In Imagined Life (Smithsonian), science writer Trefil and his coauthor, Michael Summers, explore the possibilities awaiting humanity in the search for extraterrestrial life.
There have been several books in the past few years that explore the possibility of alien life. How is your book different from them?
The central strength of our book is that we lay out the scientific “rules of the game” and then follow them as we explore how they operate in new environments. We stay as close to accepted science as we can.
What worlds do you think exoplanet researchers should focus on when looking for signs of life?
As a practical matter, we have to start our search on “Goldilocks” planets. That’s where life similar to Earth’s is most likely to be, and it will be the easiest for us to recognize.
The book describes many different types of planets where life might evolve, from Earth-like to rogue planets wandering sunless through space. Which one would you most like to see life on?
I have to confess, I’m fascinated by Iceheim—the planet with a layer of ice over a rocky core with hot volcanic vents. A civilization centered on ocean vents would be something to see!
Your book describes how the scientists searching for extra-terrestrials, in order to agree on what they’re looking for, typically adhere to certain conditions for considering something alive, such as being composed of one or more cells. Are any of these dispensable?
I don’t think lists of properties are a good way to define life. These are all too Earth-centric. For example, I can imagine life without cells. I guess my answer is that I’d be willing to give up any property on the list so long as we meet the thermodynamic requirement—that a living thing must take in nutrients to maintain itself.