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Yeah, so it's highly speculative, but... NASA design for a 'warp' ship


vger

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It loos like there's not 1, but 2, red HAL 9000 eyes in the cockpit. Yeah... I'm not betatesting this. :D

It looks, swell/cool enough... but in the short term I'd prefer something more lowtech, but still pretty high utility like the nautilus x.

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Any sort of Alcubierre or Warp drive is nothing more than an theoretical construct at this time.

As previously discussed, it's based on solid physics. Sub-light warp is basically an engineering problem at this point. There are some questions about FTL warp, and whether that will ever become feasible, but that's a separate issue. And even there, a lot more understanding exists than you seem to imply.

We do have full theoretical understanding of physics related to warp drive. We do know the requirements. We are conducting actual experiments to see if we can create a measurable effect. This is well past "theoretical construct," and well into the "technology we are developing." Of course, it can still be decades before we can build a prototype that moves at any measurable speed using warp, let alone an actual practical warp ship. But we aren't talking about anything speculative here, either.

Yeah, the picture is obviously just an artist's rendering of what this might be like. Of course, it will be completely different. But it is important to have people thinking about these things, because it is something that needs further work, and it is something that's going to need the budget. And whatever else you may think about space fiction of the 50s and 60s, pictures like the one you've linked are a big part of why the space program didn't just die with the cold war.

We are likely to have invented antigravity and teleportation before we have the energy make warp bubbles.

Shows how much you understand about either. Sub-light warp can be done with very small amount of energy, and is by far the easiest of these three to achieve. And exotic energy needed to push warp pust the light barrier would be a precursor to anti-grav tech. As for teleportation, true teleport might never exist. It's too complicated of a process if you need more than a few particles.

Side note to K^2: Do you have a PF account?

Yes, that's me. Though, I haven't been to that site in a while.

Edited by K^2
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http://www.askamathematician.com/2013/02/q-is-the-alcubierre-warp-drive-really-possible-how-close-are-we-to-actually-building-one-and-going-faster-than-light/

There's even a warp drive mod for KSP somewhere. Though, from what I've heard of it, it doesn't do parallel transport in Schwarzschild metric correctly.

Interstellar has a pretty good implementation of the hypothetical AD. However the Interstellar mod is also limited by the game engine like all mods. You can't have 100% realism. And also having something realistic that is only possible hypothetical yet is absurd.

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[citation needed]

http://wallacegsmith.wordpress.com/2012/09/18/will-alcubierre-be-the-real-worlds-cochrane-after-all/

Alcubierre worked out in physics what science fiction writers like to take for granted: the possibility of traveling faster than the speed of light. Actually, Alcubierre has stated that he was inspired by the “warp drive†of the Star Trek fictional universe.

The one I really want though is going to be hard to pull up. I first heard it in a youtube vid where Miguel talked about the inspiration.

Hmm. I hope they're just doing this as advertising so people get at least slightly interested in NASA again...

More or less...

In 30 years, you'll be looking back at this and finding it just as laughable as this:

http://muscleheaded.files.wordpress.com/2013/07/spaceship.jpg

There's a reason things like this are done. Both now and in the past. Sadly, it's something we need MORE of in the modern age. People no longer look to the future. Speculative space art was all over the place at the time space interest was at its peak. This is probably not a coincidence. Who cares if Flash Gordon rockets and Mars hotels are unrealistic if they can get the general public excited? Sometimes you need to show people the end result of centuries of development, rather than just show how we're going to get to that point. Realistic or not, hope is a necessity.

Edited by vger
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Interstellar has a pretty good implementation of the hypothetical AD. However the Interstellar mod is also limited by the game engine like all mods. You can't have 100% realism. And also having something realistic that is only possible hypothetical yet is absurd.

It's not about the engine limitation. It's about actual physics of it. It doesn't transform the craft velocities correctly as you climb out of the gravitational well.

Edit: From the thread itself.

In terms of game function it applies a temporary velocity change to your orbit which is reversed when you turn it off. In this way the game correctly plots your trajectory at high speed but it still simulates the effect of an alcubierre drive correctly.

Which isn't at all how the warp drive works in gravitational well.

Edited by K^2
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Which isn't at all how the warp drive works in gravitational well.

It's a sufficient hack to make it work. O.o If you want better...then you really are talking about limitations in the game. Maybe not specifically the engine itself, but still.

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It's a sufficient hack to make it work. O.o If you want better...then you really are talking about limitations in the game. Maybe not specifically the engine itself, but still.

Not at all. The final velocity is completely wrong. And it's something you can fix knowing just a bit of GR.

So why not? What should happen in your opinion?
I second this question. What would happen to a warpship going from Earth to Mars for example?

Well, lets look at flat space time first. The ship never accelerates under warp. If it was still in your chosen frame of reference, it will be still when it comes out of warp. Thanks to relativity, that also means that if it went in with some velocity, that's the velocity it will come out at. And that's what the Fractal_UK just took and ran with.

But what does it mean to have the same velocity in curved space-time? How can you tell if two vectors are the same if the metric is different? And the answer is, you can't comapre two vectors in two different places. Not without taking into account the path connecting the two points in space. That's the whole idea of parallel transport, and a big part of the 'why' of General Relativity. Specifically, you can tell if two vectors are the same if they are separated by some infinitesimal distance. So as you slide along the trajectory that the warp ship took, you can maintain "the same velocity". For a game like KSP, I'd use the "patched conics" idea extended to GR, saying that what you are dealing with is Schwarzschild Metric centered on the source of SOI. But before we jump into heavy math, lets take a step back.

Lets forget warp for a moment. Lets look at how the ship travels around a planet. Why does it go around in orbit, rather than keep moving straight? Trick question. Within framework of GR, it is going straight. Or the next best thing in curved space-time. Specifically, the ship's velocity "stays the same" in much the same way as when we talk about warp. Because the ship moves along a trajectory, we can only compare velocity at two infinitesimally displaced points along that trajectory, and velocity "doesn't change". Formally, ∇uu = 0. That's the differential equation for a space ship trajectory, where u is four-velocity. The only reason we see it as acceleration is because our chosen frame of reference is not an inertial one. After all, gravity.

Same exact thing has to apply to velocity of our ship under warp as we travel through the space-time slightly curved by a celestial body, except ship's own velocity now has nothing to do with how fast we are moving through space-time. It's all determined by warp trajectory which, strictly speaking, can be almost arbitrary. Alcubierre used straight line for simplicity, but you can get creative with that. Let us call the speed of the bubble v, and then we consider covariant derivative with respect to that. Specifically, we need to integrate ∇vu = 0 along the trajectory. Writing ∇vuα = vβ ∂uα/∂xβ + Γαβγvβuγ, and expanding Γαβγ in terms of Schwarzschild metric tensor, we have equation for ∂u that we need only to integrate along ship's trajectory. There are some numerical challenges here, but nothing dramatic.

Interestingly enough, if we were talking about sub-light warp, at speeds much lower than speed of light, like, say, 10% of c, I suspect Fractal_UK's approach of adding warp velocity to ship, and subtracting it when ship comes out of warp would have worked. The reason for that is the same why ∇uu = 0 gives you acceleration due to Newtonian gravity in the classical limit. And the reason why Fractal_UK's approach fails for an FTL ship is the same why you can't get correct trajectory for a beam of light by simply assuming that it's a particle traveling at c. The Newtonian approximations to gravity simply do not hold at these speeds. So velocity of a ship dropping out of warp will be quite different.

For a specific case, I'd need to run some numbers, and like I said, it depends on trajectory. If you give me a "for example," type situation, I can do the calculations in Mathematica easily enough.

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Not at all. The final velocity is completely wrong. And it's something you can fix knowing just a bit of GR.

Well, lets look at flat space time first. The ship never accelerates under warp. If it was still in your chosen frame of reference, it will be still when it comes out of warp. Thanks to relativity, that also means that if it went in with some velocity, that's the velocity it will come out at. And that's what the Fractal_UK just took and ran with.

But what does it mean to have the same velocity in curved space-time? How can you tell if two vectors are the same if the metric is different? And the answer is, you can't comapre two vectors in two different places. Not without taking into account the path connecting the two points in space. That's the whole idea of parallel transport, and a big part of the 'why' of General Relativity. Specifically, you can tell if two vectors are the same if they are separated by some infinitesimal distance. So as you slide along the trajectory that the warp ship took, you can maintain "the same velocity". For a game like KSP, I'd use the "patched conics" idea extended to GR, saying that what you are dealing with is Schwarzschild Metric centered on the source of SOI. But before we jump into heavy math, lets take a step back.

Lets forget warp for a moment. Lets look at how the ship travels around a planet. Why does it go around in orbit, rather than keep moving straight? Trick question. Within framework of GR, it is going straight. Or the next best thing in curved space-time. Specifically, the ship's velocity "stays the same" in much the same way as when we talk about warp. Because the ship moves along a trajectory, we can only compare velocity at two infinitesimally displaced points along that trajectory, and velocity "doesn't change". Formally, ∇uu = 0. That's the differential equation for a space ship trajectory, where u is four-velocity. The only reason we see it as acceleration is because our chosen frame of reference is not an inertial one. After all, gravity.

Same exact thing has to apply to velocity of our ship under warp as we travel through the space-time slightly curved by a celestial body, except ship's own velocity now has nothing to do with how fast we are moving through space-time. It's all determined by warp trajectory which, strictly speaking, can be almost arbitrary. Alcubierre used straight line for simplicity, but you can get creative with that. Let us call the speed of the bubble v, and then we consider covariant derivative with respect to that. Specifically, we need to integrate ∇vu = 0 along the trajectory. Writing ∇vuα = vβ ∂uα/∂xβ + Γαβγvβuγ, and expanding Γαβγ in terms of Schwarzschild metric tensor, we have equation for ∂u that we need only to integrate along ship's trajectory. There are some numerical challenges here, but nothing dramatic.

Interestingly enough, if we were talking about sub-light warp, at speeds much lower than speed of light, like, say, 10% of c, I suspect Fractal_UK's approach of adding warp velocity to ship, and subtracting it when ship comes out of warp would have worked. The reason for that is the same why ∇uu = 0 gives you acceleration due to Newtonian gravity in the classical limit. And the reason why Fractal_UK's approach fails for an FTL ship is the same why you can't get correct trajectory for a beam of light by simply assuming that it's a particle traveling at c. The Newtonian approximations to gravity simply do not hold at these speeds. So velocity of a ship dropping out of warp will be quite different.

For a specific case, I'd need to run some numbers, and like I said, it depends on trajectory. If you give me a "for example," type situation, I can do the calculations in Mathematica easily enough.

Well i understand your objection, but honestly i really don't think this is doable with the limitation of the engine KSP offers. IMO the API does not have enough funtionallity to do the math correctly because you have somehow to get your speed relative to the source of SOI every time. In it's current state you can obtain it only for the body you are orbiting. The programmer could however include some tables with precalculated values for the different bodys to do the math but it would only work on an unmodded install. As soon as you install mods modifying the KSP universe your math's won't work anymore. The warp drive mod would get unnecessary complicated. For me it's fine like it is now, at least it does not put you in stable orbit around a body everytime you stop the drive like some other warp drive mods. I am sure Fractal knows about this problem but he just did not see any other way to do it.

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Well i understand your objection, but honestly i really don't think this is doable with the limitation of the engine KSP offers.

*sigh* Again. Yes, it is completely possible. The only values you need are the planet's mass, your velocity with respect to it, and your position with respect to it. Can you get these things? Yes, you can. The rest involves storing pre-warp velocity and updating it using numerical integration algorithm. That's it. That's all you have to do.

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Hmm... Well, I think some research into this area is warranted because, if possible, it would literally open up more space for mankind than all of exploration so far. The potential pay out is worth it imho. ... Or in other words playing the lottery is fine, it allows you to dream. Spending all your money on the lottery is stupid.

But I'll still want to see a detection of actual manmade warping space before I see it.

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But I'll still want to see a detection of actual manmade warping space before I see it.

Predicted amounts are right at the edge of detectable right now. Which is why NASA has experiments looking for it. It's all been inconclusive so far, which is to be expected, but getting to conclusive experiments will really be just a matter of years now.

Of course, bending space and making a warp bubble, even a sub-light one, are very different things.

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If I'm reading K^2's description right, sounds like a transfer using warp would still be pretty complicated, in that you will still need to execute some serious burns in order to properly orbit your destination.

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