So I’ve flown my spaceship all the way out to KIC 8462852, better known as Tabby’s Star, and what do you know? The aliens really are building a megastructure out here.
This whole situation is pretty weird, I know; but the weirdest thing is that when I check my ship’s sensors, I can’t detect any thermal emissions from the megastructure or any of the spaceships involved in constructing it.
The lack of thermal emissions (or the lack of an “infrared excess,” as the experts call it) is one of the main reasons why Tabetha Boyajian and other legitimate scientists don’t really buy the alien megastructure hypothosis.
Think about it. If Tabby’s Star hosts an active work zone, with spaceships flying around and construction workers welding space girders and stuff, you’d expect all that activity to produce some heat. Even without the construction activity, the megastructure itself should be pretty warm due to the star it encircles.
And all that heat should be detectable in the form of infrared radiation. But whether you observe Tabby’s Star with a telescope back on Earth or the sensor grid of my imaginary spaceship, the total amount of infrared light is exactly what you’d expect from an F-type main-sequence star. No more, no less.
Since I’m here, I decided to ask one of the alien construction workers about this. Here’s what he told me: “Yeah, we been masking our thermal emissions. What of it? We don’ts wants nobody snooping in our business. Now scram, smelly human!”
Not exactly the answer I was expecting, but I guess I’ll take what I can get.
P.S.: If you want to learn more about Tabby’s Star and how citizen science helped uncover its mysterious behavior, I strongly recommend this SciShow interview with Tabetha Boyajian. That’s where I first learned about the “infrared excess” issue that I discussed in today’s post.
Planet Pailly 
Slightly disappointing. Alien megastructures would be a great way to detect intelligent life. I guess we probably won’t find any in the Milky Way, which isn’t too surprising, otherwise they’d probably already have called in to say hello.
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I wouldn’t give up hope yet. In all honesty, I very much doubt that there’s a megastructure at Tabby’s Star, but it seems that astronomers are now on the look-out for this kind of flickering and dimming around other stars. Apparently no one thought to look for this sort of thing before; now that we are looking, maybe we’ll find something.
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There must be something interesting going on, whatever it is.
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That’s for sure. It may not be aliens, but it’s still something we’ve never seen before.
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We on Earth have discovered the secret of absorbing IR radiation and converting it to electricity, thanks to solar cells designed to capture the IR band. I’d expect any civilization capable of building structures around entire stars would have mastered this technology as well.
Of course, the energy output of a star is so great that any construction surrounding it–even with spaceships zipping around and aliens welding space girders–would put out such a tiny amount of energy compared to that star that it would almost certainly be lost in the star’s output… a few thousanths or millionths or billionths of a percent of the overall output.
The most likely way to tell that a structure is being built would be the steady decline of the star’s output as it was captured by the structure, while at the same time giving no detectable sign that the star was quickly decaying or becoming unstable (something present sensors can detect).
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I had similar thoughts when I started reading up on this topic, especially since the megastructure is presumably designed to capture as much energy from the sun as possible.
However, there should still be some heat loss, or some other form of energy loss, unless these aliens have managed to beat the laws of thermodynamics. Boyajian and company seem pretty confident that they’d be able to detect that energy loss, though I have to admit I don’t know what their detection range or margin for error is.
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I think the issue is one of degree: That is, there may be energy loss, but when coming from the same vector as the output of a star, could they really distinguish between the two? It seems to me it would be akin to pinpointing a burning candle in the middle of the daytime Sahara from, I dunno, Uranus; but then again, I’m not a scientist or astronomer, so I concede that they should know the capabilities of their equipment better than I.
What would not surprise me is that an alien race, capable of building such a structure, may have found ways to rewrite the laws of thermodynamics in order to conserve that energy, in ways that our instruments might not be able to detect or measure.
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That would be a big effing deal if they’ve gotten around thermodynamics. But you’re right. We can’t totally rule out the possibility.
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I’m not sure I see the problem here. Even if you surrounded a star with a sphere, it would have to re-radiate the energy coming from the star, or it would continually increase in temperature and melt. So, shouldn’t we expect a lot of heat output from a structure?
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Well put. I think that’s basically Tabetha Boyajian’s argument. Unless the aliens have some technology way, way beyond our science, their megastructure should radiate heat in the form if infrared radiation. And given the size of the thing, we should expect to be able to detect it.
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