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Quantum Setback For Warp Drives
KentuckyFC writes "Warp drives were generally considered impossible by mainstream scientists until 1994 when the physicist Michael Alcubierre worked out how to build a faster-than-light drive using the principles of general relativity. His thinking was that while relativity prevents faster-than-light travel relative to the fabric of spacetime, it places no restriction on the speed at which regions of spacetime may move relative to each other. So a small bubble of spacetime containing a spacecraft could travel faster than the speed of light, at least in principle. But one unanswered question was what happens to the bubble when quantum mechanics is taken into account. Now, a team of physicists have worked it out, and it's bad news: the bubble becomes unstable at superluminal speeds, making warp drives impossible (probably)."
Or is it *both* Impossible and not Impossible?
is this where the improbability drive comes in?
yeah, someone had to say it.
The SCI-FI buff in me holds out hope that physics will uncover a trick to FTL, but...
It doesn't really matter if we cannot travel faster than the speed of light so long as we can live long enough to get there.
Who cares if it takes 50 years to fly to Alpha Centauri if we can engineer ourselves to live for a thousand!
This is my sig.
Just do what the Planet Express Ship does and use a Dark Matter drive to move the Universe around us instead... :)
THE HONOUR OF THE KNIGHTS - CC Licensed Sci-Fi Novel
From the article... "strongly implies that such a bubble would be unstable." Sounds like proof to me! Right. Just like it was proved impossible for planes to fly. It might indeed - eventually - prove to be impossible, or impossible to do meaningfully / reliably, but it's pretty unlikely we're in a position to make that call at this time. That's why we do research.
=cjs
So you mean to say my brand spanking new SSDs have become obsolete already???
Faster-than-light travel always causes causality paradoxes, so a priori, FTL drives are impossible unless special relativity is wrong. (That's is a bit like saying that perpetual motion machines are impossible unless thermodynamics is wrong.) The proposed mechanism behind the FTL drive doesn't matter -- it'll still cause a time paradox.
Just like we know any proposed perpetual motion machine must have a flaw, any proposed FTL drive must also have a flaw. They belong to the same class of impossible device, and deserve the same degree of consideration.
Please note the submission date:
Semiclassical instability of dynamical warp drives
Heck, after 8 weeks of army basic training none of the 50 or so people in my company were strangers.
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That's it, cancel the Star Trek Movie. Now that I know it's all fake it just ruined it for me.
Play me online? Well you know that I'll beat you. If I ever meet you I'll "/sbin/shutdown -h now" you. -Weird Al, kinda.
Right. At about one G acceleration you can reach any point in the universe in a few years of ship time.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
I thought we knew that combining these two theories resulted in answers we know to be nonsense. So the implication is one or both of them are wrong in some way. So I'm a little confused why we should trust results based on the combination of two theories that don't work together.
Granted I'm just a laymen, but does anyone else want to comment about the intersection of these two theories?
AccountKiller
Quantum would be an atomically short distance...
IE: a "Quantum leap" is just an electron jumping to another valence level in an atom... it's not a very large distance =)
up 12 days, 22:30, 2 users, load averages: 993.20, 994.21, 994.56
*makes note to limit user processes...
It always works.
That doesn't work. You can't transmit information faster than light; contrary to popular conception, quantum entanglement does not involve classical information transfer.
If you have one of a pair of dice, and the other is a thousand light-years away, one way to think of entanglement is to imagine that whatever number you roll is the number that shows up on the other die the next time it is rolled. Even if the two dice are linked, you can't control which number shows up, so you can't use the dice to communicate information.
No we don't, and no you couldn't. I suppose you're thinking of the EPR paradox? Very well. Let us say that I have a set of electrons in equal spin superpositions, and you, at some distant location, have their entangled counterparts. What's the protocol for communication?
Well, if I measure the spin of my electron 0 about the x axis, then in doing so I will also establish the spin of your electron 0 about that axis. The superposition on your electron has vanished without you touching it. Terrific, that's communication, right? I collapse your electrons in sequence, this one on the x axis, this one y, this one x, and so on, a binary code?
Well, no, it doesn't work like that. How can you tell if I've done anything at my end? By making measurements of your electrons? No - because that will collapse the superposition too. Let's say I measure electron 0's spin around the x axis to be positive. Immediately and instantaneously, faster than light across the universe, the superposition on your electron 0 collapses and I know it to be positive about the x axis.
But you don't know that. You might pick the y axis to measure, which is still a superposition. Or you might pick the x axis, and certainly you'll get a +, but you might have got that anyway. You can measure each electron only once - you change its state in doing so - so you can't do a series of tests, build up the statistics and find that on the y axis it's a 50/50 shot but on the x axis it's + every time. That's what you'd need to do in order to determine that I'd chosen the x axis. That's what you'd need in order to communicate faster than light. But since you only ever get one measurement, you get no information about what I did at the other end.
Real Daleks don't climb stairs - they level the building.
The very people who should be aware how little they know compared to what is possible. They come up with these statements, and they forget that for every problem, there IS a solution, even if they can not figure it out themselves.
The question their current "findings" should be asking is "what makes it unstable?". They may not know, but that is the key to solving the problem.
People forget that scientists used to think that it was impossible to break the sound barrier for various reasons. Then they came up with the idea that the speed of light could not be broken. Time has proven again and again that the only thing stopping ANYTHING is not having the knowledge to do it. Not having knowledge does not make something impossible, it just means a CURRENT inability to do something.
People do not want this world to be disposable, but they want the option to get off this crazy panet, in the hopes that there will be some sanity once you get away from the current cultural stupidity we see from terrorists and those who support terrorism.
There is also the concern that the stupidity of a few may destroy the world, so getting off the planet is also a survival instinct for the species at this point.
First of all it's worth remembering that quantum mechanics and relativity are not 100% incompatible. In fact "relativistic quantum mechanics" has been around for a long time. Quantum theory was greatly advanced when relativistic effects were included.
But you're right that we have good reason to believe that something is wrong with either quantum mechanics or relativity (or both), since they give contradictory predictions in a certain number of extreme cases. (Quantum gravity is not yet solved...)
However we also have ample evidence that quantum mechanics and relativity are incredibly accurate and predictive theories in a vast range of circumstances. We have every reason to believe that the correct "Theory of Everything" will reduce to conventional quantum mechanics and conventional relativity in the appropriate limits. And thus we have every reason to continue using those theories to make predictions all over the place.
Now a warp bubble is one of those extreme situations where the two theories might be expected to give contradictory results, in which case only the hypothetical theory-of-everything would give the correct answers. But it is certainly still useful to ask what our current theories would predict for these extreme situations. It helps us better understand the theories. And, again, we have reasons to believe that many of the things our current theories predict (even in extreme situations) will be right. Absent the theory-of-everything, quantum mechanics + relativity will give us the "best guess" about how such objects would behave
That's just silly...No one would mate with Kate Mullgrue...
Unless...
Go East
You have been molested by a Mullgrue
-=Bang Bang=-
That doesn't work either because Joe doesn't know if you have rolled the dice or not.
Entangled particles are like dice that are already rolling, and they stop rolling the moment that either particle is observed.
So you and Joe each have a dice that, say, always roll the same number as each other. You look at your dice to cause it to stop rolling, and see that it rolled a 6. Joe can look at his dice too, and will also see a 6, but he doesn't know if he was the one that caused the dice to stop, or whether it was you who stopped it.
You both see a 6, but no actual information was transferred.
The entanglement usually occurs to conserve some physical quantity, such as spin or momentum. So for the dice example, let's say that every pair of entangled dice must add up to 7.
The problem is that they can only become entangled while they're still in luminal communication range - so you have to roll all the dice before the ship leaves.
If neither of you looks at your dice, then the number rolled remains undefined. As soon as one of you looks at a given die, both it and it's twin instantly take on their respective values (or you spawn 6 universes identical in every way except for the values rolled, if you like the multi-universe theory.) But when you look at a die, all you see is a number. You know that the number on the previously entangled die must be 7-#, but you have no way to tell whether you looked first or your counterpart on the ship.