In 1943, Erwin Schrödinger gave a lecture in Dublin that later became the book What Is Life? A physicist who had fled the Nazis, he asked a question that seemed almost indecent at the time: can living things be explained by the laws of physics? He proposed that heredity is stored in an "aperiodic crystal," ten years before the discovery of the DNA double helix. Since then, biology has absorbed the language of thermodynamics and information, but a coherent set of minimal physical principles for adaptable life has never emerged.
A new paper proposes six such principles. They are not conclusions drawn from equations but postulates: a source of entropy, durability of information, fast response, repeatability, efficiency, and networks of interacting switches. The author built no models and ran no experiments. He gathered scattered observations into a single framework and checked how well the consequences of these principles agree with known facts. Life here appears as an orchestra, where every musician is a switch and the score is a flow of entropy.
The source of entropy shows up in photosynthesis and chemosynthesis, where organisms tap external gradients. Durability of information is visible in the hierarchy of metastable states: from DNA, with memory spanning generations, to synaptic plasticity, with memory spanning decades. Fast response is provided by protein conformations and post-translational modifications, which operate on timescales of milliseconds to minutes, unlike slow gene regulation. Repeatability is realized through cycles of ATPases, GTPases, ion channels, and cell division. Efficiency appears in the work of enzymes and neural codes, which optimize the trade-off between accuracy and energy cost. Finally, multiple switches form networks: from gene regulatory circuits to neural ensembles and ecosystems. All these motifs recur across different scales, which points to their universality.
For now this is pure knowledge, with no applications in sight. The framework could become the basis for a future quantitative theory, but today it serves only to organize observations. The next step is to translate qualitative principles into quantitative ones. For each of the six postulates, measurable constraints need to be found: the maximum lifetime of information, the trade-off between switching speed and energy cost, the limits of network complexity, the link between dissipation and adaptive performance. If that succeeds, the framework will turn from a classification into a predictive theory that can be tested experimentally. Then the orchestra will play from a score that can be calculated.
In 1943, Schrödinger called the presumed carrier of heredity an "aperiodic crystal," ten years before the discovery of the DNA double helix. His hunch proved right: information in DNA really is written as an irregular sequence of nucleotides, not a periodic lattice.