Time Dialation Question

owenhbrown

I have a problem more related to GR.

I read that if you have a stop-watch on the ground and another on a very high tower the one at the top, from the perspective of an observer on the ground, would move slower.

I can deal with that.

But then I read, I think, that if the stopwatch was brought down from the tower the two stop-watches would be in unision, reading the same time....

Now did I read this wrong? That just doesn't make sense to me... Is this example true?

I would imagine that the stop-watch on the tower, when brought back to Earth, should be BEHIND the time of the stop-watch at the bottom.

Please clarify...

Ich

It would tick faster.
You probably read this wrong.

Yes, but it would be ahead, not behind.

owenhbrown

Ok thanks... that all makes sense to me... Now I feel like reading more =)

bydavies

With all the material I have read about time dialatiion, I have learned that the only effect is the illusion the observer sees and there is no physical time difference once the object traveling and the observer are brought together.

There's a nice demonstration here http://uk.youtube.com/watch?v=KHjpBjgIMVk, which explains the theory in ways that even I could understand.

Doc Al

Read up on the "Twin Paradox"; the time difference when the twins reunite is quite real.

That's just an illustration of time dilation. Note that the ship and the earth observers never get to reunite and compare clocks.

owenhbrown

You see what I mean now? ByDavies brought up the exact point that made me want to never try to understand time dilation - the suggestion that the clock moving faster at the top of the tower is only an illusion and no difference would be observable when the clocks are brought together again.

How does the act of bringing the clock back to Earth suddenly make the time go back to normal, Earth time?

JesseM

But as pervect pointed out, bydavies was wrong--"the time difference when the twins reunite is quite real."