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Not bad ones, either. We have an Iranian girl studying particle physics in our department. To be fair, Iran's main obstacle is purifying Uranium and/or breeding Plutonium. That said, if someone just gave you a chunk of either, constructing a bomb is still an extremely complicated affair. Your best bet is a gun type built with enriched uranium. But you have to know its properties extremely well. If you weren't the one to enrich it yourself, you'd need to do a lot of experimentation on it. Failing that, instead of a nuclear explosion, you'll get an ordinary thermal explosion, resulting in no destruction, and merely mild contamination of the area. And that's the simplest type of a-bomb with all of the required materials simply handed over to you.

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Or I can light up a consumer firework and get a few more orders of magnitude of power output from an even more portable package. So what's your point? How exactly to you expect it to be misused? I bet I can replicate anything you come up with using things that are already perfectly legal. It's not defenses. It's physically impossible to release energy without appropriate trigger. Not because of some fail-safes, or some security device. It is physically impossible. To release that energy all in one go, you will need a custom trigger, and that's the only part of the battery that's actually hard to obtain. If you can build a trigger, you can build a bomb. There are no special materials from the battery that you can obtain that you can't get elsewhere. Assuming things out of ignorance is never a good idea. It's safe. We know it to be safe. You want to invent some sort of potential problem, because it's something you don't understand, so you imagine that people who do this sort of stuff don't understand it fully either. We do. That's our job. That gave me a good laugh. Thank you. I've spent several years doing particle physics research at the university, so yeah, I can tell you right now that this is a complete fantasy.

Not locally. With respect to outside observer, using Schwarzschild coordinates, objects bellow event horizon are in-falling at FTL speeds. Again, depends on coordinate system. But from perspective of the in-falling observer, yes. The fall takes finite amount of time.

Any neighborhood transformer will handle up to a few MW of power. Yes, a single house/apartment is usually closer to a small general aviation aircraft than an airliner. But you'll still have multi-MW power lines within your immediate neighborhood and within easy access. Because triggering it is extremely complex. So much so, in fact, that only a handful of successful trigger experiments have been conducted so far. It can't happen by accident, and you can't force an existing trigger to release more energy than it is designed for. And the principle of operation can, certainly, be weaponized. DARPA didn't keep TRIP experiment classified for nothing. But you will have to build your own trigger. Which is the hard part. If you can build the trigger, you don't need the actual battery. You can build your own completely from scratch.

Ah, you're right. I didn't think about the abort procedure. Still, I hope it's reliable enough. I mean, you really want separation than boom, not the other way around.

Ok, we do need to keep this separate. There is classical General Relativity, in which no QFT nonsense takes place. Within General Relativity framework, there is no problem with Alcubierre Drive. Period. Even the energy density within the walls of the bubble is well-behaved locally. Of course, some areas of space-time end up having negative energy density, but again, within GR itself, that's not a problem. QFT is a separate matter. For starters, it's not clear what QFT tells us about negative energy densities. It would appear that things like Casimir Effect allow this, but given how much zero-point energy computations are off, I can't make a solid statement on that. The other part is what happens to the fields in the walls of the bubble. Everything I've read, and it seems reasonable, indicates that with sufficiently thick walls, there are no weird quantum phenomena going on, and all is fine. But with thick walls, the energy required to create the bubble is impossibly large. As the walls of the bubble get thinner, things get weird. Bellow plank scale, we simply don't have a field theory that would describe what happens. But at wall thickness a few orders of magnitude higher than plank scale, energies are much more reasonable, and we should still be able to predict what happens with an effective field theory. I'm not too familiar with research on that. I'll take a look at Finazzi et al paper later to see what they actually did. Renormalization in framework of General Relativity is no trivial matter. (It's not always trivial even in classical QFT, but GR is particularly bad.) I think, you might be thinking of internal part of the Kerr Metric. If you extend the solution to the rotating (Kerr) black hole into the interior region, it looks as if inside of the black hole is another "inside-out" event horizon, beyond which lies an entire universe. Problem with that is that Kerr metric is known not to be a stable solution in the interior. So the actual metric inside of the rotating black hole is different. It's unlikely that it actually contains another universe, either, purely from energy considerations. Other than that, though, in principle, you can have any weird topology, with any number of interconnected universes within the framework of GR. General Relativity only specifies the geometry of space-time. Not its topology. Which can lead to any sort of craziness. But until we have any direct evidence of these things existing, it's as much speculation as any other parallel universe hypothesis.

0_0 I hope they don't plan to have that feature standard on manned rockets.

magnemoe, you just refuse to read on principle, don't you?

You can get the same energy output from your house's power grid. I guess, we shouldn't connect houses to electricity. After all, it's dangerous in the wrong hands. A nuclear isomer battery is inherently safer than any fuel or explosive, because it can only release its energy at some maximum rate. It can't go all at once. So you are inherently limited in any mischief you can cause with it. Not only should we replace fuels in civilian aircraft with these. We should replace car batteries with these. Again, because they are far, far safer and far more difficult to misuse. Yet, you were eager to jump in and make a comment about it. It's ok that you don't know something or don't understand something. And I'm always happy to explain what I can. What bugs me a little is when people charge into discussion when they clearly don't understand the subject. I just ask that you slow down and think for a bit, and maybe start by asking questions. If you read the thread carefully, you'll see that I'm thinking nuclear isomer batteries. And everything you wrote doesn't apply to them. They have several orders of magnitude higher energy density, and yet are far safer than any chemical battery or chemical fuel, precisely because accidental or intentional catastrophic energy release is impossible.

Oh, wow. I hope the accident is caused by something unique to 9R. I'd hate to see this cause problems for the v1.1. Although, if it is something they have in common, I'm gad it came up during a test launch like this.

So is jet fuel. You are looking at something with half life of many decades, emitting relatively soft gamma radiation at a very low rate. It's inert compared to your fire alarm. It's completely inert compared to jet fuel. I stand by my statement.

I don't think you understand what a nuclear isomer battery is. It's completely inert if you aren't extracting energy from it. And when you are, it can only release energy in measured amounts. It would never turn the airplane into a dirty bomb. On the contrary, it would prevent energy release in case of a crash. That means far, far less damage to anything the plane hits, as well a much higher chances of survival to passengers in crew in event of an accident. That's the same kind of conclusion-jumping that resulted in medical MRIs being called just that, instead of NMRI, which is the proper term. (Nuclear Magnetic Resonance Imaging) The word "nuclear" in the name doesn't mean danger of radiation.

Lets see... Which is safer? A battery made of material that's essentially inert, unless triggered by very intricate electronics, at which point it releases controlled and measured amounts of energy, or literal tons of jet fuel which contain exactly the same total energy? Yeah, I'm going with nuclear isomer batteries as the safe alternative here.

Constant angular velocity. So yes, you would have gotten stronger effect at higher altitude, if it weren't for exponentially decreasing density.

Nothing moves FTL "across fabric of space" in Alcubierre Drive. Everything has sub-luminal speeds in the local coordinate system. The only time you get apparent FTL motion in both cases is when you try to extend your local coordinate system. And you don't have to involve anything complicated here. When you watch stars rise and set over the horizon, they are moving faster than light with respect to coordinate system fixed to Earth Surface. And that isn't a problem, because you are still dealing with an accelerated (rotating) frame of reference. Alcubierre Drive and universe expansion work exactly the same way. If you take your local coordinate system and extend it to distant stars under assumption that space-time is mostly flat, than you can observe things apparently moving faster than light. If by "first theory", you mean Special Relativity, then the reason speed of light is a global limit there is because Poincare symmetry is a global symmetry of Minkowski space-time. Once you go to General Relativity, Poincare symmetry is local, resulting in all of the SR rules obeyed only locally. That includes things like causality, speed of light limit, velocity addition, and many other things we tend to take for granted.

That's not how science works. If it fits present data, you have a valid hypothesis. A valid theory must withstand attack by critical experiments.

Forcing people into anything is always a bad thing. But issue isn't religious freedom of people being vaccinated or not. It's religious freedom of parents vs protection of children. Once you reached age of majority, there is no question. But children, technically, aren't deciding for themselves. And the question is whether right to chose should belong to the State or the parents. We don't give parents a choice on whether children receive education, for example, and for good reasons. Yes, we allow home-schooling, but the program is still mandated by the State. The other part is that we should be more aggressive about educating population, so that people don't make dumb decisions for dumb reasons, the way the OP does. That's not even a religious freedoms issue. It's pure idiocy over which hundreds of thousands of children suffer.

In pure weight ratio, maybe. But combustion engines are less than 50% efficient, while electric ones are well over 90%. Jet fuel is expensive. Electricity is cheap. Add to that various environmental concerns and related taxes, and while you'll never have airplane with chemical battery be lighter than a combustion fuel one, it can be cheaper to operate. Also, who said we have to be stuck with chemical batteries? Nuclear Isomer Batteries research is advancing at a decent rate.

Mostly just one celestial body. The Sun. And that's precisely what determines SoI which Javster quoted.

These results have a lot of similarity to what I got using policy optimization in this thread. In particular with thrust curves, which I did not show in the thread. The method is somewhat similar, but I used polynomials for the velocity functions.

That's objective.

Linkxsc, you can do rigid body and still do stress calculations. That would already be faster, provide more stable flight, result in fewer errors, and be more aesthetically pleasing. It would not reduce the design challenge, and unless you are in it for the absurd bouncing contraptions, I don't see how it would take away from the fun of it either. That is another mod idea, by the way, but it would require some highjacking, since this would not be covered by general plugin stuff.

At least, he's consistent. I wish, more religious fundamentalists, of either faith, were like that. There is nothing about fire arms, high explosives, or nukes in any holy book. Of course, this is something that's easily verified as false by simply observing ship from different elevations. By his argument, observing a ship from high elevation would require looking down, which means it'd be harder to see. On curved Earth, it's easier to see the ship from elevation. Having two groups watching for approaching ship, and setting off a smoke signal when they see it would resolve the argument. Not that this sort of, frankly, Aristotelian approach towards natural philosophy will ever involve actually testing of any conclusions. Magister Dixit!

Don't have to have a border to be finite. And there is no guarantee that expansion is uniform beyond observable universe. So I'm basing things only on observable universe. And I don't recall if objects at the edge of observable universe are currently receding from us faster than light. Probably would take a minute on Wiki, but it's not really essential to the topic, so consider me too lazy.