Sara Imari Walker is a theoretical physicist and astrobiologist whose work is primarily concerned with the question of whether there are "laws of life" that could universally describe life on Earth and on other planets. The aim of her research programme is therefore to understand what new laws of physics might be discovered, how the living arises from the non-living, and how we might recognise life. She is a professor at Arizona State University, where she is also associate director of the Center for Basic Concepts in Science and leads a research team that investigates the origin, patterns and possible forms of life.