Asri-unix.919 net.space utzoo!decvax!ucbvax!ARPAVAX:C70:sri-unix!OTA@S1-A Sun Mar 7 21:22:29 1982 A nearest neighbor calculation This is an interesting calculation. I think it is a cop out, however, to assume that the probability of a very long lived race is zero. It is also ridiculous to assume a life time as the same as that of a star. Clearly a race that survives that long could outlive its original solar system. It seems extremely likely that a few civilizations would have matured sufficiently to survive forever. It is impossible to evaluate the likelihood of losing interest in technology, but who knows? I'm afraid that the problem with these numbers is that V0 is much smaller than .01. Perhaps 1e-4 to 1e-6 would be more conservative. Still the inverse cube root dependence means this isn't too important an effect. We still have the question then: "where is everybody?". I think we're in a "game preserve". Ted Anderson