And real estate is incredibly cheap by British standards.
Alien Structure or just rocks? I'm thinking rocks..
- Thread starter Gingerbread Demon
- Start date
And the interstellar economy begins.
Exactly.
I doubt if it will be a Dyson Anything, but I don't think it will be mundane.
Quite so, relatively mundane then, as in of astrophysical origin.
However, in my more paranoid musings I conflate the possibility that this phenomenon is artificial in origin with other contentious observations that suggest that the rate of mutations in humans has been higher than would be expected by chance since we diverged from our common ancestor with the chimpanzees.
[yt]https://www.youtube.com/watch?v=3rzDXNQxjHs[/yt]
Hmm. The observations could be explained by rapidly multiplying Monoliths. I guess we'll know if KIC 8462852 inexplicably goes nova sometime soon.
No radio signals detected in the range 1 GHz to 10 GHz (30 cm to 3 cm; upper UHF to lower SHF), which encompasses the neutral hydrogen-line frequency of 1.42 GHz (21 cm):
http://www.seti.org/seti-institute/press-release/looking-deliberate-radio-signals-kic-8462852
http://www.seti.org/seti-institute/press-release/looking-deliberate-radio-signals-kic-8462852
OK guys I am sorry. I am so sorry.
It was my summer house, I didn't put the handbrake on and it drifted out of orbit..
It was my summer house, I didn't put the handbrake on and it drifted out of orbit..
[yt]https://www.youtube.com/watch?v=bQD14VPLOLI&t=1s[/yt]
It's disappointing that nothing's been detected, but not really surprising. Even if they are a they, the odds of them directing a signal at us are almost non-existent. We'd have more luck detecting leakage of their own internal communications, and a civilization that advanced probably wouldn't leak much.
SETI also intend to look for coherent optical radiation I understand, which again would require a powerful source, perhaps serving to propel lightsails as well as for communication. However, I think the best approach is to continue monitoring the star for further dimming episodes. Modulating stellar output by occultation is probably the easiest way to advertise your existence, should you want to do such a thing. Of course, whether that's what the dimming represents is moot.
ETA: Just playing with some numbers for a laugh. The volume of the galactic disk is about pi * (10^5)^2 * 2*10^3 cubic light years (diameter = 10^5 ly and thickness = 2000 ly) so the volume occupied by 2*10^11 stars (90% of which are main sequence) is about 1.5*10^13 cubic light years (cly). That gives an average of roughly one main sequence star per 100 cly or an average spacing of about 4.5 ly. If there were 1 megastructure per 80,000 stars, the nearest one might be (80,000 * 100)^(1/3)/2 or 100 ly away. Perhaps we need a Kepler Space Telescope 2 to examine all the stars within 200 ly or so of Sol rather than just 145,000 stars in a 0.25% patch of the sky in the approximate direction of Cygnus-Lyra.
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You see a lot of explding planets in Star Trek. We were told this impossible.
Not so fast
https://www.newscientist.com/article/mg21929242.000-tick-tick-boom-the-earth-spits-out-a-moon
http://cosmoquest.org/forum/showthread.php?145115-Mistake-in-the-National-Geographic
I can't help but wonder if this was an end-of life hot jupiter that blew its guts out.
http://news.nationalgeographic.com/news/2012/121121-planet-death-shroud-nasa-space-science/
Some nice designs in terms of megastructures
http://nextbigfuture.com/2012/05/adam-crowl-design-for-dyson-bubble-of.html
http://nextbigfuture.com/2014/10/brute-force-terraforming-of-mars-moons.html
But it is such a nice quarry.
The Pakleds tried to make a Death Star--but it was made of rocks and became the moon.
Not so fast
https://www.newscientist.com/article/mg21929242.000-tick-tick-boom-the-earth-spits-out-a-moon
http://cosmoquest.org/forum/showthread.php?145115-Mistake-in-the-National-Geographic
I can't help but wonder if this was an end-of life hot jupiter that blew its guts out.
http://news.nationalgeographic.com/news/2012/121121-planet-death-shroud-nasa-space-science/
Some nice designs in terms of megastructures
http://nextbigfuture.com/2012/05/adam-crowl-design-for-dyson-bubble-of.html
http://nextbigfuture.com/2014/10/brute-force-terraforming-of-mars-moons.html
But it is such a nice quarry.
The Pakleds tried to make a Death Star--but it was made of rocks and became the moon.
But the Pakleds need stuff to make them go....
I still remember that episode of TNG..
"We need things to make us go"
That episode (Samaritan Snare) about the Pakleds would be considered incredibly not politically correct now.
But it's such a funny episode..
Today people would be bending over backwards to help the Pakleds..
But solar systems would become increasingly unstable (and irradiated) as you get deeper into the disk, so the the actual candidates are a fraction of that. How much of a fraction is debatable. And those stars are all different ages. I have a feeling that the number of technological civilizations is low and the number with interstellar capability far lower. If that really is a Dyson Something only 1400 light years away, it probably says something about the practicality of interstellar travel.
Yet you pooh-poohed the notion that alien civilisations could not develop around class F stars. Even if the number were one tenth of my estimate, the nearest such structure might still be only 215 ly away.
Maybe the aliens are all living in their parents' basements.
If you can create virtual environments that simulate any possible alien world, why go to the expense and take the risk of leaving home? Perhaps you would only abandon your home star when it's dying?
I still expect this to turn out to be a new type of variable star, transits combined with gravity darkening, or experimental error due to failing CCD elements or some such.
Don't take this the wrong way, I very much like such plays with numbers and I am grateful you took the time. And it does say what I said earlier – if there is a sea of megastructures out there, it would be no surprise that we spotted our first one already. So if we were to seriously consider the possibility of such in general, so should we in this instance.
However, this makes the extremely generous assumption that anyone out there would build one. However:
1. We assume there are aliens, because we're here. It's a reasonable assumption, but like there are 200 billion stars in the galaxy, there are 200 billion galaxies. Having one civilization in a million galaxies still accounts for our existence pretty well, and even that's not required by any measure – selection bias says that we'd experience ourselves even if we were practically impossible. In comparison, one civilization in a 80000 is already way way way too generous.
2. We assume anyone would attempt, not to mention succeed, in building such a thing. From our uneducated point of view, it seems like a crazy and economically infeasible exercise. Stars lose a lot of energy, but storing it seems incredibly difficult, so you'd only do it if you also needed the power of the star as well. Something that only makes sense if you already had your megastructure in the first place.
Humans consume close to 20 TW of power. Earth receives close to 200 PW from the Sun. A Dyson ring would feature 120 collectors, or close to 20 EW of power. That's a million times more than humans consume. So these aliens would need a population of seven quadrillion people, without breakthroughs in energy efficiency and without spreading out to different stars, just to the need the smallest (and least visible) megastructure imaginable. And for that many people, your Dyson ring would have to be crazily overpopulated – it would be the equivalent of 70 trillion people living on Earth. I believe that you'd need the space first, and the power second. So you'd use a Dyson ring to collect power only if you had a Dyson ring in the first place.
If you need to store the energy so that you can use it after the star dies, you'd also go a different route. If you had the means to build a nearly impossible megastructure, wouldn't it make more sense to put your resources in trying to split the star into self-orbiting gas giants in effort to pause its fusion? That's also mindbogglingly insane, but gives you 400000 times more energy than a Dyson swarm, and a whooping 20 million times more energy than a Dyson ring. If a Dyson ring sustains your civilization for mere 2 billion years, splitting a star can sustain it until the degenerate era of the universe. (And you'd avoid your structure being blown together with your people by the coming red giant.)
Conversely, even if that's way too insane, a Dyson swarm would still give you... 400 times LESS energy than mining Jupiter as fuel for fusion (at like the half the Sun's efficiency). It makes absolutely no sense to build one if you had Jupiter.
The two reasons why I think it is still a possibility – any space-faring civilization would be quick to spread throughout the galaxy, and some of them would be crazy people. Crazy people build crazy things. I am sure that if we left this rock, we would eventually build a Dyson swarm, and only because we're idiots. More advanced aliens will spot it and think “Oh, look, there's the Galactic insane asylum, we need to stay away from there!” – basically the same reaction they had when they first saw the pyramids, or when they read my post
(Oh, and spreading across the stars is a better way to maximize your person-hours spent in the universe than trying to squeeze one star forever.. I should have just said that, instead of wasting all those words...
)
A lot of all that assumes you can get sustainable fusion working outside of a star. We haven't managed it yet -- it's been 30 years away for the past 50 years or so. I haven't run the numbers on fusion using hydrogen from a gas giant, but I don't see how that would give you more energy output than from a star with 1000 times the mass. Not taking into account the energy expenditure extracting hydrogen from the gravity well, you might be able to manage it in the short term but it would run out a lot faster.
Anyway, if it's so easy, where are they?
Anyway, if it's so easy, where are they?
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Fusion of Jupiter gives you 1000 times less energy than the Sun (at same efficiency). A Dyson swarm gives you 400000 times less energy than the Sun (at 100% efficiency, assuming Earth-sized collectors in this configuration). That's still 400 times more for Jupiter.
And if you think fusion is difficult, try building a Dyson swarm.
And if you think fusion is difficult, try building a Dyson swarm.
You don't show how you arrive at a figure of 1/400,000 of the insolation. Do you mean that the collector area only covers 1/400,000 of 4 pi steradians?
ETA: Using the figures given for the Wiki illustration.
Collector diameter = 25 * Earth-Moon distance = 10^7 km.
Collector area = pi/4 * 10^14 km^2.
Number of collectors = 12 loops * (360 degrees/3 degree spacing) = 1440
Ratio of collecting area to total area assuming distance from star is 150 million km
= (1440 * pi/4 * 10^14) / (4 * pi * 2.25 * 10^16)
= 3.60 * 10^16 / 9 * 10^16
= 40 %
ETA: Using the figures given for the Wiki illustration.
Collector diameter = 25 * Earth-Moon distance = 10^7 km.
Collector area = pi/4 * 10^14 km^2.
Number of collectors = 12 loops * (360 degrees/3 degree spacing) = 1440
Ratio of collecting area to total area assuming distance from star is 150 million km
= (1440 * pi/4 * 10^14) / (4 * pi * 2.25 * 10^16)
= 3.60 * 10^16 / 9 * 10^16
= 40 %
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