Orchestrated objective reduction

Orchestrated objective reduction (Orch OR) is a theory postulating that consciousness originates at the quantum level inside neurons (rather than being a product of neural connections).

[1] The hypothesis was first put forward in the early 1990s by Nobel laureate for physics Roger Penrose, and anaesthesiologist Stuart Hameroff.

[17] In his first book concerning consciousness, The Emperor's New Mind (1989), Roger Penrose argued that equivalent statements to "Gödel-type propositions" had recently been put forward.

Penrose proposed that isolated systems may still undergo a new form of wave function collapse, which he called objective reduction (OR).

In Shadows of the Mind (1994), Penrose briefly indicates that this Platonic world could also include aesthetic and ethical values, but he does not commit to this further hypothesis.

[29] Feferman argued that mathematicians do not progress by mechanistic search through proofs, but by trial-and-error reasoning, insight and inspiration, and that machines do not share this approach with humans.

[21] Penrose outlined a predecessor to Orch OR in The Emperor's New Mind, coming to the problem from a mathematical viewpoint and in particular Gödel's theorem, but lacked a detailed proposal for how quantum processes could be implemented in the brain.

Hameroff read Penrose's book and suggested to him that microtubules within neurons were suitable candidate sites for quantum processing, and ultimately for consciousness.

In addition to providing structural support, microtubule functions include axoplasmic transport and control of the cell's movement, growth and shape.

It proposes that when condensates in the brain undergo an objective wave function reduction, their collapse connects noncomputational decision-making to experiences embedded in spacetime's fundamental geometry.

[36][37] Hameroff proposed that the gap between the cells is sufficiently small that quantum objects can tunnel across it, allowing them to extend across a large area of the brain.

[38] In a study Hameroff was part of, Jack Tuszyński of the University of Alberta demonstrated that anesthetics hasten the duration of a process called delayed luminescence, in which microtubules and tubulins re-emit trapped light.

It took very precise and careful application of standard protein spectroscopy methods, but guided by the theoretical predictions of our collaborators, we were able to confirm a stunning signature of superradiance in a micron-scale biological system.

"[39] The study states that "by analyzing the coupling with the electromagnetic field of mega-networks of tryptophans present in these biologically relevant architectures, we find the emergence of collective quantum optical effects, namely, superradiant and subradiant eigenmodes. ...

our work demonstrates that collective and cooperative UV excitations in mega-networks of tryptophans support robust quantum states in protein aggregates, with observed consequences even under thermal equilibrium conditions.

[49] A highly disputed theory put forth in the mid-1990s by Hameroff and Penrose posits that consciousness is based on quantum vibrations in tubulin/microtubules inside brain neurons.

Computer modeling of tubulin's atomic structure[50] found that anesthetic gas molecules bind adjacent to amino acid aromatic rings of non-polar π-electrons and that collective quantum dipole oscillations among all π-electron resonance rings in each tubulin showed a spectrum with a common mode peak at 613 THz.

[52] In a study published in August 2024, an undergraduate group led by a Wellesley College professor found that rats given epothilone B, a drug that binds to microtubules, took over a minute longer to fall unconscious when exposed to an anesthetic gas.

[64] In 2000 Max Tegmark claimed that any quantum coherent system in the brain would undergo effective wave function collapse due to environmental interaction long before it could influence neural processes (the "warm, wet and noisy" argument, as it later came to be known).

Earlier versions of the theory had required tubulin-electrons to form either Bose–Einsteins or Frohlich condensates, and the Reimers group noted the lack of empirical evidence that such could occur.

McKemmish et al. argued that aromatic molecules cannot switch states because they are delocalised; and that changes in tubulin protein-conformation driven by GTP conversion would result in a prohibitive energy requirement.

[67][68] Biology-based criticisms have been offered, including a lack of explanation for the probabilistic release of neurotransmitter from presynaptic axon terminals[69][70][71] and an error in the calculated number of the tubulin dimers per cortical neuron.

[72] In 2014, Penrose and Hameroff published responses to some criticisms and revisions to many of the theory's peripheral assumptions, while retaining the core hypothesis.