poly: What Aliens Aren't Doing

I've been doing some reading on SETI (search for extraterrestrial
intelligence). Turns out that they have some interesting data in
the last few years.

Project Phoenix (http://www.seti-inst.edu/phoenix/) looked at a
bunch of stars for slowly drifting (< 10^-9) narrowband signals
(< 300Hz wide) across most of 1-3GHz for 276 seconds each. They
found nothing with an equivalent isotropic radiation power (EIRP)
greater than the following limits (here as fraction of the 2x10^13W
EIRP Arecibo radar, the strongest radar on Earth).

 # Stars | 209 27 10
------------------------------
% Arecibo | .25 .005 .002

When the project is done, they will have these limits.

 # Stars | 1000 200 10
-------------------------------
% Arecibo | .25 .005 .0003

It looks like we can start to say that we see that aliens at the
nearest dozen stars aren't using radars near as big as what we have
hear on Earth.

It seems that someone who understands better than I what radars
are good for might be able to say something interesting about what
aliens aren't doing at the nearest stars.

Robin Hanson
hanson@econ.berkeley.edu http://hanson.berkeley.edu/
RWJF Health Policy Scholar, Sch. of Public Health 510-643-1884
140 Warren Hall, UC Berkeley, CA 94720-7360 FAX: 510-643-8614
Received on Mon Apr 13 22:34:04 1998