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Quantum Setback For Warp Drives
Posted by
kdawson
on Fri Apr 03, 2009 07:58 AM
from the warp-zero-mister-sulu dept.
from the warp-zero-mister-sulu dept.
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)."
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Science: Warp Drive Breakthrough 264 comments
NIck Porcino writes "Warp drive one step closer to reality!
From the abstract:
A spacetime is presented for which the total negative mass needed is only
the order of grams, accompanied by a negligible amoung of positive
energy. This constitutes a reduction of the absolute value of the energy
by 65 orders of magnitude. The new geometry satisfies the quantum
inequality concerning WEC [Weak Energy Condition] violations and exhibits
the same advantages as the original Alcubierre spacetime.
Read it here.
The two big problems to be resolved are 1) how do you get an object inside a warp bubble? 2) What happens to the object when the warp bubble collapses?
"
[+]
Science: Introducing the Warpship 361 comments
astroengine writes "Dr. Richard Obousy, a guy who has put modern science into the warp drive, has designed his very own warpship. Now, for the first time, he's shared it with the world. It might not be the sleek Starship Enterprise, but its structure has been optimized to harness local 'dark energy,' generating a warp bubble so faster-than-light velocities are possible." Now, the only question is: will the ship achieve faster-than-light travel ... or will the company hit those speeds once it has enough money from investors?
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Hiesenberg says.... (Score:5, Funny)
Re:Hiesenberg says.... (Score:5, Funny)
That's the only statement you could come up with?
What a Bohr.
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Re:Hiesenberg says.... (Score:5, Funny)
If I were you I'd stop poking about with things we don't understand. After all, it was curiosity that did and didn't kill the cat. ...
I'll get my coat.
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Re:Hiesenberg says.... (Score:5, Funny)
Fourier information, I thought it was pretty funny.
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Re:Hiesenberg says.... (Score:5, Funny)
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Re:Hiesenberg says.... (Score:5, Funny)
I always just have Mr. Scott handle the warp drive. He does the impossible instantly, miracles take longer. When Spock lends a hand, hours can seem like days...
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Re:Hiesenberg says.... (Score:5, Funny)
Or is it *both* Impossible and not Impossible?
Only when you're not observing and you don't hear it meowing
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Re:Hiesenberg says.... (Score:4, Funny)
You guys talk as if you haven't heard of the Heisenberg Compensator.
http://en.wikipedia.org/wiki/Transporter_(Star_Trek) [wikipedia.org] states, "Heisenberg compensator remove uncertainty from the subatomic measurements, making transporter travel feasible."
Its clear this is a dual use technology used both for Warp drives and transporters.
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Re:Hiesenberg says.... (Score:5, Funny)
Perhaps it's only Infinitely Improbable?
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Re:Hiesenberg says.... (Score:5, Funny)
Frankly, I never get invited to any of those parties, either.
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Re:Hiesenberg says.... (Score:4, Funny)
> Or is it *both* Impossible and not Impossible?
Well, yes and no...
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Re:Hiesenberg says.... (Score:4, Funny)
"So many of our dreams at first seem impossible, then they seem improbable, and then, when we summon the will, they soon become inevitable."
- Christopher Reeve
...then you fall from a horse and reality hits you like a freight train.
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Re:Hiesenberg says.... (Score:5, Informative)
He was slowly recovering, something that seemed impossible at the beginning.
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improbability drive (Score:5, Funny)
is this where the improbability drive comes in?
yeah, someone had to say it.
Re:improbability drive (Score:5, Funny)
Will that allow ludicrous speed?
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Re:improbability drive (Score:5, Funny)
* - Possibly also Nazi-Nazi.
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Re:improbability drive (Score:5, Funny)
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Re:improbability drive (Score:5, Informative)
Also, 0 is not "nigh impossible" - it is the definition of impossible.
Not necessarily. It may be that there are an uncountable number of possible outcomes, and each individual outcome has a zero probability, but large sets of them collectively still have positive probability. At least, models exist where this makes sense...
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Re:improbability drive (Score:5, Funny)
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Re:improbability drive (Score:4, Funny)
A: 42
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Re:improbability drive (Score:5, Funny)
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Longer lifetimes is the answer (Score:5, Interesting)
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!
Re:Longer lifetimes is the answer (Score:5, Insightful)
Depends on whether we can engineer ourselves to live 50 years in a tiny spacecraft with a bunch of strangers.
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They won't be strangers for long. (Score:5, Insightful)
Heck, after 8 weeks of army basic training none of the 50 or so people in my company were strangers.
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Re:They won't be strangers for long. (Score:5, Funny)
Oh my.
This is why we need women in the army to stop that nonsense.
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Re:Longer lifetimes is the answer (Score:4, Insightful)
Why make the ship tiny?
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Mod parent up (Score:5, Insightful)
Right. At about one G acceleration you can reach any point in the universe in a few years of ship time.
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Re:Mod parent up (Score:5, Funny)
With magic, you can ride a unicorn.
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Re:Mod parent up (Score:5, Funny)
Perhaps this is why, despite our best efforts, no other civilization has contacted us. It's simply too hard to bridge the huuuuge gap between the stars.
More likely, they've just chosen not to. Like why we tend to not talk to people from Alabama.
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Re:Mod parent up (Score:5, Interesting)
Yeah but you need a massive amount of fuel to accelerate to C and then slow down again. About 40,000 times the size of the shuttle's boosters.
Perhaps this is why, despite our best efforts, no other civilization has contacted us. It's simply too hard to bridge the huuuuge gap between the stars.
Yes, if I was going to build a universe with all sorts of playthings in it, I'd probably separate the experiments with enough spacetime that when the odd experiment blows up it doesn't really affect any others around it.
Not that I think that the universe was actually designed, but if it was, that would be how I would do it.
Michael
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Re:Longer lifetimes is the answer (Score:5, Interesting)
No, it's time dilation and space contraction. If you're traveling at 0.9c relative to earth, your gamma is something like .44. So if you travel one light year, an observer on earth will see you go one light year in about 1.1 years. But from your perspective, you will have traveled only about .44 light years, and it would take something like .48 years. If you travel fast enough, you can reach even distant stars in very short times from your perspective. But you won't get a nice, tidy Galactic Federation, because people on earth will be getting very old very fast. That's the real problem with relativity. It's not that you can't get somewhere fast. Tell me where you want to go and how fast you want to get there, and we can calculate how fast you need to go (relative to the earth) to make it in that time, and it will be less than c.
In other words, we could (in theory) colonize all of the habitable planets in the galaxy in a fairly short time. But the colonies would all basically be cut off from each other. Even sending a radio message to another colony would take prohibitively long. And forget about "rescue" or "supply" ships.
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So we can't go there, big whoop... (Score:5, Funny)
Just do what the Planet Express Ship does and use a Dark Matter drive to move the Universe around us instead... [wikipedia.org] :)
Proof! (Score:5, Insightful)
Re:Proof! (Score:4, Informative)
THANK YOU. Once upon a time we all knew that the gods made things fall to the ground. Then we knew that things have the falling nature, and the world was flat so things fell "down" no matter where you were. Then we knew that F=MA. Now we know that E=MC^2. What will supersede relativity? (QM is just too wacky, it has been said that if it doesn't confuse you, you don't understand it. I think that means it's a bad model, and we should just abandon particles. But whatever.)
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Re:Proof! (Score:5, Interesting)
The problem is that in order to have a region of spacetime moving in relation to the outside universe, space has to expand behind it and contract in front, which demands negative and positive gravity in those regions. You need a large negative mass held in place in front of you, and a large positive mass behind. (We'll leave aside the problem that nobody has demonstrated the existence of negative mass, I personally don't believe it could exist precisely because it would enable FTL, but that's seperate to this point.) What you have to achieve is to have the centre of gravitation of the two masses at the centre of the edges of distortion. It means inevitably that half of the negative mass you are using has to stick out of the bubble ahead of you into normal unwarped space, and so that in order to keep generating the field ahead of you, it has to travel faster than light in its local frame. That is strictly not allowed.
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Warp Drives?? (Score:4, Funny)
Re:Warp Drives?? (Score:5, Funny)
Zing!
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Causality (Score:5, Interesting)
Faster-than-light travel always causes causality paradoxes [orionsarm.com], 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.
Re:Causality (Score:5, Interesting)
IIRC Einstein said they GR and SR may be proven wrong, but that the laws of entropy will never be broken (ie entropy is always getting bigger). I would aggree with this. ie FTL is less sci fi than "vacuum energy" or anti inertia drives.
But if I were a betting man, I would bet on light speed as the ultimate speed limit of the universe.
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Re:Causality (Score:4, Interesting)
I'm not sure perpetual motion is, strictly speaking, impossible.
Thermodynamics doesn't seem to preclude 100% efficiency, allowing motion in perpituity. Some real-universe examples:
Light on the fringes of the universe will continue travelling forever (unless we assume something new to stop it).
The electron on an atom that never falls into a star, black hole, or the like will forever circle the nucleus.
Heck: the atom itself will never stop moving.
Nor, best as we can tell, will the universe. It will be in motion perpetually (I suppose unless it all disintegrates into Hawking radiation, but then *that* will be in motion.
There are two problems with perpetual motion machines. One is the false math that you can derive infinate energy from one. That's not true at all. You could derive exactly the energy put into one.
The second is 100% effeciency, which is required for perpetual motion to obey thermodynamics, is not possible in what we would likely call "a machine"
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Re:Causality (Score:5, Informative)
entropy dictates that that everything loses to heat. This heat is at such a low energy level eventually that it can't cause any increase in energy to anything at all around it. This is how a system winds down, eventually all the energy in the atom will get sapped off this way and then it will start breaking down. Eventually devolving into the quantum soup that makes up the subatomic particles. Eventually, those too will lose energy to the space around them until everything is the same indistinguishable quantum soup.
This is the cold death scenario, and the only thing that can stop it is space itself increasing the density of energy instead of forever decreasing it. It's the expansion of space that continually provides for this loss of energy.
so no, atoms aren't perpetual motion machines. Though, for practical reasons, unless you need the machine to be functioning billions of years from now, you can call it perpetual.
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Re:We already have faster-than-light communication (Score:5, Informative)
That doesn't work [wikipedia.org]. 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.
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Re:We already have faster-than-light communication (Score:4, Informative)
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.
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Paper was submitted 1. April (Score:5, Insightful)
Please note the submission date:
Semiclassical instability of dynamical warp drives [arxiv.org]
Cancel the Star Trek movie (Score:5, Funny)
Quantum mechancs+General relativity incompatible? (Score:4, Interesting)
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?
I don't think that means what you think it means.. (Score:4, Informative)
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 =)
What scientists do not know could fill a universe. (Score:4, Insightful)
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.
Re:One major reaction (Score:4, Insightful)
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.
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Re:WARP 10 (Score:5, Funny)
Unless...
Go East
You have been molested by a Mullgrue
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