Ha... I thought the article was going to be about relativity. From non-rigurous studies and Sci-Fi, I usually remember that a fast moving clock will tick slower than a slow moving or "stationary" clock... but what I forgot or didn't realize from my high-school / college physics until I was watching a show the other night is that General Relativity means that a clock closer to a large mass will move slower than one further away. So a clock at an altitude, or in space, will move faster than one at sea level. That just sort of blows my mind. Granted, both effects are small in terms of human experience... but they definitely had to be accounted for when they deployed GPS or else all of the location info would start varying to an ever increasing amount each day...
