Interstellar Archaeology

An interesting post up at Centauri Dreams about the possibilities of interstellar archaeology:

Suppose a civilization somewhere in the cosmos is approaching Kardashev type III status. In other words, it is already capable of using all the power resources of its star (4*1026 W for a star like the Sun) and is on the way to exploiting the power of its galaxy (4*1037 W). Imagine it expanding out of its galactic niche, turning stars in its stellar neighborhood into a series of Dyson spheres. If we were to observe such activity in a distant galaxy, we would presumably detect a growing void in visible light from the area of the galaxy where this activity was happening, and an upturn in the infrared. Call it a ‘Fermi bubble.’

That’s the term used by Richard Carrigan (Fermi National Accelerator Laboratory) in his latest work on what he calls ‘interstellar archaeology,’ the search for cosmic-scale artifacts like Dyson spheres or Kardashev civilizations. A Fermi bubble would grow as the civilization creating it diffused through space. Carrigan notes that, as Carl Sagan and others observed, the time to colonize an individual system is small compared to the travel time between stars. An expanding front of colonization might then move forward at a rate roughly comparable to the space travel velocity. A civilization could engulf its galaxy on a time scale comparable to the rotation period of the galaxy, and perhaps a good bit shorter.

We may not have gotten our jetpacks or domed cities on moon and in the oceans, but the mere fact that ideas like this are not just interesting speculations but actually testable proposals should convince anybody we’re living in the future. The only disavantage is that the more we are able to observe from Earth or Solar System based space telescopes, the less likely it will be that the old science fiction future of three men scouting rockets exploring the Galaxy will come to pass…