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by hugh3 5482 days ago
While it's impossible to send information at speeds that exceed c, it should be possible to bend the spacetime (e.g. using worm holes) so that the information would appear to have traveled faster than light.

Wormholes, it should be noted, are "possible" in only a rather remote sense. If you put a wormhole into the equations of general relativity and say "Hey general relativity, is this a valid solution to your equations" it'll say "Uhhh, sure!". But then if you ask it how to arrange masses in order to actually get that solution it'll say "Haha, you can't do that."
1 comments
TomasSedovic 5482 days ago
Can you please expand on that last line? I read it two ways and I'm not sure which one you mean.

Does the "you can't do that" refer to getting a how-to-build-a-wormhole recipe from general relativity, i.e. "I can't tell you how to build one, go figure it out yourself".

Or is it more along the ways of "You don't have a worm hole? Well too bad, there's no way you can create one. But hey, it could totally hypothetically exist."

If it's 1) then we could possibly build one (or find it in the universe somewhere) and GR just doesn't tell us how. If it's 2) then we know it can't even be created.

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hugh3 5482 days ago
I'm not an expert on wormholes, but: general relativity will tell you how space curves for any ol' distribution of mass you like, and it tells you there ain't no distribution of mass you can arrange that'll give you a wormhole.

On the other hand, we still don't understand the whole relativity/quantum-mechanics overlap region, so it's possible that whatever new physics are waiting for us in that regime just might include wormholes.

I'm really reluctant to say that, though. Many people seem to jump straight from that to drawing pictures of wormhole-hopping spaceships. Sorry, it's very very very very very very very unlikely to happen.

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TomasSedovic 5482 days ago
I didn't know that you couldn't arrange mass in any way to get a wormhole.

I've never been able to figure out in my (broken, I'm sure) mental model how you could create a wormhole but I suspected that the people who actually understood physics did know.

Thanks a lot, man. Interesting stuff.

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