Randomness and Determination from Physics and Computing towards Biology

Niveau: Supérieur
Randomness and Determination, from Physics and Computing towards Biology Giuseppe Longo CNRS, Dépt. Informatique – ENS, and CREA, Polytechnique, Paris Abstract. In this text we will discuss different forms of randomness in Natural Sciences and present some recent results relating them. In fi- nite processes, randomness differs in various theoretical context, or, to put it otherwise, there is no unifying notion of finite time randomness. In particular, we will introduce, classical (dynamical), quantum and al- gorithmic randomness. In physics, differing probabilities, as a measure of randomness, evidentiate the differences between the various notions. Yet, asymptotically, one is universal: Martin-Löf randomness provides a clearly defined and robust notion of randomness for infinite sequences of numbers. And this is based on recursion theory, that is the theory of effective computability. As a recurring issue, the question will be raised of what randomenss means in biology, phylogenesis in particular. Finally, hints will be given towards a thesis, relating finite time randomness and time irreversibility in physical processes1. 1 Introduction In classical physical systems (and by this we mean also relativistic ones) random- ness may be defined as ‘deterministic unpredictability'. That is, since Poincaré's results and his invention of the geometry of dynamical systems, deterministic systems include various forms of chaotic ones, from weak (mixing) systems to highly sensitive ones to border conditions.

• discrete state


• finite time


• machine can


• hilbert space


• identical iteration


• time predictability


• randomness


• entangled quanta