Are we alone and life is an anomalous fact that can only be explained by an unpredictable and uneventful circumstances? Or, life is implicit in the nature of the universe and its appearance anywhere is unavoidable? The systematic search for extraterrestrial life has just begun. Its discovery would be the most important news in the history of mankind. Presently, from out there only the echo of an intense silence reaches us.
Interstellar clouds occupy space that is thousands of times greater than the solar system. Hundreds of organic molecules accumulate in their interior. Many of them are identical or similar to those that make up the living beings on Earth. As knowledge of the universe advances it is confirmed that the ingredients of life do not exist only on Earth. To the contrary, as living beings we are made from raw material that is abundant in the universe.
We can think of the origin of life in three different ways. In one extreme, life is a miracle; life comes from God, a unique event. If so, science can't address the question because science can't address miracles, miracles by definition define natural law. But life may have been consistent with physics and chemistry and yet a very rare, perhaps a unique event. Very improbable because of chance, and if so again, science has trouble addressing the question because how can one go to a laboratory and study an improbable event? So only in the third case if life is an inevitable consequence of chemistry and physics, if anywhere where there's water, rock and air life arises, then science can hope to answer the question.
When we ask ourselves about the mystery of life we almost always look at the Earth for the answer. We have no other reference, although the Earth with its inexhaustible variety of forms, plants and animals, is like a box of surprises and new questions more than a direct answer. No one is sure where life begins and ends on Earth. Is it possible that something exists that is not just a copy, more or less advanced than what we have on Earth?