eli5 how is time on earth different to time on other planets?

Question

Starting off my first question, how is time in space or on other planets different to earth is it just that it takes longer for that planet to do a full rotation meaning longer or more hours in a “day”?

then if Space/planet time is different to time on earth, how dose someone age slower in space than they do on earth, wouldnt your body still be replacing cells at the same rate and be “aging” at the same time?

is the “1 hour here is 7 hours on earth” just some movie gimmick for drama

In: 1

Answer 1

It gets very complicated very quickly, well beyond what you can easily describe in an ELI5 post.

Yes, time ticks differently on different planets or in space relative to those on Earth. Technically it ticks differently for everyone here on Earth too, it’s just so immeasurably small that it can be ignored for any practical sense. Gravity and motion through space both influence how time passes for you relative to how it passes for somebody else. You can think of it a bit like a teeter totter with the three dimensions of space (up / down, front / back, side / side) on one side and the one dimension of time (past to future) on the other. The faster you move through the three dimensions of space the slower you move through the dimension of time, and vice versa, relative to something else. Gravity is wildly more complicated but it’s essentially the effect of curving your motion out of the dimension of time (time slows down) and into the dimensions of space (what you experience as falling “down”).

To answer your question about aging your body ages just as it normally would because for you 1 second always ticks at a rate of 1 second. It’s only when you compare your clock to someone else’s that you would notice that your 1 second isn’t the same as their 1 second. Remember that all of this is relative.

The 1 hour on Planet X to 7 years on Earth is a real thing that could really happen but would require extreme conditions that you almost certainly wouldn’t be able to survive in, like orbiting near the Event Horizon of a black hole.