K^2

So it's supposed to be a fly-by and return? Something similar to Apollo 8?

No, that's precisely something it can't do. Momentum has to be conserved. It's a local conservation law, but because it's a bulk quantity, that implies global conservation. The only way a ship could gain momentum using gravity, without a reaction mass, is with gravity waves carrying away the momentum. And that requires a lot of energy. (300MJ / Ns) And odds are, it will be less efficient than photon drive, which does the same thing. So whatever else happens, warp along a given trajectory will have to conserve momentum. Energy is also conserved, but energy changes are not as significant. If we end up with a trajectory where we have to pump extra energy into warp field to compensate, it's something we can live with. Alcubierre Drive can take an arbitrary trajectory. But in this case, yes, I think a straight line is optimal. One will not encounter any curvature along that path. And if stars A and B are of the same mass, then by symmetry, when you come out of warp, you will be moving at the same orbital velocity as you left A with. So you'll be able to go from orbiting A to orbiting B. Assuming, there are no problems in the middle. I'd need to do the computations, but it's foreseeable that proper-velocity of the ship would turn complex in map coordinates. That's not a problem by itself, because it's purely an issue with a coordinate system, but it should imply a coordinate singularity in between. Also, if you dropped out of warp in the middle, what should happen? And if you can't drop out of warp, what's actually preventing you. My best guess is that you end up with an event horizon on the bubble, and that's clearly bad mojo. This is the main reason why I'm much happier with the idea of using warp only after you got yourself going at an escape velocity. I'll play around with humbers, though. I've been meaning to do so, but it would take up a better chunk of the day, and I haven't had that sort of time lately.

Superconductors aren't my area, but my department has good condensed matter people. I can ask around to see if there have been any serious breakthroughs with HTSCs. But in either case, SCs would make for very poor shielding. The problem is that they only shield up to a critical field strength. There are some cryogenic SCs that can hold a strong mag field at 2K or so, and that's what they use in accelerators, but HTSCs are crap at it without exception. A high energy charged particle will exceede critical fields locally, force a transition to normal state, and just keep going. SC will probably provide better shielding than same material in normal, non-superconducting state, but not by enough. Your best bet in shielding from charged particles is still Compton Scattering, and that just scales with density. So grab a chunk of led, or depleted uranium if you can afford it, and build your shielding out of that. (Now that is my area.)

There are trajectories for particles impacted by your bubble that will pass through the center, right where your ship is. So you do have to worry about radiation. But these particles will slow down with respect to ship, so you won't be slammed as hard. (Naturally, if you're in FTL warp, you can't have a particle actually hit you at FTL speeds. At close range, all relative speeds must be within c even in GR. So particles that pass into the bubble do pick up speed, but not enough to actually accumulate in the bubble.) I'll have to look up that article on geodesics of Alcubierre Metric. These computations tell you exactly how energetic the particles are going to be, and that would let one estimate the levels of radiation. Off the top of my head, I honestly couldn't tell you how bad it's going to be. IIRC, for FTL warp it's bad. But I'm not sure if I've ever even seen figures for sub-light warp.

Whatever you want. That's the point. Well, that's not true either. Warp bubble moves along an arbitrary world-line, which is part of the definition of the relevant warp metric. Alcubierre wrote his paper in coordinate system in which ship is initially at rest, and it still carries it to the destination which is also at rest with respect to the ship. He chose a straight line for ship's trajectory, but it's something you can get creative with as well. That's a common misconception. It's not actually what Alcubierre Drive does. What it does is locally tilts your light cone. What Aethon says about riding a surf wave is far from physics of it, but it's a very good metaphor for what happens. Normally, inertia means that you have to apply force to start going. But when space-time metric changes, inertia can mean that you have to apply force to prevent yourself from being swept along. If the ship doesn't fight warp, it will carry it along. This is similar to concept of frame dragging. So it's not about ship already traveling towards destination, and AD making the path shorter, but about AD actually carrying it along towards the destination.

That is actually completely wrong. If it makes it easier for you to think of it this way, you can picture the ship as always moving, but mostly through time. Alcubierre Drive boosts the coordinate system of the ship, so its movement through time ends up being motion through space as well. In other words, ship can be totally static to begin with, and still pick up speed via AD. Otherwise, you'd end up with a contradiction. If the ship had to be moving to activate warp, what would the observer see that's moving at the same speed as the ship? Relativity is all relative. What works in one frame of reference has to work in all the others as well. If a moving ship can use warp, so can a static one, and vice versa. Now, when you have a source of gravity, things do get a bit more interesting, but unless you are trying to use FTL Warp to go through a black hole, it's not that much more interesting. Just some extra complications in terms of how your pre-warp velocity relates to your post-warp velocity. You actually have total control over your trajectory during warp. Some might be more energy-efficient than others, and there could be issues with radiation when bubble accelerates, but otherwise, strictly speaking, you could be flying around in zig-zags without the ship itself ever experiencing acceleration. And if the space-time around was completely flat, it wouldn't have any effect on ship's final speed, either. So in terms of warp bubble itself, there are no problems just leaving earth orbit using warp. However, Earth's gravity is still going to affect the ship and accelerate the ship. It's a very indirect effect, because the space-time inside the bubble is flat, and so gravity's effect is actually on the bubble, which will cause the bubble to shift, which will require you to correct for, which will end up changing the exit velocity of the ship as if the ship was being affected by gravity. But then you're not taking a ballistic trajectory, so the effects of gravity will not be exactly the same as just gravitational force acting on the ship. I don't know what will happen to the ship if warp takes it out of the system that it didn't have velocity to escape, though. That's an interesting question. I think I'll have to run a simulation on that and see if there is an inherent problem. Might not be. Strictly speaking, energy need not be conserved, since you might be supplying energy via the warp bubble. On the other hand, momentum should be conserved. Otherwise, it's a gravitational wave drive, which is probably the least energy-efficient method of propulsion in existence. You definitely would want to avoid that.

AD has NOTHING to do with your engines. The only reason you need to burn fuel is to make sure your velocity relative to target isn't too high. And yes, it will bring you along an (almost) straight line without needing to expend any fuel. I suggest you read up on the subject. And you seem to be extra confused on this part. Travel with Alcubierre Drive is actually faster. Not just takes less time from perspective of the ship. When a warp ship travels faster than light, it's actually going faster than light. With an Alcubierre Drive you can do a round trip to Alpha Centauri and be back before eight years pass on Earth. Sub-light warp within the system works the same way. You actually get to destination faster. Not just by ship's clock, but by everyone's.

Earth passing by Mars. You want to fire up your reaction engines and get roughly up to escape velocity. You probably want to wait until you are far enough from Earth to not be a hazard to any satellites as well. Then you fire up warp and go on an almost straight line trajectory from Earth to Mars, where you will drop out and star breaking heard with reactions to assist the capture. You'll probably end up wasting almost as much reaction fuel as you would with classical transfer, but you'll get there much faster. There might be some advantages to Earth or Mars being slightly ahead along the orbit, but likely not too much. You definitely don't want them to be in completely different places with respect to Sun. It'd both make for a longer travel and make it way harder on your propulsion.

Doesn't matter. When you drop out of warp, you'll still have some particles in the bubble. Space is nowhere near as empty as some people seem to think. White's design might reduce the effect, I have not seen it being worked out for an oscillating field, but it's still going to be there. And it's still going to make warp entirely too dangerous in Low Earth Orbit. But there is no reason to use it in LEO. You are still going to need conventional thrust to get yourself going, because of the way gravity interacts with a warp ship, and so you can just wait until you pull away to a safe distance from Earth before engaging warp. Same deal with approaching any station. There is really no reason to go into warp or drop out of it right at your origin/destination.

Hm. It's on GitHub, so yeah, I suppose I could grab it and make modifications. I'll look into it.

Yup. As Nuke says, bladders. The advantage of non-cryogenic fuels is that you can keep them in a bladder without adding much weight. If RCS required ullage, they'd be quite useless, as you could just use ullage engine for maneuvering.

That's correct, during uniform travel. But that's not what happens when bubble accelerates or decelerates. While particles do pass through, they take some time to do so. Any particles still in the bubble when the ship drops out, these are released with a lot of energy. I might be able to find the article on that, if you are interested.

Suit yourself.

That's essentially correct. An Alcubierre Drive warp bubble can travel along an arbitrary trajectory. That trajectory defines the field's metric, and that, in turn, tells you where you need to pump energy to maintain the field. So unless you want to be falling towards the Sun, you won't be. Not directly, but yes. Any particles picked up by the warp bubble that have not been released during transit will be released with a lot of energy when the ship drops out of warp. That's just one of the reasons why you wouldn't want to arrive or depart from LEO using warp.

It won't save you much on fuel, but would you rather a trip from Earth to Mars take months or hours? This is basically the difference that sub-light warp could make.

Initial trajectory? Warp trajectory? Warp speed? These are the important factors. Also, that trip crosses SOI, which is a bit of a pain to compute.

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.

*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.

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.

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

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.

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

I see text in three different places, and in each one, it's clearly "IXS Enterprise". I have no idea where people are getting the "USS" from. There is really no reason to try and build a ship that big for the first warp tests, though. First warp engines would be sub-light, not fast at all, in fact, small, and probably powered up by an external unit, with only enough on-board power to maintain stable warp and drop out properly.

Division in chimeras isn't at organ level. All it really means is that zygote was made up of cells with different genetic makeup at some point. It's quite common in some animals. Very rare in humans. You can end up with entire organs or particular tissues having different genotype than the rest of the organism, of course. But you can also end up with cells fairly thoroughly mixed. Something similar happens to mammal females, where only one of the two X chromosomes is actually necessary. The other one goes dormant, making up the Barr body in the nucleus. Selection of which X chromosome goes dormant happens early on at random and persists through further divisions. As a result, mammal females are chimera-like on any X-linked gene. A great example of that are calico cats. The color of their fur, black or brown, is set on the X chromosome. So a female with two different color genes on two different X chromosomes ends up having patches of black and brown fur. This reflects the fact that it's not different organs, bur rather different areas of the cat's skin that has differences in genetic expression. Chimera cats have similar fur patterns sometimes, but can be of either gender, naturally.

It wouldn't. If these were fair random guesses, it'd be a uniform distribution. (In reality, as ZetaX pointed out, there would be some patterns there.) In order to get a Gauss, you need to add a bunch of random numbers together and do a histogram. Say, make a hundred pools of 5 d6 each. Roll them all, add up the numbers in each pool, and plot the histogram. That will be pretty close to Gaussian.