As conscious beings, we have a deep-seated desire to explore our own relationship with the cosmos, to answer questions such as: Does life exist elsewhere, and if so, is it widespread or rare? Does intelligent life exist “out there”? Are there advanced civilizations with whom we may be able to communicate, or are we unique and wholly alone in this vast universe? Is the universe itself unique, or is there a multiplicity of universes? Was the universe “designed” to provide the conditions in which sentient observers can arise and flourish, or is our existence the result merely of a fortunate combination of chance circumstances?

LIFE ELSEWHERE?

The only place in the universe where we know for certain that life does exist is on our own planet, Earth. Although it is conceivable that there may be lifeforms that are utterly different in all respects from life as we know it, we cannot conduct a rational discussion on the basis of out-and-out speculation. When trying to establish whether or not life exists elsewhere, therefore, we have to examine the conditions that are necessary for life based on the same kinds of chemistry and structures as we find here on Earth in order to originate, evolve, and flourish.

Life on Earth is based on the ability of carbon, in combination with such elements as hydrogen, nitrogen, and oxygen, to form the complex molecules, chains, and self-replicating structures that have enabled living organisms to grow and pass on the coded information (genetic information) that is needed to reproduce their own kind.