The Physical Foundation of Biology by Walter M. Elsasser (review)

BOOK REVIEWS The PhysicalFoundation ofBiology. By Walter M. Elsasser. New York: Pergamon Press, 1958. Pp. 219. $4.75. Are there any absolute general principles ofbiology that can be derived from physics? Until recently each field had to generate its own absolutes. Physics made its own, from the laws ofthermodynamics to the uncertainty principle. Only later were bridges thrown across to philosophy, to fundamental definitions ofwhat an observer is and how he gets his information. Biology grew its own laws: natural selection, homeostasis, or principles such as "entelechy" ifyou happen to be a vitalist. It is only lately tliat homeostasis has come to be inferable from the feedback ofa stable electronic circuit. But, ever since quantum mechanics, speculative physicists have been trying hard to generate largedeductiveprinciplesfiatcould be grafted onto otherfields. In WhatIsUfe? Schrödinger proposed that the quantum mechanics ofstrong chemical bonds would explain die remarkable stability ofour hereditary units under thermaljostling. Thermodynamics can even jump into biology, where living systems are "open systems" and "life feeds on negentropy." In Atomic Physics and Human Knowledge, Niels Bohr has proposed "generalized complementarity ," a more radical principle. It asserts, like the uncertainty principle in atomic physics, diat certain types ofmeasurements must be mutually exclusive. For example, if we want to measure die detailed internal relations in an atom, we find that our light beams necessarily put in so much energy that they destroy the atom and prevent any measurement ofits stability properties. Bohr says this holds for biology too: "Every experimental arrangement with which we could study the behavior ofthe atoms constituting an organism . . . will exclude tie possibility ofmaintaining the organism alive. . . . Only by renouncing an explanation of life in the ordinary sense [ofusing detailed physical and chemical measurements to make predictions] do we gain a possibility oftaking into account its characteristics [ofwholeness and purposefulness]." Ifwe are to keep it alive, "die minimal freedom we must allow the organism will bejust large enough to permit it, so to say, to hide its ultimate secrets from us." This is fine cocktail conversation, paradoxical enough to titillate a roomful ofphilosophers . Unfortunately, it makes biology look more impossible than it is. For one thing, it skips over the possibility ofpredictions from duplicate organisms. This seems to suggest that biopsies would have to be renounced, as well as molecular genetics, which is absurd. It is true that the cells that grow are not the cells we know, but they are identical twins. Also, as Schrödinger implies, any organic structure that participates in stable biological operations can participate equally well in stable operations with our tracers and molecular 243 amplifiers, regardless ofits wholeness or purposefulness. Success in measurement is then limited by our subtlety in mimicry, not by some fundamental barrier to the explanation oflife. (A diffèrent barrier may yet be set by complexity, for the analysis of io8 or ??10 structural elements may become too much for our apparatus or minds to encompass.) But this leaves Bohr's ultimate secrets pretty empty except for unstable behavior, like the pattern of noise from a Geiger counter, which is predictable by neither biology nor physics. I found myselflisting these objections to Bohr's thesis in the course ofreading this new elaboration ofit, TAe Physical Foundation ofBiology, by Professor Walter Elsasser, a wellknown theoretical physicist at the University ofCalifornia. Dr. Elsasser is concerned with how to avoid a deeper paradox which he thinks he sees. Consider a viable germ cell or (correcting Bohr) a clone ofidentical cells ofa known strain. Is there any possible set of physical measurements on these that would enable us, even in principle, to predict the complete structure ofthe adult organisms, the full hereditary information content? No, says Elsasser. But will biological observation, the knowledge of their parentage, enable us to? Yes, ofcourse, and with considerable detail. Ifthese answers are correct, there is indeed a paradox. For ifthe latent hereditary information in the germ cell is unobservable in principle, then it is not real information in the physicist's sense. The organism must then be creating "new" real information as it develops. But for the cell to know more than the physicist about what will happen is against both quantum mechanics and strict causality...