- JustSteph:
- I never managed to get my head around the whole thing about time being different depending on gravity or the speed you're moving.
Like the theory that you could time travel by going faster than the speed of light because less time would pass for you than it did for everything else. Doesn't your body just age at the same rate?
It's something I want to understand, but just don't. An hour is an hour no matter how fast you're travelling. =/
Can anyone explain it?
The thing is that all is relative.
Firstly according to Newton's gravity law there is no absolute space: if you're in a train and I'm somewhere outside looking at the train I will think/feel/perceive that the train is moving while I am sitting still, on the other hand you will think that you're still while I am moving, so there is no way of telling who is truly moving. However this means that if you were to throw a ball on the floor (of the train) and it would jump up and then back down in the exact same place after a second and you would think it hasn't moved at all, while I would think it has moved 40 meters (or some other distance, depending on how much the train has moved while the ball was in the air).
Newton thought that time is the same for all observers, so if a light bean would pass between point A and B two different people could think AB has different lengths, but they must think that the light bean reached from A to B in the same time-thus different observers would think light has different speeds. The problem here is that we know light speed is -always- constant. This proves that there is no absolute time either, and each observer has its own way of measuring time. And this is why time is relative too.
So an hour is an hour to you no matter how fast you're traveling indeed, but it might be less than an hour to somebody who is watching you move.
I'm rather bad at explain, so I wholeheartedly recommend books like George Gamow
Mr Tompkins books or Stephen Hawking's
A Brief(er) History of Time, they're much better than me at explain it all.