6 ideas
Schrödinger proposes that hereditary information sits in a solid that is not built by repeating one unit over and over, as ordinary crystals are. It is built from a non-repeating arrangement of a few kinds of elements. A small number of atom types in an irregular sequence can encode a huge number of possibilities, the way Morse code's dots and dashes can spell any text. That makes a single molecule enough to hold a 'code-script' for the whole organism.
A living system resists decaying into thermodynamic equilibrium by continually drawing order from its environment and giving back disorder, as heat and simpler waste products. What we take in from food is not really energy or matter, since both are conserved. It is low-entropy order, which the body uses to maintain its own improbable structure. Life is therefore defined thermodynamically as a local, temporary reversal of the drift toward disorder, paid for by increasing disorder elsewhere.
Physical laws are statistical. They become precise only when averaged over enormous numbers of atoms, and their error shrinks roughly with the square root of the number involved. An organism must therefore be vastly larger than its atoms so that its physiology can run on reliable, law-like behaviour instead of random molecular fluctuation. The puzzle follows from this: genes contain relatively few atoms, yet they behave with extraordinary permanence.
Schrödinger separates two ways that regularity arises in nature. In the first, statistical laws produce macroscopic order out of countless chaotic molecular events, which is the physics of heat and gases. In the second, a small, highly stable structure directly dictates orderly events, like the parts of a clockwork. Living things mainly run on the second mechanism. The gene's small but stable molecule directs development, so biology may need 'other laws of physics' built on this principle.
Mutations appear as discontinuous, all-or-nothing changes rather than gradual variations. This matches the quantum picture of a molecule shifting between discrete stable configurations separated by energy thresholds. The height of those thresholds explains why genes stay stable for centuries at body temperature yet can occasionally flip. It also explains why X-rays raise mutation rates in proportion to dose. Seen this way, the permanence of heredity is guaranteed by quantum mechanics rather than threatened by it.
Schrödinger holds that his body works as a deterministic mechanism, yet he directly experiences himself as steering it. From this he concludes that the 'I' is whatever directs the motions of atoms according to natural law. He argues that consciousness is never actually experienced in the plural. The apparent many minds are aspects of one, much as Vedanta identifies the individual self (Atman) with the universal one (Brahman).