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Q & A: time and GPS satellites

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Most recent answer: 01/03/2020
Q:
Please consider all the GPS satellites' atomic clocks. We calculate the location based the time dilation from the ground. But at Any point of time, all the clock will have the same time. Am I right? we just record the delay due to observation(appears to be slower/faster). My friend is arguing that time actually slows down/going fast due to the velocity. If we assume there are several men to record the time in those clocks, all will record the same time right at a single frame? but when we communicate, due to distance and velocity dilation occurs. is my understanding correct?
- Santhosh Mohan (age 27)
Chennai
A:

The phrase "at any point in time" already refers to something that we've found does not exist in our universe. Whiichevents of the different satellites are simultaneous, i.e. at the same point in time, depends on the observer

As for the different rates of different closcks, there are two effects. One is that for clocks in motion relative to each other, an oberver on either clock sees the other one as going slow. The other is that in the presence of gravitational fields or accelerations, there are observer-independent differences in the rate of the clocks.  The net effect is that one each orbit the clocks on the GPS satellites have advanced more than a clock on earth. Any effects due to signal transmission times can be made comparatively negligible just by allowing many orbits for the other effect to accumulate. For lower-orbit satellites, it turns out the net effect is opposite, so that they advance more slowly than a clock on earth.

I'm not sure that answered your questio, so you might want o follow up.

Mike W.


(published on 01/03/2020)

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