“The Concept of Life and The Second Law of Thermodynamic: a history of challenge and success through an interdisciplinary dialogue”

In the first half of the 20th century, we had two major characters (and their research groups) that will influence the fundamental studies on the concept of life: 1) The Phage group, in the US, and the Cologne school, in Germany, centred around Max Delbrück (1906 – 1981) in the thirties and forties. Schrodinger’s book “What is life?” showed many results about the cellular replication mechanism in molecular biology produced by Delbrück and his colleagues, evidencing the clear positivist flavour that guided many members of this group. 2) The group lead by Sir Frederick G. Hopkins (1861 – 1947), which had a different metaphysical background to define life. According to him life is “not a mass of matter composed of a congregation of like molecules, but a highly differentiated system: the cell, in the modern phraseology of physical chemistry, is a system of co-existing phases of different constitutions”.

Ilya Prigogine’s work synthesised both traditions, i.e. the reductionist and the holistic one. In the sixties, studies in thermodynamic on systems far from equilibrium got a tremendous development with the Brussels’ school, and Ilya Prigogine was becoming one of its main and most renowned members. He aimed at defending that behind of the dynamic of life existed an autonomous principle which pervaded all living beings, i.e. the irreversibility. This principle along with the systems out of equilibrium help to prepare the conditions that make life possible. The openness of living beings make possible to keep entropic features under control because livings beings have the capacity to decrease their internal entropy due an increase of external entropy. Such proposition is stablished upon a general principle that led Kay & Schneider to proposed a reformulation of the second law of thermodynamics in such specific way: “the reformulated second law suggests that systems […] will take advantage of all available means to resist externally applied gradients. When highly ordered complex systems emerge, they develop and grow at the expense of increasing the disorder [negentropy] at higher levels in the system’s hierarchy. We note that this behavior appears universally in physical and chemical systems.”