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Old September 20 2012, 06:10 PM   #53
Crazy Eddie
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Re: Warp Drive May Be More Feasible Than Thought, Scientists Say

The Green Mushroom wrote: View Post
newtype_alpha wrote: View Post
So when it arrives, it's clock indicates that perhaps a day has passed
No, nearly a year has indeed passed. From your point of view, EVERYONE ELSE seems to have slowed down.
Except that a journey of one light year at .9999c or something to that effect would seem to take a day.
Again, only when measured from someone else's perspective. Because you are stationary with respect to your own reference frame, your subjective travel time is unchanged.

While nowhere near light speed, the GPS satellites are precise enough and moving fast enough that their data needs to be adjusted for the fact the clocks on a satellite are moving slower than the clocks on the surface of the Earth.
No they don't. That's a common but oddly pervasive myth.


Manticore wrote: View Post
I curse the twins experiment for the amount of confusion it's caused with relativity. :bitch:

Twins works in general relativity, because acceleration is absolute. However, in special relativity which is what [B]newtype[b] is discussing, each twin sees themselves aging at the normal rate, and their other twin as aging slowly. Special Relativity involves two objects moving in completely different frames of reference that never meet - ie they don't accelerate. In General Relativity, the frames of reference meet, which causes it to be a lot more complicated, so that's where the Twin thought experiment comes into play.
And even then it only works because General Relativity allows for a universal reference frame in the context of the timelike curves of gravity and energy. In the end, the Twins Paradox doesn't demonstrate anything other than GR's inapplicability to local reference frames, in the same way Schroedinger's Cat demonstrates the inexplicability of quantum mechanics to macroscopic objects.

Which is ironic, because:
Not that any of this applies to a warp drive because the ship isn't accelerating, decelerating, or moving. The spacetime around it is, and that's a separate kettle of fish entirely.
Actually, the ship IS accelerating, but it's doing it in a non-inertial reference frame. This is ironic because it means that General Relativity should apply locally, even if it is not really valid beyond the space ship and its enclosing warp field.
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Last edited by Crazy Eddie; September 20 2012 at 06:29 PM.
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