The Information - James Gleick [135]
Schrödinger felt that evading the second law for a while, or seeming to, is exactly why a living creature “appears so enigmatic.” The organism’s ability to feign perpetual motion leads so many people to believe in a special, supernatural life force. He mocked this idea—vis viva or entelechy—and he also mocked the popular notion that organisms “feed upon energy.” Energy and matter were just two sides of a coin, and anyway one calorie is as good as another. No, he said: the organism feeds upon negative entropy.
“To put it less paradoxically,” he added paradoxically, “the essential thing in metabolism is that the organism succeeds in freeing itself from all the entropy it cannot help producing while alive.”♦
In other words, the organism sucks orderliness from its surroundings. Herbivores and carnivores dine on a smorgasbord of structure; they feed on organic compounds, matter in a well-ordered state, and return it “in a very much degraded form—not entirely degraded, however, for plants can make use of it.” Plants meanwhile draw not just energy but negative entropy from sunlight. In terms of energy, the accounting can be more or less rigorously performed. In terms of order, calculations are not so simple. The mathematical reckoning of order and chaos remains more ticklish, the relevant definitions being subject to feedback loops of their own.
Much more remained to be learned, Schrödinger said, about how life stores and perpetuates the orderliness it draws from nature. Biologists with their microscopes had learned a great deal about cells. They could see gametes—sperm cells and egg cells. Inside them were the rodlike fibers called chromosomes, arranged in pairs, with consistent numbers from species to species, and known to be carriers of hereditary features. As Schrödinger put it now, they hold within them, somehow, the “pattern” of the organism: “It is these chromosomes, or probably only an axial skeleton fibre of what we actually see under the microscope as the chromosome, that contain in some kind of code-script the entire pattern of the individual’s future development.” He considered it amazing—mysterious, but surely crucial in some way as yet unknown—that every single cell of an organism “should be in possession of a complete (double) copy of the code-script.”♦ He compared this to an army in which every soldier knows every detail of the general’s plans.
These details were the many discrete “properties” of an organism, though it remained far from clear what a property entailed. (“It seems neither adequate nor possible to dissect into discrete ‘properties’ the pattern of an organism which is essentially a unity, a ‘whole,’ ”♦ Schrödinger mused.) The color of an animal’s eyes, blue or brown, might be a property, but it is more useful to focus on the difference from one individual to another, and this difference was understood to be controlled by something conveyed in the chromosomes. He used the term gene: “the hypothetical material carrier of a definite hereditary feature.” No one could yet see these hypothetical genes, but surely the time was not far off. Microscopic observations made it possible to estimate their size: perhaps 100 or 150 atomic distances; perhaps one thousand atoms or fewer. Yet somehow these tiny entities must encapsulate the entire pattern of a living creature—a fly or a rhododendron, a mouse or a human. And we must understand this pattern as a four-dimensional object: the structure of the organism through the whole of its ontogenetic development, every stage from embryo to adult.
In seeking a clue to the gene’s molecular structure, it seemed natural to look to the most organized forms of matter, crystals. Solids in crystalline form have a relative permanence; they can begin with a tiny germ and build up larger and larger structures; and quantum mechanics was beginning to give