A fundamental contradiction in quantum biology remains unresolved after 25 years:theoretical estimates of decoherence time in microtubules range from ~10-13 s (Tegmark,2000) to ~10-6 s (Mavromatos et al., 2025) — a discrepancy of 7–8 orders of magnitude.No direct experimental measurement of quantum decoherence time in microtubules ortubulin at physiological temperature (37°C) has been performed to date. This noteidentifies this gap, reviews existing theoretical predictions and indirect experimentalevidence, and proposes a minimal experimental protocol — cavity QED Rabi splittingspectroscopy on single microtubules at physiological temperature — capable of resolvingthe contradiction. Resolution has direct implications for the physical plausibility of quantumtheories of consciousness.
A fundamental contradiction in quantum biology remains unresolved after 25 years:theoretical estimates of decoherence time in microtubules range from ~10-13 s (Tegmark,2000) to ~10-6 s (Mavromatos et al., 2025) — a discrepancy of 7–8 orders of magnitude.No direct experimental measurement of quantum decoherence time in microtubules ortubulin at physiological temperature (37°C) has been performed to date. This noteidentifies this gap, reviews existing theoretical predictions and indirect experimentalevidence, and proposes a minimal experimental protocol — cavity QED Rabi splittingspectroscopy on single microtubules at physiological temperature — capable of resolvingthe contradiction. Resolution has direct implications for the physical plausibility of quantumtheories of consciousness.
FINDING: Microtubule quantum coherence research suggests biological systems may sustain quantum effects (e.g., superposition, entanglement) at physiological temperatures, challenging decoherence dogma—but the mathematical core remains speculative, with no closed-form equations yet published in the cited sources. | MATH: No explicit equations, constants, or ratios extracted from the video/abstract titles. The arXiv paper (1401.3218) deals with cavity QED ground-state quantum beats—relevant to coherence control, but not directly to microtubules. Key physical parameters implied: decoherence time τ_d, coupling strength g, thermal energy k_BT (~25 meV at 300K), and vibrational mode frequencies of tubulin dimers (~THz range, inferred from protein dynamics). No golden-ratio or base-60 constants appear in the evidence. | CONNECTION: Microtubules are hollow cylinders with 13 protofilaments (a prime number, not crystallographic in the Penrose-tiling sense). However, tubulin dimers arrange in a l Author: Andrew Stewart Caldin, Independent Researcher, UK. Part of the E8 Intelligence Research series. Platform: e8intelligence.com
Recent experimental research with marine algae points towards quantum entanglement at ambient temperature, with correlations between essential biological units separated by distances as long as 20 Angströms. The associated decoherence times, due to environmental influences, are found to be of order 400 fs. This prompted some authors to connect such findings with the possibility of some kind of quantum computation taking place in these biological entities: within the decoherence time scales, the cell "quantum calculates" the optimal "path" along which energy and signal would be transported more efficiently. Prompted by these experimental results, in this talk I remind the audience of a related topic proposed several years ago in connection with the possible rôle of quantum mechanics and/or field theory on dissipation-free energy transfer in microtubules (MT), which constitute fundamental cell substructures. The basic assumption was to view the cell MT as quantum electrodynamical cavities, providing sufficient isolation in vivo to enable the formation of electric-dipole quantum coherent solitonic states across the tubulin dimer walls. Crucial to this, were argued to be the electromagnetic interactions of the dipole moments of the tubulin dimers with the dipole quanta in the ordered water interiors of the MT, that play the rôle of quantum coherent cavity modes. Quantum entanglement between tubulin dimers was argued to be possible, provided there exists sufficient isolation from other environmental cell effects. The model was based on certain ferroelectric aspects of MT. Subsequent experiments in vitro could not confirm ferroelectricity at room temperatures, however they provided experimental measurements of the induced electric dipole moments of the MT under the influence of external electric fields. Nevertheless, this does not demonstrate that in vivo MT are not ferroelectric materials. More refined experiments should be done. In the talk I review the model and the associated experimental tests so far and discuss future directions, especially in view of the algae photo-experiments.
Prompted by recent experimental results in marine algae, indicating quantum entanglement at ambient temperature, with correlations between essential biological units separated by distances as long as 20 Angstroms and decoherence times, due to environmental influences, of order 400 fs, I review here a related topic proposed several years ago in connection with the possible rôle of quantum mechanics and/or field theory on dissipation-free energy transfer in (brain) microtubules (MT). The basic assumption was to view the cell MT as quantum electrodynamical cavities, providing sufficient isolation in vivo to enable the formation of electric-dipole quantum coherent solitonic states across the tubulin dimer walls. Crucial to this, were argued to be the electromagnetic interactions of the dipole moments of the tubulin dimers with the dipole quanta in the ordered water interiors of the MT, that play the rôle of quantum coherent cavity modes. Quantum entanglement between tubulin dimers was argued to be possible, provided there exists sufficient isolation from other environmental cell effects. Thus, decoherence times as long as 10 −7 −10 −6 s could characterise the MT systems. The model was based on certain ferroelectric aspects of MT. In the talk I revisit these decoherence time scales in light of the algae measurements and argue that, even if the environmental decoherence implies short time scales of order of a few hundreds of fs, this is a sufficient time for some kind of quantum computation to take place in (brain) MT, so that within these time scales the cell "quantum calculates" the optimal "path" along which energy and signal (information) are transported most efficiently along the MT.
We propose a testable hypothesis linking quantum coherence in neural microtubules to gamma-band oscillations (30-100 Hz) observed in neural networks. Building on recent experimental evidence of electromagnetic oscillations in microtubule bundles and quantum super radiance in tryptophan networks, we hypothesize that microtubule quantum dynamics may influence the temporal precision of established gamma-generating mechanisms rather than serve as primary oscillation generators. Our empirically-grounded model incorporates measured microtubule electromagnetic properties and realistic decoherence calculations to predict specific correlations between microtubule coherence states and gamma oscillation timing precision. We present detailed decoherence analysis showing that while individual tubulin coherence is limited to femtosecond timescales under physiological conditions, recent experimental evidence suggests collective electromagnetic effects across microtubule networks might create mesoscopic domains with enhanced stability. The framework provides concrete experimental pathways using nitrogen-vacancy center quantum sensing combined with high-resolution neurophysiology to test quantitative predictions about quantum-classical coupling strengths. Key predictions include measurable correlations between microtubule electromagnetic activity and gamma timing precision (correlation coefficient r > 0.3), specific temperature dependencies matching quantum decoherence theory (characteristic temperature Tc= 12 ± 3 K), and selective pharmacological effects of microtubule-targeting drugs on neural timing precision while preserving oscillation power. These predictions distinguish our framework from classical models and provide clear falsification criteria for experimental validation.
Abstract We examine the quantum coherence properties of tubulin heterodimers arranged into the protofilaments of cytoskeletal microtubules. In the physical model proposed by the authors, the microtubule interiors are treated as high-Q quantum electrodynamics (QED) cavities that can support decoherence-resistant entangled states under physiological conditions, with decoherence times of the order of O(10−6) O ( 10 - 6 ) s. We identify strong electric dipole interactions between tubulin dimers and ordered water dipole quanta within the microtuble interior as the mechanism responsible for the extended coherence times. Classical nonlinear (pseudospin) σ σ -models describing solitonic excitations are reinterpreted as emergent quantum-coherent—or possibly pointer—states, arising from incomplete collapse of dipole-aligned quantum states. These solitons mediate dissipation-free energy transfer along microtubule filaments. We discuss logic-gate-like behaviour facilitated by microtubule-associated proteins, and outline how such structures may enable scalable, ambient-temperature quantum computation, with the fundamental unit of information storage realized as a quDit encoded in the tubulin dipole state. We further describe a process akin to “decision-making” that emerges following an external stimulus, whereby optimal, energy-loss-free signal and information transport pathways are selected across the microtubular network. Finally, we propose experimental approaches—including Rabi-splitting spectroscopy and entangled surface plasmon probes—to validate the use of biomatter as a substrate for scalable quantum computation.
The Penrose-Hameroff orchestrated objective reduction (orch. OR) model assigns a cognitive role to quantum computations in microtubules within the neurons of the brain. Despite an apparently "warm, wet, and noisy" intracellular milieu, the proposal suggests that microtubules avoid environmental decoherence long enough to reach threshold for "self-collapse" (objective reduction) by a quantum gravity mechanism put forth by Penrose. The model has been criticized as regards the issue of environmental decoherence, and a recent report by Tegmark finds that microtubules can maintain quantum coherence for only 10(-13) s, far too short to be neurophysiologically relevant. Here, we critically examine the decoherence mechanisms likely to dominate in a biological setting and find that (1) Tegmark's commentary is not aimed at an existing model in the literature but rather at a hybrid that replaces the superposed protein conformations of the orch. OR theory with a soliton in superposition along the microtubule; (2) recalculation after correcting for differences between the model on which Tegmark bases his calculations and the orch. OR model (superposition separation, charge vs dipole, dielectric constant) lengthens the decoherence time to 10(-5)-10(-4) s; (3) decoherence times on this order invalidate the assumptions of the derivation and determine the approximation regime considered by Tegmark to be inappropriate to the orch. OR superposition; (4) Tegmark's formulation yields decoherence times that increase with temperature contrary to well-established physical intuitions and the observed behavior of quantum coherent states; (5) incoherent metabolic energy supplied to the collective dynamics ordering water in the vicinity of microtubules at a rate exceeding that of decoherence can counter decoherence effects (in the same way that lasers avoid decoherence at room temperature); (6) microtubules are surrounded by a Debye layer of counterions, which can screen thermal fluctuations, and by an actin gel that might enhance the ordering of water in bundles of microtubules, further increasing the decoherence-free zone by an order of magnitude and, if the dependence on the distance between environmental ion and superposed state is accurately reflected in Tegmark's calculation, extending decoherence times by three orders of magnitude; (7) topological quantum computation in microtubules may be error correcting, resistant to decoherence; and (8) the decohering effect of radiative scatterers on microtubule quantum states is negligible. These considerations bring microtubule decoherence into a regime in which quantum gravity could interact with neurophysiology.