[quote]As an aspiring astrophysicist[/quote] Same fam. What college? I'm Cornell [spoiler]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. As you probably know, the faster something is moving the slower time seems to flow to it. To Bob everything Jill does is in slow motion 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. To her Bob (and the Earth) is the one first moving away from her and then moving closer as it comes back to her. Since they are the ones moving in her perspective, they are the ones moving through time slower. Jill sees everything Bob does as in slow motion and when she returns she can claim he has only aged 8 years and she has aged much more. This is a seeming paradox, but Einstein's Theory of Relativity seems to allow it. Can you save our universal constant?[/spoiler]