Visiting Professor at The Rockefeller University

At present, most questions about how things work in biological systems are viewed as questions that must be answered by experimental discovery. Implicitly, the assumption is that things are as they are, tied together only by evolutionary history. The situation in physics is very different, in that theory and experiment are more equal partners. In each area of physics we have a set of general theoretical principles, all interconnected, which define what is possible; beyond providing explanations for what has been seen, these principles provide a framework for exploring, sometimes playfully, what ought to seen. Can we imagine extending the predictive umbrella of theoretical physics to include the phenomena of life? Or is there something different about biology that frustrates any attempt to discover general theoretical principles?

In broad terms, Dr Bialek's research is concerned with this confrontation between theoretical physics and experimental biology.

Although opinions may vary, it seems fair to say that theory in the spirit of theoretical physics has made inroads into our understanding of specific biological phenomena ranging from protein folding to short term memory in neural circuits. The emergence of quantitative experiments on a wider range of biological systems raises the possibility of much more ambitious theoretical efforts. Beyond the immediate goal of having quantitative models for a broad set of specific processes, Bialek hopes to identify fundamental theoretical principles that cut across the standard subdivisions of biology.

From a physicist's perspective, we would like to find ideas with the power and generality of broken symmetry and the renormalization group, which have revolutionized and unified our understanding of physics on all scales from the interactions of quarks deep inside the nucleus to the behavior of liquid crystals to the dynamics of the universe as a whole. From a biologist's perspective, one could say that we are searching for principles at the level of systems that parallel the universality and interchangeability of components at the molecular level. In the same way that the DNA polymerase of a bacterium living in thermal vents at the bottom of the ocean can replicate the DNA of a human, we would like to know if such distant cousins on the tree of life also make use of common principles in how their many molecular components interact to drive the emergence of macroscopic biological functions. Is it possible, for example, that the genetic regulatory circuits that help the bacterium adapt to its changing environment have something in common with the neural circuits that help us to deal with our changing environment, and that this commonality is expressed at the level of system organization despite the evident differences in molecular components? Most importantly, we would like to state such common principles in precise mathematical terms, giving them the quantitative predictive power that have we come to expect in physics.

Bialek is a theorist, but a central component of his work has been close collaboration with experimentalists working on a wide range of biological systems, from studies on morphogen gradients and gene expression in developing embryos to the electrical activity in large populations of neurons, and from the mechanics and biochemistry of single muscle fibers to the sensory-motor transformations in the control of primate eye movements. The most extended example of this interaction between theory and experiment has been in neuroscience, where Bialek and his colleagues showed how to connect abstract probabilistic and information theoretic ideas to the analysis of real data on the structure of the neural code. Common themes in much of this work have been the problems of signals, noise and information flow, and the idea that biological systems often reach near-optimal performance in the face of profound physical constraints on their function.