[quote] Same fam. What college? I'm Cornell[/quote] URI. Not as prestigious, I know, but they have a good physics program, and I'm biting the bullet of being an idiot in high school. [quote]Also, there are two twins, exactly the same age, Bob and Jill. Bob is on Earth and Jill decides to take a near-light-trip around the local supercluster. Jill travels the 4 lightyears to Alpha Centauri and back at just below the speed of light. To Jill, it takes 8 years to travel to the star and back moving at almost light speed. [b]As you probably know, the faster something is moving the slower time seems to flow to [u]it.[/u] [/b][/quote] Reread that sentence I bolded. [quote]To Bob everything Jill does is in slow motion[/quote] This is false. We see photons move very fast. They don't see us move at all. Apply same logic. [quote] and thus to him Jill appears to age less and by the time she returns, only eight years have passed to her and much more have passed to Bob. Now according to Einstein's Theory of Relativity all motion depends on your point of view. Jill can just as surely claim that she herself isn't moving, but rather everything else is moving and she is staying still.[/quote] Jill would be sorely mistaken. Obviously Jill cannot move at the speed of light, so she is still moving through time slower than the rate at which time passes, so she is still moving along with everything else, just relatively slower. Bob can also not claim that he is standstill, as he has mass and is on a mass. What special relativity proves is that Bob will have aged more than Jill, as he is moving slower therefor less symmetric in spacetime. Not both sides.