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Comment by ealexhudson | Hacker News Reader

In general I agree, but the lack of radiation is a real problem - we would need to have some fundamental error in our understanding of thermodynamics for their tech to be capable of that. That, or the structure itself isn't collecting the energy but only [somehow] redirecting visible wavelength light.

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what if they were getting the energy from this star system and "beaming" it somehow somewhere else? you would not get any IR from that because it would not be used in this system at all

The report seems to be saying that the IR is unchanged - i.e. there is IR, it's just what is expected from the star. As the other commenter suggested, it would need to be some reflector which was IR-transparent, which would be a pretty strange setup.

Could this be explained by a black hole, slowly slowly siphoning matter from the star? Maybe it's behind the star and we're less likely to observe the radiation from it..

You shouldn't be getting downvoted for this, but also no.

A black hole would have an accretion disk in this case and be a very bright object. It would also be in orbit so we would've spotted the traversal of it given the timespan or the matter siphon if it was in a large orbit.

Like a mirror? Or a mirror that selectively reflects certain wavelengths but not others?

Guys these are just solar panels. Their race is better at alternative forms of energy than us.

Solar panels heat up. It's the law!

Perhaps they use the heat very efficiently?

No dice. Conservation of energy and other thermodynamic laws say that [a] there are limits to efficiency, and [b] if you absorb energy you must re-radiate it. Among other things. There's no point in speculating about the blatantly unphysical. @Sharlin is right, it's just "Goddidit" dressed up.

Do any of them say it must be re-radiated omni-directionally as infra-red light?

Pretty much.

You can make it cooler than infra-red light (like microwaves), and you can irradiate for half a sphere, or even a bit less. But that's all.

Don't forget entropy. Matter can absorb energy without necessarily radiating it immediately. Two objects can be the same temperature but of totally different energy. The easiest to understand is probably phase changes. Ice can melt into water, absorbing energy, without changing its temperature. Even stranger, ice can sometimes melt, still absorbing and retaining energy from its surroundings, while the temperature of the system actually drops (ie if you pour salt on ice).

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