# Curious about time dilation?

Here's a scenario:

A crew travels through the Universe in a spaceship capable of 100% light speed. Relativity states that anyone inside of said craft will experience time dilation, possibly to the point of time coming to a complete stop for the crew/passengers. But time passes much quicker for the outside Universe in relation to the crew/passengers. So, in theory, the crew could survive the death of the Universe itself. Is that possible...assuming, of course, the ship could actually achieve light speed?

## Answers and Replies

But the ship cannot travel at 100% the speed of light for it would require infinite energy.

Just say for the sake of argument it could achieve light speed...what then? Would the crew be able to survive the death of the Universe through time dilation?

A thought experiment must still make theoretical sense no matter how technically improbable. Therefore you cannot postulate a thought experiment that contains elements that are not possible within the current understanding of physical laws and yet still ask that the question be answered in terms of the very physical laws that are forbidden by your thought experiment.

Otherwise in the 'photon in a box' experiment postulated by Einstein, he could have just said to Bohr, "but what if we pretend that there is no time dilation due to relativity', then surely I have proved that quantum mechanics is inconsistent"

Hmm...

put it another way. If you can postulate that you have a magic fairy who gives your spaceship the ability to defy the laws of physics and travel at 100% the speed of light, thereby creating a conundrum, then I am also allowed to use my magic fairy who will magically counter any conundrum that your magic fairy causes.

DrGreg
Gold Member
A crew travels through the Universe in a spaceship capable of 100% light speed. Relativity states that anyone inside of said craft will experience time dilation, possibly to the point of time coming to a complete stop for the crew/passengers. But time passes much quicker for the outside Universe in relation to the crew/passengers. So, in theory, the crew could survive the death of the Universe itself. Is that possible...assuming, of course, the ship could actually achieve light speed?
If you insist on 100% light speed, then relativity cannot answer your question because relativity says this is impossible. However if you are prepared to accept, say, 99.999999999999% of the speed of light relative to some observer, then in theory you could travel to the end of the Universe if you add enough 9s to the end.

(In practice you'd never make it because you'd need an astronomically huge amount of energy to reach that speed, you would eventually collide with something and be destroyed, and in any case you'd be fried by blue-shifted gamma radiation.)

DaveC426913
Gold Member
Boy, I really wanted to participate in this thread. But there is nothing to add YummyFur's and DrGreg's concise responses.

I will add that he is more speaking of the "Death of the universe" in a time-line sense, so no, you would not out-exist the universe, the universe would just die much faster to you?[Given the 99.999999999% accepting part of course]

Dale
Mentor
2021 Award
If you can postulate that you have a magic fairy who gives your spaceship the ability to defy the laws of physics and travel at 100% the speed of light, thereby creating a conundrum, then I am also allowed to use my magic fairy who will magically counter any conundrum that your magic fairy causes.
:rofl: Well said!