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Transportation Sci-Fi Science

Quantum Setback For Warp Drives 627

Posted by kdawson
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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Quantum Setback For Warp Drives

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  • by MeNotU (1362683) on Friday April 03, 2009 @09:01AM (#27443497)
    Or is it *both* Impossible and not Impossible?
  • by phrostie (121428) on Friday April 03, 2009 @09:01AM (#27443499)

    is this where the improbability drive comes in?

    yeah, someone had to say it.

  • by tjstork (137384) <todd.bandrowskyNO@SPAMgmail.com> on Friday April 03, 2009 @09:02AM (#27443507) Homepage Journal

    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!

    • by SnapShot (171582) * on Friday April 03, 2009 @09:05AM (#27443533)

      Depends on whether we can engineer ourselves to live 50 years in a tiny spacecraft with a bunch of strangers.

    • Re: (Score:3, Insightful)

      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!


      Either that, or we can just figure out how to get really close to the speed of light, and reap the benefits of time dilation to make the journey only last hours from the traveller's point of view.
      • Mod parent up (Score:5, Insightful)

        by John Hasler (414242) on Friday April 03, 2009 @09:20AM (#27443707) Homepage

        Right. At about one G acceleration you can reach any point in the universe in a few years of ship time.

        • by maxume (22995) on Friday April 03, 2009 @09:36AM (#27443895)

          With magic, you can ride a unicorn.

          • 1 G isn't magic (Score:3, Interesting)

            by jmichaelg (148257)

            Sustaining 1G for several years isn't magic. It's just advanced technology.

            James Powell, the co-inventor of super-conducting maglev, described a mechanism to build a 1G rocket to travel to the stars. His basic idea was to use Mercury as a solar collector to manufacture a few tons of anti-matter. When you react the anti-matter, you get both power and ejectable mass moving at very high speed. A sci-fi author, Charles Pelligrino, wrote up the idea in the appendix to his book, Flying to Valhalla [amazon.com].

            The Orion desig

      • Re: (Score:3, Informative)

        Either that, or we can just figure out how to get really close to the speed of light, and reap the benefits of time dilation to make the journey only last hours from the traveller's point of view.

        Hours?

        1g to Alpha Centauri - 3years, 205 days.

        Compress that trip to, say, sixty hours...

        2575g.

        It gets worse fast. 1g only gets us to 95% lightspeed. Higher acceleration pushes us way up into relativistic effects.

        • Re: (Score:3, Funny)

          by ArsonSmith (13997)

          3 years 205 days is 31,200 hours. so yes the trip will only last for hours, 31k of them.

    • by CTalkobt (81900) on Friday April 03, 2009 @10:42AM (#27444945) Homepage

      The problem with traveling faster than light is that my wife would never go with me on a trip:

      "Traveling that fast is going to make my ass look big."

      (Hmm, leaving her behind might be a good thing... )

    • Re: (Score:3, Informative)

      by timholman (71886)

      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!

      Ah, but you could travel to the stars without immortality at FTL speeds - at least from the point of view of a ship's occupants - as long as you choose not to go home again. A constant acceleration drive would enable you to cross the galaxy in a few years of ship time, thanks to

    • Re: (Score:3, Insightful)

      by gad_zuki! (70830)

      Lets say we do that tomorrow. Now you still need to figure out how to keep food and water on that ship for 50 years. Engineer a fuel source that can carry you with strict safety controls to keep the bag of flesh that is you in alive. Oh, while we're at it we'll need a new groundbreaking psychology that can keep 1,000 yo humans sane, especially ones stuck in a smelly spacecraft for 50 years. I wont hold my breath.

  • by bhunachchicken (834243) on Friday April 03, 2009 @09:08AM (#27443551) Homepage

    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)

    by cjstaples (810734) on Friday April 03, 2009 @09:08AM (#27443553)
    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.
    • Re:Proof! (Score:4, Informative)

      by drinkypoo (153816) <martin.espinoza@gmail.com> on Friday April 03, 2009 @09:19AM (#27443693) Homepage Journal

      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.)

      • Re:Proof! (Score:4, Insightful)

        by radarsat1 (786772) on Friday April 03, 2009 @10:49AM (#27445037) Homepage

        E=MC^2 doesn't contradict that F=MA.

        F=MA doesn't contradict that things fall down.

        What makes you think that new developments in physics will contradict that E=MC^2?

        In short, physics is further and further refined by research, not contradicted, because new theories don't change the empirical evidence that was used to determine old theories, they just explain it better.

        Of course, that doesn't mean new theories don't help development of new technologies, so your point stands.

    • Re:Proof! (Score:5, Interesting)

      by geckipede (1261408) on Friday April 03, 2009 @09:37AM (#27443903)
      This isn't anything new, it's an old idea being analysed more rigorously with quantum mechanics.

      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.
      • Circular Argument (Score:3, Insightful)

        by Comboman (895500)

        (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.)

        That's sounds like a circular argument:

        • Negative mass can't exist because it would allow FTL travel.
        • FTL travel can't exist because it would require negative mass.
  • by rodrigoandrade (713371) on Friday April 03, 2009 @09:08AM (#27443557)
    So you mean to say my brand spanking new SSDs have become obsolete already???
  • Causality (Score:5, Interesting)

    by QuoteMstr (55051) <dan.colascione@gmail.com> on Friday April 03, 2009 @09:08AM (#27443559)

    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)

      by delt0r (999393) on Friday April 03, 2009 @09:24AM (#27443745)
      There have been some papers that even survived peer review on possible resolutions to this. But this is by far the biggest stake in FTL heart. Ironically this is not the biggest problem with the Alcubierre drive. Negative mass energy being one of them.

      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.
    • Got a Better Idea? (Score:3, Insightful)

      by d3ac0n (715594)

      While what you say may be very true, the problem is that we have yet to come up with a more feasible method of reaching distant planets in a reasonable amount of time.

      The next closest idea that Science and Science Fiction have come up with is Wormhole/Space Fold travel. And unless you have some safe way of generating more power than a large star in a safe and contained manner, that's going to be even tougher than FTL or Warp Bubble drive.

      So our best bet is to spend the time doing a full scientific inquiry

      • Re: (Score:3, Informative)

        by MozeeToby (1163751)

        As has been pointed out, there are many answers to the problem of interstellar travel that don't involve rewriting the physics of the past 150 years.

        Medicine may allow us to live indefinitely, making travel to the stars possible by the sheer power of our lifespan.
        Computers may allow us to upload our consciousness into them, leading to an indefinite lifespan.
        Medicine may allow us to freeze ourselves and re-thaw when we get to the destination.
        Space propulsion may allow us to accelerate at 1g for long periods

    • Re:Causality (Score:4, Interesting)

      by JerryLove (1158461) on Friday April 03, 2009 @09:35AM (#27443887)

      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"

      • Re:Causality (Score:5, Informative)

        by SafeMode (11547) on Friday April 03, 2009 @10:09AM (#27444401) Homepage

        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.

  • by 49152 (690909) on Friday April 03, 2009 @09:12AM (#27443597)

    Please note the submission date:
    Semiclassical instability of dynamical warp drives [arxiv.org]

  • by Onyma (1018104) on Friday April 03, 2009 @09:17AM (#27443679)
    That's it, cancel the Star Trek Movie. Now that I know it's all fake it just ruined it for me.
  • by benwiggy (1262536) on Friday April 03, 2009 @09:23AM (#27443735)
    I think I've seen this episode.

    Don't they remodulate the shield frequency (or reconfigure the emitter array), and that keeps the bubble stable just long enough?

  • by Vellmont (569020) on Friday April 03, 2009 @09:25AM (#27443751)

    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?

    • by JustinOpinion (1246824) on Friday April 03, 2009 @10:37AM (#27444849)

      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

  • 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 =)

    • Re: (Score:3, Informative)

      by Chris Burke (6130)

      Yeah it is funny hearing people say they have made a "quantum leap" which would mean "the smallest possible discreet leap". I mean even the show with that name wasn't implying huge leaps, so I don't know how it came to mean that in their heads. Or maybe they mean it's an advancement worthy of Scott Bakula?

      I actually liked how the last Bond movie, "Quantum of Solace", used the term correctly. Though this probably confused some people. My roommate thought the name was stupid till I told him what "quantum"

  • One major reaction (Score:3, Insightful)

    by Dasher42 (514179) on Friday April 03, 2009 @09:59AM (#27444239)

    I am completely hopeful for the sake of knowledge and experience that we get to into space like in Star Trek. However, I do note a bit of escapism in some of the hopes for a warp drive. I think people are a bit afraid of the idea that this Earth might be the only world humanity will ever live on. The cynic in me suggests that people want this world to be disposable.

    We co-evolved with the planet all the way back to when we were microbes. This world is a part of us. Yes, let's try to break past the speed of light, for the sake of science and achievement. Are we existentially okay with our fate as a species being completely contained in this world? I think we can be.

    • by Targon (17348) on Friday April 03, 2009 @10:32AM (#27444781)

      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.

  • by Targon (17348) on Friday April 03, 2009 @10:29AM (#27444735)

    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.

  • 3 laws (Score:3, Interesting)

    by davek (18465) on Friday April 03, 2009 @10:56AM (#27445127) Homepage Journal

    Arthur C. Clarke formulated the following three "laws" of prediction:

    1. When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.

    2. The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

    3. Any sufficiently advanced technology is indistinguishable from magic.

    (http://en.wikipedia.org/wiki/Clarke%27s_three_laws)

    I assume then, a statement about superluminal travel being impossible, is actually good news.

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