When is piece of matter said to be 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 remain more ticklish, the relevant definitions being subject to feedback loops of their own.

Much more remained to be learned, Schrodinger said, but how life stores and perpetuates the orderliness it drawn 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 form species to species, and known to be carriers of hereditary features. As Schrodinger put it now, they hold within them somehow, the “pattern” of the organism: “it is these chromosomes, or probably only an axial skeleton fiber 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.

There 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,’” Schrodinger 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 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 patterns 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 the 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 deep insights into the forces involved in their bonding. But Schrodinger felt something was missing. Crystals are too orderly – built up in “the comparatively dull way of repeating the same structure in three directions again and again.” Elaborate though they seem, crystalline solids contain just a few types of atoms. Life must depend on a higher level of complexity, structure without predictable repetition, he argued. He invented the term: ‘aperiodic crystals.’ This was his hypothesis: “We believe a gene – or perhaps the whole chromosome fiber – to be an aperiodic solid.” He could hardly emphasize enough the glory of this difference, between periodic and aperiodic:

“The difference in structure is of the same kind as that between an ordinary wallpaper in which the same pattern is repeated again and again in regular periodicity and a masterpiece of embroidery, say a Raphael tapestry, which shows no dull repetition, but an elaborate, coherent, meaningful design.”

Some of his most admiring readers, such as Leon Brillouin, the French physicist recently decamped to the United States, said that Schrodinger was too clever to be completely convincing, even as they demonstrated in their won work just how convinced they were. Brillouin was particularly taken with the comparison to crystals, with their elaborate but inanimate structure. Crystals have some =capacity of self-repair, he noted; under stress, their atoms may shift to new positions for the sake of equilibrium. That may be understood in terms of thermodynamics and now quantum mechanics. How much more exalted, the, is self-repair in the organism: “the living organism heals its own wounds, cures its sickness, and may rebuild large portions of its structure when they have been destroyed by some accident. This is the most striking and unexpected behavior.” He followed Schrodinger, too, in using entropy to connect the smallest and largest scales. ~ Pages 282 to 286