I am curious if anyone is aware of a quantum mechanical discription of redshift. Is there a slick (or any other) way to derive this effect from the foundations of QM?
It may help if you specify what sort of redshift you’re talking about. a quantum explanation of gravitational redshift, for example, probably can’t be derived solely via QM (though principles of QM do come into play), because we don’t have a quantum theory of gravity
I usually treat redshift from the viewpoint of relativity, not QM, but that’s probably because of the kinds of redshift (e.g. Hubble expansion, gravity, etc.) I end up discussing moat often.
Thanks for the clarification KP, I was refering to gravitational redshift. I’ve also seen gravitational redshift discussed (though not derived from first principles) in the context of relativity.
As KP says, a quantum-mechanical theory of gravity does not exist yet. But the behavior of quantum systems in curved “background” spacetimes (where the quantum system is not massive enough to appreciably affect the curvature of the spacetime) can be predicted using relativistic quantum field theory. If you’re interested in, for example, the behavior of (not outrageously-high-energy) photons near stellar-mass black holes, then the background spacetime is essentially independent of the photon’s state and RQFTs are a pretty good model.
Semi-classical theories of gravity try to describe the effects of gravity on quantum systems, by (as Omphla says) performing quantum field theory (relativistic quantum field theory is a correct and used term but as most quantum field theories are relativistic QFT automatically implies relativistic) in a background of curved spacetime.
Maybe M-Theory has some sway here.