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Mysteriously Variable Star Causes Speculation About Dyson Sphere (slate.com)
gurps_npc writes: Phil Plait just wrote an interesting article about a star that is extremely variable. We generally look for cyclical, minute (1%) variations in star light to detect planets. But we found one that has a variation in starlight of over 20%. We don't have a very good explanation for this, and some people are speculating that such variation could be caused by a civilization building a Dyson Sphere around the star. From the article: "Such a sphere would be dark in visible light, but emit a lot of infrared. People have looked for them, but we've never seen one (obviously). Which brings us back to KIC 8462852 (PDF). What if we caught an advanced alien civilization in the process of building such an artifact? Huge panels (or clusters of them) hundreds of thousands of kilometers across, and oddly-shaped, could produce the dips we see in that star's light." Plait says it's overwhelmingly unlikely, but interesting nonetheless.
That would only apply if it was finished being built. The rabid distortions and exaggerations are claiming it's "under construction", which means it would be all patchy and full of mostly open areas still.
I'm far from an expert, but the wild speculation that's coming from outsiders (i.e. not scientists who published the paper) is that it could be a civalization in the process of building a Dyson sphere. I suppose if they only had a piece complete maybe we'd see something like this?
Anyway, my money would be on something much more boring, like some dark-type binary star scenario, although, I suppose they could tell if that was the case. IDK, it's interesting. Any other ideas from the astronomers on what it could be?
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While we "watch" them build their sphere, they would have already completed it, detected us using their advanced long range sensors, and used their FTL armada of battleships to come destroy us. Since we are still here, that is a NOT a Dyson sphere.
Go to the Wikipedia page on the subject. The math has been done and even rough estimates say that our solar system contains only about 1/100th of the material necessary to construct a full Dyson Sphere (ignoring the many other problems with such a construct - drift of the sphere wrt the star, no known material strong enough to withstand the compressive forces, etc).
Basically, constructing a full sphere would require harvesting about 100 solar systems, hauling all that material back to a single star, creating materials unlike anything we know of and marshaling a construction force beyond imagining... The heat signature of the harvesting, hauling and construction would dwarf any star (and hence be easily detectable).
But sure, lets have "fun" and speculate about things that simply could not be just so as to pollute the waters with pseudo science until no one can discern the difference between real science and malarkey.
A pocket sized collection of things going very quickly around the solar system to account for the periodic occlusions?
But what if it was an object orbiting another dark object, in a plane perpendicular to our line of sight (around axis parallel to our line of sight)? It would periodically occlude that much more distant and much bigger bright object.
Giant solar sails would dim the light from the star (small object occluding at a distance and all that), and the brightness could actually be a giant laser array constructed to propel the ship faster towards us.
How about a more sane and more plausible... larger brown dwarf twin?
The signal is highly aperiodic (read the article), so a brown dwarf won't be a good explanation. I'd expect a protoplanetary disk would be a more reasonable explanation than a brown dwarf, but then there's the problem with the missing IR. It could be a trinary system with lots of occlusions from our perspective (which would mean that the stars would all be very close together). This star is just ... odd, no matter what the explanation ends up being.
What we need is a set of extra-terrestrial telescopes flying in precise formation so that we can do 100,000 km baseline interferometry and get the sort of resolution to see detail like that.
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All it would need to be is an irregular object with a spin. Think about it. If I put you in one spot, and an irregular, spinning object more-or-less between you and what you want to look at, what happens to your view of the object?
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What he said.
From TFA, we're talking something that occults 20% of the visible area of the star in question. That something would have to ~40% of the diameter of the star in question to do that. So, for a Sol-sized star, we're talking 300,000km in diameter.
No, we're not going to be finding any natural objects that size that aren't emitting light themselves.
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The mass of a Dyson Sphere of carbon with a radius equal to the orbit of Ceres that is 1 millimeter thick turns out to be...
drumroll...
slightly less than the mass of Earth.
And that's using the density of solid carbon. You could probably get a sphere out past Saturn's radius switching to a fancy aerogel or something.
And with "all material of our solar system" at "one atom thick"...
With that we'd get a Dyson sphere with radius a third the way to Alpha Centauri.
Ummm... about that remark of estimatory prowess...
How is it that Plait says no excess infrared means it isn't dust clouds and unlikely comets, but then he turns around and suggests Dyson sphere? One of the defining characteristics of Dyson spheres is excess infrared.
Here is a hypothesis that fits the data gathered so far: interstellar debris. It can be oddly shaped. It can block the star's light without generating excess infrared. A cloud of it passing between Earth and KIC 8462852 would produce non-periodic luminosity variations. If the debris was a light year away from Earth, the largest chunk would have a diameter of around 500 km. There would be no constraints due to orbital velocity, and no aliens.
If you're anywhere inside a symmetrical spherical shell, there's no gravitational pull from the shell. It all balances out. So, unless the sphere was spinning fast, you'd just fall into the sun - and you could only tune the spinning for one narrow band, you'd still get too much or too little everywhere else.
This problem is what inspired Larry Niven to publish his idea for a "ring world" - a more practical, lower tech approach. First as a non-fiction article in a SF mag, then as a series of SF novels. Now most people only know the idea Halo, sadly.
Plus a sphere isn't gravitationally stable - you'd have to constantly work to keep the star centered. Without some sort of gravity control, the whole idea is impractical, which is why finding one would be a big deal to physicists - we have no reason to think any such thing is possible today (but then, we don't have a good quantum gravity theory either).
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Whatever the explanation is, something that is big enough to block over 20% of a star's light isn't going to be boring.
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