Sean Carroll in Preposterous Universe:
We are all alive, but “life” is something we struggle to understand. How do we distinguish a “living organism” from an emergent dynamical system like a hurricane, or a resource-consuming chemical reaction like a forest fire, or an information-processing system like a laptop computer? There is probably no one crisp set of criteria that delineates life from non-life, but it’s worth the exercise to think about what we really mean, especially as the quest to find life outside the confines of the Earth picks up steam. Sara Imari Walker planned to become a cosmologist before shifting her focus to astrobiology, and is now a leading researcher on the origin and nature of life. We talk about what life is and how to find it, with a special focus on the role played by information and computation in living beings.