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Everything posted by Warhorse

  1. There is some question as to whether planets can actually form around blue supergiant stars, as the radiation from them is so intense that it tends to vaporize anything that gets remotely close to them. There is also the issue that these stars only live for a few tens of millions of years, and stars tend to get brighter as they age, so the life zone, and indeed the zone where planets can survive, shifts rather rapidly. Assuming that you can get around all of that, the life zone for these sorts of stars is centred more than 200 AU out (which means the star, as seen from there, is probably little more than a point). Even at that distance, UV is going to be a MAJOR issue, because these stars are 25000 to 30000 times brighter than the sun, and far more of their output is above the visual range.
  2. Engine part corrosion won't be an insurmountable problem. Some US ICBMs used red fuming nitric acid as an oxidizer in Real Life . As an FYI, the Kethane mod already contains a jet engine that can use non-oxidizing atmospheres.
  3. Actually, regular hydrogen fuses just fine; it is, after all, what most stars run on. You just need a bit more energy to get it started.
  4. Interesting ... My major concern would be that in order to pull it off, you have to have a fairly high precision machine working to rather close tolerances for extended periods of time, without any possibility of maintenance. I'm sure they'll get it right eventually, but I would bet that Comrade Murphy will get a couple of good rounds in before they do ... :-)
  5. Sokar, have you seen this thread: http://forum.kerbalspaceprogram.com/threads/27999-ISA-Mapsat-Ideal-and-Non-Ideal-Altitudes ?
  6. You did indeed say that "the new universe inherits the same basic physical constants as the parent universe, but with perhaps a few minor tweaks here and there." However, this does not solve the problem. If you assume that the initial universe was life bearing, then it's reasonable to assume that most of its descendants might also be life bearing, but that begs the question of how the first universe managed to be life bearing. If on the other hand you assume that the first universe was not life bearing, then there is enough flexibility in the evolutionary process for a descendant to reach the sweet spot. However, that in turn means there's enough flexibility for *that* universe's descendants to *leave* the sweet spot, and most of them will. Either way, you're not solving the problem ...
  7. Warhorse


    There's a rather decent SF novel by Stephen Baxter that explores similar issues ... http://en.wikipedia.org/wiki/The_Light_of_Other_Days
  8. Time passes more slowly at high speeds and in strong gravity, so you could certainly travel forward in time. IIRC there are solutions to the relativity equations which imply the possibility of traveling backwards in time as well, but the conditions for realizing them IRL are sufficiently ... tricky ... that nobody has (yet) demonstrated them.
  9. Sorry, I guess I wasn't clear. My objection is not that life bearing universes wouldn't happen, merely that, even ignoring any considerations of eternal inflation, they will be a tiny minority, since there is no reason to expect that a universe spawned from a life bearing universe will itself be life bearing. (A few probably will be, most probably won't.) Throw in eternal inflation, and it just gets worse. Unless the boys and girls in the lab have the ability to control which laws of physics get selected in the child universe, your theory, although quite interesting, does not appear to solve the problem.
  10. Hmmm ... I think there's a snag to this theory. If we accept that the laws of physics are fine tuned to produce a life-bearing universe, then that means that most of the possible combinations *won't* give you a life-bearing universe. That in turn means that most likely, the original universe was non-life-bearing, and its children gradually evolved to the point where at least one of them reached a state where life was possible. But, if there was enough variability possible between generations to get from non-life-bearing to life-bearing, there has to be enough variability for the reverse to occur as well, and the finer the tuning needs to be to produce life, the more likely it is that any changes take you out of the sweet spot. Thus, most of the experimentally produced universes should still be sterile ...
  11. Heh ... there's a line I read once, I think it was in a Larry Niven novel, to the effect that trying to change one law of physics is like trying to eat one peanut: it's theoretically possible, but it just doesn't happen IRL ...
  12. So what? It still relies on your opponent being improbably dumb. And there are still cheaper and easier ways to achieve the same effect. The point is, the target is not even going to be made of magnetic materials, never mind radiating a magnetic field of whatever polarity.
  13. Well, if your enemy obligingly passes within a few inches of your bomblets, at no more than a few fps speed difference, then I suppose it might possibly have some effect. Of course, if you can manage something like that, it would be a whole lot easier and cheaper just to use a warhead that generates regular high-speed dumb shrapnel. Spacecraft are fragile ... PS --- Magnets do not have a 'negative mode'. The will repel other magnets of similar polarity, but not random objects. Also, weight being at a premium in spacecraft, they are frequently made of light, non-magnetic materials such as aluminum, titanium, or composites.
  14. This, of course, presumes that the defender survives the attack and is able to maneuver afterwards. Which is not a given, especially since the attacker, assuming identical ships, will be more maneuverable during the interface due to lower mass ...
  15. What, you've never heard the expression "Nuke 'em from orbit, it's the only way to be sure" ??? There will be battles in space, because control of space conveys *HUGE* advantages in C4ISR and early strikes. Which is to say, if you try to launch an invasion without at least denying space (and air!) to your opponent, your invasion forces will get zapped before they can leave your own soil!
  16. One of the quiet nightmares for NATO planners during the cold war was the realization that just about all the satellites in GEO belonged to the western powers --- the Soviets tended not to use that orbit, since much of the USSR is too far north to be seen from GEO. It was posited that the Soviets could launch an ASAT mission atop a large booster, and use a lunar swing-by maneuver to place it in a retrograde orbit at geosych altitude. Detonating the warhead would then create a cloud of debris moving in the opposite direction to most of NATO's commsats, thereby taking out a dismayingly large portion of their communications in one fell swoop ... :-(
  17. Naval reactors aren't really suitable for spaceflight, as they all weigh at least hundreds of tons. The last I heard, the biggest reactor anyone had flown was rated for a couple of hundred KILOwatts, on late Cold War era Soviet radar ocean recon satellites. The infamous Kosmos 954 was such a beast.
  18. This is a likely path for species X to follow, IMO, if and only if X chooses to expand by actually moving population around directly. If X expands by using von Neumann probes to create population in situ, the expansion will proceed much more swiftly, and there's no real reason to assume it will run out of steam, absent programmed limits. Since the latter method is orders of magnitude cheaper than the former, it is, IMO, rather more likely to be used ...
  19. One comes with the download, for the more extreme one search for attosecond on spaceport.
  20. I think that as long as we are limited to chemical propulsion, expendables are the only thing that makes sense. There's no point in hauling a lot of empty tankage any further than you have to, chemical rockets just don't have enough power. Once we graduate to something better (nuclear? ion? solar sail?) the answer will depend a lot on how reliable the engines are, and how much maintenance they require.
  21. It's also not uncommon for the rating of an engine to really mean "maximum sustained output without risk of failure", which rating the engine can exceed for brief periods, though that is apparently not the case here.
  22. Well, the ice is 100 km thick. It's not stable on a scale of millennia the way Earth's surface is, but it's certainly stable enough for anything short of a permanent colony. Scientific estimates typically place the average age of the surface in the range of 20 - 180 million years.
  23. I don't think you'd want to do that, ice that is suddenly heated can shatter rather violently ...
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