Can Closed Timelike Curves Violate Entropy by Allowing Time Travel?

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Discussion Overview

The discussion centers around the implications of Closed Timelike Curves (CTCs) on the concept of entropy and the nature of time travel. Participants explore theoretical aspects of time flow, entropy, and the potential paradoxes arising from time travel scenarios.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants question the relationship between the flow of time and entropy, suggesting that if CTCs exist, they could allow travel to a state of lower entropy.
  • One participant describes a scenario involving an ice cube melting, arguing that while the future state is more probable due to entropy, the initial low-entropy state of the universe remains a mystery.
  • Another participant notes that while entropy has been observed, CTCs have not, implying a distinction between established phenomena and theoretical constructs.
  • Several participants discuss the implications of encountering a younger version of oneself through time travel, raising questions about identity and the existence of multiple versions of a person.
  • One participant challenges the notion that there can only be one true version of a person, asking for the origin of this supposition.
  • Another participant suggests that the existence of a younger self alongside the present self does not inherently pose a problem, but interactions between the two could lead to paradoxes, referencing the "grandfather paradox."

Areas of Agreement / Disagreement

Participants express a range of views on the implications of CTCs and entropy, with no consensus reached on whether CTCs could violate the principles of entropy or the nature of identity in time travel scenarios.

Contextual Notes

Participants highlight the lack of consensus on the foundational reasons behind the low-entropy state of the universe and the theoretical nature of CTCs, which remain unobserved.

Who May Find This Useful

This discussion may be of interest to those exploring theoretical physics, particularly in the areas of time travel, entropy, and the philosophical implications of identity in the context of Closed Timelike Curves.

TheQuestionGuy14
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What makes time flow forward? Why does it never flow backward? Some people say entropy, but if Closed Timelike Curves exist, wouldn't it violate entropy? As you can go back in time to a universe of lower entropy and more order?
 
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The flow of time is both mysterious and not very mysterious.

The not-very-mysterious explanation. Let's take a situation in which you have an ice cube sitting in a puddle of water on a hot slab of concrete. As far as the laws of physics, the following two futures are both possible:
  1. The ice cube gets smaller and the puddle of water gets larger and the concrete gets cooler.
  2. The ice cube gets larger and the puddle of water gets smaller and the concrete gets warmer.
So why is it that we only see #1 and not #2? That's actually not mysterious. There are an enormous number of ways you can assign velocities to the water molecules in the ice and puddle. The vast majority of those choices will lead to the ice melting in the future. So it is almost certain that the ice will melt.

So that's not mysterious. But back up a little further, and ask why was there a block of ice sitting on a slab of concrete, in the first place? THAT seems enormously unlikely, as well.

So that's the mysterious and non-mysterious sides of the question. Given that the universe is the way that it is, with hydrogen to burn in stars, and with plants to absorb light to grow, and with creatures to eat the plants, etc., it's very likely that events will unfold in one direction only: the direction of increasing entropy. So that's not mysterious. But the fact that the universe started out having a very low entropy is mysterious. I don't think there is a consensus about why it should be that way, other than: that's just the way it is.
 
TheQuestionGuy14 said:
Some people say entropy, but if Closed Timelike Curves exist,
Entropy has been observed. Closed timelike curves have not.
 
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When I think about it, if you took a wormhole or timewarp to a previous time, you could encounter the younger you. However, supposedly there can only be one true version of each person so that might be what makes it not possible.
 
osilmag said:
supposedly there can only be one true version of each person

Where does this "supposition" come from?
 
I've never been replicated or cloned. And if I went back in time, my younger self would exist along with the present self. That would be quite a conundrum.
 
osilmag said:
I've never been replicated or cloned. And if I went back in time, my younger self would exist along with the present self. That would be quite a conundrum.
It would, but this is no scientific reason it cannot happen under the assumption that traveling back in time is possible at all. Thus it is not suited to falsify this hypothesis.
 
osilmag said:
if I went back in time, my younger self would exist along with the present self

Yes, but not because you were replicated or cloned; because your path through spacetime would have a loop in it, so it could return to the same small region of spacetime twice. That doesn't require duplicating anything.
 
osilmag said:
I've never been replicated or cloned. And if I went back in time, my younger self would exist along with the present self. That would be quite a conundrum.
The mere fact of existing alongside your younger self would not seem to be immediately problematic. The difficulty is with possible interaction. For instance, the temptation to advise your younger self not to make the same mistakes you've made. That is just the "grandfather paradox" posed a different way.
 
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Closed. No more threads on CTC existence please.
 
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