Connection between entropy and time travel?

[mollwollfumble]

My background is that I'm an applied mathematician and engineer, self-taught in GR and QFT. It's an old idea, in some dozen or so SciFi books. But I'm looking for a mathematical framework for handling it. The second law of thermodynamics, that entropy always increases in a closed system, can be broken only in pocket quantum systems with temperatures below absolute zero or hotter than infinity. I want to add here that the second law of thermodynamics holds when statistical mechanics fails, in the early universe when baryon numbers are not conserved.

There is no law forbidding backwards time travel, but let's suppose that there is. This law can also be violated, but only in pocket relativistic systems in the vicinity of singularities. Could there be a consistent mathematical framework that ties together "there is no perpetual motion machine" and "there are no closed timelike loops in GR"? What would this mathematical framework look like?

 

[PeterDonis]

The second law of thermodynamics, that entropy always increases in a closed system, can be broken only in pocket quantum systems with temperatures below absolute zero or hotter than infinity.

How can such systems break the second law?

I want to add here that the second law of thermodynamics holds when statistical mechanics fails, in the early universe when baryon numbers are not conserved.

Why would the non-conservation of baryon number cause statistical mechanics to fail?

There is no law forbidding backwards time travel

There isn't? Why not?

 

[Paul Colby]

There is no law forbidding backwards time travel

What about energy conservation? To the poor sods not time traveling the mass equivalent of the time traveler can't just appear where it wasn't before.