That's where string theory actually comes in, to help (somewhat) defend the idea of backwards time travel. Of course, it involves Schrodinger's idea of reopening a new parallel dimension, a universe separate from the one you came from. A universe that could have an entirely different future without affecting the future you came from. That still affects Thermodynamics in a way, but I always found that idea plausible.
So the onlything I know is that some kids on my MC server was talking about this and they were saying "No light = No time" I responded with "Thats right, Cause if i turn off the light, I can't see the clock." +rep for who was there, and Drpresident63, who isn't even a member here.
Quantum stuff hasn't been brought up because it's a different beast altogether. In fact, one of our major issues right now is marrying what we know about the quantum world with what we know about physics on a larger scale. They don't match up, and while string theory has attempted to bridge the gap, we're still at odds until we make another considerable breakthrough, hopefully by way of CERN.