Meeting the Universe Halfway (2007). For anyone who knows Whitehead's philosophy of organism, Barad's relational ontology that she develops in response to the mysteries of quantum physics will be familiar. Like Whitehead did in his time, Barad is interacting with the physicist Neils Bohr and the Copenhagen interpretation of quantum physics. However, while Whitehead's primary philosophical conversation partners were William James, Spinoza, and Leibniz, Barad engages post-structuralists like Judith Butler and Michel Foucault.
Very much like Whitehead's "actual occasions," Barad argues that the basic constituents of the world are "intra-active phenomena" or "relational atoms." In other words, they agree that everything is agential in some sense, so nature is not divided in two. This ontology also implies a view of nature as interconnected or "entangled." As such, nature is not composed of preexisting entities or individuals but is fully relational and always in becoming. Anything that endures (i.e., sensible matter) only arises out of various relational processes in repetition. There are therefore no substances or essences, which Whitehead identified as examples of "the fallacy of misplaced concreteness" and Barad calls "the metaphysics of individualism." There are only relatively stable patterns of repeating processes, which we might call "habits" (Whitehead) or "sedimentations" (Barad) of nature.
One additional similarity that I will note between Whitehead and Barad is that they each affirm a type of realism. Neither of them are talking about a naive realism, which is the position that we directly experience the world as a collection of external objects in an unmediated way. And they equally reject representationalist realism, which is the dualistic view that we can stand back from the world as an external collection of individual objects and indirectly re-present them to our mind. Instead, Whitehead and Barad affirm relational realism (not their term, but an accurate one nevertheless). This position affirms a real world that is irreducible to our social constructions, and also affirms that scientific theories can provide reliable access to the ontology of the world. But it rejects the basis of representationalism - the notion that there are external and unitary objects that we, as internal subjects, can perceive more-or-less accurately.
What relational realism affirms is that humans, like anything else in a panagential world, are always in becoming and relationally constituted. The traditional realist divides between external world and internal knowing, nature and culture, nonhuman and human, matter and mind, dead matter and lively matter do not hold in this view. Instead, our knowing directly participates in and influences the world - even as the world reciprocally influences our knowing. Knowing is thus a creative event of intra-acting material processes. Knowing, theorizing, or experimenting never take place from the outside in some sort of neutral space but always from within, as material practices. There is therefore no such thing as purely "objective knowledge" because - as quantum physics teaches us - objects only emerge as a result of particular intra-actions. Knowing is always involved in particular intra-actions as much as any other type of activity, human or otherwise. As such, we are responsible for our knowledge claims and cannot separate ethics from epistemology or ontology. Barad thus coins the term "ethico-onto-epistemology."
While post-structuralists are usually identified as anti-realists, Barad goes out of her way to argue for an extremely critical kind of realism that she calls "agential realism." Whitehead calls his similar perspective a "pluralistic" and "provisional" realism. I find this connection between process thought and Barad's new materialist ontology to be encouraging and exciting, especially since Barad never interacts with Whitehead's thought in her work.