Science Alert reports:

Biologists usually define ‘life’ as an entity that reproduces, responds to its environment, metabolizes chemicals, consumes energy, and grows. Under this model, ‘life’ is a binary state; something is either alive or not.

This definition works reasonably well on planet Earth, with viruses being one notable exception. But if life is elsewhere in the universe, it may not be made of the same stuff as us. It might not look, move, or communicate like we do. How, then, will we identify it as life?

Arizona State University astrobiologist Sara Walker and University of Glasgow chemist Lee Cronin think they’ve found a way.

They argue that chance alone cannot consistently produce the highly complex molecules found in all living creatures.

To produce billions of copies of intricate objects like proteins, human hands, or iPhones, the universe needs a ‘memory’ and a way of creating and reproducing complex information – a process that sounds very much like ‘life’.

“An electron can be made anywhere in the universe and has no history,” Walker told New Scientist.

“You are also a fundamental object, but with a lot of historical dependency. You might want to cite your age counting back to when you were born, but parts of you are billions of years older.

“From this perspective, we should think of ourselves as lineages of propagating information that temporarily finds itself aggregated in an individual.” [Continue reading…]