Sean Carroll in Preposterous Universe:
Physics is extremely good at describing simple systems with relatively few moving parts. Sadly, the world is not like that; many phenomena of interest are complex, with multiple interacting parts and interesting things happening at multiple scales of length and time. One area where the techniques of physics overlap with the multi-scale property of complex systems is in the study of phase transitions, when a composite system transitions from one phase to another. Nigel Goldenfeld has made important contributions to the study of phase transitions in their own right (and mathematical techniques for dealing with them), and has also been successful at leveraging that understanding to study biological systems, from the genetic code to the tree of life.
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