WHAT IS LIFE

Today we know that cellular processes are driven precisely by these discernible differences in molecular compositions. What statistical physics describes as fluctuation is a signaling process to cell biology. We are no more concerned about the size of the system, as we are about the size of the fluctuation. The size of random fluctuations can no longer be neglected, because in small systems they are significant with respect to the total size of the system. Single molecular events can trigger a cell division, fatty acid synthesis, or glucose degradation. Hormonal signals depend on the behavior of small systems, where fluctuations can push a system beyond a threshold level where a chemical reaction suddenly becomes spontaneous. Because biological systems are so extremely sensitive to small fluctuations, they can also react very quickly to changes in the environment.