There is a difference between understanding diffraction as a classical
physics phenomenon and understanding it quantum-mechanically. I have
taken this wonderful metaphor that Donna has given us and I have run
with it by adding important non-classical insights from quantum physics.
Diffraction, understood using quantum physics, is not just a matter of
interference, but of entanglement, an ethico-onto-epistemological matter.
This difference is very important. It underlines the fact that knowing is a
direct material engagement, a cutting together-apart, where cuts do violence
but also open up and rework the agential conditions of possibility. There
is not this knowing from a distance. Instead of there being a separation of
subject and object, there is an entanglement of subject and object, which
is called the “phenomenon.” Objectivity, instead of being about offering
an undistorted mirror image of the world, is about accountability to marks
on bodies, and responsibility to the entanglements of which we are a part.
That is the kind of shift that we get, if we move diffraction into the realm of
quantum physics. All of this is to say that we come up with a different way
of thinking about what insights the Sciences, the Humanities, the Arts, the
Social Sciences, and let’s not forget insights derived outside of academia,
can bring to one another by diffractively reading them through one another
for their various entanglements, and by being attentive to what gets excluded
as well as what comes to matter.
(Barad, "Matter feels, converses, suffers, desires, yearns and remembers", 52)