Which Quantum Effects Survive in Microtubules? Structure-Grounded Calculations and Direct Experimental Tests

This preprint asks a narrower and more experimentally decidable question than whether microtubules are simply “quantum”: which specific quantum-sensitive mechanisms survive a structure-grounded audit strongly enough to justify direct measurement? Using deposited tubulin and microtubule geometries, embedded-fragment electronic couplings, trajectory-derived site-energy statistics, open-system dynamics, network calculations, and explicit evidential tiers, the study strongly disfavors a sustained, globally delocalized tryptophan Frenkel-exciton conduit. That negative result narrows the problem to two experimentally actionable paths: blinded replication and chemical identification of a reported Mg(25)-by-magnetic-field effect on tubulin assembly, followed conditionally by phase-sensitive spin spectroscopy; and mutation-controlled optical tests of structurally specified local aromatic dimers, progressing from near-ultraviolet difference circular dichroism to two-dimensional ultraviolet spectroscopy. The paper also distinguishes excitation transport from collective polarizability, preparation from persistence, coherence from nonclassicality, and local quantum effects from the much stronger claims of Orch OR. Driven whole-microtubule temporal order, including proposed fractal-time-crystal dynamics, is treated as a conditional route outside the audited state space rather than confirmed or excluded.