What is life? This is among the most difficult open problems in science, right up there with the nature of consciousness and the existence of matter. All the definitions we have fall short. None help us understand how life originates or the full range of possibilities for what life on other planets might look like.

In LIFE AS NO ONE KNOWS IT, physicist and astrobiologist Sara Imari Walker argues that solving the origin of life requires radical new thinking and an experimentally testable theory for what life is. This is an urgent issue for efforts to make life from scratch in laboratories here on Earth and missions searching for life on other planets.

Walker proposes a new paradigm for understanding what physics encompasses and what we recognize as life. She invites us into a world of maverick scientists working without a map, seeking not just answers but better ways to formulate the biggest questions we have about the universe. The book culminates with the bold proposal of a new theory for identifying and classifying life, one that applies not just to biological life on Earth but to any instance of life in the universe. Rigorous, accessible, and vital, LIFE AS NO ONE KNOWS IT celebrates the mystery of life and the explanatory power of physics.

"Reading LIFE AS NO ONE KNOWS IT is like engaging in a mind-bending conversation about the biggest questions of all" - creator of Wait But Why

"With wit and clarity, Walker outlines a radical new approach to bridge the conceptual gap between non-life and life" - author of WHAT’S EATING THE UNIVERSE and THE DEMON IN THE MACHINE

"Walker's defence of her 'assembly theory' is a virtuoso intellectual performance ... full of wit, mischief and bursts of insolent brevity, which for newcomers to this territory are like oases in the desert. Walker shows us that what we call 'life' is but an infinitesimal fraction of all the kinds of like that may arise out of any number of wholly unfamiliar chemistries" - Daily Telegraph

"An honorable addition to a small genre that began with Noble Prize-winning physicist Erwin Schrodinger's WHAT IS LIFE? ... Ingenious" - Kirkus Reviews

"Bracingly original ... This has the potential to be a game changer" - Publishers Weekly