Physics of Life

Synopsis

Physicists have been interested in the phenomena of life for centuries.  During the twentieth century there were many dramatic successes at the interface of physics and biology, often changing the course of biology but leaving physics largely untouched.  Something changed circa 2000, and biological physics emerged fully as a part of physics itself.

In the first part of this talk I will review some of this history, drawing on the recent Decadal Survey of the field organized by the US National Academy of Sciences.  This survey led to the identification of four big questions that organize the physicists’ exploration of the living world. In the second part, I’ll describe work my colleagues and I have done addressing two of these questions. (1) How do macroscopic functions of life emerge from interactions among microscopic constituents?  Here we use ideas from statistical physics to uncover surprisingly precise scaling behaviors in the dynamics of neurons and behavior.  (2) How do living systems represent and process information? Here we use the early events in a developing fly embryo to show how maximizing information subject to physical limits generates successful predictions for system behavior, with no free parameters.  These ideas have a chance of being more general than the examples we have chosen.