My hypothesis is that the building blocks of life were created during the Big Bang. Comets became the seeds of life, carrying the necessary amino acids and other molecules through space in the same manner as maple seeds floating on the wind. Some crash into gas planets, molten planets, or stony, dead planets and are lost. Some hit oceanic planets at just the right angle and voila! Life! Think of the comets as sperm and the oceanic planet (water) as the egg. Nature finds a useful model and utilizes it over and over. This would mean, of course, that there are billions and billions of inhabited planets.
Last edited by Rohirrim; 06-10-2013 at 04:05 PM..