Warp Drive May Be More Feasible Than Thought, Scientists Say

Re:Warp Drive May Be More Feasible Than Thought, Scientists Say by nessus42 on Thursday September 20, 2012 @08:46AM (#4548202)

And what happens if you try to make a loop? Do you think it sensible that the universe provide you with the ability to make causal loops and then somehow forbids you from actually making them, even though once you've been given the ability, they are very easy to generate?

Additionally, if the universe is going to keep stepping in your way of what it has given you the ability to do, there's no reason for it to forbid you from making causal loops. All it has to do is forbid you from generating a paradox via such a loop.

I.e., you can have a self-consistent universe that has unlimited FTL and unlimited time travel as long as everyone plays nice. In fact, you can have unlimited time travel even is everybody is trying to kill their grandfather. They just won't ever succeed.

Never did I assert anywhere in this entire thread that a universe where causality is violated--or even one with closed causal loops--is impossible. They do have serious issues, however. And for anyone to propose FTL travel as a serious possibility and then ignore the causality issues as non-serious, either indicates some amount of either ignorance, disingenuousness, or rationalization.

If, on the other hand, a proponent of FTL travel plainly states that they have no problem with a universe that always steps in somehow and prevents you from succeeding in killing your own grandfather, then at least they've made their position clear, and everyone can make up their own mind as to whether that's a likely way for the universe to be.

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Re:Warp Drive May Be More Feasible Than Thought, Scientists Say by Dylan16807 on Saturday September 22, 2012 @12:59AM (#4557168)

There are other solutions, too. It might simply be infeasible to accelerate an FTL device to sufficiently relativistic speeds. Or what if there were fields coming off of FTL devices that interfered with the speed when they criss-crossed. That one would stop any sort of loop and it wouldn't require the universe to somehow specifically forbid paradoxes.

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Re:Warp Drive May Be More Feasible Than Thought, Scientists Say by nessus42 on Sunday September 23, 2012 @12:12AM (#4559959)

FTL devices don't have to "criss-cross" for you to be able to create causal loops. And even if you don't have any causal loops, other violations of causality violate thermodynamics. It's not as if if you've solved the problem of causal loops--which as far as I'm aware, no one has done without postulating a preferred frame of reference, which is basically rejecting Relativity outright--then you're off the hook. All violations of causality are going to make most scientists shake their heads. And, if it is infeasible to accelerate an FTL drive up to speed, then the point is moot for space travel or communication.

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Re:Warp Drive May Be More Feasible Than Thought, Scientists Say by Dylan16807 on Sunday September 23, 2012 @01:35AM (#4560148)

By 'criss-cross' I mean that your FTL devices in different reference frames need to repeatedly get close enough for causal contact. Is there another way to make a loop using simple FTL devices?

And I might not have been clear enough on acceleration. I meant you might be able to construct a device capable of FTL transport, but it might be far harder to traditionally accelerate this entire device to high speed. The FTL isn't moot, but if your FTL is only 5c and you can't accelerate your turned-off FTL device faster than .1c you're not going to make any loops with it.

In other words, in this scenario, there isn't a preferred frame of reference per-se, but there's no way for such a large and complex construct as an FTL device to get far enough away from the galaxies' default reference frame.

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Re:Warp Drive May Be More Feasible Than Thought, Scientists Say by nessus42 on Sunday September 23, 2012 @04:45AM (#4560409)

You might be able to cook up something, but I doubt that it will be any more plausible than positing a preferred reference frame.

Personally, I think that supporters of FTL should stick with subspace and run with it. And, hey, the author of the FTL faq even wrote a whole subspace faq too.

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