Physics

As my dissertation advisor, Stephen Carlip, likes to say "It's not that we don't have a quantum theory of gravity, it's that we have too many!" One of the first attempts at quantizing gravity, the Semiclassical Theory of Gravity, by Einstein, Moller and Rosenfeld, was a simple-minded and naive approach, and although nobody believes it, nobody has been able to disprove it in over a 100 years of trying. My focus was to explore this theory, and its state equation, the "Schrodinger-Newton Equation", and find a way to test it experimentally.

I found a prediction that this theory makes about a special type of diffraction that we should be able to use to test its validity. The problem is that the experiment is on the very edge of what is technologically possible: the diffraction of something as massive as a virus. If we can force a virus to diffract, we can test the theory. Actually, a diffracting virus would be a tragedy because it would mean that the theory is simply not wrong (i.e. it could still be right and we have learned nothing). If we can do the experiment and the virus does NOT diffract, then the theory is wrong and can finally be laid to rest forever.

During my research, I discovered a fascinating phenomena predicted by the Schrodinger-Newton Equation: under a Newtonian potential, an extended particle collapses under its own gravitational well: gravitational wavefunction collapse. This is astonishing because it explains why we don't see weird quantum effects in everyday life: gravitational self-interaction of extended objects is so strong that it forces them to behave classically.

Although nobody in their right mind believes that the Schrodinger-Newton Equation is the correct theory of quantum gravity, this particular prediction is precisely what almost everyone believes: it explains one of the weirdest things about quantum mechanics. It would finally solve Einstein's famous cat paradox!

But like I said, nobody believes the theory. I believe even Einstein, Moller, and Rosenfeld simply used the idea as an academic springboard, hoping that the idea would germinate other good ideas in other people.