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arXiv:quant-ph/9907009quant-ph

The importance of quantum decoherence in brain processes

Max Tegmark

Abstract

Based on a calculation of neural decoherence rates, we argue that that the degrees of freedom of the human brain that relate to cognitive processes should be thought of as a classical rather than quantum system, i.e., that there is nothing fundamentally wrong with the current classical approach to neural network simulations. We find that the decoherence timescales ~10^{-13}-10^{-20} seconds are typically much shorter than the relevant dynamical timescales (~0.001-0.1 seconds), both for regular neuron firing and for kink-like polarization excitations in microtubules. This conclusion disagrees with suggestions by Penrose and others that the brain acts as a quantum computer, and that quantum coherence is related to consciousness in a fundamental way.

arXiv comments
Minor changes to match accepted PRE version. 15 pages with 5 figs included. Color figures and links at http://www.physics.upenn.edu/~max/brain.html or from max@physics.upenn.edu. Physical Review E, in press
Journal reference
Phys.Rev.E61:4194-4206,2000
DOI
doi:10.1103/PhysRevE.61.4194
Subjects
quant-phQuantum Physics cond-mat.dis-nnDisordered Systems and Neural Networks cs.NENeural and Evolutionary Computing physics.bio-phBiological Physics q-bioq-bio

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Linked by 4 identifiable commenters in 5 comments across 5 threads, from Mar 2012 to Nov 2018. Found in 3 HN submissions from Sep 2017 to Jan 2019. Open submission discussions.

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Discussed in comments5 threads

  1. The Strong Free Will Theorem (2009) [pdf] 1 comment

    • I am myself skeptic of this. First of all - How does on control indeterminism? And does QM indeterminism really play a role on a neuronal level? This paper by Tegmark argues it doesn't - https://arxiv.org/abs/quant-ph/9907009

      lainonView on HNParent context

  2. I'm Scott Aaronson, quantum computing/computational complexity researcher. AMA 1 comment

    • There have been some poorly received hypotheses to this effect, most notably Roger Penrose's Orch-OR: https://en.wikipedia.org/wiki/Orchestrated_objective_reducti... That said, most attempts at quantifying whether or not distinctly quantum mechanical processes in the brain…

      basculeView on HNParent context

  3. Simulating 1 second of real brain activity takes 40 minutes and 83K processors 1 comment

    • It's Penrose's view that a brain is quantum, but this paper http://arxiv.org/pdf/quant-ph/9907009v2.pdf shows human brain is more classical than quantum. Maybe the simulation algorithm is the thing that needs improvement. Some day one finds a way to reduce the complexity an…

      luikoreView on HNParent context

  4. The Brain is Not Computable 1 comment

    • According to Max Tegmark's calculations, the importance of quantum mechanical effects on brain processes is negligible: http://arxiv.org/abs/quant-ph/9907009 This paper posits the brain can be modeled as a classical (e.g. Newtonian, "billiard ball"-style) physical system

      basculeView on HNParent context

  5. Gödel's Incompleteness Theorem explained 1 comment

    • Penrose's The Emperor's New Mind addresses this idea. Basically, Penrose assumes that: 1. Gödel's Incompleteness Theorems are equivalent to the halting problem (provable) 2. If the human mind is deterministic, it can be modeled with a deterministic algorithm (provable). 3. The…

      duanebView on HNParent context

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