Science is awesome update 2
The GPS satellites orbiting Earth have to add 3 milliseconds a day to the time on the atomic clocks. This is to account for General Relativity because time goes 3 milliseconds a day faster on the ground than up in space. If they didn't ad these three milliseconds a day, the GPS system would be out by about 50 miles per day. It's General Relativity that makes the GPS system work.