He said that time goes slower, the faster your speed. A few minutes later he was talking about GPS stellites going 18,000 miles per hour, and sending an image to Earth. I was half asleep, but I could have sworn that he said that if the time was traveling slower for the satellite, then the image would be jumbled! Or he might have said that it is proof that time does travel slower when you travel faster. Which one is it?
2007-12-20 03:34:44 · 3 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Time is relative to the frame it is measured in. Thus, on the GPS satellite, time appears to be passing at what might be called rest-time rate. Rest-time because an on board observer would be at rest wrt the GPS.
But an outside observer (and receiver of the GPS signal) would see time dilate on the GPS. As f = n/T; where f is frequency, n is number of cycles, and T is the period, we see that if T' = T + deltaT, the dilated frequency f' < f will lower than the rest frequency f as far as the outside observer is concerned. deltaT is that bit of time dilation seen by the outside observer and due to the velocity and gravity effects on the satellite.
Unless the GPS receievers are tuned to f' instead of f, the rest frequency, they will be jumbled just like any radio that is not tuned in properly. To a point, the difference between f and f' is very very tiny because the velocities, compared to light speed, are very very tiny. So the receivers won't be that messed up.
2007-12-20 04:02:50 · answer #1 · answered by oldprof 7 · 5⤊ 0⤋
I don't know what he said, but GPS is accurate enough that is needs to take into account both special and general relativity so, yes, the satellites can measure the effects. It's easy enough to do - have a compensated clock and enough bandwidth to cover Doppler shift.
2007-12-20 04:19:42 · answer #2 · answered by Dr. R 7 · 4⤊ 0⤋
the twin thing and the gps thing are similar, but different, as far as i've read.
the twins experience of time is different... due to the speed they're travelling compared to eachother (special relativity)
the gps thing varies by this
http://en.wikipedia.org/wiki/Gravitational_time_dilation
(general relativity)
since they know it's going on, they can compensate for it
++++++
apparently the special rel effects on the GPS system is about 7us a day slower, while the general rel effect is 46us faster per day
i guess the gps problem kinda supports both, but proves neither, since they're both involved in the same thing
2007-12-20 03:57:27 · answer #3 · answered by Anonymous · 1⤊ 3⤋