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Everything posted by wumpus

  1. Pretty sure they also had to be careful about having two planes (going different speeds/directions) and the clouds on at the same time. Computer graphics can look good at low framerates until you have multiple competing frames of reference. The eye will "fill in" a certain amount of jerkiness for something, but the effect will be jarring on everything else. The opening scene in Oblivion (Elder Scrolls IV) was particularly bad when a tower would move into the foreground (which was really bad as otherwise the game didn't need high fps and could show what was then state of the art graphics on lesser hardware).
  2. As far as I know, the difference is largely vitamin A. Source it from plant proteins (not beta-caroteen. That's just a precursor that plenty of mammals including humans and dogs can use to create vitamin A) and you'd be able to create vegan cat food without the issue of providing animal flesh. Granted, I'd assume that eventually rats will stowaway to Mars (along with other assorted vermin) and the cats will go back to being their normal serial-killing selves. Seems pretty pointless feeding them vegan if they kill multiple times that mass in critters.
  3. I didn't think it was the cost of the electricity (at least not when it was used as a rare metal), but it wasn't until the whole process of discovering that alumina would melt in cryolite (and the whole mixture would be sufficiently conductive to allow electrolysis) that allowed aluminum to even be considered an industrial metal. It is still one of the most common elements on the planet (after things like silicon and oxygen. Not sure about carbon), but the electricity cost still dominates the cost to make it. When I hear "use excess electricity to make hydrogen" I think "why waste perfectly good methane on an energy sink when there is always a need for aluminum?".
  4. Pretty sure the wavelength of the photon matters (blue LEDs are probably the best you can do now). And make sure you carefully paint the "exhaust" side of your heat sinks black and the "front" side white. You'll get a significant amount of thrust from just the heat sinks.
  5. I once described the movie 2001 as "watching a glacier move", granted that was watching a VHS tape on a 1980s CRT TV. Watching the whole thing later on a real movie theater with Dolby sound was enjoyable. Perhaps NASA didn't include cameras partly to spare people the nagging feeling that they should be watching the JWST unfold.
  6. The chromatic bits of stars is a dead giveaway it is wrong. Stars shift one way or the other, not spread out that way. Since you are heading towards them, they should turn blue thanks to the "blueshift". Presumably at (or above) light speed, everything hits you as a singularity.
  7. Some googling implies that the concept is taken over by "technological determinism", which completely gets it wrong [I'll have to stop using the phrase, sad]. The original was from Charles Fort, so it makes sense that he doesn't understand why steam came when it did. Also same reason airplanes occurred when they did: as internal combustion engines got more powerful and lighter, it became easier and easier to build an airplane. The Wright brothers were well aware of this and knew they were pressed for time before better engine builders would "invent" the airplane (there's a motorcycle built by Glen Curtis in the Smithsonian. Presumably built to test an engine, or as a marketing stunt (I think it set a speed record)). Probably the bit were "the exception proves the rule" is the Turbo Code. From 1970-2000ish, there was almost no improvement in digital encoding of transmitted messages (for error correction). Then, suddenly, someone developed the Turbo Codes which can reach near enough to theoretical perfection with a slight delay as massive calculations are done. So this invention is decades "late". Except it isn't the only "perfect" code we currently use. The other is the LDPC family, which was invented decades "too early" and forgotten until somebody looked hard for patent-free competitors for the Turbo Codes... [this will teach me to to include a random side rant in a post. But the topic was so fanciful I thought it was safe.]
  8. Except that you hit each footfall with more force running downhill. The downhills of the Boston Marathon are said to be worse than "heartbreak hill".
  9. Do you have an ansible? Otherwise you need to pack a second inside the first (not sure if allowed) to bring the information back faster than 7 years. You also have to think long and hard about what this is doing to the causality of such a universe.
  10. Steel, not plastic. It is relatively easy to find plenty of metals, especially the components of steel. Finding enough hydrocarbons off Earth might be trickier. If you are hauling the mass off Earth, you likely will shape it there (unless you are using something like spinlaunch).
  11. There was Escape Dynamics and their attempt to build a SSTO craft by heating it with microwave power as it lifted off to orbit. Isp should approach NTR, but have even more issues of the "heating chamber" heating up everything around it (including the less focused microwaves). https://en.wikipedia.org/wiki/Escape_Dynamics It was my favorite "power point rocket company". Probably 20 years before their time*, but I suspect that once Starship lands (with or without a crew), that cutting fuel costs will be a real thing in space research. Also there are electrodynamic tethers for raising your orbit using electricity once you are in orbit (of the Earth, don't try it on the Moon, Mars, or any other body without a magnetic field). * this is not a good thing. You can't make payroll until the infrastructure exists to get things going. Building a "steam engine before steam engine time" kills many people every time the pressure vessel explodes. Generally speaking, the whole "great inventor" theory of technology completely misses that most of the inventions are useless before the infrastructure is ready, and had the "great inventor" merely slept in that day the next day someone else would have done it.
  12. Probably because nobody believed him when he tried to fence the bridge. Even when he showed them to it on the truck.
  13. The "just so stories" I've heard about such things imply that cats "domesticated themselves" by hunting vermin in granaries. Those that could tolerate humans in closer proximity were the ancestors of domestic cats. When the early farmers realized that the cats killed things that ate the grain (and not the grain), they suddenly liked that cats a lot more (although the ancient Egyptians took it to extremes. Perhaps they had more vermin to manage?). Certainly not true in fish. I've also read anthropologists and others who ate lion insist that it is rather good. While this is a serious consideration for any hunter society, you can expect boys (and old men, and sometimes women and children if the men aren't bringing enough "big game") to hunt the little stuff (and could therefore get away with "hunting" cats and dogs). And they often bring back more total calories than their "mighty hunter" fathers.
  14. I don't think there is any advantage to a single nozzle. I've only seen that method done with multiple combustion chambers. With multiple chambers/nozzles, you have less combustion instability issues (unsure of the disadvantages). There are also hard limits to the size of expansion (see RL-10) turbopumps, but that is only based on the maximum size of the combustion chamber and nozzle, not the total volume of each.
  15. Presumably the "space agency" would be like NASA's current subsonic programs. Certainly still there, but hardly noticed. Similar to the Naval Research Center still working on [ocean] ship design. The only reason to include them in a sci-fi story would be if a strange problem fell in their lap.
  16. I've heard of suggestion of flying by attaching wings to arms Icarus-style on the Moon and Titan (Titan wouldn't need additional atmosphere, just a SCUBA tank for breathing). I'd assume that using the hands in winged quidditch would be still legal, but you'd probably size the quaffle so you couldn't carry it and fly at the same time (or at least fly well).
  17. Since Huble's was glass, I'd suspect that the similar keyhole mirrors were glass. Or possibly they didn't, and used a rookie company to polish the lens (thus the error). More likely, all the Keyhole birds have the same abberation, but it doesn't matter for looking at Earth. I suspect that NASA checked this time for previous experience, and that somebody had ground similar mirrors for NRO.
  18. Fun fact - the mirrors of the JWST are beryllium (covered with something non-reactive). For when you really, really, want light weight (also helps if they aren't going to almost always be in a clean room or otherwise outside of an oxidizing atmosphere).
  19. Even in WWII, I'm pretty sure the US Marines were happy to have battleships firing their 16" (and possibly some lesser ones as well) at any beach defenses before storming the beaches. Not sure if they could get any in place for Normandy, but I'm sure they had them for taking later Japanese islands. I've heard a retired sailor brag about how during the 1990 Gulf War, Iraq forces immediately surrender to the Iowa (specifically a targeting drone) to avoid such naval bombardment. Just because their main use was obsolete, don't discount their use as floating artillery. But apparently they weren't enough use to make heavy cruisers (the armament of a battleship with much less armor), which would presumably be what a post-WWII "battleship" would look like.
  20. More likely he believes that he can eventually scale bigger than anyone else and wants to make sure he can build to scale. It worked for Amazon, it worked for AWS, but it isn't clear how it will work for BO. I can't see New Glenn launching before Starship, at which point catching up becomes profoundly difficult (you can try to out-scale Rocket Labs, but I don't see the point).
  21. Why wouldn't it be a SSTO? Simply use the electricity to heat hydrogen, then use as a NTR with an Isp>1000s (first pass the hydrogen over the battery to cool the battery, then pass it through heating coils to further heat the hydrogen). Other than the unbearably large fuel tank, it should have no other SSTO issues. The big question is how in the world does adding charge create antimater, and how a reversed operation would create electricity (I thought I posted a reply yesterday which assumed that the battery would be nuclear. A chemical battery storing electricity better than chemical fuels seems unlikely. Of course once you are in Earth's orbit, you can theoretically use the Earth's [or any other planet with a magnetic field, not sure their are any good targets] magnetic field for a truly reactionless drive. Note that such a drive would likely be slower (no matter the tech) than current ion drives, so perhaps your fictional people won't even use it for cargo, but I'm pretty sure a proof of concept was done on a [tiny?] sat. And you are discovering part of the reason that Rocket Labs only uses electricity to drive the pumps in the Rutherford engine (and not even the planned larger Archimedes engine).
  22. When the witness testified to the existence of soil before the existence of life, he easily discredited himself as an "expert". The attorney should have used seawater.
  23. "second stage, which will have an annular aerospike" Any idea why? Presumably the first stage (assuming they build one, it might not make sense to compete in that area) would also be an aerospike, but traditionally it makes no sense in vacuum.
  24. They certainly would have trouble building in Miami. Anything not highly developed near Miami is protected Everglades, and I'm fairly sure they can't build in Key West (and launching over the Keys is probably a no go as well). I'm guessing they also don't want to pay Hawaiian salaries (although if you advertise in Chicago during the winter, you might get bites from people who are used to expensive living).
  25. I'm rather curious if we are dealing with the Gell-Mann Amnesia effect. In the 1980s it was not trivial to do fact checking the same way you can do it in the age of google (although this doesn't seem to help the Facebook crowd). I distinctly remember reading quite a few things in the 1980s and being shocked just how wrong they got it. It seems rather suspicious that an institution suddenly becomes so very wrong at almost the same time it becomes possible to check how wrong they are.
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