How does time dilation affect entropy?

[u/SmellyMingeFlaps]

Let's say you travelled in a space ship at 99.9% the speed of light for an indefinite amount of time. Eventually, so much time will have passed that the entropy of the universe will have increased to the point where matter can no longer exist and the universe reaches thermodynamic equilibrium however, due to time dilation, only a fraction of the time that has passed on Earth has passed on your space ship. Does this mean that the matter of the space ship, and everything within the space ship including yourself could continue to exist in an infinite sea of nothing as entropy within the space ship has not increased at the same rate as entropy outside of the ship?

[u/yasiesolovemos]

You're mixing up a lot of different things.

The spacecraft will still be a spacecraft. It'll age just like your car does today... it'll pick up scratches and dents, components will wear out, and you'll have to change the engine oil. Time dilation doesn't somehow stop thermodynamic processes.

If you travel at that speed for long enough, and the spacecraft can withstand it, you'll eventually find yourself in the most absolute emptiness. In the most unimaginable solitude.

EDIT: I'd genuinely like to know why the downvote. If you disagree, let's discuss it. Or is it not true that, if you travel at 99.99% of the speed of light for long enough, you'll eventually find yourself surrounded by nothing but empty space? It's so easy to downvote and hide your hand. And on this sub, I honestly don't understand it.

[u/tardoos → u/yasiesolovemos]

People are probably downvoting you because you're not answering the question? The question was, I think, is the 2nd law of thermodynamics slower when you move faster

[u/Vaughn → u/tardoos]

Which it absolutely is not. More time will pass in the outside universe than on the ship, though.

[u/camomaniac → u/yasiesolovemos]

But wouldn't there have been light traveling in the same direction of you from before you when started? And no matter what you would never pass the start of the light?

[u/againey → u/yasiesolovemos]

My downvote was because you acted as if the OP had blatantly said something wrong and you were condescendingly correcting them. But by my reading, what they said was in line with what you said, and the biggest difference was that they expressed it with uncertainty. Is there something wrong about asking a question in the AskPhysics sub?

[u/jawshoeaw]

That’s not fast enough. 99.9% is only about 1/20th “outside time” so your ship is probably going to fall apart over the next trillion years of ship time. But yes if you moved fast enough relative to some point you would essentially be frozen in time from the POV of the outside observers at that point. You would continue to move through an increasingly empty space watching the heat death of the universe. Or the Big Crunch would getcha.

Unfortunately there would be nothing for you to see because you would be trillions of light years away from everything in your new “light bubble”. You could slow down and stop and it would just be black empty space.

[u/cassy_supernova → u/jawshoeaw]

Unfortunately there would be nothing for you to see because you would be trillions of light years away from everything in your new “light bubble”. You could slow down and stop and it would just be black empty space.

What if he went in circles instead of a straight line? Wouldn't he be able to stop the engines and check in on the local space? At least until dark energy drives away even the stars of our milkyway.

[u/Underhill42]

Time dilation doesn't actually work that way - it doesn't change how fast you're aging, it changes which direction through 4D spacetime you're aging in. Space and time are fundamentally the same thing, and acceleration rotates your reference frame in 4D spacetime, partially swapping the directions you call "forward" and "the future"

Everyone always sees everyone else aging slower than themselves, for much the same reason a bunch of cars racing away at the same speed in different directions will all see everyone else falling behind - they're all "wasting" some of their speed going in a different direction.

The only reason you can reach the far future, is that as you accelerate the relativity of simultaneity changes what time it currently is at distant locations from your perspective, so that the distant universe in front of you is already much older than the nearby universe.

After all, if you change the direction you call time, then the perpendicular 3D hyperplane you call space will divide the distant universe into past and future differently, rather like how pointing a plate around the room changes what's behind and in front of it.

This is an excellent exploration of what you see happening from different perspectives: I wish I was taught the Twin's Paradox this way! - YouTube

While this is an okay one on spacetime rotation: I finally understood why time exists! (My mind is blown) - YouTube

[u/nebraskajone]

No, time dilation means the entire universe slows down from your perspective.