Recursive Worlds

In Recursive Worlds, Sara Walker redefines life as a physical process that structures matter through recursive information across deep time. Challenging conventional physics, she introduces assembly theory to describe how complex objects—including molecules, technologies, and living systems—emerge only through informational lineages. Rather than viewing life as spontaneous or reducible to chemistry, Walker argues that living systems operate beyond a measurable threshold of complexity, constructing new possibility spaces in a combinatorially vast universe. Earth, in this framework, is the largest known object in time, hosting a biosphere and technosphere that are recursively stacked and increasingly capable of perceiving their own origins. As the technosphere grows, it becomes not merely a byproduct of biology but a continuation of planetary evolution, possibly leading to biospheric reproduction. The talk invites a shift in physics toward a model where information, history, and recursive causation are central to understanding life, intelligence, and the future of planetary systems.