Is The Brain A Quantum Computer? The Decoherence Numbers Say No

The gap is ten orders of magnitude, not a close call. Tegmark’s 2000 calculation puts a superposition inside a microtubule at ten to the minus thirteen seconds and one across a neuron at ten to the minus twenty. Neurons work on timescales between a ten thousandth of a second and a second. The microtubule camp’s reply narrowed the gap without closing it. Hagan, Hameroff and Tuszynski recalculated at ten microseconds, which is still a hundred times too short. The further stretch to a tenth of a second rests on ordered water, metabolic pumping and actin gelation, none of which has been measured in living tissue. Orchestrated objective reduction needs physics that has been tested and failed. It requires Penrose’s own gravitational collapse mechanism. The parameter-free version of that model was ruled out by the Gran Sasso underground experiment and reported in Nature Physics. Nuclear spin is the one part still open. Matthew Fisher proposed that phosphorus nuclei in a calcium phosphate cluster could hold a state for around a day, because nuclear spins couple to their surroundings far more weakly than electrons do. The proposal has survived a decade and has also failed several of its own tests. Quantum biology…