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Originally Posted by Damien
So the 470 light years is time relative to us and not the speed of light?
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In a vague sort of way, yes. Yay for relativity.
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If we could travel at within a hair's width of the speed of light then time, relative to those doing the travelling, would be a fraction of the time?
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Yeah.
The way I like to think of it is light = time. It's an awkward concept but pretty amazing once you get your head around it. Imagine a flash of light, e.g. from a lightning strike, travelling outwards from Earth as a wave at the speed of light. The peak of that wave equates to not only the flash of light, but also the exact time it took place. If you were to travel with the wave at the speed of light, you would be travelling along with time itself, staying in the same moment forever, and the flash of lightning would seem to last forever. Until you hit something and die.
As for brakes - that's the problem. We can't put enough fuel onto a spacecraft to make it go fast enough so we have to propel it, at least partly, from Earth. Without somebody building something at the other end to slow you down, you can't. Which is why you won't be coming back ;-)