misuse and abuse have been discussed, however.  There is also commercial rivalry, and a [greenwash] PR strategy by firms.  [The example of producing spider silk from goats' milk via genetic engineering is discussed 365f.  One account says that spider silk can itself be seen as an evolution of the arms race between spiders and bugs—nice and apologetic—and this justifies the collaboration between a Canadian corporation and the U.S. military in this development.  There will be useful civil developments as well, like in medicine.] There are principled complaints against genetic engineering, including a rebuke that it is not natural, usually met by saying that it might have once been an experiment in nature as well, however, and citing unfortunate examples of natural justifications of social selection and hierarchy.  We may have to admit human exceptionalism [Barad repeats her views that there is no hard and fast barrier between nature and culture, no pure nature, and rehearses the dubious political history of naturalism—so genetic engineering that undoes nature can also help with 'destabilizing sexism, racism, and homophobia' (369).  So bioengineering at least raises questions about the relation between nature and culture—but the whole thing requires further 'ethical considerations'].

Haraway is quoted in arguing that vision is a matter of the activity of visual systems, not just a passive matter, and that modern technology has developed this point.  [We then embark on a long discussion of a particular starfish, a brittlestar, which apparently has no eyes or brain, 370 F.  It still seems to react to light, however, and biologists eventually realized that the whole of its body is a kind of compound eye, of particular value in its actual environment where it needed lots of lights at night and not too much during the day.  This was confirmed by an inspection of the microscopic structure of one arm plate, with some resemblance to a digital camera.  There could even be a technological application.  One scientist at Exeter argued that the animal's micro structure exceeds human ingenuity.  This shows that nature is more imaginative than modern science.  There are implications for the fabrication of smart materials, and much good publicity for the lab doing the research]. 

There's even a chance to rebuke representationalism again because the starfish rebukes the notion of 'epistemological lenses or the geometrical optics of reflection' (375).  Its visual system is embodied, so that being and knowing entailed each other.  As it has no brain, there can be no knowing subject [quite -- so no real knowledge as such either].  The animal can break off a damaged body part and regrow it, so it has flexible bodily boundaries.  This leads to a ludicrous ambiguity—the reworking of its bodily boundaries can be seen as 'discursive practices—the boundary drawing practices by which it differentiates itself from the environments with which it intra acts...  materially enacted'.  It displays some logical activity and thus 'plays an agentive role role in its differential production'(376).  Its enactment of the difference between its body and the environment is rendered as 'the agential cut between "self" and "other" (eg "surrounding environment")'.  The starfish challenges traditional notions of embodiment, and of objectivity if that depends on a detached view.  It shows that the body is a performance, and that there is no newtonian separation between bodies, that 'the relationship between space, time, and matter is much more intimate' [for fucking starfish!].  Embodiment is more a matter of 'being of the world in its dynamic specificity' (377).  The starfish also shows 'great diversity in sexual behavior and reproduction', and some can reproduce asexually by regenerating bodies out of parts.  This activity also challenges conventional understandings of the difference between body and environment, or bodily boundaries: 'rethinking embodiment in this way will surely require rethinking psychoanalysis as well' [she comments on the 'possibilities for lost limb memory trauma' -- only relevant is we want to psychoanalyze starfish or develop a psychoanalysis so general that it can apply to starfish?]. 

We can see brittlestars as diffraction gratings, attuned to processes of differentiation, within determinate boundaries.  Since the animal is engaged in a struggle for survival, this bodily diffraction is 'not about any difference but about which differences matter' [to a starfish -- a pretty limited list I'd have thought] (378).  They 'know better than to get caught up in a geometrical optics of knowing'.  Since that optics is also found in classical physics, to use it necessarily limits the analysis, as we saw all with the neglect of quantum effects.  The use of that optics in effect marks 'the epistemological limit of science studies' as well, since it does not allow nature an active role.  We continue to think of this as located in human subjects, but 'the democratizing move is to invite nonhuman entities into our sociality', not on our own terms but after a proper 'account for the ontology of knowing'. [So it is not just a theoretical imperative?]

[Then unbelievable anthropomorphism] 'Brittlestars literally enact my agential realist ontoepistemological point about the entangled practices of knowing and being.  They challenge our Cartesian habits of mind' (379) and show us that knowledge making is not mediated but is rather 'a direct material engagement...  a part of the world in its dynamic material configuring'.  Apparently they make stimuli intelligible through intra actions.  Knowing is not exclusive to humans.  It requires no thinking brain [! If we define it as reacting].  Subjects may be differently constituted across the presumed boundaries, so knowing itself is a distributed practice.  Our own participation in practices of knowing is 'part of the larger material configuration of the world and its ongoing open-ended articulation'[usual stuff about one part of the world becoming intelligible to another part.]

It is not just that knowing involves 'having different responses to different stimuli' (380) but in dealing with  'differential accountability as to what matters'.  Responsiveness will include accountability to marks on bodies 'as part of the topologically dynamic complex of performances'.  [and then a bit that seems to imply that measurements are 'discursively significant' only when they appear 'in reliably recognizable and normatively accountable ways' [citing Rouse].  A recognition does not mean human cognition, however, since even a brittlestar can recognize a predator [what—the concept of one?].  It can differentially respond in ways that matter for its survival.  Recognizability is not fixed but affected by specific practices [I think this means it is not abstract but connected to significant, 'normative' circumstances].  Different intra actions themselves produce different materializations which provide different stakes for recognizability and its enactment [and then pure bullshit: 'in an important sense, it matters to the world how the world comes to matter'—well, it matters to actors, but she then insists they are nothing but parts of the world]

The Cartesian legacy means we put our faith in representations instead of matter, thinking that we have better access to representations.  This is why we develop representationalism and geometrical optics [it's all down to Descartes?].  The diffraction metaphor shows how we should operate instead via a clean break.  Diffraction is the key.  It does not just disrupt representationalism and metaphors of reflection, but is 'an ethico-onto-epistemological matter'(381).  This is a part of the intra actions of the world, and we see this better if we abandon notions of separability of subject and object and all the rest.  Once we accept entanglement, we can see that diffraction follows, hence that there are differences that matter—hence 'diffraction is a material practice for making a difference, for topologically reconfiguring connections'[this breathy conclusion follows from all the mutually interlocking definitions] Starfish are agentive beings not just objects for us to understand.  [Then this crap—'"humans" and "brittlestars' learn about and co- constitute each other through a variety of brittlestar - human intra actions'(381 - 2) [how the fuck do brittlestars learn about us?  What actual  agency do they have compared to ours?].

[Flowery crap about sameness and its symmetry, 382].  Attentiveness to difference is what matters in biomimesis [after arguments for sameness in terms of agency!].  Technologists do not just imitate nature but take it is an inspiration and embrace the new [she admits 'for very practical reasons', including the need to gain copyright].  Mimesis is not reproduction, and she sees the problem with claiming something is original—everything is produced through intra activity, even the past, and everything that exists 'holds the memories of the traces of its enfoldings' (383), so phenomena do not simply exist at one location in space and time, so copyrighting something is [equals should be] a matter of the responsibility for producing difference.

The new biotechnologies reveal more complex entanglement.  They are being enthusiastically supported by government and private industry, as well as hybrid teams of researchers.  Interdisciplinary study has long been advocated by social sciences but has not had the same sort of support.  Now there's the possibility 'for forming [very very unequal] partnerships with brittlestars and other organisms', to form assemblages that mimic existing entanglements of objects and tools.  These also reconfigure human being, imagination, institutions and societies.  Ethical questions extend to these projects too, and should not be limited to some notion of mechanical intervention with objects.  It is about mattering, developing new configurations and new possibilities, new cuts and some new entanglements, in a 'specific case by case accountings for marks on bodies'[in other words hopeful stuff endlessly deferred].

Quantum entanglement has had a high profile as a result of possible quantum computers where we might read the characteristics of one distant particle from another local one—'information teleportation'(385).  It is a serious possibility, and several major institutions are interested.  Quantum theory is no longer just philosophical, a sideline.  Now the metaphysical issues are prominent—a second quantum revolution.  Quantum entanglement is the key, and the implications for new technology.  Quantum computers are a major interest and might produce considerable increases in computing power.  They offer parallel processing and considerably more miniaturization.  The technology is crucial 'for maintaining our competitive edge' (386) and the implications extend to National Security and global information.  Processing large integers is the basis of encryption systems used by major banks.  Quantum cryptography might speed up the transmission of information over a distance and would offer a secure transmission: this is already commercially available (387) [apparently used in synchronized atomic clocks].  Quantum teleportation involves 'transporting the properties of one object to another' across unlimited distance.  This has been realized in the laboratory.

So there's a whole entangled web of phenomena [impressive diagram on 389 showing how it all links together].  It all constitutes  'an ever changing multi dimensional topological manifold of spacetimematter' (388) [although the diagram of course is a two dimensional graph in effect, although it has blobs which are in the process of materializing, and it clearly cannot show dynamic change and relations—Barad says it's is an example of how conventional representations struggle with the notion of entanglement and intra action—all the individual items, naturally are intra acting with each other 'and mutually constituting one another'(389)].

Apparatuses are phenomena themselves and can be enfolded iteratively into other practices.  If these cross boundaries of space, time or subculture, they can produce new phenomena.  The shifts which occur are important—some 'can materialize a different configuration of the world' (390) as well as a change of the way we understand it.  We are responsible because our particular practices, which we shape and are shaped by, can produce different segments of reality.  We need to understand this reconfiguring if we are to do responsible practice.  That will require 'a rich genealogical accounting' of the apparatuses and their entanglements—definitions, correct operation of equipment, determinate effects, standards of interpretation, 'constitutive practices in the fullness of their materialities' (391).  It is not just a matter of the results, but how the very possibilities for change have altered.  Although 'we are not the only active beings...this is never a justification for deflecting our responsibility on to others'[which expresses the weaseling about whether there is or is not something distinctive about human beings in a nutshell].

We can turn to Levinas to understand that responsibility turns on acknowledging  'the otherness of the Other', as an essential and fundamental part of subjectivity.  The ethical subject therefore is 'an embodied sensibility'.  It operates through a 'a mode of wonderment that is antecedent to consciousness'.  A feminist called Ziarek says this should be expressed through touch and sensibility, a form of embodiment as prototype ethical experience.  Embodiment includes the other, the '"non coincidence with oneself within the lived body"' (392).  We do not choose responsibility—it is 'an incarnate relation that precedes the intentionality of consciousness'.  This should extend to the nonhuman especially as the boundaries of the human are being reconfigured—a 'post humanist ethics, an ethics of worlding'.  Cultural responsibilities not just added on but are essentially embodied, and we can argue that similarly, 'nature expresses itself, that nature is not the other of thought or speech'.  Thus responsibility to others, including nonhuman ones, is a primary mode of objectivity as well as subjectivity [nice try].

Matter is intra active becoming.  All bodies, including nonhuman ones, come to matter through iterative intra activity [only in the most abstract way].  All boundaries, properties and meanings are enacted.  Differentiation is not something radical and exterior but agential, and it implies not othering and commitments, but 'making connections and commitments'.  Entanglement includes the other, and the subject/object boundary is enacted not eternal, so in a way the other is already included in us.  'This is as true for electrons as it is for brittlestars as it is for the differentially constituted human' (393).

Human subjects are not the only location for knowing, nor for ethicality, so responsibilities for the other are shared [what shared by electrons and brittlestars?  She is simply trying to get away with glossing over human ethics as a material factor, because otherwise she would have to admit that humans are separate after all]. We are responsible not only for the other but for the 'lively relationalities of becoming of which we are a part'[that is for our tinkerings with nature?  Is anyone or anything responsible for all the other kinds of becoming?]. 

[As before] We have to rethink causality as a matter of intra activity and as an enactment so that some things come to matter and other are excluded.  We might call it emergence in a strong sense.  Space time and matter are all 'iteratively produced and performed'(393).  Each intra action reconfigures the manifold, so there are no individual causes or agents of change.  'Responsibility is not ours alone', but it takes an even greater form than before, because we must now be responsive to all these entanglements, including relations with things that are far off and in the past: these are never out of touch, except as an act of exclusion.  We are an intimate part of the universe.  The effects of our action are extensive, ranging through the 'interconnectedness of being', not limited to simple effects.  Each act reconfigures the world and therefore is 'sedimented into our becoming'.  We cannot go on to separate again.  We are in a cascade experiment [like a game of dominoes].
[I reworked this section with a bit more detail, tryng to pin down this strange phrase about incarnate relations preceding consciousness which crops up a lot]:

From Barad 2007, on the incarnate relation.
It takes place in a section called 'towards an ethics of mattering' 391F, and begins with Levinas saying that the otherness of the other is given in responsibility which is the primary mode of subjectivity, so ethics itself is a part of subjectivity and existential base. It's not a matter of individuality but a relation of responsibility to the other. The ethical subject is not the usual one 'but rather an embodied sensibility which response to its proximal relationship to the other through a mode of wonderment that is antecedent to consciousness' (391), and this links to feminist work on how ethical significance is crystallised in touch [the same one, Ziarek, who appears in the touching piece], and she interprets Levinas to mean that embodiment is not the surface for the inscription of culture nor just the biological body, but '"the condition of relations to objects but also a prototype of an ethical experience"' (Barad p.391 quoting Ziarek) — it is not the body in self reflection because the self is always embodied — the embodied self is 'the pre-logical, pre-synthetic entwinement of thought and carnality, or what Levin asked calls "being in one's skin"'.
Barad says that this means we can't escape responsibility, because this is 'a prior ethical relation', referring to 'non-coincidence within oneself'which therefore becomes the basis for ethical relations to others — 'before all reciprocity in the face of the other, I am responsible' (392). Therefore responsibility is an incarnate relation [that is embodied?], Something prior to every engagement. She wants to extend alterity to include other than human as an aspect of non-coincidence with oneself. And then argues that this is not just a matter for human embodiment, that responsibility is not just about human encounters because the boundaries of the human are continually being reconfigured. This is why humanist ethics won't suffice and why we need post-humanist ethics, 'an ethics of worlding' (392).

Levinas says that culture does not add extra attributes onto some representation of the thing, but '"the cultural is essentially embodied thought expressing itself, the very life of flesh manifesting" [quoted by Z]. Barad goes on to suggest that we might think of this as being 'true of nature as well… That nature expresses itself, that nature is not the other of thought or speech' (392) [she actually puts this in subjunctive form — 'what would it mean', 'what if we were to acknowledge']. The materiality of everything as well as human embodiment 'always already entails "an exposure to the Other"'. If we did acknowledge that then 'responsibility is "the essential, primary and fundamental mode" of objectivity as well as subjectivity'

In agential realism matter is indeed a dynamic expression or articulation of the world in its becoming all bodies come to matter through the performative at a of the world. Interactivity produces differential enactments of boundaries properties and meanings. Differentiation is not radical exteriority but 'agential separability' as much about 'making connections and commitments' as 'othering or separating'(392). Matter is always entangled with the Other. Intra-action co-constitutes parts of phenomena. This applies to objects as well as subjects, so [extending Levinas] the other is not just in our skin but in our material bodies and 'this is as true for electrons as it is for brittle stars as it is for the differentially constituted human'.

The human subject is neither the locus of knowing nor of ethicality because we are always already responsible to others with whom we are entangled even if 'not through conscious intent' but rather through 'ontological entanglements that materiality entails' (393). Agential cuts do not separate totally, nor do they individuate. Ethics is not about the right response to others as exterior but about 'responsibility and accountability for the lively relationality is becoming of which we are a part' (393) ]

For some physicists [somebody called Dyson], this has led not to indecision and doubt but to a cheerful life of decisions and actions, taking risks, facing tough questions [he seems a bit of a nut who is capable of justifying any project, and seems to believe he will be answerable in the end to his maker].  The dilemmas about intervention or detachment are chronic, and there are many specific questions we should answer [lots of rhetorical ones 396], so we need to start asking ethical questions.  Ethics are integral.  We must not tear 'holes in the delicate tissue structure of entanglements that the lifeblood of the world runs through'.  We must be alive to the possibilities of becoming, to meet the universe halfway, 'to take responsibility for the role that we play in the world's differential becoming'[so it all ends on the usual pious notes about how we must all agonize about stuff, as long as it doesn't stop technology and science and actually getting on with it. We can see that she has already accepted competitive capitalist science and sometimes openly apologized for it].

The poem which include the term 'meeting the universe halfway' appears in an appendix

NB. Barad K (2014) Diffracting Diffraction: Cutting Together-Apart. Parallax 20 (3) 168--87. DOI: 10.1080/13534645.2014.927623 [Only got the first page. Didn't want to spend £37 on the rest]

'Diffraction owes as much to a thick legacy of feminist theorising about difference as it does to physics...diffrraction is a lively affair...one that troubles dichotomies...intra-acting with diffraction is particularly apt...intra-actions [must?] enact agential cuts which do not produce absolute separations but rather cut together-apart...there is no moving beyond, no leaving the 'old' behind...Diffraction is not a pattern but a (re)configuring of patters...Matter itself is diffracted, dispersed,threaded through with materialising  and sedimented effects of iterative reconfigurings [at the quantum level these might be important, at the macro level so small as to be insignificant?]...Matter is a sedimented intra-acting, an open field. Sedimenting does not entail closure (Mountain ranges in their liveliness attest to this fact).'

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