---
title: "Quantum mind"
chunk: 6/6
source: "https://en.wikipedia.org/wiki/Quantum_mind"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T03:37:55.019769+00:00"
instance: "kb-cron"
---

The problem with trying to use quantum mechanics in the action of the brain is that if it were a matter of quantum nerve signals, these nerve signals would disturb the rest of the material in the brain, to the extent that the quantum coherence would get lost very quickly. You couldn't even attempt to build a quantum computer out of ordinary nerve signals, because they're just too big and in an environment that's too disorganized. Ordinary nerve signals have to be treated classically. But if you go down to the level of the microtubules, then there's an extremely good chance that you can get quantum-level activity inside them.
For my picture, I need this quantum-level activity in the microtubules; the activity has to be a large-scale thing that goes not just from one microtubule to the next but from one nerve cell to the next, across large areas of the brain. We need some kind of coherent activity of a quantum nature which is weakly coupled to the computational activity that Hameroff argues is taking place along the microtubules.
There are various avenues of attack. One is directly on the physics, on quantum theory, and there are certain experiments that people are beginning to perform, and various schemes for a modification of quantum mechanics. I don't think the experiments are sensitive enough yet to test many of these specific ideas. One could imagine experiments that might test these things, but they'd be very hard to perform.

Penrose also said in an interview:

...whatever consciousness is, it must be beyond computable physics.... It's not that consciousness depends on quantum mechanics, it's that it depends on where our current theories of quantum mechanics go wrong. It's to do with a theory that we don't know yet.

A demonstration of a quantum effect in the brain has to explain this problem or explain why it is not relevant, or that the brain somehow circumvents the problem of the loss of quantum coherency at body temperature. As Penrose proposes, it may require a new type of physical theory, something "we don't know yet."

=== Ethical problems ===
Deepak Chopra has referred a "quantum soul" existing "apart from the body", human "access to a field of infinite possibilities", and other quantum mysticism topics such as quantum healing or quantum effects of consciousness. Seeing the human body as being undergirded by a "quantum-mechanical body" composed not of matter but of energy and information, he believes that "human aging is fluid and changeable; it can speed up, slow down, stop for a time, and even reverse itself", as determined by one's state of mind. Robert Carroll states that Chopra attempts to integrate Ayurveda with quantum mechanics to justify his teachings. Chopra argues that what he calls "quantum healing" cures any manner of ailments, including cancer, through effects that he claims are based on the same principles as quantum mechanics. This has led physicists to object to his use of the term quantum in reference to medical conditions and the human body. Chopra said: "I think quantum theory has a lot of things to say about the observer effect, about non-locality, about correlations. So I think there's a school of physicists who believe that consciousness has to be equated, or at least brought into the equation, in understanding quantum mechanics." On the other hand, he also claims that quantum effects are "just a metaphor. Just like an electron or a photon is an indivisible unit of information and energy, a thought is an indivisible unit of consciousness." In his book Quantum Healing, Chopra stated the conclusion that quantum entanglement links everything in the Universe, and therefore it must create consciousness.
According to Daniel Dennett, "On this topic, Everybody's an expert... but they think that they have a particular personal authority about the nature of their own conscious experiences that can trump any hypothesis they find unacceptable."
While quantum effects are significant in the physiology of the brain, critics of quantum mind hypotheses challenge whether the effects of known or speculated quantum phenomena in biology scale up to have significance in neuronal computation, much less the emergence of consciousness as phenomenon. Daniel Dennett said, "Quantum effects are there in your car, your watch, and your computer. But most things—most macroscopic objects—are, as it were, oblivious to quantum effects. They don't amplify them; they don't hinge on them."

== See also ==

== References ==

== Further reading ==

== External links ==
Center for Consciousness Studies, directed by Stuart Hameroff
PhilPapers on Philosophy of Mind, edited by David Bourget and David Chalmers
Quantum Approaches to Consciousness, entry in Stanford Encyclopedia of Philosophy