At 5/3/09 07:05 AM, GustTheASGuy wrote: Time slows down the more you accelerate close to the speed of light. We're all basically standing still so time goes as fast as it can. Astronauts aging or not isn't due to the time flow changing though.
You're over (or under :/ ) complicating this. Essentially, all of this extends from the principle that it's impossible to tell whether your reference frame is at rest or moving - all laws of nature hold true in all reference frames. The speed of light in a vacuum is therefore constant in all reference frames.
This presents an essential problem - if you're standing still, and your mate is running at a speed of half the speed of light (just for the sake of making this example a little simpler), or 0.5c, you will both measure exactly the same speed for light, contrary to what we expect from classical mechanics. Since the speed of light is constant in each frame, the things we determine it by, i.e. time and distance, must be relative. This has been experimentally verified.
The effect of gravity is interesting too, since a uniform gravitational field is indistinguishable from constant acceleration. Relativity also has lots of cool side effects, e.g. magnetism.