Cancer Posted December 21, 2011 Report Share Posted December 21, 2011 Re: More space news! Weird sci-fi question--Assuming the HZ is proportional to luminosity, and that if one were to build a Dyson Sphere/Ringworld or other structure, one would want to conform its dimensions to the HZ of the star it was co-habiting with(orbiting seems like the wrong term here). Wouldn't that mean, for stars of extremely high luminosity(say, 10,000 to 1,000,000+ x Solar luminosity), the HZ distance would be quite large, and consequently any DS around one would be mind-staggeringly ginormous? Just asking because I'm thinking about doing something like that for a campaign. Remember that high-luminosity stars are also high mass, and very short-lifetime. They evolve very quickly, and their endpoint of evolution is (if you are high enough mass) rather violent. Lower-mass stars tend to get more luminous as they age, so that the radius of the HZ changes (gets larger) with time. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Remember that high-luminosity stars are also high mass, and very short-lifetime. They evolve very quickly, and their endpoint of evolution is (if you are high enough mass) rather violent. Lower-mass stars tend to get more luminous as they age, so that the radius of the HZ changes (gets larger) with time. Well, a few million, or even tens of thousands of years is still a pretty long time from the standpoint of a humanoid civilization. Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Well' date=' a few million, or even tens of thousands of years is still a pretty long time from the standpoint of a humanoid civilization.[/quote'] Well, you also have to build that sphere around it first. And once your star starts out with about 20 time sun mass, you get a supernova and a black hole and the end of it's lifetime. Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! With a Dyson Sphere, what keeps the people, objects, water, and air stuck to the *inside* of the sphere, in direct opposition to the contained star's gravity? Quote Link to comment Share on other sites More sharing options...
Escafarc Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! With a Dyson Sphere' date=' what keeps the people, objects, water, and air stuck to the *inside* of the sphere, in direct opposition to the contained star's gravity?[/quote'] Lots of these?: http://www.dyson.com/homepage.asp Quote Link to comment Share on other sites More sharing options...
SteveZilla Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Lots of these?: http://www.dyson.com/homepage.asp That idea sucks. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Let's see--you could spin it, but since centripetal acceleration = v^2/r, to get a value of 10m/s^2, with r= 150 billion km(1.5 x 10^14 m), v= 1.2 x 10^7 m/sec. That's about 3 percent of lightspeed. Kind of a fast spin there. OTOH, maybe the interior just collects and redistributes energy, and the exterior surface is where people live...but then you need a whole lot of artificial light, or some really fast-moving satellite stars. Quote Link to comment Share on other sites More sharing options...
Matt the Bruins Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! It probably depends on how thick/dense the sphere is. On the interior surface the nearness of the mass underneath your feet should counterbalance the far more distant star's gravity in terms of just floating away into the sky, though I doubt you'd be able to maintain an uncontained breathable atmosphere. Then again, someone capable of building a Dyson sphere out of all the material in a solar system would probably either be able to generate artificial gravity or have the benefit of mechanical solutions we can't even conceive of. Quote Link to comment Share on other sites More sharing options...
McCoy Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! With a Dyson Sphere' date=' what keeps the people, objects, water, and air stuck to the *inside* of the sphere, in direct opposition to the contained star's gravity?[/quote'] The power of script? Spin would might work on a ringworld, not a sphere. Handwave some sort of artificial gravity. Remember, Dyson's original concept was not a solid structure. Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! With a Dyson Sphere' date=' what keeps the people, objects, water, and air stuck to the *inside* of the sphere, in direct opposition to the contained star's gravity?[/quote'] This is indeed still a major question in all theories about dyson spheres or rings. It probably depends on how thick/dense the sphere is. On the interior surface the nearness of the mass underneath your feet should counterbalance the far more distant star's gravity [...] Afaik, it has been proven that the inside surface of a hollow sphere will never have a gravitational pull (I think because the "ohter side" will negate it). Afaik gravity does not really weakens over distance the way most radiation does. Quote Link to comment Share on other sites More sharing options...
Cancer Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Let's see--you could spin it, but since centripetal acceleration = v^2/r, to get a value of 10m/s^2, with r= 150 billion km(1.5 x 10^14 m), v= 1.2 x 10^7 m/sec. That's about 3 percent of lightspeed. Kind of a fast spin there. And that only works at low latitudes, and a latitude-dependent solution sort of defeats the whole-sphere concept. Yes, you'll need some kind of sci-fi tech gravity generators. It probably depends on how thick/dense the sphere is. Actually ... not. I think it's a freshman physics-with-calculus problem (if not freshman, then sophomore) to show that at all points inside any spherically symmetric distribution of mass, the net gravity due to that sphere is identically zero. It cancels out exactly. This is Gauss's Law. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! I remember calculating that, as to the exterior of the sphere, you could have Earth-like gravity for a hollow sphere of any size, so long as the shell thickness was = R(earth)/3 and density ~ Earth for the shell itself. I have no idea how far the atmosphere might extend, though, since the gravitational pull would drop off verrrry slowly for a Dyson Sphere. Quote Link to comment Share on other sites More sharing options...
Sociotard Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Deep fried twinkies? Deep fried snickers? They got nothing on Deep-fried planets discovery offers hope for Earth’s future Essentially, there is a star collapsing into a subdwarf B star. As it collapses, it is revealling two little rocky planets. This means that the planets had been circling inside the old star. I have no idea how they didn't just vaporize. Quote Link to comment Share on other sites More sharing options...
megaplayboy Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Deep fried twinkies? Deep fried snickers? They got nothing on Deep-fried planets discovery offers hope for Earth’s future Essentially, there is a star collapsing into a subdwarf B star. As it collapses, it is revealling two little rocky planets. This means that the planets had been circling inside the old star. I have no idea how they didn't just vaporize. Maybe stars don't do 975d6 KA, x8 AP, x16 Penetrating every segment after all. /snark Quote Link to comment Share on other sites More sharing options...
Cancer Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Reference is a paper in Nature, and since I'm at home, I can't get to that. Maybe next week. Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 22, 2011 Report Share Posted December 22, 2011 Re: More space news! Maybe stars don't do 975d6 KA, x8 AP, x16 Penetrating every segment after all. /snark When it's becomming a Dwarf now, it was propably a Red Giant before. Red giants are big, but comparably cold and short lived. Only about 5000 Kelvin for a few Million Years. Our sun is now hotter than most all Red Giants we know... Quote Link to comment Share on other sites More sharing options...
tkdguy Posted December 22, 2011 Author Report Share Posted December 22, 2011 Re: More space news! Hey! Where did this thing come from? Quote Link to comment Share on other sites More sharing options...
Escafarc Posted December 23, 2011 Report Share Posted December 23, 2011 Re: More space news! Mythbusters? Quote Link to comment Share on other sites More sharing options...
dmjalund Posted December 23, 2011 Report Share Posted December 23, 2011 Re: More space news! here? Quote Link to comment Share on other sites More sharing options...
John T Posted December 23, 2011 Report Share Posted December 23, 2011 Re: More space news! "No one would have believed in the last years of the nineteenth century that this world was being watched keenly and closely by intelligences greater than man's. No one gave a thought to the older worlds of space as sources of human danger. Yet across the gulf of space, minds that are to our minds as ours are to those of the beasts that perish, intellects vast and cool and unsympathetic, regarded this earth with envious eyes, and slowly and surely drew their plans against us." H.G. Wells, The War of the Worlds Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 23, 2011 Report Share Posted December 23, 2011 Re: More space news! Hey! Where did this thing come from? Sound similar to this find: http://www.euronews.net/2011/08/03/shuttle-debris-found-amid-texan-drought/ I think it's perhaps part of some spy sattelite or some long ago failed mission. Certainly nothing extraterestial. Quote Link to comment Share on other sites More sharing options...
tkdguy Posted December 23, 2011 Author Report Share Posted December 23, 2011 Re: More space news! Or weather satellite. Lots of space junk out there. Quote Link to comment Share on other sites More sharing options...
Sociotard Posted December 24, 2011 Report Share Posted December 24, 2011 Re: More space news! I remain unconvinced it was ever in orbit. My suspicion is "men aged 14-30 and lacking in common sense and common courtesy built a crude mortar for kicks and giggles. The ball is what they shot. Oopsie." Locals apparently heard several small explosions a few days before the ball was found. yeah . . . Quote Link to comment Share on other sites More sharing options...
Escafarc Posted December 24, 2011 Report Share Posted December 24, 2011 Re: More space news! I remain unconvinced it was ever in orbit. My suspicion is "men aged 14-30 and lacking in common sense and common courtesy built a crude mortar for kicks and giggles. The ball is what they shot. Oopsie." Like we haven't all done that at one time or another. Quote Link to comment Share on other sites More sharing options...
Christopher Posted December 24, 2011 Report Share Posted December 24, 2011 Re: More space news! Like we haven't all done that at one time or another. Quote Link to comment Share on other sites More sharing options...
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