http://www.centauri-dreams.org/?p=25064 Again, science melds with science fiction. Wouldn't it be fascinating if our first confirmation of artificial construction and therefore intelligent life came through Dyson spheres rather than alien radio signals?
I like the idea, I really do. But can we tell with current technology the difference between a Dyson Sphere or even a nonsensical Dyson Shell from a regular old dim or small star? Or would a Dyson Sphere's star appear as otherwise normal star that was clearly dimmed?
My guess is that a Dyson shell would irradiate all the energy it received from the star at a much lower frequency in the spectrum. A Dyson swarm might be more difficult to detect, depending on how dense the swarm is. If I had to make a guess I'd say that any plausible Dyson swarm will be close to undetectable – I don't think that building megastructures detectable at those distances is possible. But if a civilisation had billions of years focusing on them, it might be.