The “quantum mind” hypothesis, the notion that quantum phenomena are causal and perhaps even essential in mentation and particularly consciousness, has met with fierce resistance. This has been particularly the case over the past 20 years, and the first task of this paper is to show that while there are indeed strong - mainly empirical - arguments against the thesis, the ‘in principle arguments published to date evince premature closure. The burgeoning field of “Quantum cognition” has established that quantum models are appropriate for decision-making, and that of “Quantum biology” has now made the notion of quantum effects at physiological temperatures plausible. If quantum effects are relevant to consciousness, they are likely to be seen in the contrast between attended to and not attended to streams of information. An exciting confirmation of this theme is the fact that attended to streams involve a decorrelation of the informational fluctuations in streams not so attended to. This gives rise to the idea that perhaps what enters our consciousness is the result of such a decorrelation from a superposed state. Decorrelation for the purposes of sparsification is prevalent in the brain; what may enter consciousness in the schema proposed here is mental processes with a duration greater than the sampling rate of consciousness (about 80ms) the wave function of which is undergoing state-vector reduction in a manner described by the Quantum Zeno effect. This allows also for truly voluntary action in the manner Von Neumann suggested. This is distinct from the situation with binocular resolution dichoptic stimuli which is a mixture, and is an example of what Fodor calls a “vertical” module with its operation mandatory. There is nothing to be gained by making binocular synthesis subject to voluntary choice. Likewise, it is realistic to propose that attention in lower animals with their less complex brains involves a much simpler mechanism than human consciousness. A model of the individual neuron as a harmonic oscillator is outlined, with a causal role for ion channels in the generation of the oscillations. It is clear that ion channels are critical for attention. Moreover, at a mesoscopic level, it is demonstrated that the brain enters a quiet “shutter” mode several times a second in which quantum effects may be appropriately amplified. If quantum effects exist in the brain, it is likely that this complex of phenomena will be central to them. The de Barros and Suppes models, in addition to the similar formalism due to Henry Stapp, are also briefly described.
The “quantum mind” hypothesis, the notion that quantum phenomena are causal and perhaps even essential in mentation and particularly consciousness, has met with fierce resistance. This has been particularly the case over the past 20 years, and the first task of this paper is to show that while there are indeed strong - mainly empirical - arguments against the thesis, the ‘in principle arguments published to date evince premature closure. The burgeoning field of “Quantum cognition” has established that quantum models are appropriate for decision-making, and that of “Quantum biology” has now made the notion of quantum effects at physiological temperatures plausible. If quantum effects are relevant to consciousness, they are likely to be seen in the contrast between attended to and not attended to streams of information. An exciting confirmation of this theme is the fact that attended to streams involve a decorrelation of the informational fluctuations in streams not so attended to. This gives rise to the idea that perhaps what enters our consciousness is the result of such a decorrelation from a superposed state. Decorrelation for the purposes of sparsification is prevalent in the brain; what may enter consciousness in the schema proposed here is mental processes with a duration greater than the sampling rate of consciousness (about 80ms) the wave function of which is undergoing state-vector reduction in a manner described by the Quantum Zeno effect. This allows also for truly voluntary action in the manner Von Neumann suggested. This is distinct from the situation with binocular resolution dichoptic stimuli which is a mixture, and is an example of what Fodor calls a “vertical” module with its operation mandatory. There is nothing to be gained by making binocular synthesis subject to voluntary choice. Likewise, it is realistic to propose that attention in lower animals with their less complex brains involves a much simpler mechanism than human consciousness. A model of the individual neuron as a harmonic oscillator is outlined, with a causal role for ion channels in the generation of the oscillations. It is clear that ion channels are critical for attention. Moreover, at a mesoscopic level, it is demonstrated that the brain enters a quiet “shutter” mode several times a second in which quantum effects may be appropriately amplified. If quantum effects exist in the brain, it is likely that this complex of phenomena will be central to them. The de Barros and Suppes models, in addition to the similar formalism due to Henry Stapp, are also briefly described.
The question of whether quantum mechanical phenomena play a functional role in brain activity and the emergence of consciousness remains one of the most controversial yet intellectually stimulating debates at the intersection of physics, neuroscience, and philosophy of mind. This review systematically examines the principal theoretical frameworks proposing quantum-level mechanisms in neural computation, including the Orchestrated Objective Reduction (Orch OR) hypothesis by Penrose and Hameroff, the quantum brain hypothesis of Stapp, quantum coherence models in microtubules, and quantum field theories of consciousness. We critically evaluate the current state of empirical evidence—including recent quantum biology findings, the challenge of decoherence in warm, biological systems, and experimental observations of quantum effects in biological systems—alongside computational models that bridge quantum formalism and neural network dynamics. Furthermore, we discuss the implications of quantum cognition models for understanding perception, decision-making, and memory. Despite significant scientific skepticism, emerging evidence from quantum biology and advanced neuroimaging technologies provides tentative support for quantum processes in neural substrates. We conclude by identifying critical gaps in current knowledge and outlining future research directions that may resolve the debate, including proposals for experimental paradigms using quantum sensing technologies applied to neural tissue. This review aims to serve as a foundational reference for researchers across disciplines approaching the quantum mind hypothesis with scientific rigor.
This note was written by a theoretical physicist currently working on physical aspects of consciousness, mind-matter relationships, and mind-body interactions. My purpose here is to inform the readers of this journal, in not too technical terms, of some recent ideas relating quantum mechanics, gravitation, and psychological phenomena. Attempts to relate the nature of consciousness to quantum mechanics have been known almost from the be+g of quantum mechanics. For an extended discussion and earlier references see, e.g., Stapp (1982). The common thread of the majority of the suggested hypotheses linking consciousness to a quantum level of description is a drawing of a between the spontaneous localization of mental patterns and (spontaneous or induced) reduction of the wave function in quantum mechanics. The latter essentially means that quantum systems are inherently described in probabilistic terms and any external observation reduces the manyfold of all potential possibilia to a single given realization. Interpretation of this process is one of the most difficult and controversial topics of quantum mechanics since in quantum mechanics it is thus far essentially impossible to demarcate unambiguously the observer from the quantum system itself. Despite that gravitational effects are usually deemed to be too weak at atomic level, a few authors recently discussed gravity as an inherent route used by nature to achieve an automatic spontaneous reduction of the wave functions of extended objects. In his recent book, Roger Penrose (1989) looks for the possible connections between consciousness, quantum mechanical reduction and gravitational phenomena. To simplify, the essence of these hypotheses is that subtle gravitational effects at the atomic-molecular level lock the brain into a particular mental state, thereby providing the materialization of the potential (quantum) mental image by the route similar to the reduction of the wave function in quantum mechanics. Isotopic diversity of chemical elements can substantially contribute to this picture, as well as to life processes in general (Berezin, 1988). Since gravity is a mass-sensitive effect, the fact that different stable isotopes of the same element (e.g., carbon, oxygen, nitrogen) have different atomic masses may affect the path of mental processing.
Quantum consciousness concerns both the possible role that quantum mechanics has for understanding consciousness as well as the role that consciousness has for interpreting quantum physics. Quantum brain theories hypothesize that quantum physical processes occur within and between the neurons of the brain and have important effects on cognition as well as consciousness. Quantum cognition is a growing new field in cognitive science concerned with the application of the mathematical principles of quantum theory to human judgment and decision-making behaviour. What do all these theories have to do with each other? Quantum theories of consciousness have more to say about quantum physics than cognitive psychology and conscious experiences. Quantum brain theories have not been sufficiently ‘scaled up’ to provide clear implications for how quantum physical processes generate more complex cognition. Quantum cognition theories have avoided addressing fundamental issues about consciousness and have remained agnostic with respect to the quantum brain hypothesis. This article will address the problem of connecting these ideas together by connecting quantum cognition to the other two topics.
The mind–matter relationship remained in the domain of philosophers for aeons. However, the inquisitiveness of the scientific minds has always been trying to understand the science behind its various functions. The scientific temper ushered in by the Renaissance about the 15th century saw the scientists exploring this problem from a science point of view. Technological advances during the later part of the 20th century enabled neuroscientists to explore and localise functions of the brain. However, the most difficult has been understanding the origin of a conscious experience scientifically or materialistically. Despite the delineation of many functions of the brain, the origin of conscious experience, the qualia, in the material brain remains elusive, so much so it came to be called the holy grail of neuroscience. Heisenberg wrote: ‘Physics entered the domain of philosophy with the emergence of consciousness in quantum observation, which incidentally opened the door for reconciliation of science and philosophy’,[1] an event which enabled the predictions of Snow of the merging of arts and sciences.[2,3] Quantum mechanics is a branch of physics relating to very small particles – subatomic particles – electrons, photons, and everything in the submolecular realm, being the smallest units in matter. Quantum theory is the most fundamental theory of matter available at present. Some basic concepts of quantum physics need to be understood. These include “superposition”, where in subatomic particles exist either as waves or particles in a dual nature, never simultaneously. They exist as waves in more than one place at a time and once an observer observes or interferes with (such as measuring) their superposition state collapses to particle state. Quantum entanglement is the phenomenon that occurs when a group of particles which are generated, interact with or share special proximity such that they remain connected even when separated by vast distances. Consciousness is a manifestation of quantum process. Q mind or Q consciousness comprises a group of hypotheses proposing that quantum mechanical phenomena such as entanglement and superposition may play an important part in the functions of the brain and could thus explain the origin of consciousness. Several theories of quantum consciousness have been proposed. Wigner proposed the idea that quantum mechanics has something to do with the workings of the mind and proposed that the wave function collapse in the interaction with conscious observation creates consciousness.[4] Vitiello and Freeman[5] proposed quantum field theory (QFT) of brain states. This theory deals with systems and provides formal elements from which a standard description of brain activity can be inferred. According to QFT, particles are only excited states or simply manifestations of a field. Every particle has its own field that covers all of the universe, which means that, according to QFT, all of the electrons of the universe belong to the same field and could be regarded as one. Bohm formulated the QFT as a deeper theory of quantum theory plus relativity.[6] He viewed mind and matter as projections into our explicate order underlying the implicate order. Quantum brain dynamics (QBD) hypothesis explains the function of the brain within the framework of QFT.[7] It is not yet known exactly how quantum superpositions and their collapse result in the genesis of the raw feels of consciousness, the qualia. Feynman stated ‘if you think you understand quantum mechanics then you do not!’[8] Pribram proposed the holonomic brain theory (quantum holography). He invoked quantum mechanics to explain the higher-order processing by the mind. Pribram provided evidence on how much of the processes in the brain take place in a distributed fashion.[9,10] The composite model of Pribram-Bohm of holoflux hypothesis addresses observed phenomenon of non-locality both spacially and temporally. Bose and Einstein, who first predicted Bose Einstein condensate proposed that water at dendritic membrane surfaces might operate by structuring condensation,[11] supporting QBD. Penrose and Hamoreff proposed the orchestrated-objective reduction (ORCH-OR) in 1989 through 2013. According to them, the microtubules in the neurons (neurotubules), the tubulin protein polymer at the site of quantum collapse, leads to conscious experience. The quantum superposed states which develop in the tubulins remain coherent and recruit more superposed tubulins until a mass-time-energy threshold is reached. At this point, self-collapse or objective reduction occurs, which is equated to a discrete conscious event. Cascades of ORCH-OR events give rise to the stream of consciousness.[12,13] Penrose suggested that objective reduction represents neither randomness nor algorithmic processing but instead a non-computable influence in spacetime geometry from which mathematical understanding and, by later extension, consciousness derives.[14] Quantum vibrations in the microtubules proposed by Bandyopadhyay[15] have been shown to be source of conscious experience by corroborating the Penrose-Hemeroff’s ORCH-OR hypothesis.[13,16] In April 2022, the results of two related experiments at the University of Alberta and Princeton University, announced at The Science of Consciousness conference, provided further evidence to support quantum processes operating within microtubules. However, in another experiment, Gregory D. Scholes and Aarat Kalra of Princeton University used lasers to excite molecules within tubulins, causing a prolonged excitation to diffuse through microtubules further than expected, which did not occur when repeated under anaesthesia.[17,18] Beck and Eccles considered quantum mechanics at the synaptic level. If Orchestrated objective reduction (ORCH-OR) theory is applicable, a similar phenomenon in the microtubules at the presynaptic level, the axon terminal could be invoked for the genesis of consciousness.[19] A recent study by scientists at Trinity College, Dublin, in October 2022,[20] suggests that quantum processes underlie the cognitive and conscious brain functions. The brain–mind operational architectonics is the boundary between and integration point of quantum physics and eastern metaphysics and that it may inspire building a richer and more inclusive paradigm of the brain–mind relation, where quantum physics and eastern metaphysics are inherently intertwined. A body of empirical evidence[21-24] supports these possibilities, strengthening the proposal that the mind–brain relationship may be partially quantum. Quantum information theory clarifies the distinction between the unobservable mind and the observable brain and supports a solid physical foundation for consciousness research. With all these theories trying to explain and understand the theoretical/hypothetical framework for consciousness to explain the subjective experience of consciousness, the experts of this field feel it is still a long way to bridge the gap between current neurobiological and physical–mathematical concepts with their associated quantum–mind theories. Though there is still a long way to go for explaining conscious experience scientifically, when ever this happens, it will become one of the benchmarks in science. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Use of artificial intelligence (AI)-assisted technology for manuscript preparation The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the preparation of the manuscript and no images were manipulated using AI.
I start from the fundamental principles of non-relativistic quantum mechanics, without probability, and interpret them using the notion of coexistence: a quantum state can be read, not uniquely, as a coexistence of other quantum states, which are pairwise orthogonal. In this formalism, I prove that a conscious observer is necessarily a physical object that can memorize local events by setting one of its parts in an exactly specified constant quantum state (hypotheses H1, H2 and H3). Then I define the probability of a future event as the proportion of initial observers, all identical, who will actually experience that event. It then becomes possible to establish the usual results of quantum mechanics. Furthermore, I detail the link between probabilities and relative frequencies. Additionally, I study the biological feasibility of this modelling of observer's mind. The second part of this paper completes the neuronal description of the mind functions, based on current neuroscientific knowledge. It provides a model that is compatible with the assumptions of the first part and consistent with our daily conscious experience. In particular, it develops a model of self-consciousness based on an explicit use of the random component of neuron behaviour; according to the first part, that random is in fact the coexistence of a multiplicity of possibilities. So, when the mind measures the random part of certain neurons in the brain, he goes himself within each of these possibilities. The mind has a decision-making component that is active in this situation, appearing then as the cause of the choice of this possibility among all the others. This models the self-consciousness which then ensures the unity of our conscious experience by equating this experience with ``what the ego is conscious about''. The conclusion details the points that remain to be developed.
Over the past decade, discussions of the roles that quantum mechanics might or might not play in the theory of consciousness/mind have become increasingly sharp. One side of this debate stand conventional neuroscientists who assert that brain science must look to the neuron for understanding, and on the other side are certain physicists, suggesting that the rules of quantum theory might influence the dynamics of consciousness/mind. However, consciousness and mind are not separate from matter. Submicroscopic world of the human brain give rise to consciousness, mind. We are never able to make a sharp separation between mind and matter. Thus ultimately there is no “mind” that can be separated from “matter” and no “matter” that can be separated from “mind”. The brain as a mixed physical system composed of the macroscopic neuron system and an additional microscopic system. The former consists of pathway conduction of neural impulses. The latter is assumed to be a quantum mechanical many-body system interacting with the macroscopic neuron system.