Cheap Time travel

[scooterscot]

Someone at sea level would conclude that time has passed more slowly for the man on the mountain.

Someone with very sharp eyesight.

[gingerjedi]

No. They aren't moving relative to each other, so there is no relative velocity time dilation - only gravitational time dilation. Gravitational time dilation doesn't mirror both ways because it falls outside of special relativity (and into general relativity).

In this case the man on the mountain would age more.


I believe Scoots comment, though, is related to you using the word 'travel' - time is a dimension and so it doesn't travel. Infact the word travel by definition implies a change in position in relation to a change in time; so that's a limitation in the english language - it's very hard to talk abut time in a non-recursive way.

I bow down to your superior knowledge, I must admit my understanding of the subject comes from the layman's version of 'A Brief History of Time' (The Universe in a Nutshell) and 'Planet of the Apes'.

I must have skipped the bit about gravitational time dilation.

[SpontaneousOrder]

I bow down to your superior knowledge, I must admit my understanding of the subject comes from the layman's version of 'A Brief History of Time' (The Universe in a Nutshell) and 'Planet of the Apes'.

I must have skipped the bit about gravitational time dilation.

Well even ignoring gravity, the clue was in your own posting. You kept saying 'relative to each other', but a man at the foot of a mountain and a man at the top are not moving at all, relative to each other.

They're only moving relative to each other if you choose some arbitrary 3rd party frame of reference. So ignoring gravity there would be no time dilation at all.

[gingerjedi]

Well even ignoring gravity, the clue was in your own posting. You kept saying 'relative to each other', but a man at the foot of a mountain and a man at the top are not moving at all, relative to each other.

They're only moving relative to each other if you choose some arbitrary 3rd party frame of reference. So ignoring gravity there would be no time dilation at all.

Ok supposing the man isn't on a mountain but flew in a fast jet Eastward (this is important I understand)? Would he experience time as slower to the man on the ground??

[SpontaneousOrder]

Ok supposing the man isn't on a mountain but flew in a fast jet Eastward (this is important I understand)? Would he experience time as slower to the man on the ground??

East or west doesn't matter.
Both would experience time as normal. But both would observe the other as 'passing through time' more slowly so long as both remain observing from an inertial frame of reference.

If the jet did a u-turn and cam back then it would have spent the time taken to do the u-turn in a non-inertial frame, and as such the scenario falls outside the scope of 'special' relativity. In this case the jet pilot would see the other guy aging more slowly, and then as he performed the u-turn he'd see the other guy rapidly age so that he is now aged more than the pilot. Then during the return trip he's see the other guy age slowly again - but not enough to fully counter that period of rapid ageing. When the pilot gets back to the start both men will agree that the jet pilot has aged less than the stationary man.

[mudskipper]

Time doesn't really matter but our perception of it does. If you want to live forever just watch party political broadcasts over and over again.

Wasn't there a character in Catch 22 who subscribed to a similar philosophy?