Could the Brain Use Quantum Mechanics

Could the Brain Use Quantum Mechanics?

Audience

Difficulty	Beginner

This page is the plain-language entry point into the question of whether the brain can — at any biologically-relevant scale — exploit quantum-mechanical effects (superposition, entanglement, coherence). It assumes no calculus and no quantum-mechanics background.

The one-sentence version

For most of the 20th century the answer was assumed to be "no" — the brain is too warm, too wet, and too noisy for quantum effects to survive. As of the mid-2020s the answer is being revised toward "yes, in some specific subsystems, and maybe more broadly than that".

Why the default answer was "no"

Quantum coherent states are notoriously delicate. A quantum superposition — the state in which a particle is, in a precise sense, "in two places at once" — collapses to a definite outcome the moment the particle interacts strongly with its environment. The hotter and more crowded the environment, the faster this decoherence happens.

For a typical molecular-scale quantum state at room temperature, surrounded by other warm molecules in liquid water, the decoherence time is unimaginably short — on the order of 10⁻¹³ to 10⁻²⁰ seconds depending on the system. The brain operates on millisecond timescales (10⁻³ s). A naïve calculation gives quantum coherence ten orders of magnitude too short to be useful for biology.

This argument — pushed most influentially by Max Tegmark in 2000 — was the consensus view for decades.

Why the answer is being revised

Three developments have softened the consensus:

1. Photosynthesis — From 2007 onwards, multiple experimental groups (Engel et al. Nature 2007; Collini et al. 2010) have shown that photosynthetic light-harvesting complexes use quantum coherence at room temperature to transfer energy from absorbed photons to reaction centres at near-100% efficiency. The coherence survives for ~ 100–500 femtoseconds — short, but long enough to matter. This decisively refuted the strong form of the "warm-wet-noisy" argument: nature does use quantum coherence in biology.

1. Avian magnetoreception — European robins (and likely many migratory birds) appear to navigate using a quantum-coherent radical-pair mechanism in their retinal cryptochrome proteins. Magnetic-field sensitivity depends on coherent spin dynamics — quantum mechanics doing biology, with timescales of microseconds.

1. Microtubule experiments — Anirban Bandyopadhyay's group (NIMS Japan, 2011–present) reports anomalously high electronic conductance in microtubule lattices, with resonant peaks at specific frequencies. Celardo et al. (2019) provide theoretical analysis suggesting collective superradiant coupling. Kalra et al. (2023) report that anaesthetics that switch off consciousness preferentially bind to microtubule sites that the framework would predict.

These are not yet a complete demonstration that the brain "computes" quantum-mechanically in any standard sense, but the warm-wet-noisy argument no longer carries the weight it used to.

Three positions

Modern researchers occupy roughly three positions:

1. Classical brain. The brain is a purely-classical electrochemical computer. Any quantum effects in biology (photosynthesis, magnetoreception) are isolated curiosities that do not enter into cognition or consciousness. Mainstream neuroscience default.
2. Quantum-assisted brain. Some specific cognitive functions exploit quantum effects in localised subsystems (microtubules, ion channels, biophoton emission), without the whole brain being a quantum computer. Penrose-Hameroff Orchestrated Objective Reduction; some interpretations of the Bandyopadhyay/Celardo results.
3. Field-coupled brain. Beyond the brain's local electrochemistry, conscious states couple to a wider field — the ψ field in the present framework, or analogues in alternative theories (CEMI, holonomic-brain, IIT). The brain participates in physics that classical neural-network models cannot capture.

The third position is the working hypothesis of the psionic framework. It does not require the brain to be a quantum computer in any standard sense; it requires only that coherent collective neural states couple to a continuous field whose quanta and propagation extend beyond the brain.

Falsifiable predictions

If quantum / field-theoretic effects play a role in cognition, then:

1. Anaesthetics should preferentially disable the subsystems responsible. Kalra 2023 reports this for microtubule-bound anaesthetics.
2. Coherent collective neural states (high-gamma synchrony, phase-locked oscillations) should correlate with conscious experience. Standard EEG/MEG literature partly confirms this.
3. Coupling to the ψ field should produce small, measurable effects in shielded environments — Faraday cages should reduce, not eliminate, certain anomalous-cognition signals.

What this does NOT mean

• It does NOT mean the brain is a "quantum computer" in the technical sense (qubits, gates, algorithms). Most proposals are much weaker.
• It does NOT mean consciousness has been "explained" by quantum mechanics. The hard problem remains hard.
• It does NOT mean that pop-science claims about "quantum healing", "quantum manifesting" etc are scientifically supported. They are not, in any rigorous sense; the legitimate quantum-biology research base does not extend to those claims.

Where to go next

• For the microtubule story: Microtubule → Orchestrated_Objective_Reduction → Bandyopadhyay_Microtubule_Conductance → Celardo_Microtubule_Superradiance → Kalra_Anaesthetic_Microtubule.
• For the broader debate: Tegmark_Critique_and_Hagan_Rebuttal.
• For the field-theoretic alternative: Effective_Field_Theory_of_Consciousness → Wilson-Cowan_Coupled_to_Psi.

See Also

• Microtubule
• Orchestrated_Objective_Reduction
• Biological_Substrate_of_Psi
• Tegmark_Critique_and_Hagan_Rebuttal
• Coherent_Quantum_Effects_in_Biology
• Effective_Field_Theory_of_Consciousness

References

• Engel, G. S., et al. (2007). "Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems." Nature 446: 782–786.
• Tegmark, M. (2000). "Importance of quantum decoherence in brain processes." Physical Review E 61: 4194–4206.
• Hagan, S., Hameroff, S. R., Tuszyński, J. A. (2002). "Quantum computation in brain microtubules: Decoherence and biological feasibility." Physical Review E 65: 061901.
• Sahu, S., et al. (Bandyopadhyay group, 2013). "Atomic water channel controlling remarkable properties of a single brain microtubule: Correlating single protein to its supramolecular assembly." Biosensors and Bioelectronics 47: 141–148.