The environment around us is full of dead, living and non-living things. Trees and animals are living things. Dry leaves on the ground are dead, but they were once part of a living tree.

What is the basic definition of life? How are living things different from non-living things? We don't know anything about what alien life forms might look like or what they're made of.

Tikhonov discusses his out-of-this-world idea in this Q&A. What is the basic definition of life? How are living things different from non-living things? We don’t know anything about what alien life ...