# A basic question about time dilation

1. Feb 17, 2014

### Commando Spaz

Hello,
It is my understanding that in the case of two observers (A and B) passing each other at high speeds that due to time dilation observer A would be moving in slow motion with respect to observer B, whereas observer B would be moving in slow motion relative to observer A (i.e. each observer perceives the other to be moving in slow motion). If this is incorrect stop me here and explain how so.

It is also my understanding that the effect of time dilation has been observed in an experiment in which one atomic clock remained in a fixed position whilst another was flown around the world (I know I'm simplifying this but there's no need for unnecessary complication). From this experiment the effect of time dilation was observed in that the clock which had traveled the world read a time which was behind that of the clock which had remained stationary (relative to us).

However, the clock fixed to earth had moved with respect to the clock on the plane. Thus, if the information in the first paragraph is correct then does it not stand to reason that when the the two clocks were compared that for the people who had been on the plane, the clock that had been fixed to earth was the one which was behind? Would this mean that the people who had been on earth (us) had one reality whereas the people who had been on the plane had another? each observing the clock which had moved relative to them to be behind?

Any help clarifying this will be appreciated, Thanks

2. Feb 17, 2014

### Staff: Mentor

Last edited: Feb 17, 2014