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 Be the first pioneers to continue the Astronomy Discussions at our new Astronomy meeting place...The Space and Astronomy Agora Re: Theory Of Relativity Forum List | Follow Ups | Post Message | Back to Thread Topics | In Response ToPosted by Zephram Cochrane/">Zephram Cochrane on February 13, 2000 03:36:56 UTC

: Ok, the theory of relativity basically states that perception is not fixed to a certain point, for example if a train is speeding by you it's no more accurate to say that the train is moving than to say that the train is standing still, and the rest of the world is in motion, correct? At least that's how I understand it. But, is this meant to be taken very literally, or not?

Yes that's correct and yes its literal.

For example, if 2 spaceships are flying directly towards each other, each at a speed of .6 C, couldn't you say that one ship is standing still and the other is moving at 1.2 times the speed of light? According to Einstein, this is impossible, so then it would be impossible for any objects to undergo any motion at all, right?

Not quite. If they are traveling toward each other at 0.60c according to some frame, then each ship's observers will observe that the other ship is moving toward them at 0.88c, not 1.2c. Relativistic velocities do not add linearly.

Maybe I'm taking the theory the wrong way, but here's another example: Say that another spaceship somehow manages to accelerate to the point that it's 1000 meters/second below light speed. Now, what happens if one of the crew members fires a bullet straight ahead at the front of the ship, at, say, 1200 meters/second? Wouldn't that bullet be traveling 200 m/s over lightspeed, in relation to a FIXED POINT in space? Since I know that somehow everything I've just said is somehow completely nonsense, if anyone out there is willing, could you explain exactly where I'm going wrong?

Your using a Gallelean velocity transformation equation u = u' + v For v much less in magnitude than c this works fine, but for high v you need to use a Lorenz velocity transformation u = (u'+v)/(1+u'v/c2)

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