what does it take to get a warp drive?

May 15, 2009

If you want to explore space firsthand, a warp drive isn’t just a good idea that could save you a lot of time and resources. It’s an absolute must. Without it, exploring even 1% of the galaxy would take eons. Luckily for future interstellar explorers, physicists are on the case and have so far been able to derive a theoretical basis for a real warp drive thanks to Michael Alcubierre from the University of Mexico. The concept he presented in 1994 has been the basis for years of theoretical fine tuning, hopes of space minded futurists and science fiction stories requiring writers to put aside relativity. But now, a group of Italian physicists think they’ve found a snag.

warp spacecraft

A warp drive as we understand it today is an asymmetric bubble of space and time wrapped around the craft that needs to move faster than light. By stretching this bubble in a certain direction, the spacecraft can move without actually moving, having the bubble of space ferry it to where it needs to go. Because special relativity only puts a limit on objects moving through space, there’s no limit to how fast space itself can be moved. For a period of time after the Big Bang, there could’ve actually been enough energy to expand space faster than the universal speed limit of 299,792,458 meters per second. A warp drive would create very similar conditions on a small scale. All it needs is an output roughly similar to converting the entire mass of Jupiter into pure energy and bend numerous dimensions into a bubble around itself. See, nothing to it!

However, by bending these dimensions, it could effectively form an event horizon around itself and that event horizon could flood the inside of the bubble with Hawking radiation. As the spacecraft approaches the speed of light, it’s bathed in a dose high enough to fry it to a crisp. The Hawking radiation itself consists of particles that appear out of the quantum mesh and ordinarily disappear back into it. In the presence of warped space though, the balance of their typical behavior is broken and they’re free to bombard anything and everything like any other type of radiation out there.

Another problem with the warp bubble is the exponential increase of something called a renormalized stress- energy tensor. This is basically stress that builds up on the deformed sections of the bubble as it moves with increasing speed. Because of the quantum phenomena that come into play when the bubble is created exert a lot of force on this shell of space and time, they build up stress. When the bubble moves quickly enough, the stress can become too great and the bubble itself pops. What will happen to the spacecraft inside? Well that is a very tricky question. Ideally, the bubble peels away and the craft is suddenly stationary somewhere in the vast expanses of interstellar space. Because the sheer distance between stars, that’s the likeliest place for it to end up. If momentum is somehow preserved through a mechanism we don’t know yet, the craft would be spat out at such an enormous speed, it would be torn apart by the interstellar medium or crushed by its own momentum as special relativity says. Or, the bubble could collapse, destroying the craft inside. Marooned or annihilated. Neither option is good, although maybe it won’t take you more than a few years to get back home from the point where your warp bubble popped.

But before you shed a tear for warp drive technology and reach for the shovel, keep in mind that these physics are so new and require so much testing to be confirmed on such a large scale, we can’t rule out the idea that one day we will have the technology to move faster than light. There are other ideas out there and maybe the combination of several different approaches will yield something that works. The very first calculations of the amount of power it would take to hit warp speed said you’d need infinite energy since the calculations were based on special relativity. After applying general relativity and extra dimensions, that requirement shrunk to just the mass of Jupiter which is an absolutely amazing and encouraging downgrade. Who knows that other phenomena we’ll find in the future or even as soon as the completion of the LHC experiments? Maybe they’ll help us overcome pretty much any quantum limitation to dreams of our faster than light travel…

See: Richard K Obousy, et al, (2008). Putting the Warp into Warp Drive Spaceflight, 50 (4) arXiv:0807.1957v2

Stefano Finazzi, et al (2009). Semiclassical instability of dynamical warp drives arXiv arXiv:0904.0141v1

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  • ColonelFazackerlely

    Erm, special relativity is the more restrictive, simpler and first published theory. It applies to things moving at constant velocity, says nothing about gravity etc.

    General relativity is the fancier one.

    I think you misused “special”.

  • Greg Fish

    You’re right, it looks like I got a little mixed up in my relativities. That’s what I get for editing my posts late at night…

    The mislabeling has now been fixed.

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  • http://www.spin-onehalf.com Eric Kuha

    I wonder what sort of mechanism could transform Jupiter into pure energy. Maybe if you had a an anti-Jupiter to collide with it, you could use the resulting energy to create the bubble. You’d then only need half of a Jupiter and half of an anti-Jupiter to achieve warp velocity.

    Bummer, man. Maybe you’re right though in the last paragraph and we’ll find some other phenomenon to break the speed-of-light limit. Thanks for the excellent article.

  • Torbjrn Larsson, OM

    I’m with computer scientist Aaronson in this. All faster than light travel is likely prohibited since it would mean time travel by way of timelike causal loops, and time travel is in Aaronson’s testable hypothesis prohibited. It would break the Church-Turing thesis of maximum capable computing. If C-T thesis is incorrect, we would see the physical world, based on algorithmic strength processes (well, duh), solve NP-complete problems fast which it observationally doesn’t. Or in other words, if ftl existed we would know everything. We don’t, so it doesn’t.

    Some physicist noted that warp drives actually doesn’t solve how to get around special relativity. All ftl solutions are based on having the warp bubble (and all its content) traveling ftl in the first place. So they aren’t physically realizable anyway.

    “exploring even 1% of the galaxy would take eons”

    Not really, I believe reproductive probes using known (but not demonstrated) feasible drives have been shown to cover the galaxy in 500 000 years. That is way longer than the typical species lifetime of course, but that isn’t a problem if the populations which benefit travel with, or in close association to, the probes.

  • Dave

    When I first read about this a couple months ago, there were a lot of comments by folks on how these potential problems might be overcome.

    First, on the Hawking radiation issue, there were several seemingly plausible solutions proposed to either avoid or shield against this.

    Regarding what happens when the bubble “pops” – there is no “momentum” to be preserved, as the ship is sitting stationary in space-time inside the bubble (this is why you would not feel any crushing G-forces when using a warp drive). This also allows a warp-drive ship to avoid the nasty time-related problems that normally result from near lightspeed travel through normal space.

    Of the other two possibilities you suggest, I guess that would depend on how the bubble came apart. According to the traditional “Star Trek” approach, a warp field collapse would typically simply drop the ship into normal space-time at that location (if you were a warp drive design engineer, I suppose that one of your first tasks would be to design the warp field so that it would lean towards collapsing in a non-destructive manner!)

    On the possible warp bubble instability issue, it has been suggested that the solution may simply be to devise a control mechanism to adjust the bubble to dynamically compensate for any instabilities, sufficiently fast enough to prevent a complete collapse (or just tell Scotty to “Stabilize the warp field, dammit!”)

    But even if you were dropped into normal space, as long as your warp drive was not destroyed in the process, you would not be “stranded” in the vastness of space as described, as you could simply re-create the field and continue on your journey!

    If the designers of early generations of “warp drives” found long-term stability of the warp bubble unobtainable with their current level of technology, what you would end up with something that has also already been contemplated in the sci-fi realm – an FTL drive that simply requires interstellar travel to be divided into discrete “hops”.

    Of course, this is all based on our present understanding of physics – to a starfaring civilization with the technological capabilities to warp space, even our present theoretical understanding of this topic would appear like savage apes trying to understand quantum gravity, barely beyond walking upright, stone tools and the invention of fire!

  • john

    I may be wrong on this but if there is nothing in space than how can you not go the speed of light. there is nothing to stop you. no gravity, no friction, nothining. time is relative, even if if you travel at warp speed it still takes time to get somewere. I think that people always look for the hardest thing instead of the simple solution to the problem.

  • Loeck

    speaking of simple solutions, we could just increase the speed of light.

    ;)

  • Patrick Burks

    Why do real scientists have to burst my bubble(get it warp bubble). I wanted a ship that would do the Kessel Run in 2 parsecs.

  • dean whitehead

    i had an idear that you could use gravity waves to warp the spacetime infront of you and behind you because gravity can effect space and time e.g black holes its a long shot because you would have to recreate the biggest explosios in the universe to create the waves. i had this idear after watching a tv program about stars exploding and producing garvity waves, that are streching and compressing the earth.

    only and idear…