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Be_Cool_Bro t1_izboo4e wrote

Probably several misinterpretation on my part, but here goes.

I keep hearing the faster something goes the faster time goes relative to its point of view. And I also keep hearing space and time are inextricably intertwined as spacetime.

So, where does the space part fit into that phenomenon? Does acceleration or lack-thereof of an object make it experience more or less space at any singular frame? Is my question completely nonsensical?

I only wondered this after seeing an explanation that says an object going at the speed of light wouldn't experience any time, so I wondered about the space part.

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nivlark t1_izc6htj wrote

An observer always measures their own time to be normal, but will see time running slower for a second observer who is in motion relative to the first. And this is reciprocal: for the second observer, their time is normal and the first observer's clock is running slow.

Space has to be involved because otherwise there are contradictions: consider observers A and B, where A is stationary on Earth and B is travelling at high speed to a distant planet. A will measure B's journey to take a certain amount of time, but because B's clock is running slower, they would conclude that the journey took less time.

If both observers were to agree on the distance B had travelled, then they would have to disagree on their speed. The solution is that they don't agree on the distance: not only does time run slower in moving reference frames, lengths are measured to be shorter. From B's perspective, the planet is approaching them and so the distance to it shrinks. Their clock measured fewer ticks, but the distance they travelled is also less, and so they can still agree with A about their speed.

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