K^2

You exaggerate the differences. If they were making mods for KSP, they can work on pretty much any Unity title with minimal training in some capacity or another, be it code, design, or art as appropriate to their skill set. But so can anyone who was trained in Unity development in general, and yes, you need people with broader experience to lead them as well. So I'm with you on your overall point, but you're being a bit too dramatic on the details. Things like differences in Unity and DirectX version aren't going to make an impact here. I also agree with you that if they have skills to jump from KSP mods to working on KSP2, they have plenty of opportunities in game development in general, and there is no guarantee they'd prefer to work on KSP2 over anything else they can be a part of. So again, with you on overall point.

Making big games isn't that simple. You can't just take a bunch of people who are good at making this kind of content and code together into a team and say, "Ok, make a game." You need all of the pieces to fit together, and that means team structure. For every 3-5 developers you need a lead or sub-lead. For every 3-5 leads you need a director. And then you need a production team to keep it all on track. If you wanted to add 10 developers to your team and you managed to hire just 20 people to achieve it, you're being rather efficient. And then all of these people need to be ramped up on tools, best practices, various details of the project... So for the first few months, these new people are mostly just learning what's there already. And this is assuming they all have some prior experience working with teams, because otherwise, there is no guarantee they'll be ramping up fast enough. And then we get into costs. The studio is in US, so even with everyone working remotely, Intercept would have to hire people who can legally work in United States. Game development in US is rather competitive. Yeah, you can take a chance on a budding developer who's making mods, but if you don't offer them a competitive salary, six months down the line, just as they're starting to contribute, they're likely to ditch you for another job. In Bay Area, an entry level games engineer costs company about $100k/year. It's a bit cheaper in Washington, but still, high 5 digits. More senior individuals cost more, and as we've discussed, you'll need management and production. So very conservatively, the addition of the above 20 people to increase your dev team by 10 developers is costing you something like $2 million per year. And as we've discussed, first 6 months are basically ramping up. Private Division tried to have their cake and eat it. They were unhappy with Star Theory, whether because of scheduling or some other conflict, doesn't matter. Private Division decided that if they torpedo Star Theory, they can staff Intercept with existing developers, patch some losses, and get everything on track. That very clearly didn't work. Maybe they lost more core people than they thought they would, or maybe the project outgrew the existing team. I think it was actually both. Regardless, they ended up short, and are now trying to recover. The dilemma for Private and Intercept is whether they pull everyone back, re-scope the game, and start production with a new scope; or they hire and train up new people to meet the scope they inherited from Star Theory. Either way, this results in delays and additional costs. Hiring new people costs a lot more, however, as it increases the burn rate while still having the same delivery date. And looking at current openings for Intercept, it looks like Private Division decided that this would cost too much. So if I was betting, my money would be that they are re-scoping, narrowing down some ambition, while merely restructuring some of the rest to fit the team and the budget they get to work with. And that means they will be making somewhat different game than they were trying to make this spring. And even if the game doesn't end up quite as big in some aspects, that might be a good thing. Because the modders will still be around, and so long as Intercept delivers a solid foundation, there will be ways to expand on it. They just have to make sure the core game is worth playing.

Yeah, I hope there's an honest post-mortem they can share at some point.

There are two sides to that. On one hand, I agree, people need to learn to chill a bit. The vitriol that got posted addressing Cyberpunk devs is not acceptable. But also, simply saying, "Games will take however long they take," isn't constructive. Even if nobody is harassing you, working on a project that keeps getting longer is excrements, trust me. It's extremely demoralizing when you were supposed to be finished with the game, but the schedule keeps getting longer and longer. And honestly, there needs to be a little bit of an external pressure from the fans to get the games released on time. We should be striving to find a balance where there is no harassment, no crunch, but also isn't a "take however long you need." The best thing you, as a fan, can do is ask for updates. Not demand. Not remind PR that you haven't seen an update since whenever. But genuinely, curiously ask if there have been any cool developments. If there's anything to share. It's a way of rushing developers along without creating negativity. And even when there are delays, and even if there is some secrecy around the project, there are usually some things devs can share.

Eh. It kind of makes sense. I did think they were entirely too optimistic about how much of the team and project they are salvaging when Private Division took development away from Star Theory and gave it to Intercept. Whether or not it was the right decision at the time, it is guaranteed to be extremely disruptive, and given that they were still looking for graphics and physics engineers well into when game was supposed to be approaching later stages of production on the original schedule... Pragmatic thing would have been for Intercept to treat the game as if in pre-production for the first time. And yes, nobody likes that, not the developers who already worked on the game, and not the publishers who already funded said development, but it's even worse if you keep trying to do production without resources on a schedule that makes no sense. Well, better late then never, in more ways than one. Best of luck to them.

Depends entirely on failure modes. I'm going to simplify a lot. Imagine a very simple bridge made from a framework of steel pipes welded together. The pipes form some sort of a grid on the top surface, so you placed wooden planks over these to make it into a bridge you can actually drive over. If the problem with the bridge is that the tank is breaking the planks, and then starts snapping individual pipes in the grid, then maybe wider track would distribute the weight better, and allow it to cross. But if the wood is holding, and some weld joints in the framework are giving out, then you probably just have too much total load on the bridge, and making tracks wider won't make any difference. In practice it's a bit more complex than that, and it's always going to be some combination of both factors - total weight and weight distribution, but the key point remains. Depending on specific bridge construction and why it's failing, changing weight distribution might or might not help. That said, I don't think there is any realistic situation where I knew there is a risk of bridge not surviving the crossing, me looking at the bridge and the tank, and saying, "Just make the tracks wider, and it will be fine." The fact that I expect bridge to fail in the former case suggests that even if I can improve the situation somewhat by changing weight distribution, the margin for safety is going to be just too narrow to be worth the risk. In the real world, there are always additional sources of stress and fatigue that you aren't aware of, and if you don't have a wide margin for these, it's just not worth it.

If the planet rotates rapidly enough, poles are your best bet. If you have a global storm situation, you're likely to have two storm systems centered on either pole, with poles themselves, or some area nearby, acting as eye of a storm with relatively quiet weather. Beyond that, hard to say. On planets with high wind speeds, excluding the quiet area very close to the poles, polar regions are very turbulent, usually with a number of vortices forming a regular polygon around the pole. (Saturn's Hexagon) Closer to equator, you usually get bands of laminar and turbulent flows. Any of the laminar bands are fine to fly in, but might make it very difficult to land due to wind speeds. Whereas, ground wind speeds in turbulent areas might be reasonably low, but good luck flying in them. Some sort of transition region might exist that would allow you to approach and land, but it's hard for me to say for sure, and these are likely to be unstable, so having landed successfully, no guarantee you'll be able to take off shortly thereafter. If planet's weather is not dominated by planet's rotation, you are likely to be looking at powerful storms at the terminator region with relatively quiet weather on the day and night sides. Unfortunately, temperatures there might be a problem. If the planet is not rotating rapidly enough to generate weather across its surface, then the day side is going to be very, very hot and night side very, very cold. Whether either of these prevents landing is going to depend on specifics. If the planet is close enough to the star, maybe night side is just fine for landing, and vice versa.

Sure. Lets greatly increase traffic fatalities and probably crime rates at least in some places just so that a few people can enjoy their hobby. There is no good reason for ground observations from general population areas. If you need to install a building-sized telescopes, you can put it on a remote mountain and have zero light pollution. And the kind of data you can collect with a hobby telescope you can get from small satellites. We haven't bothered with it so far, because it was easier to just have hobbyists buy their own equipment, but we're now shifting into the world where it makes more sense for research institutions to launch small telescope sats and time-share it to hobbyists to do studies. Very similar to how we have been crowd-sourcing a lot of data analysis on exoplanet search. Hobbyists aren't finding exoplanets using their own telescopes, they are sifting through data collected with serious equipment, and there is no reason not to do the same thing with visual observations.

That's been a solved problem since the first jets. Nothing about using NTR makes this conceptually different from a jet engine. If you want an air-breathing engine operating at low speeds, you need a compressor. You'll spin the compressor up with electric motor on the ground. Once you have it going, you can run exhaust past the turbine to keep the compressor running. That's every single turbojet out there. And switching to a ram mode is also a solved problem. See aforementioned SR-17. Don't think of NTR as something special. From perspective of building a propulsion system, it doesn't matter how you get heat into the working fluid. You can burn fuel or you can use a heat exchanger with a nuclear reactor. The effect is identical. And the way you force working fluid into the combustion chamber or heat exchanger is also the same. If you have an NTR running from on-board propellant, like NERVA, you must pressurize the tank or use pumps to get propellant into heat exchanger. If you are running an air-breather, then the working fluid is air, and you force it into combustion chamber or heat exchanger by using compressor or a ram scoop. The rest of the physics is identical. You don't need a larger scoop for NTR turbojet or a scram jet than you would with conventional, kerosene-burning turbojet or a scram jet. Depending on what kind of reactor cycle you're going with, even the dimensions of the engine might end up very similar, with the reactor core located external to the engines. There are additional challenges to building NTR equivalent of a scram jet, because it's difficult to organize heat exchange with supersonic flow, but you either get that problem solved or you don't. Larger scoop is just going to generate more drag, and if you can't produce thrust to counter drag of a small scoop, making scoop larger isn't going to help.

At low speeds, you don't need to scoop a lot of air, because you don't need a lot of thrust. Once you get going, you don't need a big scoop, because you'll be collecting enough air as is. Take a look at intakes on SR-17 and compare them to intakes on a commercial jet. Even if you're planning to compress and store collected air to use as oxidizer at high altitude, like on SABRE engine, you still don't need huge scoops. So for what an SSTO like that might look like, I would look at Skylon, since it's pretty much exactly what you're describing in principle. They use chemical fuel, rather than NTR, but that doesn't actually make nearly as much difference as you might think it does. Most of the propellant weight of conventional rocket is in oxidizer, not fuel, and air-breathing NTR won't give you a lot of ISP advantage over LH2. A lot of ISP advantage of NERVA, for example, comes from using a very light propellant, hydrogen gas, which you sacrifice when switching to much heavier air mixture. If anything, I suspect air-breathing NTR will be closer to ISP of a kerlox rocket. So yeah, an air-breathing NTR SSTO seems plausible in principle, and I would expect it to look mostly similar to Skylon. And given that Russians are believed to be developing air-breathing NTR cruise missiles, we probably even have the tech to build something like this, but various treaties prevent anyone from turning it into actual orbital capability.

Absolutely. And I would encourage @Chillboy to experiment with creating mods, possibly using existing mod as a starting point, because that's the best way to see if your ideas are good or not.

Just want to add to this that it's not true for just any arrangement in general. 3-body dynamics can be very complex and nothing like orderly movement of bodies about common barycenter. But such systems are inherently unstable. Any stable star system or planetary system will, indeed, have bodies orbiting common barycenter. That typically means that at most two bodies are dominating the mass of the system. As a point of interest, there are known stable arrangements of N-bodies orbiting common center, such as hexagonal variants of Klemperer Rosettes. But I can't imagine any natural process that would result in these, and even they do orbit a common barycenter.

Negative temperatures correspond to excited metastable states. Thermodynamically speaking, a lasing medium of a laser has negative temperature. That's why things like laser cooling are possible. But it's not like having negative thermal energy, so in terms of kinematics, you still have positive temperature. So utility is rather limited.

This isn't about efficiency, really, while I do understand how that discussion started. It's just not a philosophical discussion. It's a lot cleaner than this. ∇μTμν = 0 Divergence of stress-energy tensor is zero. Always. This is mathematically precise. It's not a question of approximations or not accounting for losses. There are no exceptions, there are no violations, because this is a consequence of symmetries in space-time. It's like if I glue two ends of a tape together, the number of twists is a fixed number now. You can move them around, you can try to stretch or flatten them, but you cannot change the number of these twists, because the topology of the tape has been fixed. This is exactly the same concept. This is embedded into the fabric of space-time. Now we can interpret it. Take a ship floating in space. Draw a boundary around it. Take center of mass of everything in the boundary and chose coordinate system where that center of mass is momentarily at rest. By Gauss' Theorem and using the conservation law above, change in net momentum inside the boundary is dependent on the flow of energy across boundary. In human terms, the object will remain on the same trajectory (moving in straight line with constant speed in open space or remaining in the same orbit if it's orbiting a star/planet) unless some non-zero amount of energy is flowing across the boundary. No propulsion without exhaust. It's mathematically precise. And we aren't talking about forces balancing out between particles and looking for losses. No, this accounts for absolutely all manner of energy flowing across the boundary, and in fact any boundary we may chose around our ship. It can be exhaust gasses, light, theoretical particles we haven't discovered, angry spirits of dead physicists - whatever you want, so long as it has energy. And if you aren't moving through some sort of medium, the only way to satisfy this condition is to produce exhaust. You have to expel energy to move, and that means you are using reaction mass. There are no loopholes, no losses to account for. This isn't a 99.9% situation. The equality from which this is derived is strict and fundamental to living in this particular cosmos.

Pretty sure that pusher plate will have a non-negligible gravity field.

Depends on nature of composite. Something coarse, like reinforced concrete, you can make very decent estimates for. Steel doesn't behave in any fundamentally new ways when encased in concrete, and neither does concrete exhibit any new properties. There are still plenty of nuances. A structure that's just a steel mesh will experience more failures than reinforced concrete, despite the fact that nearly all of the strength is provided by steel. Concrete, however, helps redistribute the stress, meaning you aren't as likely to have a critical failure point. That's a bit tricky to get from a simulation, but if you know what you're looking for, you can build a mathematical model that will work. Other composites are similar in that regard, but things get rapidly more complex as the mix between fibers and matrix becomes finer. At the extreme range of this you get ceramics suddenly turning superconductive. That is, you suddenly have completely new physical properties not exhibited by any of the components going in. Emergent behavior. You don't get things going quite that badly with typical construction materials, fortunately, but you still can't rely on each material having same mechanical properties in a composite as it does outside of it. For example, when considering strength of glass fiber hulls, you have to keep in mind that resin matrix behaves differently in the composite due to viscous forces. So if you were to model glass fiber composite the same way you would reinforced concrete, you are likely to underestimate material's strength. In general, the smaller your fibers get, the less predictable material becomes. I'm worried that in case of Pycrete you'll get additional complication of water doing very strange things near the cellulose fibers. Everybody knows that water is weird because it is less dense when frozen. But it's even more weird when it's near freezing. Water at 1°C is less dense than water at 4°C, because while it won't start forming actual ice until it drops to freezing point, the molecules of water start forming large ice-like complexes that stick around long enough to offset average density. This all has to do with strength of hydrogen bonds and is part of the reason why hydrates can get weird. Concrete's actually a good example. I suspect that structure of ice near cellulose fibers in Pycrete is nothing like structure of pure ice. You'll get long chains of water molecules pulling on each other adding to material strength. It is effectively a different phase of water with different physical properties, and you'll never get that from simple mechanical analysis of the composite. There are entire fields of condensed matter and soft matter physics dealing with these kinds of emergent phenomena in materials. A lot of it is studied in simulation, so it's not a hopeless task. But you do need to know in advance which phenomena you need to account for. If you suspect that viscosity plays a role, you can't use simple rigid body simulation. If you suspect phase transitions are taking place, you'll have to account for the new phase. It's all doable, but it's not trivial, and without doing tests on the actual material, I don't know if you could ever be certain you didn't miss something.

I haven't. I can do the math for these with a computer, of course, but I don't actually know how you'd stick it into a table for quick lookup. I know that artillery makes corrections for it, but no idea how they do it in practice. My only practical use has been in impressing undergrads in a physics classroom. Using spring-loaded cannons, of course, as discharging firearms on campus would get me into trouble, and it's hard to demonstrate the effects at these speeds on classroom scale anyways. But I tell you, when you land a steel ball into a plastic cup someone places on the other side of the classroom using a single shot, the students always look at you like you've summoned the devil to guide the projectile. The fact that they just learned relevant formulae never seems to convince them that the math actually works in the real world. XD I'm pretty sure that the only reason we were teaching labs is to convince kids that we aren't just making up these equations for fun.

Yeah. The horizontal velocity has effect of increasing vertical drag slightly, but it won't make a huge difference until you start getting close to terminal velocity in vertical speed, and that would require a lot more height and would mean that bullet is basically dropping at that point. And, well, casing's drag-to-weight is already a bit higher, so the time it takes the two to fall is going to be pretty close. Not identical, for sure, but it's close. In that Mythbusters episode, they actually did see effect of drag, but they treated it as error. Which is kind of fair, as it's a small effect, but if you do the math for drag properly, the theoretical value ends up closer to their result than if you do the math without accounting for drag. Drag in ballistics is actually a fun topic. It sounds very complicated, but there are some very interesting formulas that make your life easier. So for the fall of the bullet you usually treat it as free-fall, which is fine, but you also have to account for wind, and that's where things get really exciting. It should be a very hard problem that requires a computer to solve, but snipers and artillerists make wind correction with a single table look-up. What you need to know is time-of-flight over a certain distance and wind speed. You look up time of flight from the table, then multiply by cross wind speed, and you get the correction. The reason this works is because it doesn't matter if you are firing a bullet through air that moves, or at a target that's moving in stationary air! So you do the math for later, and you get an easy answer.

If you run out of fuel on a blackhole ship, you have a few months to a few years to either get somewhere or ditch the core. Whether or not you can still use it for propulsion in that time will depend greatly on design, but you can certainly use it for power, so you'll still have life support, etc, and if you have an emergency "parachute" for braking against solar winds in a destination system, it still gives you more chances for getting rescued than any other feasible propulsion system we know of. But yes, a tiny black hole suitable for power generation is basically a very powerful bomb with a timer once you stopped feeding it matter. It's definitely not something you want to sit in your ship yard without supervision. I didn't say it was perfect. :p

If you put butt of a rifle against your forehead then pull the trigger (and please, don't do that), you will suffer a serious injury, likely concussion, and possibly brain damage. Broken neck isn't out of the question either. How the force is transferred matters. For any helmet to be effective, you need not just the armored outer shell, but also significant amount of padding to distribute the impact temporally.

I don't understand how you get that. Pluto is more massive, so it pulls on Charon more than Charon pulls on Pluto, and influence of the Sun on either is identical. Even looking at the formula, the only value that's different is mp and that's higher for Pluto. Of course. But again, practicality. I claim that we should be making definitions that are most useful for studying and reporting on study of exoplanets. How many of these do you expect you'll be able to measure for an object in another star system? With a really large orbital interferometer we might some day be able to optically resolve some of the gas giants out there enough to measure their atmospheric wind speeds. For smaller planets and moons, though? You aren't going to know for sure if they are tidally locked or how they formed or any of that stuff. Tug-of-war value does help you make some educated guesses, though. If you see a planet with a solitary candidate for a moon with low tug-of-war value, it almost certainly didn't form from accretion disc. It's also very unlikely to be tidally slowing or be a capture. That's interesting. I'll absolutely give you angular momentum. It's also a strong indicator that the object in question didn't form from a protoplanetary disc but was either ejected or captured. Unfortunately, it tells us very little about stability of the system, but then tug-of-war isn't a complete picture on that either. I still think tug-of-war definition is a better one. Pluto-Charon system is more gravitationally bound than Earth-Moon system with respect to their neighborhood. The idea that it doesn't take much to have a moon for something floating out there among the asteroids doesn't seem contradictory to me. But angular momentum definition is still better than barycenter. It's measurable to about the same precision as tug-of-war value, doesn't vary over time without external interaction, and tells us useful information about the system. Not my favorite, but I would find that definition of the moons acceptable. If there was a strong push in IAU to adopt either one of these, I would back it up.

The situations where tug-of-war is indeterminant are typically unstable. Carpo is on its way to get ejected from the system. Also, it doesn't meet any of the other qualifications for a planet, so it's sometimes an asteroid that happens to share orbit with Jupiter and sometimes its minor moon. For now. For our Moon, you are greatly overestimating initial state, as Roche limit is merely the inner boundary for the disk that formed, with a lot of debris, initially, in highly elliptic orbit, and the entire inner boundary of the disk moving up as the Moon began to coalesce. By the time Moon formed as a body, it was significantly further out, though, likely still with tug-of-war value well above 1. Regardless, with the total angular momentum we have in the Earth-Moon system, having the two of them close together is not stable. They will drift apart until they are only loosely bound gravitationally. Likewise, any captures that don't have sufficient angular momentum and descend in orbit will eventually get sucked in, so that's not a stable situation either. And that's kind of the point. Tug-of-war value tells me something about the system. Even knowing that it's borderline or variable tells me things about the system. We don't get any of that with other definitions for what makes a moon. They are either difficult to measure without knowing precise orbital and physical characteristics of objects involved, are entirely arbitrary from perspective of relevance to system dynamics, or both. And of course there will still be exceptions and weird cases. But we should still try to pick an option that works more often over the one that works less often. And yes, if we were talking just about Sol, saying that the Moon is one of the weird exceptions would have been fine. But that doesn't work when we start discussing exoplanets and potential exomoons. The Moon was important factor in formation of Earth and making it habitable. And a small moon deorbiting and devastating Venus might have been a factor in why it's not. So taking an arbitrary geometrical definition just to make us happy with the Moon being a moon here over taking a definition that aligns neatly with categories we might actually care about for everything out there seems kind of silly.

No. Photons produce less thrust for the same energy input, but they produce far better ISP. The ISP of a perfect photon drive can be as high as c/g. ISP of a steam rocket would be comparable to LH2/LOX chemical rocket, so it's not a huge improvement at a big increase in cost. There are other intermediate technologies that can use antimatter as power source and a dedicated propellant to produce much higher ISP than a steam rocket, but it's a bit more complex than just heating water with gamma radiation from a matter-antimatter reaction. Simplest one is firing pellets or plasma beams of antimatter into larger propellant pellets and have the explosion push the damper similar to nuclear pulse propulsion, but there are more creative ideas as well, down to using antimatter to drive a plasma rocket of some sort. Nonetheless, the absolute best ISP you can get is if 100% of fuel mass is converted into energy, and that's a photon drive. That, too, comes with huge technological challenges. We don't have mirrors that work at these photon energies, which means the shielding behind a photon rocket will be absorbing the radiation. That wastes a major fraction of your theoretical ISP. Indeed, the best you can do is c/(2*pi*g) with a kind of photon rocket we know how to build. But worse, it produces enormous quantities of heat you have to get rid of at anything like reasonable thrust. If you want to get full impulse you'll have to get rid of over 1GW of thermal energy for every 1N of thrust. That's a small nuclear power plant's output worth of energy for a few ounces of thrust. If you sacrifice some ISP you can bring that down to about 300MW per 1N, but that's still an enormous amount of energy to get rid of for any practically useful thrust. So antimatter propulsion is a bit complicated. It's not just a problem of making antimatter and storing it, but even turning that energy into useful thrust is very far from being a solved problem. I would go as far as to say that for practical interstellar torch ship, black holes are probably more practical than antimatter. Outside of the problem of making one, the only real difficulty with these is confining that black hole, and that's basically equivalent to balancing a skyscraper on top of a needle point. While clearly not an easy task, I can at least picture how to reduce that one to an engineering problem rather than requiring conceptually new understanding of matter and energy.

Atomic composition isn't an issue here. Many ceramics are carbides, for example. Definition of ceramic is material made by heat treatment of non-metallic mineral. The synthesis of superconducting material in this article is achieved by combining pure carbon and sulfur. Both of these are minerals. But instead of pressure and heat, pressure and laser are used to fuse the material. I don't know if you would expect to get the same material if you could heat up the diamond cell to high enough temperature. If you would, I'm not sure why you wouldn't call this material a ceramic. But it might be a bit of a stretch to apply definition this way.

@NFUN Thanks for the article link. Looks like they did due diligence on testing, but the bit about metastability is definitely just speculation. I was hoping they'd present some findings that hint at it.