K^2

I'm pretty sure the only real difference is that compressor blades are high RPM, low torque, and prop is going to be high torque, low RPM. So you'd need a gearbox if you want that prop to do something useful, just like normal turboprop. But otherwise, there is nothing really wrong with the idea. It's just that an extra compressor stage is going to be lighter and easier to make.

There is a pretty good overview paper on Arxiv. You should have no trouble following most, if not all of it, with a general QFT background. Alternatively, just read the first two introductory sections and the summary in the end just to get an idea of how Effective Field Theory fixes the problems at low energy scales, and what problems remain unpatched.

Nope. Same reason lightning strikes tall objects. The physics of it is pretty straight forward too. The mobile charges are precisely what makes the field inside zero. And the voltage drop along any path is the integral of the electric field along that path. Since inside the body that field is zero, it the entire difference is going to result in the field between the head and the ceiling. Coronal discharge happens when the object is small compared to the distance, so charges moving to the top do not change the electric field by much. Then you get something like Saint Elmo's fire around the person's head. But if the charges moving makes a difference between 2m of path and 20cm of path, that's going to result in a proper breakdown.

Who said anything about KSP?

Erm... Humans are conductors. That means electric field inside human body is zero, and it's going to be 2MV between crewman's head and the ceiling. Average adult male height is 1.8m. That makes it 2MV/20cm = 10MV/m, which is more than 3x the dielectric strength of dry air. Air is going to undergo electric breakdown, like a miniature lightning, and your contraption just started frying the crew. But even if you get rid of that particular issue, human bodies are still conductors. How are you planning to keep all this charge distributed evenly through the body in this strong of a field? Or keep everyone perfectly insulated? Anyways, if you want to use electromagnetism, go with diamagnetic levitation.

We've covered this on the previous page. It shouldn't pick up particles during cruise. Only during acceleration/deceleration.

I don't think you'd be able to travel in the precise North-South direction with an air ship. Predominant winds will definitely carry you East and West by a lot. But if you don't care about it being in the straight line, it's doable. Especially, if you figure out how to get supply planes to dock with it in flight. This seems like it'd be a long mission. The only impossible thing about all of this, though, is getting funding for it.

There is no approximation. Unified theory of Gravity and QCD is the Yang-Mills theory on R1,3â‹ŠSO(1,3)+xU(1)xSU(2)LxSU(3). That's it. That's the theory that brings all the forces together, and there have been papers on it since the 60s. People like Feynman have wrote papers on it. Hell, Feynman has a lecture series on Quantum Gravity where he talks about all of this stuff. This theory is non-renormalizable in its exact form, and so totally useless. But there is an Effective Theory that is renormalizable, and it only breaks down at plank scale. So again, if you don't go down to Plank scale or bellow, we have the theory of everything. The only reason people aren't happy about it is because they want to have description bellow Plank scale, because a lot of interesting questions lurk within it. Like, is there truly a singularity at the center of a black hole? If it's a singularity, it's smaller than Plank scale, and therefore, has to be described with a better theory. But we are talking about Warp Drives. And one of the design parameter of absolutely every Warp Drive ever is that the bubble thickness is significantly thicker than Plank scale. So now, how about you stop talking nonsense and listen to smart people for a change. You'd think that this would be a light bulb moment. What, you've been arguing about Warp Drives all this time, and you haven't figured out that they have something to do with expanding space? The Alcubierre Drive assumes that other than effects of the drive, space-time is flat. So there is no potential energy change. Of course, that's not realistic, but it's not a crucial requirement. Alcubierre Drive works so long as space-time is "reasonably" flat. That is, there is no significant curvature on the scale of the bubble size. You do, however, have to take global curvature into account when you are designing your logistic function. Choice of logistic function will determine energy density with which you need to "energize" the bubble. How this ends up working is entirely up to you. I would recognize three key options. 1) You can have the bubble completely compensate for the energy changes. However, that would require something to feed energy into the warp bubble, which is rather tricky to organize. So while this would be the simplest in terms of logistics, it's also probably the most technically complex, if not all together unfeasible. 2) You can have the bubble simply ignore the curvature. But then you're going to experience acceleration with respect to bubble. So throughout the journey, you'll have to use ship's engines do the work that compensates for the difference in energy. Given speeds, the required acceleration might be too high to be practical. 3) Probably the simplest thing you can do is simply have the bubble follow the geodesic. That's what you are going to get if you just carry over Alcubierre Drive as is to the curved space-time, so it's probably the easiest thing to do from all perspectives. The momentum vector of the ship will evolve as its supposed to along the geodesic, but since you're in effective free-fall both relative to the star and relative to the bubble, you will not experience any of it. This kind of warp, however, only makes sense if you travel along the direction that you'd be traveling either way. So for example, suppose you are in the outer Solar System, and decide to come back to Earth. You'd first perform a normal sub-light burn to establish a transfer orbit to the inner Solar System. You would then Warp along that same trajectory you'd take either way, but at much higher speed. And once the bubble dissolves, you are near transfer to Earth's orbit, traveling at whatever velocity you would be traveling. So that'd work a lot like time-warping in KSP, except that it only affects your ship, and not positions of all the other bodies in the system, which makes it even more useful. But like I said, that's up to Warp Drive design. That last option is what I'd go for simply out of simplicity. But if we figure out how to build a Warp Drive in the first place, all of the above might seem like equally easy in comparison.

Except for bubble destabilization and everything that follows. Haven't you been paying attention?

Not how warp drives work.

You aren't seriously calling something that can be fixed with a pair of matchsticks through the throat a problem, do you? Sorry, I assumed your numbers were wacky because you used equation for compressible flow. But if not, you just did your math wrong. 200kPa @ 1g/cm³ yields 20m/s. Likewise, 2kPa gives you 2m/s. I don't know where you picked up an extra factor of 3.7. Even if you did 200kPa + 1bar, it's still only 24.5m/s. If we are talking about 200kPa driving the stream, by the way, it gives us a good estimate on losses. Since the above suggests 20m/s exit velocity, while we see an only 13m/s exit velocity on Earth. Edit: Unless that's meant to be 200kPa total, working against atmospheric? In that case, Mythbusters managed something very close to theoretical maximum. Isn't that what I said? But pressure drop without nucleation sites is not going to do anything. It's like having superheated water. It won't boil if there aren't sufficiently large bubbles for vapor to expand into. You still want metos in there. Or some other source of nucleation sites. Totally fair. Objection on temperature withdrawn. Bottle ruptures at around 500kPa. That gives you a little over 30m/s with the Bernoulli method, and since we know that it overestimates actual ISP and that it only holds while the pressure does, even if you want to turn it into a steam rocket, you'll need much better casing than a coke bottle.

That's not exactly right. The bubble is neither indestructible nor impermeable. Matter will pass through it, but anything passing through the bubble will be shredded into plasma by the extreme tidal forces. Not unlike falling into a black hole. A sufficiently high flow of matter will, furthermore, destabilize the bubble, causing it to collapse. We've been having a bit of a debate on what's "sufficiently high", but hitting Earth would definitely do it for any plausible warp drive. Most likely, bubble will collapse in upper atmosphere. And yes, that will release the ship at a potentially very survivable speed, but it will also release a lot of radiation, so it'd be like being dropped into the middle of a nuclear explosion. Again, we haven't really established whether it's going to be a small nuclear explosion or a very large one, but it will matter little if you're right in the middle of it.

Errors are natural. Flaws in error detection are "intentional". We have just the right amount of error correction for diverse yet stable system. Take a look at how many things have to go wrong for cancerous cells to develop. Note that some of these things are left intentionally loose because survival of the organism is more important than the perfect preservation of data. It's called error-correcting codes. Ever had a CD player? Audio CDs use these codes to let the player skip over scratches and smudges. The idea is that given n bits of data you want to hold on to, you encode them with n+m codes, such that if any m bits are missing, you can recover the data. And if you are clever about it, error checker will not make errors, because it checks its own operation. That's the basic idea behind CRCs, for example.

You can do error checks with any quality you need. Definitely enough to prevent mutations of a self-replicating system over a 5-billion year span. The only reason life forms mutate is because it's actually beneficial for spreading. If your goal is to preserve information in a self-replicating system, you can build a system that does it.

Well, you don't have to quantize gravity. So yeah, in pure GR, such a thing as graviton is neither sensible nor necessary. But if you want to consider matter fields in GR setting, without quantizing the fields, you are kind of screwed. So if you want to consider how gravity influences interactions of elementary particles, there are just no mathematical methods for dealing with this without introducing graviton. As for whether or not there is such a particle in nature, that's really just a matter of perspective. You can say that a photon is just a convenient mathematical model, and that there is really no such particle either. Then, of course, one has to concede that from this perspective, there are no particles at all, and all of the particle phenomena are just artifacts of first quantization in our measuring equipment. There is nothing wrong with such perspective from philosophical standpoint, but from perspective of physics, math with particles is not just easier, it's doable, unlike what it would be if we just had the fields.

It does matter which one fires its engines. If you are standing aboard the ship that fires its engines, you can actually tell that it's your ship that accelerated. And the ship on which you can experience an acceleration is not an inertial frame of reference. You cannot use SR from that ship's perspective. The ship that continues drifting at constant speed, however, is an inertial frame of reference. And you can use SR equations to describe time dilation on the other ship. So the ship that accelerated away and then back is the one that's going to age less due to time dilation. You know what? All of this is covered relatively well in Twin Paradox article.

Satellite is not an inertial frame of reference, because it is accelerating. Hence, you cannot use Special Relativity to describe the world from perspective of a satellite.

Earth is not accelerating. Satellite is. Earth is an inertial frame of reference, and you can use Special Relativity. Satellite is not, and you have to use formulas from GR.

Going around in circles also requires acceleration. By the way, there is also contribution due to gravity, which also has to do with acceleration, but for LEO, gravitational time dilation is pretty much the same as that on the ground. On a high orbit, however, both velocity and gravitational time dilation are lower. So on GPS satellites, for example, time runs faster than on the ground.

As the ship passes the Earth, from Earth's perspective the ship's time is dilated. From ship's perspective, it's the Earth's time that's dilated, because, as you pointed out, velocity is relative. However, if the ship slows down to land on Earth, after comparing the two clocks, it will be the ship's clock that's behind. The reason for that is acceleration. Unlike velocity, acceleration is absolute. And acceleration also causes time dilation effects. If you have to describe time dilation from perspective of an accelerated object, you have to use General Relativity. Since Earth does not accelerate, however, from its perspective, Special Relativity still works. So you can describe ship's time dilation using Earth's frame of reference and the SR time dilation formula.

Well, there is certainly an upper bound. Energy is still conserved. And even if it ends up "borrowing" vacuum energy, there is still a limit. But it could be a lot and unpleasant, certainly. As for duration of acceleration, that goes into the logistics curve, and is one of the design parameters. This should just be the time required to fully energize the bubble, and from all angles, this seems to be something we want to be short rather than long. I'm sure there would be technical limitations, but most of the trip should be in cruise. Of course, that's just for normal voyage. If it ends up slamming into atmosphere, and if I'm reading that paper right, it's going to turn into a death ray. Again, I can't tell what sort of intensity that will have, but you're probably right about weaponizing it. What's better than a nuke? A nuke that gets to destination before you even have a chance to detect a launch.

I only see problems with particles encountered during bubble acceleration and deceleration. During most of the voyage, particles pass right through without change in energy, according to this paper.

You don't. You just ask stupid questions just to be difficult. That's not winning you any arguments, and only highlights how little you know about the subject. To be honest, I'm starting to grow tired of it. Covered at least three times in this topic. Same as we do about positive energy. How about you estimate stability. Or energy required. Or anything. You just make empty claims again. How about you learn a few things about interpretations before going off to make stuff up again. Like, the fact that all interpretations are equivalent for starters. This isn't like interpreting bible. There is math, and theorems, and a lot of other stuff you didn't bother to even get the basic idea about before jumping to conclusion and start throwing accusations. We do. You are still living in fantasy land. Bwahahahaha. Sorry. Come back when you actually know what M-theory is about and how it relates to standard model. And you're making more stuff up. No, keep going. We're having an excellent and very productive discussion here. Why don't you tell me what local symmetries are, which ones are available to which fields, and how they actually relate to any physical particles. You first. How is anything you've asked relevant to what we are talking about? We had these in 1930s. And since then, greatest minds of the century, starting from Einstein himself, to Dirac, Pauli, Feynman, Fermi, Bohr, Noether, and many less known, but still incredibly talented physicists just sat on their rears doing nothing. Nope. Haven't seen it by that name. I'll keep it in mind. Of course, that only makes it more funny that you don't have a clue what holographic interpretation means. You've read something about them, and you still didn't realize that they have to have more dimensions than observable universe, and not fewer. I've addressed that a number of times. You are arguing purely from your ignorance of how QM and GR work together. We know how this stuff works on every relevant scale. SR also says that light always travels in a perfectly straight line. According to SR, gravitational lensing is impossible. Now, I could try and explain why SR applies to Warp Drive only locally, but these sort of things have been like talking to a wall so far, so why don't you explain to me how SR is supposed to hold in a space-time that's not Minkowski. That's because you don't have a first clue what any of these things are. We've already covered all of these points. Fact that there are other people on internet just as confused as you are doesn't mean that you're right. Oh, good sir, why don't you tell me about the difficulties in quantum computation. Like, why we have a quantum algorithm that breaks factorization problems in poly time, and yet public keys are perfectly secure. Or why we have quantum teleportation, but I still have to drive to work. Maybe you'd like to learn a few things about QM before you start saying stuff? These aren't vocab problems. They are problems with you understanding concepts you are trying to discuss. That'd be nice. You just don't know any. How am I supposed to talk physics with you if you don't know first thing about it? Please, tell me. And you are wrong. There are already objects in this universe that are traveling faster than light relative to each other. So can you please stop talking out of your posterior? In other words, you have your opinion, founded in nothing but fantasy, and you refuse to learn any actual science, or acknowledge observations that contradict it. Good to know. I'll let you work out what I'd say that makes you, because I'd probably get banned for typing it out. You're hopeless. If you don't even understand difference between knowledge and information, there is just no helping you. I've been continuing to answer questions I've figured might be useful for someone else, if they are reading by chance, but I honestly give up with you. Thickness of the bubble varies. Variations depend on particular parameters which also vary. You're asking pointless questions, and you don't even seem to have understanding to realize why they are pointless. So lets try it the other way, explain which part of the theory suggests that QM effects are going to be unpredictable. Something? Anything? No. Because you don't know QM even at undergraduate level. Let alone have any idea what QFT even is or how it applies here. Yet you have the gall to argue with somebody who does QFT for the living. Fantastic. More arguments from ignorance. Awesome. You keep on going with life like that. You know what would help, though? If you didn't disrupt discussion where other people are talking about actual science of it. You keep wanting to drag in unrelated topics which you don't understand anything about. Q-Thruster is just a rocket. It's a type of a photon drive. It does not help you at all in crossing interstellar space. It is absolutely useless if you don't have a matter-antimatter reactor with high efficiency. Even with a nuclear reactor, you are much better off using an ion drive, because Quantum Thruster is such a horrible energy hog, and you'll have better net ISP using actual reaction mass than burning through massive reactors for no good reason. Again, learn some freagin' theory. Start with classical mechanics. You really don't need much to understand why Q-Thruster is useless without all the other technology for which we don't even have a starting point yet, and even with one, you're still limited to fractions of light speed, which is completely pointless on interstellar level.

I'll let you figure out how these two relate. Where do I even start with all of this. First, you aren't propelling yourself with gas. It's going to be coke forced out of the nozzle. So you can throw the Bernoulli Equation for Ideal Gas out. You are way over-estimating available energy this way. Second, main purpose of mentos in a bottle is the same as that of a boiling chip. You need it to speed up carbon exiting liquid. As soon as you open up that valve, pressure in the bottle will drop. And it's the rate at which CO2 can be released compared to rate at which fluid is forced out that's going to determine pressure inside. Good luck estimating that. Finally, as soon as water begins to boil, temperature will drop, and that will mean both vapor pressure and CO2 pressure will drop as well. Care to enter that into your estimates? I did not think so. As I've said earlier, the main limiting factor is the fraction of energy stored in Coke that's going to be used up on its way out. And that just isn't going to change a hell of a lot in vacuum. You will get a boost to ISP, but nowhere near that much. There is no way a bottle will deorbit itself in a single stage.

It's relevant, but not going to make a big enough difference, unfortunately. Mostly, because there is no way to ensure that all of the energy is given up before fluid exits the bottle, and that's your biggest limiting factor even on Earth. Even if it boosts you to 20m/s as per Z-Man's estimate, which is definitely high end, then best you can count on from a bottle is a 30-something range on delta-V. With two stages of that you might get into dense enough atmo to start de-orbiting rapidly.