Hello everyone,

 

Suppose there is an observer standing on a body A and there is another body B at a distance. Now this observer sees that B is coming closer towards him. From this observation, can he conclude that whether A is moving towards B or B is moving towards A ?

Edited October 16, 20169 yr by Sriman Dutta

Relativity says that you cannot say this.

 

And Relativity has yet to be shown experimentally to be wrong (in the large scale universe)

 

I think this observation may also be related to the fact that there is apparently no "centre" to the universe because if there was a centre then it would be possible to say that A (for instance) was more "stationary" vis a vis this "centre" and so B was by that definition was more "in motion" -but you cannot say this if there is no "centre" .

 

If you adopt A as a frame of reference then B will seem to be in motion vis a vis A

 

If you adopt B as a frame of reference then A will seem to be in motion vis a vis B

And it is important to note that, at low speeds, you only need Galilean relativity (and everyday experience) to answer this.

 

https://en.wikipedia.org/wiki/Galilean_invariance

Edited October 16, 20169 yr by Strange

Thanks....

"Suppose there is an observer standing on a body A and there is another body B at a distance. Now this observer sees that B is coming closer towards him. From this observation, can he conclude that whether A is moving towards B or B is moving towards A ?"

 

Relative to A, B is moving and A is not. Relative to B. A is moving and B is not. You cannot say anything is moving without saying relative to what.

If the is no alternative points of reference then the answer is no, also there could be stresses on his body which could tell him he is moving although these would be elevated if the velocity he is moving it is constant over time.

If the is no alternative points of reference then the answer is no, also there could be stresses on his body which could tell him he is moving although these would be elevated if the velocity he is moving it is constant over time.

Even with external points of reference an inertial observer would not know. If he experiences stresses then he is not inertial.

If the is no alternative points of reference then the answer is no, also there could be stresses on his body which could tell him he is moving although these would be elevated if the velocity he is moving it is constant over time.

 

 

There would be NO stresses on his body if moving at a constant velocity.