March 1, 2014
Stuart Hameroff, Roger Penrose
384 citations
Consciousness may arise from quantum processes inside microtubules within brain neurons, orchestrated by biological mechanisms and culminating in moments of conscious awareness through a specific form of quantum state reduction. This orchestrated objective reduction (Orch OR) theory links brain activity to the fundamental structure of the universe, connecting quantum mechanics and space-time geometry. The review also suggests that faster microtubule vibrations could produce beat frequencies corresponding to observed EEG patterns. The authors conclude that consciousness is an intrinsic feature of the universe.
Timing & Time Perception
November 6, 2023
Stuart Hameroff
The Penrose–Hameroff 'Orch OR' theory proposes that consciousness arises from discrete, irreversible quantum state reductions (objective reductions) occurring in microtubules within brain neurons. These self-collapses of the quantum wavefunction are orchestrated to regulate neuronal functions and produce sequences of 'NOW' moments of conscious experience. Connected to fundamental spacetime geometry, this process creates a flow of time by ratcheting forward in the fine-scale geometry of the universe. The theory suggests that time in physics—as a process or a dimension—and time as a conscious experience may all be consistent explanations.
Cognitive Neuroscience
January 1, 2021
Stuart Hameroff
The 'Orch OR' theory proposes that consciousness arises from quantum computations occurring in microtubules within brain neurons. Quantum computers process information as superpositions of multiple possibilities (quantum bits or qubits), which in Orch OR are alternative collective dipole oscillations orchestrated by microtubules. These oscillations entangle, compute, and terminate via Penrose objective reduction, producing sequences of moments that correspond to conscious experience, more like music than computation. Each event selects microtubule states that influence neuronal functions. The theory has broad explanatory power and is easily falsifiable.
Journal of Integrative Neuroscience
June 1, 2014
Stuart Hameroff, Travis J A Craddock, Jack A Tuszynski
Quantum physics, originally developed for inanimate matter, is increasingly applied to biology and consciousness studies. Individual biological phenomena such as photosynthesis and bird navigation have been analyzed using quantum methods, building conceptual foundations for quantum biology. Several proposals, especially the Orch OR hypothesis, suggest microtubules as the substrate for conscious processes based on quantum coherence and entanglement. Quantum Metabolism, quantum processes in ion channels, and quantum effects in sensory stimulation are also discussed. The paper reviews challenges and merits of quantum consciousness approaches and their potential extensions.
Topics in Cognitive Science
January 1, 2014
Stuart Hameroff
Cognitive decisions are best described by quantum mathematics, and this paper argues that quantum information devices may operate in the brain. It describes how quantum lattice registers, in which superpositioned pathways interact through 'quantum walks' similar to Feynman's path integral in a lattice (the 'Feynman quantum chessboard'), can reduce or collapse to select a particular pathway in a cognitive decision. The paper shows that these quantum walks are conceptually identical to 'topological qubits' in brain neuronal microtubules, as described in the Penrose-Hameroff 'Orch OR' theory of consciousness.
Frontiers in Integrative Neuroscience
January 1, 2012
Stuart Hameroff
Conscious free will faces three challenges: unknown brain mechanisms for consciousness, delayed neural correlates that suggest consciousness is an epiphenomenal illusion, and deterministic algorithms. The Penrose-Hameroff theory of orchestrated objective reduction (Orch OR) proposes that discrete conscious moments arise from quantum computations in microtubules inside brain neurons, occurring at around 40 times per second in sync with gamma synchrony EEG. These computations terminate via objective reduction, a proposal linking quantum state reduction to spacetime geometry, which can trigger axonal firings and control behavior. Orch OR suggests temporal non-locality, sending quantum information backward in classical time to enable conscious control, and invokes non-computable influences from spacetime geometry to avoid algorithmic determinism. This framework rescues conscious free will from being an illusion.
Cognitive Science
November 12, 2007
Stuart Hameroff
A commentary defends the Penrose-Hameroff 'Orch OR' quantum computational model of consciousness against earlier criticism. Orch OR proposes that consciousness arises from quantum computations in microtubules inside neurons, particularly in dendrites connected by gap junctions called dendritic webs. These webs act as input layers in the brain's neurocomputational architecture, and consciousness is suggested to occur during gamma EEG-synchronized sequences of discrete quantum events within integration phases of neurocomputational integrate-and-fire cycles. The author argues that Orch OR is compatible with neurocomputation and questions whether neurocomputation alone can account for coherent gamma synchrony EEG, a candidate neural correlate of consciousness.
Trends in Cognitive Sciences
November 1, 2001
Nancy J. Woolf, Stuart Hameroff
Visual consciousness may arise from quantum computations inside microtubules within neurons, according to the Penrose-Hameroff 'Orch OR' model. A physiological model is presented that could allow such quantum states to survive in the warm, wet brain and extend across the whole brain. In this view, visual consciousness occurs in a series of several-hundred-millisecond epochs, each containing 'crescendo sequences' of quantum computations at approximately 40 Hz. The approach resolves some enigmatic features of visual consciousness but raises questions about how delicate quantum states avoid decoherence in the brain's environment.
Advances in Consciousness Research
April 12, 2001
Stuart Hameroff
The Penrose-Hameroff 'Orch OR' model proposes that quantum superposition and computation occurring in microtubules inside brain neurons could explain puzzling aspects of consciousness. Although standard quantum technology demands extreme cold and isolation to prevent thermal decoherence, making biological quantum processes in the warm, wet, and noisy brain seem unlikely, the paper discusses methods biological systems may have evolved to avoid decoherence.
The Geometric Universe
April 30, 1998
Stuart Hameroff
Roger Penrose argued that conscious thought involves non-algorithmic processing beyond computation, requiring a new physical principle. He proposed that 'objective reduction' (OR) of quantum coherent superposition, a quantum gravity solution for wave function collapse, performs these non-computational actions. The author suggests that macroscopic quantum effects enabling OR occur in neuronal microtubules within the cell cytoskeleton, the most likely site in the brain.