Making Sense of Life

Abstract

Erwin Schroedinger, who had the privilege of having his name attached to one of the most important equations in physics, being at the basis of quantum mechanics, was a fascinating character. Eccentric in his social behavior, he occupied a prominent position in the intellectual landscape of the first half of the previous century. The only son of a wealthy Viennese family from the last decades of the Austro-Hungarian Empire, he taught theoretical physics at Breslau and then at the ETH of Zurich, where he remained until 1927. After a brief period in Berlin, he left Germany in 1933 as a rebuke to Nazi politics, and found hospitality in Dublin at the Institute of Advanced Studies, where, in 1943, he delivered a series of public lessons entitled “What Is Life?”, in which some fundamental problems of biology were addressed. In those years, the subject was generating interest in the world of physics, thanks to the contributions of Max Delbruck, a German-American physicist who was launching a research program in molecular biophysics in the USA. In particular, Schroedinger was fascinated by the ongoing developments in genetics, arising through the research works performed by Gregory Mendel, an Augustinian friar whose research into inheritance was receiving widespread posthumous recognition. The enormous impact of the Schroedinger lessons led him to write a book, published in 1947 with the same title as the conferences, that aroused great interest and some perplexities. In fact, someone went so far as to say that the things already known that were mentioned in the book were trivial, whereas his original ideas were simply wrong. If so, it must be concluded that a Genius has the prerogative of making a contribution to the advancement of science even when he is mistaken. On the first page of the book, the following sentences appear: “The large and important and very much discussed question is: How can the events in space and time that take place within the spatial boundary of a living organism be accounted for by physics and chemistry? The preliminary answer, which this little book will endeavor to expound upon and establish, can be summarized as follows: The obvious inability of present-day physics and chemistry to account for such events is no reason at all for doubting that they can be accounted for by those sciences”. This preamble contributed to the increase in the number of physicists and physico-chemists who put their skills in the service of biology, with results, over time, of great relevance. While short, the book addresses different aspects of biology, especially the problems of inheritance, highlighting what may be the characteristics of a natural system capable of transmitting information. By claiming that biology had to encompass new laws of physics not previously seen in inanimate matter, he was able to anticipate the discovery of DNA. An important point in his analysis concerns the thermodynamic behavior of a living organism, such as a cell, which is taken into consideration with the intent of explaining how it can maintain its stability. In this context, it deepened the role of entropy in vital processes, as far as concerns its connection with the degree of disorder of a system. In fact, the most striking feature of life is that entropy may reduce locally while it increases globally, and therefore suggests that, because this occurs, the cell must be subjected to a negative stream of entropy, with Schroedinger literally writing: “It is by avoiding the rapid decay into the inert state of ‘equilibrium’ that an organism appears so enigmatic. An organism is fed upon a negative entropy”. In a footnote, however, it is explained that by ‘negative entropy’, he really meant the free energy, but unfortunately, many subsequent authors have deceptively taken “neg-entropy” as simply being entropy with a negative sign. By replacing the flow of “neg-entropy” with that of the free energy introduced by Gibbs, it turns out that the total amount of energy of a system must be separated into a part able to produce useful work and a useless part expressed by the product of the absolute temperature times the entropy. In essence, if a free energy flow is present, it can produce the work necessary to keep a living organism in a non-equilibrium state. In other words, a hypothetical Maxwell devil present in a cell could take advantage of a flow of free energy to classify the molecules, and thus prevent their degradation.