# Newbie question about time dilation

1. Jan 17, 2007

### salamander3x

"In 1971, scientists used these clocks to test Einstein's ideas. One atomic clock was set up on the ground, while another was sent around the world on a jet traveling at 600 mph. When the clock flown around the world returned to the spot where the other clock was, it was behind by a few billionths of a second."

and I just wanted to know if the speed reduce the frequency to feed the clock counter or it have nothing to do with that.

2. Jan 17, 2007

### HallsofIvy

Staff Emeritus
Well, that is the whole point of the experiment! A 'clock' moving at speed v will run slower that a stationary clock by a factor of $\sqrt{1- \frac{v^2}{c^2}}$. I put 'clock' in quotes because any sort of regular motion or pulse that can be used to measure time (a pendulum, atomic disintegration, your pulse) will run slow as seen from from a "stationary" frame of reference. In that sense, time has slowed.