What Kind of World Supports Darwinian Evolution? Quantum Foundational Options
Partha Ghose
TL;DR
Darwinian evolution in a quantum world requires a realized classical data sector to enable copying and deletion; the paper uses Categorical Quantum Mechanics to show copying and deleting are not generic quantum operations and that decoherence selects a pointer basis without ensuring a single outcome. It then outlines four ontological options—unique history, unitary+decohered multiplicity, agent-relative facts, and a stochastic diffusion foundation—and analyzes their treatment of records, outcomes, and agency, with extended Wigner's Friend as a stress test. A Nelson-based stochastic-mechanics option with variable diffusion provides a continuous quantum–classical bridge and treats measurement update as conditioning with a time-symmetric minimal-change rule, avoiding an independent collapse postulate. The agency constraint emphasizes that classical resources are necessary for records and agency, guiding how to coherently integrate the record/outcome/issues and suggesting experimental tests in WF-type setups. Overall, the work clarifies foundational requirements for heredity in quantum regimes and offers a unifying framework that connects classical records, decoherence, agency, and stochastic dynamics to inform interpretations and future experiments.
Abstract
Darwinian evolution requires (i) heritable records, (ii) repeatable copying with variation, and (iii) routine irreversibility. Categorical quantum mechanics (CQM) makes precise why ``copy'' and ``delete'' are not generic quantum operations: they exist only for a realized \emph{classical data} sector (a preferred basis/observable; a commutative structure). Decoherence explains how a pointer basis can be selected dynamically, but it does not by itself select a unique outcome. This motivates a neutral presentation of the main ontological options (unique-history, decohered multiplicity, agent-relative facticity, and a stochastic foundation with variable diffusion). We also note the relevance of the ``agency constraint'' argued by Adlam-McQueen-Waegell: in a strictly coherent, basis-unselected ``purely quantum'' regime, minimal agency fails due to no-cloning and linearity, which sharpens the role of classical resources for record-based processes. Extended Wigner's Friend scenarios then serve as a stress test, since they treat ``friends'' simultaneously as coherent quantum systems and as agents possessing stable records. Finally, a stochastic-mechanics foundation (with variable diffusion) offers a continuous bridge between quantum and classical regimes, and suggests a principled way to implement measurement update as conditioning plus a time-symmetric minimal-change rule.