Nikolai
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Everything posted by Nikolai
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I know. And there's no such thing. EDIT: By which I mean, even things close to each other are moving with respect to each other. You might statistically reach a certain level of confidence that you're moving when you're traveling at a high fraction of c compared to most matter you can detect, but you can't tell when you're sitting still. And more to the point, the rules work the same way whether you're rushing past the universe or the universe is rushing past you. Neither reference frame is "preferred".
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Yes, it would. It would appear to you to race past you at c (exactly 299,792,458 m/s by definition), and it would appear to the one who fired the laser to be rushing away from her at c. Your definition of "meter" and "second" would be different from hers, though. You would also disagree on the color of the laser. The speed of light in vacuum appears to be constant to every observer, regardless of where that light originated. Perception of spacetime itself changes to keep that true. There is no "speed of the universe" to fight. The whole point of relativity is that no reference frame represents the "true" frame of the universe.
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A two-sided die? Like a coin? Sometimes, though, the two aren't mutually exclusive. Which is why I have fierce admiration for people who do this, and the people who try to make things that allow them to do it and survive.
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Not necessarily. Are they canyons or rilles?
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I think it has something to do with what Freud called the Tyranny of the Small. Once you really get interested in something, you start to learn a lot of details. And then you develop passionate opinions about things (because the root subject matter is something that interests you), and the depth of that passion completely bewilders people outside who don't see the point of all the bickering. For example, in Real Life Rocketry, there's active and ongoing debate among some about whether we should call the thing that makes the rocket go an "engine" or a "motor". It has salient characteristics of both, and ways in which it resembles neither. And some people care a whole awful lot that their preferred nomenclature be used. (My personal favorite take was someone who suggested that the whole traditional naming system ought to be ditched, and we should call it something completely different, like "whoosh generator".) Besides, in picking favorites, no one's implying that other astronauts/cosmonauts are second-best... just that there's something about their personality or career or some other random detail that intrigues us.
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Yes, but when you do, they are created by erosion. There doesn't seem to be anything to cause erosion on that kind of scale on Mun. Perhaps micrometeorite "weathering" was more significant in the past, but I'd need additional evidence to accept something like that.
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Charles "Pete" Conrad, Jr. He was famous for saying, "It's better to be colorful than to be right", and he lived like he meant it.
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Simulated gravity using rotating two-part rope-linked ship
Nikolai replied to Cesrate's topic in Science & Spaceflight
They actually tested this idea for creating artificial gravity on Gemini 11, tethering the spacecraft to its (Agena) docking target and thrusting sideways. They ended up creating about 150 millionths of a gee. The funky thing about Coriolis forces is that you'd feel a stronger force going with the direction of the station's spin than you would sitting still, and the force you'd feel going against the direction of the station's spin would be less than sitting still. As noted, these effects would be minimized with a "long enough" turning radius, but it's interesting to contemplate what this means in terms of simple things like pouring drinks and urinal placement. Not to mention that these Coriolis effects make people queasy in the stomach because they do weird things to the otoliths that tell our brains how our heads are oriented with respect to "gravity". A long-time station resident might be able to tell which direction is "spinward" and which direction is "anti-spinward" if you blindfolded her simply by turning her head from side to side. -
True, but that still doesn't make the problem go away completely. Who decides what rides on the elevator, and how is it decided? How is it protected from those who would attempt to damage or destroy it? Personally, I think that if we develop the materials science necessary to make a space elevator a reality, the other technologies made possible by the same technological breakthroughs would win out. For example, if making long carbon nanotubes becomes a reality, how would that capability change the construction of space vehicles? Wouldn't it be possible to reduce structural weight and make them more efficient as well? As a caveat, I should mention that I haven't actually crunched any numbers; I have vast, gaping ignorance when it comes to materials science. I'd really appreciate it if someone more knowledgeable could weigh in and let me know if my thoughts are completely baseless.
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Space Docks, Orbital Refueling Stations and other such things.
Nikolai replied to bradley101's topic in Science & Spaceflight
There are a lot of things that would have to happen before it could become a reality. We have very limited experience assembling things in space. We have even less experience handling hazardous materials (like fuel) in space. We have almost zero experience smelting, calcining, or refining ores in space -- or building things from any kind of raw material. (There have been some interesting experiments with concrete made from lunar dust, though.) The cost of lifting things from Earth is high enough that developing these technologies is a necessary step. Planetary Resources is a company you may want to look into (http://planetaryresources.com/). They're working to develop and deploy some of the technologies we'll need to create things we need for space exploration in situ (with a focus on asteroid mining). I'm ardently hoping that they'll be successful. -
We had one of those. The Saturn V could deliver 120,000 kg to LEO -- more than twice your hypothetical mass -- and it took a lot less than five hours to do it. The American people decided that it was not desirable. It's not just that we no longer make Saturn V rockets; we no longer make the machines that were used to assemble the Saturn V rockets. A gigantic chuck of aerospace infrastructure was utterly dismantled and removed. A lot of questions come to mind with your hypothetical question. How expensive is this space elevator to run? How much time must we wait between trips? Are there trade agreements to be negotiated with the equatorial nation that owns the land where the base of the elevator sits? How cheaply? How cheaply could we contain it or transport it? I expect there would be efforts to guard the secret of cheap antimatter initially, since it promises to place a lot of destructive power in a lot of hands.
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Well, yes. My point was more that the ascent engine was not directly affected by damage that might be caused by flying debris during descent. In that sense, it was somewhat "shielded" until it was needed. I looked this up. Thanks for the correction. Serves me right for trying to post from memory.
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It's not exactly a series, but there are a number of Stephen Baxter titles that are excellent fodder for realistic space travel enthusiasts -- with the caveat that he seems to believe that 1960s and 1970s space travel technology was magically far more reliable than we have reason to expect. I've read Voyage (which posits a late twentieth-century manned mission to Mars, at the expense of Viking, Voyager, and the Shuttles) and Titan (about the first manned mission to Titan -- darned depressing, though); if there are others, I don't know whether they're good or bad. A few of the things that really spooked me about Titan were the destruction of the Columbia on re-entry and the election of a bit-too-religiously-scary President , both of which seemed eerily prophetic. Even the book's destruction of the entire human race didn't shake me up as badly. EDIT: Forgot the "didn't".
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Oh, yeah, the Pilgrim Project. Fun times. They even made a movie about it (starring James Caan) titled Countdown. It's interesting watching because it's pretty faithful to the science of the time -- including jagged mountains (which we figured should be everywhere because of the lack of erosion). I found the ending kind of abrupt, but it's still good watching for the realistic sci-fi fan. (Unfortunately, it was eclipsed when it came out -- as was every other sci-fi movie at the time -- by 2001.) It wasn't just the Americans floating ideas like that. The Soviet program kind of distrusted its pilots, and required automatic overrides on all their spacecraft. Between that and the fact that there were some upsetting design issues with their LK lander(*), the plan was to send two landers to the surface, one manned and one landed automatically. If anything happened to the manned lander, well, you had a backup. (*) For example, the LM had two main engines -- one for descent and one for ascent. While this might seem wasteful, one of the advantages was that any damage caused to the descent engine by flying debris would not affect the ascent stage during its attempt to rendezvous with the CSM in lunar orbit. The LK, however, had only one engine for both tasks... so a backup would be nice to have around.
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Why? No, seriously. Games deliberately restrict reality to add to the fun. I'm a software developer who's taught several introductory programming classes. I can tell you that there's always someone who wants to learn how to program because they want to make a game that simulates every aspect of some part of reality perfectly. Their shooter will allow for realistic reload times, and machining gun barrels, and accidental jamming, and bullets that change trajectory based on temperature and wind conditions, and and and and and. What they end up learning is that game designers restrict the representation of reality in games for a reason, and that reason often has very little to do with ease of coding. Reality represented in every detail just isn't fun. (Gamers generally don't care what the orc who's guarding the trasure room on Level 10 has been doing with his time until they get there... even if, "realistically", tasks like eating and eliminating are necessary and "fundamental" to such a living creature.) Game designers have a concept called "dirt". Every feature added to games requires the addition of some amount of overhead to make sure it behaves properly. In other words, every new feature has some disadvantages to its implementation. A good game designer can weigh the amount of extra gameplay afforded by a new feature as well as the amount of extra "dirt" it introduces, and determine whether or not adding the feature would be a good idea. Now, there's certainly room to allow for the fact that this game just isn't done yet. But at the current level of implementation, I think it's pretty plain to see that adding cities is almost pure "dirt". It would be eye candy and nothing else if it were just parts of the map that lit up on the night side of Kerbin, time that the graphic designers could better spend on more essential elements in the game; going so far as to include actual city models represents a lot of extra work with virtually no gameplay payoff unless some function is added to them. Until we're at the point where eye candy is substantially cheaper to add (in terms of artist prioritization), it really doesn't make much sense to add them. (If it's still not clear why, consider other "eye candy" elements that could be added to the game on the level of cities. Which should the artists do? Why? How much time should it take? What would it add to the game?) There's also the argument that it breaks mimesis for some people playing the game, but frankly, that's a very subjective thing and hardly "fundamental". (As I mentioned in a different post, I'm sure someone out there has found the weird densities and chemistry of the bodies in the star system too much to stand.) The game designers have been making very good choices thus far. I'd like to see cities, too, but I'm willing to be patient because I also recognize that their addition is not urgent.
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It's been suggested that if you want to create a closed life support system for humans, you'd need tanks with about six liters of Spirulina algae. Being substantially smaller, I imagine that Kerbal respiratory needs are much less burdensome; their spacesuits could simply house the algae needed to recycle the gases they need to respirate, with a little extra for a replenishable food source. Of course, how that algae manages to photosynthesize at Jool's distance from the Sun is anyone's guess. Perhaps there are small sunlamps in the suit (which must use an RTG for sheer battery life).
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I have no idea what Lesarthoid meant, but Pluto has five known moons. http://hubblesite.org/newscenter/archive/releases/2012/32/image/a/
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I landed on Bop over the weekend and was impressed at how far from "straight down" I had to move to keep up with the surface. I love the way these unexpected things just keep popping out of the software to keep our landing skills sharp.
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The technology for doing this with microwaves is well-proven. Goldstone, California (1975) and Grand Bassin, Reunion Island (1997) conducted experiments that transmitted in the range of tens of kilowatts of power. An experiment in Hawaii transmitted twenty watts over 92 miles.
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What makes you think that the point of creating major colonies on other worlds is to have them get materials and send them back to Earth?
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Then it kind of boils down to how efficiently we collect and use it, doesn't it? There is enough energy from the Sun hitting 100 square meters on the Earth to launch a kilogram of mass at escape velocity every seven and a half minutes or so. And that doesn't count the amount of energy we can produce if we duplicate the Sun's energy-generation mechanism.
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"Philosophy will be the key that unlocks artificial intelligence"
Nikolai replied to Ted's topic in Science & Spaceflight
What's curious is that modern psychological science has come to disagree with you. Research has shown that cognition and emotion are interwoven systems, with emotion helping logic decide what is desirable and what is virtuous. (In fact, there's been some work done with people who've had damage to their ventromedial prefrontal cortex. People with damage to this area of their brain often have difficulty connecting emotions to how they make decisions or plans. Individuals thus afflicted can make long pro-versus-con lists and can obviously explore the implications of following a particular decision or plan, and in great detail, but never reach a final decision on their own, apparently because they lack emotional weight as some kind of stalemate-breaker that helps us to opt for one or the other.) -
"Philosophy will be the key that unlocks artificial intelligence"
Nikolai replied to Ted's topic in Science & Spaceflight
You're far from alone. Turing wasn't trying to create an infallible proof of intelligence, though. He lived at a time when people's notions of what constituted "human intelligence" were being seriously challenged. For a long time, it was reason that was considered the defining characteristic of human thought. After all, even animals had emotions, for example. But then machines were created with the ability to manipulate symbols in a way we might call "reason", and do it more reliably than the humans that created them! So what is this thing we call "human thought", anyway? Turing's suggestion was his test. If it could carry on a human-seeming conversation in a convincing way, could it be considered to be thinking like a human? Many people decided the test was good enough. Sure, it has holes, but so does every test for human thought yet devised. (That's arguably the biggest obstacle to AI programming; for many things, we're not exactly sure how our own thoughts work. For example, we recognize ourselves in a mirror as nothing more than a reflection; but exactly how do we do that?) There's an important concept called "meta-reasoning" that I think will prove the key to unlocking artificial intelligence. We humans can examine our thoughts; determine whether our examinations are valid; process whether those determinations might be reasonable; and so on, seemingly ad infinitum (at least in principle). Computers can only examine their own programming to a level that is determined by some elementary instructions somewhere. Ultimately, the question is whether symbol manipulations can ever be arranged in patterns that resemble intelligence. I don't see any good reason why not (though that's hardly a proof that they can). Of course, there's also no guarantee that intelligence has to resemble human intelligence. Our own brains were constructed from the inside out, and we still bear our evolutionary heritage in the bugs in our thinking (our tendency to follow charismatic leaders without question, our tendency to assume we're better at things than we really are, our tendency to collect information that agrees with our preconceived notions and discard information that disagrees as irrelevant, and so on). Perhaps AIs won't have those bugs, or will have different ones. Perhaps even emotions and considerations we think of as basic are more intimately tied into the conditions that led to the survival of our ancestors than we currently appreciate. -
I expect that reliable fusion rockets will be the technology that opens the Solar System to human exploration. The fuel is everywhere, and the specific impulse is high. This will allow us to colonize further and further outposts in bodies that circle the Sun. Colonizing comets in the Kuiper Belt and Oort Cloud will give us practice in erecting self-contained societies with limited resources, while allowing us to mine abundant fuel in the frozen volatiles. (There are billions of them, but they occupy an enormous volume; each one is largely isolated from its neighbors by vast amounts of space.) It doesn't seem too much of a stretch to think that we might hop from the Oort Cloud to its equivalent around nearby stars. By that time, I expect human lifetimes will be much greater than they currently are.