K^2

I hope this misnomer doesn't stick. But haptic feedback for projected images is a cool idea.

It is in no danger of collapsing. The expansion of the universe is accelerating. There is no guarantee that this will keep up, but it's pretty much certain that universe cannot shrink bellow current size. Whether it expands ad infinitum or reaches an equilibrium size is somewhat debatable. The later case would make the entropy question more relevant. But that's exactly where fine grain vs coarse entropy distinction becomes critical. Time will simply have to become a local phenomenon. If the universe keeps expanding, it's a moot question. As energy density drops to zero, heat death is inevitable regardless of what you do about entropy.

Only due to the statement. You are trying to achieve something that contradicts itself. Forward direction in time is due to increase in entropy. You can make entropy decrease in that direction, but then it will be reverse direction in time, and you still have entropy increasing in a forward direction. It's how our perception of time works. On the dynamics level, time direction is irrelevant, but on dynamics level you don't care about coarse entropy, and fine grain entropy is conserved as I've pointed out.

The fine grain entropy is a conserved quantity. The increasing coarse entropy is the direction of time. Either way, the answer is no.

Depends on how you add it. But if it's in the drag mode, like you're flying through it, and it sticks to the ship, yeah, drag would have to be negative. Which is just one more reason that I'm glad stable negative mass matter doesn't exist and I don't have to think about it.

Lets start from perspective of classical mechanics. The first thought would be yes, it should help. You want to bring ship to some velocity v. So you take some big mass M, add some smaller amount of negative mass (-m), and now total momentum you need is (M-m)v. Requiring less thrust and less fuel. But consider the actual interactions between chunks of mass and negative mass. Imagine that you have a big block of negative mass sitting in front of you. You try to push it out of the way. You apply a force forward, but F = ma, and the mass is negative. The block tries to accelerate towards you instead. If you want it to move forward, you have to pull on it instead! I cannot imagine how one would build a structure out of this stuff. At best, it'd probably rip itself apart. Now, from perspective of Quantum Mechanics. What you are really suggesting is that part of the matter in the ship has forward velocity but reversed momentum. This is, indeed, possible. Virtual particles do this routinely. However, such particles cannot propagate freely. They can only hold on to that momentum for a brief time, and then mast pass it on to other matter. Any stable matter must propagate in direction of the momentum. And so you end up with no way to create negative mass. Which might be for the best, keeping the above paragraphs in mind.

The results are usually quoted as p<value. You cannot reject on p=value. Although, if they are coming out exactly equal, I would try to get a bit more data or to improve computation precision to make sure.

You need vis-viva and angular momentum conservation to do transfer calculations. If you apply these to apsides of the elliptical orbit, you get the equation vp = sqrt(GM/a) * sqrt(ra/rp). The formula for va is the same, with ra and rp switched around. Between two co-planar circular orbits the simplest and usually (but not always) most efficient transfer is the Hohmann, which simply connects the two orbits with an elliptical one. The above formula is all you need to compute the dV cost of such transfer. In general, the most efficient transfer between two circular orbits is the bi-elliptic transfer, which requires some numerical work to compute on case-by-case basis.

Depending on the properties, it might make sense to use it as a very fuel-rich hybrid, using the ox flow for throttling. Otherwise, you are dealing with a solid booster with very little control. Of course, when the ISP in question is on the order of several thousand seconds, it seems like a minor inconvenience either way.

Mid 90's. Post collapse Russia. I was able to get, and I remember it still, about 200 bytes/s on average out of a 14k, because the lines were bad and the only available connection point was overloaded. It sufficed for e-mails, though, which is pretty much all I've used it for.

PB666, you keep using words you don't understand. Your entire paragraphs are devoid of any meaning. Especially this gem. There are words. There are even phrases that might mean something. But the sentence is meaningless. "Assymetry tucked into vacuum space"? And "Handed of by other virtuals"? This isn't poetry. This crap might fly in a theology discussion. Or some branches of pseudo-philosophy. But it's useless babble just about anywhere. There is no practical application to any of this. The symmetry in question is the local gauge symmetry. That might sound like just words to you, because you have made zero attempt to learn any science. But to anyone who has had to deal with gauge theory, it is a mathematically precise statement. It means that we have a symmetry group that can be applied to the Lagrangian of the problem. That the Lagrangian is invariant under the symmetry transformation. That furthermore, we introduce a gauge field to allow the Lagrangian to be invariant under the continuous field of local transformations. That Yang-Mills theory can be applied. That there is going to be an interaction field, for which we can write an interaction Lagrangian. And so on, and so on. For every single one of these sentences, there are precise mathematical formulae. And you are proposing handing these off to virtuals? Handing what exactly? The mathematical group? Or the formulae? Do you want to write down these equations on the paper and pass them off to virtual particles as notes? Your first order of business needs to be to stop using words you do not understand. Second, if you want to actually understand how something works, which is a prerequisite for discussing it, you need to learn formulae that go into it. You then need to learn to structure your sentences to reflect the mathematical relationships between concepts you are describing. For example, if I was going to tell you that for small amplitude, the period of oscillation of a pendulum depends only on gravity and length of the arm, what I am really saying is that given a mass m suspended by an arm of the length L, making a displacement angle x with the vertical, the equation of motion for the pendulum is mx'' = -mg/L sin(x), which can be approximated for x<<1 as x'' = -x g/L, which has a period of 2 pi sqrt(L/g). There is a precise formula that goes with the statement. If you want to talk about any scientific principle, you have to communicate in just as precise a fashion. Because if you do not, you are just making stuff up and make yourself look bad. No, you do not. You have more words to go with it that have zero meaning. To get this, you need to be able to compute it. Can you compute energy density associated with Alcubierre Metric? Do you know where to even start? And I'm pretty sure these are rhetorical questions.

If metallic hydrogen is metastable (MSMH), it is by several fold the best chemical rocket fuel we will have ever discover. That's a huge if, though. So far, none of the experiments that have claimed brief existence of metallic hydrogen have been capable to test any of its properties. So while there is some theoretical indication that it may be possible, there have been no experimental confirmation. Nitromethane wouldn't give you great performance as a rocket fuel. There are far better rocket fuels available if you plant to launch something into space. But it might be a pretty good fuel for a hobby rocket with liquid fuel engine for a lot of the same reasons that make it a pretty good fuel for RC models.

This is totally irrelevant. Lets say photons had mass. Hell, you can simply uze the Z bosons. They're massive, and they're produced in Quantum Vacuum just as easily. If they are virtual, they cannot leave the ship. In order to propagate freely to any finite distance, a particle must be on the shell. Otherwise, it has a decaying amplitude. If it is on the shell, then E² = m² + p². And now you not only have to waste energy to gain momentum, but also to generate that mass. You might as well propose generating matter and anti-matter and expelling that. This is not something new. This isn't some exotic fields, or some new state we are discussing. These are the absolute basics of particle theory. And they arise from the absolute fundamentals for field theory. We are talking about conserved currents of fundamental symmetries. You can invent any particles you want, with any interactions you want. You can fill vacuum with any families of virtual particles. You can give vacuum as much energy/mass as you want. You still cannot create a current without giving it energy that at least satisfies E = pc. This is the absolute minimum of energy you need to generate propulsion. Period. In any vacuum. With massive or massless photons. With virtual or real particles. This is like me telling you that "Sum of two even numbers is even," and you telling me, "But what about 6 and 8? Have you considered 6 and 8?" I'm not going to break it down to every single point, because I can stop it on the very first one. The thickness of the bubble is some sigma. It is a parameter. It is a parameter that can be varied in time, and it is a parameter that can be varied in magnitude around the ship. In the simplest geometry, the Alcubierre drive, the warp bubble is spherically symmetrical and invariant in time. There, the thickness is a constant, and reducing the thickness reduces the amount of negative energy needed for warp. This is one special case, which is only useful for illustration. The physics of the warp drive is contained within the relationship between interior and exterior metrics. Your entire analysis is like trying to prove that flight is impossible because you've only considered wings with square cross-section made out of solid oak. No **** Sherlock. Now, how about proving that negative energy is a requirement in a general case? Oh, wait, you can't even do the computation required to demonstrate that energy is negative in the basic example given. And just to make this a touch more interesting, the frame dragging in the viscinity of a rotating black hole works pretty much like a sub-light warp drive with very thick bubble. Still not achievable, and comes with a whole bunch of unwanted side effects even if it were, but your entire argument on requirement of negative energy collapses on itself. Again, the difference is that Warp Drive is derrived from well-understood theory. We haven't figured out a practical configuration yet, and it might not exist. But we do not know any reason why such configuration wouldn't exist. On the other hand, EMDrive contradicts every available theory in the most fundamental way. We do know the exact reasons why it cannot exist. Are you grasping the difference here?

Yeah, the Voskhod missions were incredibly rushed. I remember an old interview with Leonov where he explains how he got stuck in the airlock trying to get back into the capsule. He had to let out some of the air from his suit to be able to actually get back in. It's quite amazing that Soviet program had as few fatalities as it did.

Open clusters don't tend to stay together forever. M67 is already considered old, and it's younger than Sol. NGC 188 is apparently one of the oldest known, and it is 5b years old. The only reason it's still together is that it's located above the disk. It seems likely, from everything I've gathered, that whichever cluster Sol came from, no longer exists as a cluster. Its stars scattered across considerable distance. Sol would have been one of the smaller stars of the cluster, and these tend to end up on the outside. This might be the reason we are having trouble finding Sol's sisters.

We do have Quantum Teleportation that attempts precisely that. The downfall is that such schemes require a classical channel to orchestrate the transfer, so you are still limited to light speed. They also get impossibly complex for macroscopic objects.

Energy requirements tend to be quadratic with speed for all known warp configurations. I don't see why it'd suddenly stop being the case. So with current-to-near-future tech levels, we'd be limited to hundreds, perhaps thousands of km/s. Which is great for in-system operations, but not going to cut it for interstellar. The space-time is "almost flat" around here. So the warp drive can still operate. There will be "side effects". Unless you want to be wasting huge amounts of energy to compensate, energy and momentum are going to be conserved throughout the warp. Which means that if you want to head out from Earth to, say, Mars, you will need to put yourself on a trajectory that can actually reach Mars' orbit before you engage warp. The trajectory itself will also be curved by gravity. This isn't exactly a requirement, but "accelerating" warp bubble tends to interact with interstellar medium in a way that will also cause huge energy losses. So you want the warp bubble to "coast" in the gravitational field. So roughly speaking, a sub-light warp from Earth to Mars would require the ship to break Earth's orbit and get to an Earth-Mars transfer using chemical rockets, ion drives, or any other conventional propulsion system. It will then engage warp to travel at something like 100-1,000km/s along an almost straight line towards Mars. There it will drop out of warp and use conventional propulsion again to enter Mars' orbit. You still need to be able to build a ship that can reach Mars. What you're really winning with sub-light warp is time. Instead of getting there in 7-8 months, you can get there in a day or less.

For FTL warp, pretty much, yes. That's the current state of things. Sub-light warp is still on the table.

Such a drive can stop on a spot anywhere it needs to. It doesn't need gravity. Indeed, it ignores it. So if you have enough unicorn horns and pixie dust to power it, the optimal solution is to just warp to wherever you need to be, exiting warp with whatever speed you wish. My interpretation was minimal "respooling", not a single warp. With a single warp, all you can do is aim for the star, pray to whatever gods you worship that your math is right, do the jump, and then use NPP to try and brake while you're still in the star system. Actually, for braking, you might be able to use a Buzzard Ramjet. And if you fail any of the above, you get to drift off into the void. Quantum Physics isn't some sort of Voodoo, where you get random errors. It's the most precise field of Physics. Most of Quantum Field Theory is really a branch of Linear Algebra. There are no "errors". No "random fluctuations". You keep talking about virtual particles, but you don't have a first clue what they are. They aren't fairy dust. They are off-the-shell excitations in the fields. As such, they can carry momentum between any two points in space-time, but the effectiveness drops exponentially with distance. The statistical improbability of what you are suggesting has enough zeroes to make scientific notation cumbersome. And you're shaking it like you've got something. Compared to that, lack of exotic matter or impossibly high energies required for practical FTL warp seem like minor engineering problems. And I don't expect that we'll have FTL warp any time soon. Quite possibly ever. But unlike magic reactionless drives, we understand the physics of warp. We can talk about what WOULD happen if we were able to satisfy the conditions. Even if it forever remains theoretical. Just like we can talk about what WOULD happen if Sun were to go Nova, or what WOULD happen if Earth got knocked out of its orbit, even if we have absolutely zero chance of making it happen.

We might not have good enough models to predict isotope composition of supernova fragments. The heavy elements are generated as the shock passes through outer layers of neutron matter in a freshly collapsed core. This is RQFT on steroids. Not only are we limited on models here, but we do not have computing power to use the ones we have. There might be some general stat mech arguments for rough initial distributions. And it might be worth running some Monte Carlo on these to see what distributions they yield over time. It is conceivable that precise details of initial distribution are irrelevant. This could be fun to try, as it would, indeed, give us an age of this star system in terms of time elapsed since nova. Provided, of course, that there was just the one contributor. I have always wondered if it would ever be possible to track our system's progress far enough back to find the origin of the nova and, maybe, Sol's sister stars.

Agreed. After we've thoroughly eliminated possibility of errors in measurement, which there is good progress on, the next step should be finding the reaction mass. We know a lot about the exhaust. To generate 50uN at 50W, the exhaust must consist of up to 250ug/s of matter traveling at over 2,000 km/s. The exhaust is likely to be charged, so this shold be quite straight forward to detect with the right equipment. In fact, if exhaust particles are at least as massive as electrons, that's at least 10eV per particle, so a fluorescent screen might be sufficient to detect it.

The mass defect to get the few uN they are measuring at relevant voltages would be miniscule. There is no way they could have verified it. Not without monitoring the vacuum chamber with mass-spec, or better yet, using radioactive tracers. That's why I'm saying that what they should be doing are far more tests in well controlled environment on Earth. Not wasting money launching this junk into space. As it stands, this is looking a lot like the story with ionocraft lifter.

So let me get this straight, I can't fly with these styrofoam wings I've just made, but I can save 15% or more by switching to Geico? lol Yeah, that's roughly how much logic you're putting into your posts. Each fly-by operation is performed without warp. Warp merely gets you to the right position to be able to do the necessary fly-by. If you have more kinetic energy than due to coming in from escape trajectory, say, due to relative velocity of the stars, you will need multiple fly-by operations. But yeah. You can have these absorb all of that energy. When you can actually do at least some basic computations on diagrams involving virtual particle exchange, or when you understand at least the math behind Alcubierre Metric, then you will have the background to actually weigh in on these discussions. As it is, you are talking total nonsense, and you don't even have the prerequisites to realize that much.

Mazon Del's post implies hard vacuum outside, but potentially either air or gas-generating polymer inside. His post states that thrust drops dramatically in the vacuum-vacuum case.

Nope. Because as you warp around the system, the velocity of your ship changes. Has to do with the way that warp bubble has to adjust to the curvature of space-time around the star, unless you want to waste mad quantities of energy on gravitational wake. Again, completely incorrect. Warp does not violate any conservation laws.