Special Relativity Question (1 Viewer)

[jskeza]

Help with this!

Say there is a spaceship and inside an astronaut, there are also two clocks (one on spaceship and one of Earth). So relative to the astronaut and spaceship the Earth would be moving away (so the time would be slowing down on Earth). But relative to Earth the astronaut is moving away and time slows down for the astronaut. Now what actually happens to the physical clocks, which clock slows down and why???????????????

Thanks

 

[bbbbbbbbbbbbb]

Help with this!

Say there is a spaceship and inside an astronaut, there are also two clocks (one on spaceship and one of Earth). So relative to the astronaut and spaceship the Earth would be moving away (so the time would be slowing down on Earth). But relative to Earth the astronaut is moving away and time slows down for the astronaut. Now what actually happens to the physical clocks, which clock slows down and why???????????????

Thanks

Time is dilated hence the clock in the spaceship will be less/ slower than the stationary clock on Earth. Both clocks are synchronised and this experiment is used as evidence for Einstein's theory of special relativity. As seen in the formula:

Time in a ‘moving’ frame appears to go slower relative to a ‘stationary’ observer. tv is the observed time for the stationary observer, t0 is the time for an observer travelling in the frame. Essentially "moving clocks run slower" relative to the stationary observer.

Hope this helps.

 

[blyatman]

Help with this!

Say there is a spaceship and inside an astronaut, there are also two clocks (one on spaceship and one of Earth). So relative to the astronaut and spaceship the Earth would be moving away (so the time would be slowing down on Earth). But relative to Earth the astronaut is moving away and time slows down for the astronaut. Now what actually happens to the physical clocks, which clock slows down and why???????????????

Thanks

I'm assuming you're referring to the twin paradox. You are correct in that both would see each other's clocks as dilated. However, it only makes sense to talk about who has aged more if they start and physically meet at the same time and location. As a result, the scenario is not symmetrical because the rocketship must accelerate away and then come back for their clocks to be compared. The asymmetry lies in the fact that the rocketship was not always in an inertial frame, and means that one observer must clearly be older than the other. The accelerating observer turns out to be older - the full reason behind it is beyond the scope of HS-level math/physics (you'd need to take a 3rd yr physics course in special relativity, or a graduate-level physics course in general relativity, to understand the full answer).

If neither observers started and finished at the same time and place, then it is meaningless to talk about who has aged more. For example, if the rocketship just flew past earth at close to the speed of light, it is meaningless to compare the clocks of those on the rocket vs those on earth since there is no way for them to compare their proper times. In this case, both would see each other's time dilated, but there is no "older" observer, since their proper times cannot be directly compared.

 

[jskeza]

I'm assuming you're referring to the twin paradox. You are correct in that both would see each other's clocks as dilated. However, it only makes sense to talk about who has aged more if they start and physically meet at the same time and location. As a result, the scenario is not symmetrical because the rocketship must accelerate away and then come back for their clocks to be compared. The assymmetry lies in the fact that the rocketship was not always in an inertial frame, and means that one observer must clearly be older than the other. The accelerating observer turns out to be older - the full reason behind it is beyond the scope of HS-level math/physics (you'd need to take a 3rd yr physics course in special relativity, or a graduate-level physics course in general relativity, to understand the full answer).

If neither observers started and finished at the same time and place, then it is meaningless to talk about who has aged more. For example, if the rocketship just flew past earth at close to the speed of light, it is meaningless to compare the clocks of those on the rocket vs those on earth since there is no way for them to compare their proper times. In this case, both would see each other's time dilated, but there is no "older" observer, since their proper times cannot be directly compared.

Thanks! This cleared it up.

 

[blyatman]

Thanks! This cleared it up.

You're welcome =)

If you want more details, you can always read the wiki page: https://en.wikipedia.org/wiki/Twin_paradox

It's fascinating stuff.

 

[Drdusk]

^ Or you could ask the guy who literally researches about General relativity

 

[blyatman]

^ Or you could ask the guy who literally researches about General relativity

Lol I'm a CFD guy now. Been out of the GR game for too long...