Originally Posted by Master_Shake

I remember reading somewhere that time travel can actually be measured. That is, relative to a stationary observer, time appears to pass more slowly for faster-moving bodies.

If you've ever travelled on an airplane you've travelled into the future, at least relative to those people on the ground, and probably only by a very small amount of time. As I said, I remember reading somewhere about hyper-accurate clocks needing to be recalibrated by a few nanoseconds after extended periods in the air or while travelling at great speed. Anybody know where these studies were conducted?