We are all familiar with the popular idea of strange alien life wildly different from life on earth inhabiting other planets. Maybe it’s made of silicon! Maybe it has wheels! Or maybe it doesn’t. In The Equations of Life, astrobiologist Charles S. Cockell makes the forceful argument that the laws of physics narrowly constrain how life can evolve, making evolution’s outcomes predictable. If we were to find on a distant planet something very much like a lady bug eating something like an aphid, we shouldn’t be surprised. The forms of life are guided by a limited set of rules, and as a result, there is a narrow set of solutions to the challenges of existence. In addition to these topics, Dr. Shermer and Dr. Cockell discuss: the origins of life on earth; the possibility of finding life on Mars and, if we did, would it have something like DNA, albeit with different base pairs?; Fermi’s paradox: if the laws of physics and evolution are so common throughout the universe, and there are so many earth-like planets in our galaxy alone (estimated to be in the billions), where is everyone?; humanity becoming an interplanetary species (possibly the first), and if so what type of governing system we should employ for, say, the first colonies on Mars.