lew (10/19/82)
It is possible to be quantitative even on the basis of null evidence. This is done routinely when upper limits are set to the rest mass of neutrinos and the half life of protons. In this spirit, we might ask "What is the upper limit on the civilization density in the galaxy given that there are none around the nearest (say) 10,000 stars?" We can answer this quickly by noting that a probability of 1/10,000 of finding a civilization around a given star gives a probability of 1/e of NOT finding one around any given 10,000 stars. This still leaves plenty of room for speculation, considering that there are ~1e11 stars in our galaxy. Our upper bound on the total number of civilizations in the galaxy then becomes 1e7. As for the proliferation argument, I think this severely understates the difficulties posed by the galactic distance scale. One has to work hard to even begin to appreciate it. The other galaxies might as well be separate universes, for all the hope technology has of communicating between them, let alone colonizing them. Roll your eyes back and GROK! Lew Mammel, Jr. ihuxr!lew