Life in the universe is a fascinating topic.  The simplest question: Are we alone? It breeds so many deeper and more profound scientific questions, like “How many habitable planets are there?” “How likely is life to develop on any given planet?” and “How long can a civilization survive?” We can’t answer them definitively, but we can narrow it down. The Drake equation, shown above, was first developed by Frank Drake, the head of the Search for Extraterrestrial Intelligence (SETI), in 1961.  He took the question of are we alone and made it quantifiable, in a probabilistic way.  It lets us...