I've written before
about extra-terrestrial life. An essay
in the current issue of PLOS Biology
examines how we might identify and detect alien life, raising a number of interesting points. Unfortunately, the author falls into the same old trap
, of assuming that all life has to be made up of the same basic materials that we're made of: carbon, nitrogen, water. Even the passing mention of possible silicon and ammonia-based life implies an unimaginative bias: silicon is carbon's big brother, ammonia could be water's. They have similar properties, and could interact as carbon and water do.
Why no consideration of something utterly alien, I ask. The basic definition of life, something which displays metabolism/entropy resistance and self-replication, could take any number of forms. I agree with Mr. McKay, how we find and identify life is a critical question, but I am unwilling to accept his limited criteria.