What, should it exist, is the universal law that connects all living things? To even dream of answering that question, and to one day find alien life elsewhere in the cosmos, humans must first reconcile the fact that our definition of life is inadequate.
For astrobiologist Sara Walker, understanding the universe, its origin, and our place in it starts with a deep investigation into the chemistry of life. She argues that it is time to change our chemical perspective—detecting oxygen in an exoplanet’s atmosphere is no longer sufficient enough evidence to suggest the presence of living organisms.
“Because we don’t know what life is, we don’t know where to look for it,” Walker says, adding that an unclear or too narrow focus could result in missed discoveries. Gaining new insights into what life on Earth is could shift our quest to find alien life in the universe.