The Fool said: > Doesn't the drake equation show that there could be anywhere from > thousands to millions of intelligent civilizations out there (in our > galaxy alone, let alone the cluster or the universe)?
The Drake equation relies on multiplying together many, many terms whose values are entirely unknown. It's pretty easy to get almost any value you'd like by selecting values for these terms. I would argue that the experimental evidence puts severe limits on the number of advanced civilisations out there. There is no sign of intelligent life elsewhere in the solar system: no artifacts at the Lagrange points, no structures on the Moon, no evidence of industrialisation of the asteroid belt. There is no evidence of industrial development of nearby protoplanetary discs. Various SETI searches have failed to find the radio noise of other civilisations. People have looked though the IRAS data looking for stars with the thermal spectra of Dyson spheres and found none. There is no sign of stellar engineering projects taking place in this or any other observed galaxy. It seems to me that either technological civilisations are inherently very rare or something out there is actively suppressing them. The fact that no Inhibitors have got us yet leads me to think that scenario is unlikely. Therefore, the best explanation is that we are alone. All the "explanations" given by Jeroen just don't work if technological civilisations are common, because they would be very unlikely to be homogeneous in attitude and it would be almost impossible to assimilate them all into a metacivilisation, and it just takes one that doesn't play by the rules for our "quarantine" to be over. Rich GCU Repeating Myself
