How queer is quantum field theory?

Karen Barad knows quantum field theory, and she knows queer, and ties the two subjects together in a hilarious intellectual tour de force. Along the way, she offers a compelling portrait of the quantum vacuum, a bubbling sea of particles popping in and out of existence on a time scale inversely proportional to their mass.

She makes one error which I’ve seen so many times before I’ll have to excuse it, although in her case I suspect she really should know better. What happens when two solid objects “touch” physically that makes them unable to occupy the same space at the same time? Barad repeats the idea we’ve heard so many times before: that the negative electron clouds in the two objects repel each other. The truth is stranger than this. When I was in school, it used to be called “degeneracy pressure”. The electrons in any solid are in their lowest energy state, but “lowest” is relative. The energy of each electron, as a temperature, actually corresponds to tens of thousands of degrees. Of course they would “prefer” to be in a lower state, but all the lower states are occupied, and the Pauli Exclusion Principle (not electrostatic repulsion) prevents them from doubling up. The reason that solids are hard and impenetrable is the same reason that solids resist enormous pressures with only the slightest compression. It is that there are electrons are occupying every availabe quantum state, and you can’t put more electrons into that space without pushing into the next quantum state up, which has a very high energy, compared to what is normally available.

(Excuse me for witing this explanation again––it’s one of my favorite topics.)

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