Undergrad Can a quantum state be thought of simply as one allowing bidirectional time travel?

[OwlHoot]

TL;DR

Quantum indeterminacy seems to share features in common with the well known contradictions of backward time travel, so could a quantum state simply be one which allows bidirectional time travel?

In relation to travel back in time, we've all heard of the grandfather paradox, whereby killing your grandfather before they sired offspring would preclude your future existence. This contradiction leads to the conclusion that time travel to the past must be impossible.

But it doesn't quite end there, because if, having killed him, you no longer exist in your "later time" then you can't go back in time and kill anyone. So, barring any other influences, one has an apparently infinite regress where you and your grandfather both exist and not exist at the same time. Sound familiar?

So could a quantum state be defined simply as one where travel back in time, as well as forward, is allowed within a system of limited complexity?

There's also the entropy aspect, in that entropy is always increasing, with near certainty. But if a quantum system is simple enough in its relevant aspects, then that need not hold. For example, if one's "system" was the sequence of results of casting two dice, and we agree that pairs of equal results are the low entropy states, then these can crop up over and over again indefinitely. But now add a hundred more dice to the system, and sets of all equal results of a collective throw become vanishingly unlikely. (I'm assuming implicitly that the "state" as actually some kind of continuous and rapid process of the system.)

 

[berkeman]

Thread closed for Moderation...

 

[Nugatory]

So, barring any other influences, one has an apparently infinite regress where you and your grandfather both exist and not exist at the same time. Sound familiar?

You are seeing a similarity with Schrodinger's cat that is dead and not dead at the same time, the virtual particles that pop in and out of existence, the particles that can be in two places at once?
All of those are urban legends fueled by sloppy pop-sci writers and have nothing to do with how quantum mechanics actually works or what it allows. So there's no escape from the grandfather paradox here.

There's also the entropy aspect, in that entropy is always increasing, with near certainty. But if a quantum system is simple enough in its relevant aspects, then that need not hold. For example, if one's "system" was the sequence of results of casting two dice, and we agree that pairs of equal results are the low entropy states, then these can crop up over and over again indefinitely. But now add a hundred more dice to the system, and sets of all equal results of a collective throw become vanishingly unlikely. (I'm assuming implicitly that the "state" as actually some kind of continuous and rapid process of the system.)

Sure, but that's just classical statistical mechanics, no quantum physics involved.

As this thread is based on a misunderstanding it will remain closed.