David Kipping

And that's difficult to

resolve with the apparent ease at which even a small extrapolation of our own technology could potentially populate a galaxy in far faster than galactic history so to me by the way yeah the firm paradox is truly a paradox for me but i suspect that if alien visit earth

Yeah, it depends exactly what they're doing.

But the Dyson sphere example is one that we already discussed where a survey of 100,000 nearby galaxies find that they have all been transformed into Dyson sphere collectors.

You could also imagine them doing things like, we wrote a paper about this recently, of starlifting where you can extend the life of your star by scooping mass off the star.

So you'd be doing stellar engineering essentially.

space.

If you're doing a huge amount of asteroid mining, you would have a spectral signature because you're basically filling the solar system with dust.

By doing that, there'd be debris from that activity.

And so there are some limits on this.

Certainly we don't see

bright flashes which would be one of the consequences of warp drives as I said is as they decelerate they produce these bright flashes of light we don't seem to see evidence of those kind of things we don't see anything obvious around the nearby stars or the stars that we've surveyed in detail beyond that that indicate any kind of

artificial civilization.

The closest maybe we had was Boyajian star that there was a lot of interest in.

There was a star that was just very peculiarly dipping in and out its brightness.

And it was hypothesized for a time that that may indeed be some kind of Dyson-like structure, so maybe a Dyson sphere that's half-built.

And so as it comes in and out, it's blocking out huge swaths of the star.

It was very difficult to explain really with any kind of planet model at the time.

But an easier hypothesis that was proposed was it could just be a large number of comets or dust or something, or maybe a planet that had broken apart, and as its fragments orbit around, it blocks out starlight.

And it turned out with subsequent observations of that star, which especially the amateur astronomy community made a big contribution to as well, that the dips were chromatic, which was a real important clue that that probably wasn't a solid structure then that was going around it.