Another physics blogger, Stephen "Cooley" Sekula, comments here:
http://steve.cooleysekula.net/blog/2...y-in-daylight/
Here's a sample of what Sekula has to say:
"What if gravity is a consequence...of a known phenomenon: superfluidity?
In the paper, Bob suggests something which has apparently not been suggested before:
neutrinos, or any other purely weakly interacting particle left over from the big bang (so-called “relics” of the big bang), interact SO rarely and SO weakly that by now, their wave functions are bigger than the space between them - they are “non-localized”, in the language of quantum mechanics. Just like electrons in a superconductor, this means that these relics are in a super-state - a super-fluid, in this case. Like electrons in a very cold conductor, below the superconducting critical temperature, if there is any force that is even slightly attractive between them they will form bound states - pairs, in the simplest case. This is analogous to the electron “Cooper pairs” of superconductors which make them superconducting.
Neutrinos - fermions, with half-integer spin - will then form bosonic bound states with integer spin. Bob identifies one of these as having the same properties as the hypothetical graviton, the particle that is alleged to carry the gravitational force. Gravity emerges as a consequence of the electroweak force - thus the title of the paper.
He might be wrong. In fact, in seminars he’s given recently he says as much. He notes that the theory is testable and falsifiable, although I would bet that will take some work even with our available technology. I find the whole notion intriguing. Rather than appealing to some far off energy scale, or vibrating 11-dimensional objects, what if gravity is as simple as neutrinos in a superfluid state?..."
Incidental information: Stephen Sekula and Edward Witten are two of the people whom McElrath thanks, for their useful comments, in the Acknowledgements section.