Time in Biology and Physics

Abstract

Traditionally, time has been modelled as a basic variable taking its values from an interval on a real axis. Although special relativity introduced Lorentz transformations mixing rectilinear time and space axes, while general relativity introduced curved spacetimes, the concept of a single underlying time dimension parametrised by a real interval remained. The pervasiveness of this concept was certainly due in large measure to the success of the models it supported, in particular to the expression of physical laws by differential equations which ultimately relied on the limiting process inherent in the notion of a (total or partial) derivativc. Despite this success at the computational level, it has long been clear that the truly ramified nature of time cannot be captured by what amounts to a mathematical convention. The current paper sets out to recall some of the perspectives on time and space that have been emerging from the study of biology and complex systems. Although these examples are still rather isolated and underdeveloped, they are already leading to some new insights. Summarising briefly, it is becoming apparent that each part of a complex system is equipped with its own intrinsic spacetime. When the system functions, the spacetimes of its constituent parts interact in various ways. As biological systems are able to insulate their component parts from environmental influences to a greater or lesser extent, one may propose an answer to Schrödinger’s question “What is life?” [1], characterising biological systems as those systems complex enough to isolate their component spacetimes. By contrast, the success of the single traditional “universal,” “clock,” or “calendar” time in physics is seen to be due to the way in which the component spacetimes of low-level systems are mutually coupled. This presents a different approach to universal time. Rather than being built in to our models ab initio, universal time should be seen as a phenomenon that emerges from the closely coupled interactions of low-level components.