Shih-I Pai Lecture/Physics colloquium

William Bialek, Princeton University

Optimization principles in the physics of life

On a dark night our visual system can count single photons.  This is one of many examples in which living systems approach the limits set by the laws of physics.  Many people have explored the idea that this may be more general, so that important features of biological function and mechanism could be derived from optimization principles.  But optimization seems to require fine tuning, and it is hard to see how evolution could find its way to optimal parameters.   I will review some recent additions to the evidence for optimality, and explore the problem of fine tuning.  We have found that in many problems there are soft modes in parameter space, so that optimality can coexist with parameter variability.  For an ensemble of organisms the entropy in a high dimensional parameter space can be extensive while the deviation from optimality is negligible.   This removes a major obstacle to the application of optimization principles in the physics of life.

The reception preceding Tuesday's Shih-I Pai Lecture will be held in the MATH ROTUNDA at 2:30 p.m.
If you are interested in meeting speaker William Bialek, please contact Anil Zenginoglu -

Hosted by Wendell Hill