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Space Transportation Science

Warp Drive Might Be Less Impossible Than Previously Thought 867

runner_one writes "Harold 'Sonny' White of NASA's Johnson Space Center said Friday (Sept. 14) at the 100 Year Starship Symposium that warp drive might be easier to achieve than earlier thought. The first concept for a real-life warp drive was suggested in 1994 by Mexican physicist Miguel Alcubierre, however subsequent calculations found that such a device would require prohibitive amounts of energy, studies estimated the warp drive would require a minimum amount of energy about equal to the mass-energy of the planet Jupiter. But recent calculations showed that if the shape of the ring encircling the spacecraft was adjusted into more of a rounded donut, as opposed to a flat ring the warp drive could be powered by the energy of a mass as small as 500 kg. Furthermore, if the intensity of the space warps can be oscillated over time, the energy required is reduced even more."
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Warp Drive Might Be Less Impossible Than Previously Thought

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  • by BitterOak ( 537666 ) on Monday September 17, 2012 @07:13PM (#41368941)
    I'll believe it when I see time travelers from the future who have used their warp drives and FTL travel to come backward in time to tell us about it. (According to special relativity, the ability to travel faster than light is equivalent to the ability to travel backwards in time.)
  • by CajunArson ( 465943 ) on Monday September 17, 2012 @07:15PM (#41368975) Journal

    If this thing truly "warps" space (no idea if it does) you could travel at effectively faster than light speed through a vacuum while never actually accelerating past the speed of light doing it...

  • by Anonymous Coward on Monday September 17, 2012 @07:33PM (#41369201)

    But that's the point of how warp drive works - you bend space so that you don't travel faster than light.

  • by pubwvj ( 1045960 ) on Monday September 17, 2012 @07:41PM (#41369285)

    I love it when people say things are impossible. Then they go whizzing backwards into forgotten history as the impossible becomes the norm. Tomorrow will be like today. The future will be surprising.

  • by Tanuki64 ( 989726 ) on Monday September 17, 2012 @07:44PM (#41369323)

    c is in vacuum always c. Regardless of your movement.

  • by SciBrad ( 1119589 ) on Monday September 17, 2012 @07:48PM (#41369373)
    That's only true in special relativity. In general relativity where you are dealing with the expansion or warping of space this constraint is not there globally. For example, objects that recede past our cosmic event horizon are moving away from us faster than the speed of light, but only because the space between us is expanding such that it appears that way. Locally nobody is traveling faster than light, but on a global scale this is essentially what is happening. That is why we have a cosmic event horizon. However the necessity of exotic matter, as alluded to in a previous comment puts a dampener on the whole thing sadly.
  • by mosb1000 ( 710161 ) <> on Monday September 17, 2012 @08:29PM (#41369703)

    People have used metamaterials to achieve results that seem to violate the laws of physics (such as materials having a negative refractive index []). Speculating that such an exotic material could be produced is not hand waving. Just because we don't know how to do something today doesn't mean we'll never figure it out.

    And no, the energy argument was not secondary. Before you could argue that even if we could make the materials necessary it would require a prohibitive amount of energy to work. Now the argument is only about the materials needed.

  • by monkeykoder ( 1820796 ) on Monday September 17, 2012 @08:29PM (#41369711)
    Again completely false they could not see you at your destination before you left because you would not be there yet. They would see you arrive at your destination faster than the speed of light but not before you left. At no point would you be violating causality unless you used the type of wormhole that links two different times which has yet to be conclusively proven impossible. As well there is no real reason to believe that my future self could not go back in time and have caused the universe to be in the state that it is currently in. Which makes the causality argument shaky at best. Also it looks like you don't have a firm understanding of special or general relativity.
  • by HappyEngineer ( 888000 ) on Monday September 17, 2012 @08:46PM (#41369843) Homepage
    There are several issues here, but I'd like to comment on your linking of light and causality.

    First, objects traveling faster than sound do not violate causality for a bat. Just because the sound they receive is confusing does not mean that the universe broke or that anyone traveled through time. A supersonic object can make two sounds at two different times and a listener at a certain position would hear the sounds reversed. That's confusing, but it doesn't violate causality (except in the strict sense that a bat would sense that events occurred in the wrong order). Sound and light are not the same of course, but getting your data out of order just means that things are confusing for the viewer.

    The reason sound and light are not the same is because sound is not synced with time. Being supersonic does not affect time significantly whereas getting closer to the speed of light causes you to experience time differently than others traveling at different velocities relative to you. Furthermore, time dilation and your speed of travel are synced such that light travels away from you at the same speed no matter what speed you are traveling at (assuming you aren't magically warping space).

    I don't know enough to comment on how exactly warping space to travel ftl works with special/general relativity, but I've never seen it debunked. The real problem is that there is no known way to warp space to create this warp drive.
  • by Anonymous Coward on Monday September 17, 2012 @09:06PM (#41369987)

    You can't go backwards in time using FTL. You can violate Causality, but that's not the same thing and isn't actually a big deal.

    Picture it this way: You have a ship that can travel to Jupiter in 5 seconds. The method doesn't matter. You leave Earth, go to Jupiter, come back faster than light, and it's still 10 seconds into the Earth's future. You did not go so fast that you ended up in the Earth's past. You did not return while they were still counting down to your launch.

    But what DID happen is that you outpaced your own light cone [].

    Since relativistic observers cannot exceed the speed of light themselves, and events can only propagate at the speed of light, then for all events, all relativistic observers will see the cause before the effect. That's Causality. But a lot of people get caught up on the whole "no absolute reference" thing and they take it a bit too far. Once something happens, it's done. You might not know about it yet, but it already happened and there's nothing you can do about it.

    So what would it mean if we could outpace our own light cone? Not much, actually.

    You could see the effect of some events before the cause, but you wouldn't be able to do anything about it. The cause already happened. The cause has its own light cone, but you're coming at it from a weird angle, so you haven't run into it yet. You might not even see the cause until you slow down and let it catch up to you "naturally".

    Similarly, some observers would see you as moving backwards, but that's just because you're moving faster than the photons you're emitting. Anyone who saw that wouldn't be able to do anything about it, though, even if they could travel instantaneously. You've already long since passed them. If they could travel faster than you, they might be able to intercept you in the future by plotting out your course from what they observered, but they wouldn't actually be able to use what they saw to affect the past. Like if I found a blog post from you that said you were hiking from DC to Hollywood starting a week ago, so I figure out how long that will take and board a plane to meet you there. The Universe wouldn't much care.

  • by NEDHead ( 1651195 ) on Monday September 17, 2012 @09:28PM (#41370125)

    don't need a physics class, as I already have my degrees in the field. All that you reference is true in its own context (spec rel). Alcubierre warp drive is valid within Gen Rel, and does not lead to time travel. It has other issues, but not this particular one.

  • by iggymanz ( 596061 ) on Monday September 17, 2012 @09:52PM (#41370267)

    you are the one in need of more physics classes, you are linking a SR page (inertial reference frames only, changing relativistic mass to change velocity only) and this drive is outside the realm of SR, it is a GR engine. your SR arguments are meaningless.

  • by kilodelta ( 843627 ) on Monday September 17, 2012 @10:10PM (#41370403) Homepage
    It's funny how Sci-Fi becomes reality on a relatively short time scale. Think about the stuff on Star Trek that is reality today, granted not exactly like ST, but damnably close. The MRI is in my opinion the preeminent scanning technology now. And cell phones and hand held radios - they're all essentially SDR's now. My little Yaesu VX-7r is a quad band radio, and I remember back in 1992 my Kenwood TH-28 was only a dual band and didn't have a general coverage receiver on it like my little Yaesu.
  • by F34nor ( 321515 ) on Monday September 17, 2012 @10:47PM (#41370665)

    I would happily throw 90% of the human race under a bus for a working warp drive.

  • by colinrichardday ( 768814 ) <> on Monday September 17, 2012 @11:11PM (#41370815)

    No, nothing can go faster than the speed of light because it will violate causality. Which is more or less forbidden by the entirety of physics.

    It is true that faster-than-light travel would mean that we have causal sequences whose order is frame dependent, but would that be a violation of causality?

  • by Requiem18th ( 742389 ) on Monday September 17, 2012 @11:31PM (#41370933)

    Excuse me as I re-post what I already asked elsewhere in this article:

    I don't see how FTL traveling implicates time travel. "Apparent" time travel i understand. But don't really see how it affects causality.

    Let's say my sun explodes and I go to a nearby system 2 light years away at twice c. Once there I will warn everybody that the closest star is going nova in a year. Now let's say you want to prevent me from delivering these news. You look up to the sky and see my planet. Obviously it is still there isn't it? So you take my warp ship and try to go to my planet. By the time you get there you are only going to find a 2 years old cloud of hot gas.

    If you travel at 4 c you will find a 1.5 years old gas cloud. Travel at 8 c to find a 1.25 years old gas cloud. Travel there at 16 c to find a 1.175 years old cloud.

    Travel as fast as you want. You shouldn't ever get earlier than a year after my departure let alone prevent it. Now, it could be that someone find out about this and tries to intercept you by going there at twice your speed. They'll get there before you and it will surely take you by surprise but that's still not time travel from your point of view.

  • by Prune ( 557140 ) on Tuesday September 18, 2012 @01:54PM (#41376775)
    Yes, it does. Someone will observe you traveling faster than light, going from point A to point B faster than light would travel the same distance. If nobody sees you traveling faster than light, then how can you say you did so at all? And the whole point of relativity is that the laws of physics have to hold everywhere. That observer, depending on their own velocity in space-time, potentially see you arrive at your destination before you left, violating causality according to them. Given a few such warp ships, you could even arrange it so that that person would receive a message they had written and sent with you before they had actually written it. And then causality is broken for everyone.

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