What Is Life?

A physicist, one of the founders of quantum mechanics, asking in public lectures how life can be accounted for by the laws physics already knows.

The outsider's position is the point. He was not trying to advance biology but to ask whether its phenomena fit within physics, and the questions he asked from that vantage were ones biologists had not been framing.

A physicist asking whether biology fits inside physics, which produced questions biologists were not asking.

Devmark’s reading — not a quotation from the book

His opening argument, and a beautiful piece of reasoning. Organisms must be large compared with atoms because physical laws are statistical: a system built from few particles would be dominated by random fluctuation.

His square-root-of-n rule — that relative fluctuation falls as the number of particles rises — explains why an organism needs to be made of enormous numbers of molecules in order to behave reliably at all.

His central prediction and the book's most consequential passage. The hereditary material must be a solid — stable enough to persist through generations — yet not a repeating periodic crystal, because a repeating structure carries almost no information.

He proposed an aperiodic crystal: a structure with regular bonding but a non-repeating sequence, capable of encoding a great deal in a small object. This is a structural description of DNA offered a decade before its structure was known.

His term for what the chromosomes carry: not a blueprint of the organism but a script, both the plan and the means of executing it.

The framing of heredity as encoded information rather than as a chemical process was the conceptual move that mattered. Both Watson and Crick credited the book with shaping how they approached the problem.

His distinction between two ways of producing orderly behaviour. Physics usually explains macroscopic regularity as a statistical average over disorder — order from disorder.

Life, he argues, works differently: a small number of molecules directs the behaviour of the whole organism, producing order from order. This is what makes biology a different kind of problem rather than simply a more complicated one.

His account of how an organism maintains its improbable order without violating thermodynamics: it feeds on what he called negative entropy, exporting disorder to its surroundings.

The formulation was criticised immediately and he added a note acknowledging that free energy is the more precise concept. The underlying point — that life is a local decrease in entropy paid for by a larger increase outside — is correct and is the standard account.

He was told the phrasing was wrong, added a note saying so, and the underlying point stands regardless.

Devmark’s reading — not a quotation from the book

His use of quantum mechanics to explain why genes are stable over many generations and yet occasionally change: discrete energy levels mean a molecular structure persists until a threshold is crossed, and mutation is a quantum jump.

The specific model was superseded, but the argument that gene stability requires quantum-mechanical explanation was correct in its direction.

The lectures end with a personal statement about consciousness, free will and a broadly Vedantic claim about the unity of minds.

It is unconnected to the preceding argument and most readers find it an awkward appendage. He signalled that it was personal rather than scientific, which is the fairest way to take it.

Schrödinger drew substantially on earlier work by Max Delbrück and colleagues on mutation and gene structure, and the degree to which his contribution was synthesis rather than origination has been debated by historians.

His achievement was arguably the framing and the audience rather than the underlying ideas. That does not diminish the effect, since the framing is what reached the people who went on to solve the problem.

It is very short, is written for a general audience of its period, and assumes more physics than a modern popular book would.

Its value is historical and conceptual rather than informational. A reader learns almost nothing current about biology and sees clearly how a well-posed question from outside a field can redirect it.