David Kipping

But there could also be unintentional signatures.

For example, you can have something like the satellite system that we've produced around the Earth, the artificial satellite system, Starlink-type systems we mentioned.

You could detect the glint of light across those satellites as they orbit around the planet.

You could detect a geostationary satellite belt, which would block out some light as the planet transited across the star.

You could detect solar panels, potentially spectrally, on the surface of the planet.

Heat island effects.

New York is hotter than New York State by a couple of degrees because of the heat island effect of the city, and so you could thermally map different planets and detect these.

So

There's a large array of things that we do that we can go out and hypothesize we could look for.

And then on the furthest end of the scale, you have things which go far beyond our capabilities, such as warp drive signatures, which had been proposed.

You get these bright flashes of light or even gravitational wave detections from LIGO could be detected.

You could have Dyson spheres, the idea of covering basically stars completely covered by some kind of structure which collects all the light from the star to power the civilization.

And that would be pretty easily detectable to some degree because you're transferring all of the visible light thermodynamically, it has to be re-emitted to come out as infrared light.

So you'd have an incredibly bright infrared star, yet one that was visibly

not present at all.

And so that would be a pretty intriguing signature to look for.

There has been.

Yeah, there has been.

And there's been, I think in the literature, there was one with the IRAS satellite, which is an infrared satellite.

They targeted, I think, a void of 100,000 stars.