K^2

I am not at all an expert in the field. I have decent background in evolution algorithms, as well as a number of other algorithms that optimize similar functionals. I have taken courses in cellular biology and genetics. I have done laboratory work on gene sequencing and splicing. And there were other misc bio classes here and there. Now, as limited as that scope is, you come off as a person who've taken a single course on the subject and considers himself an expert without any practical experience. I am well aware of how local optima work and difficulties they present in achieving true optimal solutions. It's not just a buzz word to me, like "dead zones" seem to be to you. What I also happen to understand is that there can be no local optima preventing factory-style reproduction from evolving, because that's how every single living cell reproduces. Unlike complex organisms, cells do not consist of self-reproducing components. They rely on an entire process for all of their components to be assembled, starting with genetic material transcription. Why don't you go and look up how ATP is produced in animal cells, and they come back and tell me that a factory cannot evolve.

You are still falling into the same fallacy. Describe to me how a human survives to reproduce without a digestive system? You are grabbing a single element, and focusing on it. If factory-style reproduction was evolutionary advantageous, it would evolve. Yes, from simpler self-replicating systems, going back to strands of wild RNA in a puddle of organics. Same way we went from single self-replicating gene to a self replicating cell, with ton of machinery without which it couldn't work. To multi-cellular organisms that couldn't work without a single type of cell. To complex organisms that couldn't function without a specific organ. And then yes, into factories, that couldn't function without a specific gear. Evolution is just an optimization algorithm solving the problem of optimizing energy consumption. And what we have is about as efficient as it practically gets, without either falling apart due to errors, overheating, or running out of resources.

Do the math on power requirements. Make sure you factor in consumption from the city of 100k+ that's riding on it.

I've heard this argument before. From creationists. In fact, that's pretty much their entire argument. I'm prepared to listen to experts on these matters when we have them. When they figure out how to create a self-replicating machine from scratch, or at least, greatly modify existing ones to do anything remotely close to the claims. So far, every attempt has simply revealed a new limitation that real self-replicating systems have to deal with.

We already have technology for self-replicating matter-consuming robots. It's called life. It's absurd to think that robots are going to spread more rapidly, or consume more matter than living things, because a self-replicating robot is just another living thing. And it will follow all the same rules. We use technology to augment our ability to survive and replicate, but our entire planet isn't made up of people. It never will be. This is a silly concept.

Sub-light Alcubierre is just as bad as an FTL one. But that has to do with certain features of Alcubierre metric that aren't necessarily general to all Warp Drives. In theory, if your drive is not capable of exceeding light speed, then energy conditions are not violated. So as far as we know, that means negative energy densities are not strictly required. But all that says is that there may be a configuration that allows for sub-light warp. I am not aware of any known configurations that would satisfy that, and I don't know if anyone is even seriously looking for one. If we do find a configuration that works, and if it happens to have similar energy requirements to Alcubierre, which scale with the speed of the bubble, then a 0.1c warp ship could actually be feasible based on technology we either have or can conceive of. This really isn't saying much, but we're really early in our attempts to understand warp drives and whether or not they are feasible.

I don't think you are picturing a fusion reactor of an interstellar generation ship quite right. It needs to generate tremendous amounts of power to get itself moving. Which means it's not going to be a handful of atoms being pumped through the confinement rings. You'll have literal tons of high energy plasma bouncing through the reactor. If confinement fails, it's not just going to shut down. It's going to rip itself apart quite violently, destroying not only the reactor, but anything around. We are talking kiloton ranges explosion. If anything, black hole drive is significantly safer. The radiation pressure is pushing along the ship, not the black hole. If you tractor the black hole along with electrostatic charge, and the force gets too weak, you simply leave the black hole behind. It will be years before it explodes, by which time you'll drift to a safe distance. If you pull the black hole in too close, the electric fields will exceed what matter can hold, and there will be an electrostatic discharge, at which point you'll lose traction, and again, leave the black hole behind. In none of these scenarios, do you get a catastrophic explosion in event of the confinement failure. Sure, you're dead in the water with your engine gone, but you're not dead, as would be a case if an equivalent of a nuke goes off in your power core. Besides, single point of failure is nothing new for us. If an airplane's wing breaks off, everyone aboard will die. You can deal with engine failures and partial control failures, but there are still critical, non-redundant systems. And we choose to live with it, because it makes economical sense. That's not going to change if and when we start running interstellar ships.

Power efficiency is irrelevant. Black hole is free mass to power converter. So only mass efficiency matters, and black hole drive matches that of an antimatter drive. Except your fuel is ordinary matter. Yes, power failure of any kind would be bad. "Abandon ship" bad at best. But that is not unique to this design. Build with redundancies. And yeah, hard to make, no kidding. That is why I do not have too much hope for it. And with all that in mind, it is still our best bet if we do not figure out something like warp drive.

Simple, you charge it. Black hole can hold a charge that's almost arbitrarily large. So you are limited by how much electric field can the structure of your ship withstand. And it just so happens that the force such a field will apply is roughly the same magnitude as structural strength limits on materials. Works out that way because electrostatic forces are responsible for maintaining matter bonds. In a way, this is exactly the same thing, only with much greater charge with a much larger gap between things it holds together.

Gravitational forces for such a large body are much too strong for any sort of rigidity Moon has to matter. It's the same reason why Moon is roughly spherical. Which also answers the question of how large a body has to be to be considered fluid for purposes of Roche Limit. If it's spherical, it's basically a fluid.

For traveling between stars without FTL? It's black hole drive or bust. So it's probably bust.

Instead, I have more than equivalent of all of the computing power they've had in the world in my pocket along with access to nearly all of Human knowledge from the same device. We did not get power and propulsion systems they've predicted in the 60s, but we got many things they wouldn't have dreamed of. You win some, you lose some. So while I agree that trying to predict if we'll have certain kind of technology in 50 years or longer is silly, the pace at which tech develops would certainly allow for many things that seem impossible today. But whether we'll finally make a leap in space exploration, biology, cybernetics, or something we aren't even thinking of now, who knows?

It's another confirmation of the math behind Alcubierre Drive, but no serious scientist has had any doubts about it for a while, so impact's negligible. It certainly doesn't give us any new information that would make it easier to build one. The soonest we could have an FTL drive is not far removed. Any breakthrough in high energy physics could be decisive. Then we can have practical implementations before the century's out. On the other hand, it's not very likely. We are far more likely to have sub-light warp long before we have FTL warp. And based on our modern understanding of gravity, that's likely hundreds of years removed, provided that we come up with a suitable configuration in the near future.

L4/L5 are a very special case. They are unstable, but because effective potential is so flat for such a large area, the dynamic instability is tiny. This means that a single large body would still get knocked out of L4/L5, such being a hypothesis for Theia. However, if you have a ton of small objects that all interact, you can still have net stability. Such as the case with Trojan asteroids.

I have explicitly addressed docking and how it works without any moving parts with a tethered design. That was the emphasis on an entire paragraph. That is a big part of the reason why I'm calling for such a design. There is a difference between skimming a long text, and replying without even reading.

I wonder if a resonance along the lines of Janus-Epimetheus one would be possible between our Moon and a smaller moon sharing an orbit. Or would the Moon eject it? You might need the two objects to have similar masses for this resonance to be stable.

Nautilus X is inherently limited. It's better than microgravity on longer missions, but it's not good enough for a permanent settlement in space. The fundamental problem with centrifugal gravity is that human anatomy is pretty good at detecting rotation and isn't happy with it. In a large section of population, problems start to occur at mere 2RPM. If you have a trained crew, you can push it to 5RPM, but past that, you are likely to start having issues even with them. At 5RPM, you need a ring 70 meters in diameter. That's too large for a ship we're likely to build in any foreseeable future. Nautilus X demonstrator module for ISS was meant to have 40 foot diameter and spin at up to 10 RPM. Even then, it could only generate 1/2 Earth's gravity. However, the main idea behind that is to have a ship with mere 5RPM that can generate roughly Moon's gravity in its habitat module, drastically reducing the negative side effects of low gravity the crew would suffer otherwise. This is not an environment you can permanently live in without developing serious health problems, but it is an environment you can suffer for over a year during, say, a Mars fly-by mission. In contrast, if we go back to the idea of building a permanent outpost, you really do have to cut it down to 2RPM and ramp up gravity to 1g in order to allow general population to live there. If you were to build it as a ring, it would be nearly 1/2 kilometer across. This isn't some crazy science fiction, and if we absolutely had to build something like this, we actually can. But it's orders of magnitude beyond what we can afford with current space exploration budgets. That's where tethered designs come in. They don't require you to build a habitat ring kilometers long. They simply require a habitat module and a counterweight module. In many designs, counterweight contains all of your power generation/collection systems. Even if counterweight ends up lighter and has to extend further out from the rotation center, it's not a huge deal. A 1km long suspension cable we can do. Especially in the windless environment of space. So realistically, if we are going to build a station with artificial gravity, the first one will be something like this. It will have a hub module with docking ports near the middle. It will have a habitat and counterweight or two habitat modules connected by long cables. And it will have a small elevator/airlock module that will be able to ride between the modules on these cables. Gentle rotation of the hub can easily be matched by any docking ship, and the elevator module will make it easy to transfer crew and supplies between modules. No complicated bearing mechanisms necessary, since the whole thing spins, including any ships that happen to be docked. In theory, a structure like this can even be expanded, with additional pairs of habitat modules added suspended from the hub. And potentially, it could even grow into a full ring over time. Not that I expect the very first station to serve long enough for this to happen.

Gravitoelectromagnetism has nothing to do with electromagnetism besides the name and similar looking equations. It is just a linear approximation to GR. Device I've suggested is electromagnetic, but coupling between forces is via a shared charge. Specifically, electromagnetic field has stress-energy, which is the gravitational charge.

Magnetogravity has nothing to do with it. Gravitoelectromagnetism does. Completely different concepts. And artificial gravity via gravitoelectromagnetic effects would work exactly the way you see in sci-fi movies. If it could be amplified to 1g ranges.

Displacement current Hall effect gravitoelectromagnetic coils. With equipment I can feasibly assemble, I was estimating artificial gravity on the order of 10-27 m/s². With expensive laboratory-grade equipment, I might be able to get 3, even 4 orders of magnitude on top of that. Which is still many orders of magnitude weaker than gravitational field of a grain of sand. I couldn't even come up with a way to measure a field that weak. But, you know, technically artificial gravity from a solid state device. If we could figure out how to build a gravitoelectromagnetic equivalent of a transformer, we'd be set. As far as practical ways go, though, you need to be constantly accelerating without going anywhere on average. That's basically definition of spinning.

The metallic phase would have a clear phase transition from non-metallic supercritical fluid that makes up the bulk of Jupiter's "atmosphere". Part of the problem is that we don't really know exactly what sort of a state metallic hydrogen is going to be in. The options are quite numerous, including some researchers believing it to be a supersolid. That would make it an even crazier compound than the plastic crystal methane available on some other worlds.

All of the US tail numbers are N-numbers, yes. And yeah, there are definitely patterns on registrations. You don't even have to look at large airline companies. Most (all?) aircraft at my university's airport were Kilo-Sierras, because they belong to Kent State University.

Kerbin does not have the same mass. It has the same surface gravity. Since the radius is about 10 times smaller, it means the mass needs to be about 100 times smaller than that of Earth to maintain the same surface gravity. So for LKO vs LEO, the GM/r is about 10 times less, which means that Kerbin's orbital velocity is about a third of Earth's. Which is on par with numbers you see.

Yeah... That's not how angular momentum of a star system works at all. It is not evenly distributed even on the protodisc level, let alone after the planetary bodies start forming and interacting.

I'm pretty sure drag is still quadratic. And they probably fixed lift to be quadratic as well. It's the drag and lift coefficients that are computed differently now. If nobody has decompiled the binaries yet to take a look at how it does these estimates and how it gets occlusion, somebody should.