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Stuart R. Hameroff, Roger Penrose | Physics of Life Reviews | (2013)
Primary Link DOI Openalex Full text (OA)

Abstract

The nature of consciousness, the mechanism by which it occurs in the brain, and its ultimate place in the universe are unknown. We proposed in the mid 1990's that consciousness depends on biologically 'orchestrated' coherent quantum processes in collections of microtubules within brain neurons, that these quantum processes correlate with, and regulate, neuronal synaptic and membrane activity, and that the continuous Schrödinger evolution of each such process terminates in accordance with the specific Diósi–Penrose (DP) scheme of 'objective reduction' ('OR') of the quantum state. This orchestrated OR activity ('Orch OR') is taken to result in moments of conscious awareness and/or choice. The DP form of OR is related to the fundamentals of quantum mechanics and space–time geometry, so Orch OR suggests that there is a connection between the brain's biomolecular processes and the basic structure of the universe. Here we review Orch OR in light of criticisms and developments in quantum biology, neuroscience, physics and cosmology. We also introduce a novel suggestion of 'beat frequencies' of faster microtubule vibrations as a possible source of the observed electro-encephalographic ('EEG') correlates of consciousness. We conclude that consciousness plays an intrinsic role in the universe.

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Sample Definition And Size

This paper is a theoretical review of the Orch OR (Orchestrated Objective Reduction) theory of consciousness, not an empirical study. It does not involve a sample of subjects or experiments, nor does it review a specific number of studies in a meta-analysis format.

Study Type

Review article (theoretical review) of the Orch OR theory, synthesizing developments and criticisms across quantum biology, neuroscience, physics, and cosmology.

Conflicts Of Interest

No conflicts of interest are declared in the accessible content of the paper; the article does not include a 'Conflict of interest' statement in the open-access version. ([doi.org](https://doi.org/10.1016/j.plrev.2013.08.002))

Results Summary

Key findings: The Orch OR theory proposes that consciousness arises from orchestrated quantum processes in microtubules within neurons, culminating in objective reduction events per the Diósi–Penrose scheme, which correspond to moments of conscious awareness. The review discusses evidence for warm quantum vibrations in microtubules, identifies microtubule 'quantum channels' affected by anesthetics, and introduces the idea that beat frequencies of microtubule vibrations may underlie EEG correlates of consciousness. It concludes that consciousness may play an intrinsic role in the universe. ([doi.org](https://doi.org/10.1016/j.plrev.2013.08.002))

Referenced In

StarTalk

Season 17, Episode 9: Is Consciousness Quantum?

Hey StarTalkians! Season 17, Episode 9 saw Neil, Chuck, Gary O’ Reilly and guest Charles Liu sit down to answer a grab-bag of “Cosmic Queries.”

The episode title, and the bulk of the discussion, was about “quantum consciousness”:

The Problem With Uploading Your Consciousness | Cosmic Queries #105

But the discussion was long and a little meandering. I was left wondering: why exactly would you think this anyway? Is it really just what Neil said – that it’d be nice if one extremely complicated thing explained another – or is there more to it than that?

The Multiverse of Theories

The basic idea takes many forms, ranging from “grand unified theories” that also (somehow) explain consciousness to hyper-specific quantum processes going on in the brain.

But Roger Penrose’s idea – mentioned briefly in the podcast – is the most interesting and fleshed-out.

Orch OR Quantum Consciousness

Nobel Prize winner Roger Penrose and Stuart Hameroff’s idea, Orch OR (Consciousness in the universe ), basically imagines the human brain as a quantum computer, of sorts.

It centres on the proposed phenomenon of “objective reduction” (aka OR). This is a take on the “wavefunction collapse” problem, which posits that unlike in the Copenhagen Interpretation (Season 17, Episode 4: The Copenhagen Interpretation Explained | StarTalk | Project Credo ), the process of wavefunction collapse is very real. The superposition is objectively reduced to one possibility.

Wavefunctions would just spontaneously collapse, in the same way a radioactive atom spontaneously decays. In fact, they propose a “half life”-like measure of when this usually happens.

Orchestrated or “Orch” OR brings consciousness into this. They propose that these collapse events take place in your neurons, specifically in microtubules. When quantum entanglement in your neurons decays via OR, this creates a “proto-conscious” event – a fragment of subjective consciousness, like a passing thought or sensation.

It’s orchestrated because in the theory, your brain evolved to do this on purpose, creating a kind of quantum computer to process this data.

The Problem of Decoherence

Max Tegmark (The importance of quantum decoherence in brain processes ) showed a very serious problem with this. Coherent quantum arrangements tend to be short-lived when they interact with the environment. Because they can entangle with ordinary, randomly-encoded matter too, they lose the original “data” in the process.

Tegmark calculated that decoherence happens on timescales over a billion times smaller than any brain process.

Basically, your brain isn’t quick enough to be a quantum computer.

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