Relative Balls

[Progenitor A]

Get a ball on the face of the earth.
Attach a tiny clock to it.
Beari in mind that the clock will run faster the higher it is in the earths gravitational field.
Have another clock that will remain on the ground while you throw the ball upward. This clock on the ground will run for 100s from the moment you throw the ball vericall upward
Now throw the ball upward for 100 seconds (registered on the ground) and when it comes back down examine the time on the ball-clock
More time will have passed by on the ball- clock - say 101 seconds.

Now trythrowing the ball again (with the clock reset). How can you ensure that the ball-clock registers the maximum possible time when it returns an is compared to the ground-clock 100 seconds?

(A Feynman experiment)

[speakertoanimals]

First, you need to think about time dilation due to velocity, which works in opposite sense to gravitational effect.

So, for GPS sateliites, we have speed slows them down, whilst being higher speeds them up. SO, 7 microseconds per day slower because of speed, but 45 microseconds a day faster because of height.

But the question asked here is actually slightly different -- it specifies the start and end times and positions, here, and here a 100 seconds later according to my ground-based clock.

The question is then asking what is the path that gives the MAXIMUM elapsed time between those two end-points?

Turns out that the answer is just the path of a thrown ball under gravity, thrown so that it falls back after 100 seconds. Means that the usual laws of mechanics which we sould use to work out that path under Newtonian garvity are replaced, in relativity, by statements about time elapsed for clocks following paths.

Principle is that in a gravitational field, objects upon which no forces act (ie UNLIKE the clock sat on the ground, where the ground is holding it up) follow paths in spacetime with a maximum possible value of elapsed time on the on-board clock.

[abacus9900]

Dec 15, 2010 14:32:05 GMT 1 speakertoanimals said:

First, you need to think about time dilation due to velocity, which works in opposite sense to gravitational effect.

You can't just state this without qualifying it for posters here who have no idea of what you are referring to. What you need to do is extend this statement to include a basic explanation as to why it is so. You then go on to deal with the difference in more detail, having provided readers with a basic framework within which to attempt to incorporate new ideas.

[speakertoanimals]

You can't just state this without qualifying it for posters here who have no idea of what you are referring to. What you need to do is extend this statement to include a basic explanation as to why it is so. You then go on to deal with the difference in more detail, having provided readers with a basic framework within which to attempt to incorporate new ideas.

If posters have no idea about relativity, they're not going to have ANY idea what the first post is about anyway, so no point.

Unless you think it is my responsibility to explain ALL of the physics background every time I post..................

If people don't know, they can ASK nicely, and I (or someone else) will help.Those that don't ask nicely can go swivel.............

[alanseago]

Absolutely Speaker, one of your simplified explanations opened many doors to me. I am very grateful, I am not a scientist just a retired engineer but I still crave knowledge.

[abacus9900]

Dec 17, 2010 14:12:02 GMT 1 alanseago said:

Absolutely Speaker, one of your simplified explanations opened many doors to me. I am very grateful, I am not a scientist just a retired engineer but I still crave knowledge.

You are allowed to discuss and challenge points from time to time, you know.