a metabolism?
I've read in many places now that "life" is very difficult to define. A big question in biology, paleontology, or science in general is "what is life?" or "how do we define life?".
NASA's definition is "A self-sustaining chemical system capable of Darwinian evolution". But I'm just wondering why life shouldn't be defined as "anything with a metabolism".
Has anything ever lived that didn't have a metabolism? Is there anything that is non-living that does have one?
Thanks.
Scott