Heredity requires a stable molecule that is simultaneously irregular enough to encode information

Schrodinger's central puzzle is reconciling the astonishing stability of hereditary traits across generations, sometimes persisting with almost no change for centuries, with the fact that ordinary physical processes at the molecular scale are governed by statistical laws that would seem to guarantee gradual degradation through random thermal motion. His resolution is to propose the hereditary material must take the form of an 'aperiodic crystal,' a large molecule stable like a crystal, resistant to thermal disruption, but whose sequence is irregular rather than repeating, letting it store a vast, specific amount of information much like the varied letters in a book rather than the repetitive pattern of wallpaper. This was a remarkable leap for 1944, since the chemical identity of hereditary material was still unknown and widely debated, and Schrodinger reasoned to this structural requirement from pure physical logic rather than biochemical evidence. The insight anticipated, in broad terms, what DNA's double helix would later be shown to be: a stable yet information-rich irregular sequence. Takeaway: hereditary information needed a molecule that was structurally stable yet informationally irregular, a requirement DNA would later fulfill.