Orchestrated objective reduction
The quantum brain hypothesis à la Penrose & Hameroff
Christopher B. Germann (Marie Curie Alumnus / Ph.D., M.Sc., B.Sc.)
The eminent Oxford professor Sir Roger Penrose and anaesthesiologist Stuart Hameroff for-
mulated a neurophysiological model which postulates quantum processes within the neu-
ronal architecture of the brain. The hypothesis is based on the premise that the neuronal
cytoskeleton isolates microtubule (Conde & Cáceres, 2009) from the environment and that
it forms a protective shield which prevents decoherence from interfering with the extremely
fragile quantum processes (viz., through the process of Einselection
(Zurek, 2003)). Ac-
cording to the Orch-OR hypothesis, action potentials are generated when superpositional
quantum states at the microtubular level collapse. Each cortical dendrite contains micro-
tubule (located at the gap junction; see Figure 1) and this creates a network structure of
microtubule which can generate a coherent quantum state. The frequency of the micro-
tubular wave function collapse is hypothesised to lie within the EEG spectrum of approxi-
mately 40Hz, i.e., within the gamma range (Fitzgibbon, Pope, MacKenzie, Clark, &
Willoughby, 2004). The collapse of Ψ within neuronal dendritic-somatic microtubules is
thought to be the fundamental basis of consciousness. The frequency of collapse is esti-
mated to occur once every 25ms. Furthermore, the truly interdisciplinary Orch-OR theory
suggests a connection between brain biomolecular processes and fine-scale structure of the
universe(Penrose & Hameroff, 2011, p. 1), i.e., it postulates an intimate relation between
neuronal processes and space-time geometry. The theory explicitly raises the question if
the conscious mind [is] subtly linked to a basic level of the universe(Hameroff, 1998)? A
panpsychist perspective (Chalmers, 2015, 2016)
which is compatible with the Fechnerian
psychophysics point of view (as it links the psychological with the physical) and also with
the Vedāntic perspective on consciousness (Vaidya & Bilimoria, 2015). However, the theory
has been severely criticized (e.g., the decoherence problem) and is currently a hotly de-
bated topic (Hameroff & Penrose, 2014b, 2014c, 2014a; Rosa & Faber, 2004; Tegmark, 2000).
Id est, collapse of Ψ via “environmentally-induced Superselection” (Zurek, 2003). A large proportion of states in
the Hilbert space of a given quantum system are rendered unstable (decoherent) due to interactions with the
environment (thereby inducing collapse of the wavefunction) since every system is to a certain degree coupled
with the energetic state of its environment (entanglement between system and environment).
In a Hegelian fashion, Chalmers argues that “the thesis is materialism, the antithesis is dualism, and the
synthesis is panpsychism” (Chalmers, 2016).
Figure 1. Neuronal microtubules are composed of tubulin. The motor protein kinesin (pow-
ered by the hydrolysis of adenosine triphosphate, ATP) plays a central in vesicle transport
along the microtubule network (adapted from Stebbings, 2005).
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Hameroff, S., & Penrose, R. (2014a). Consciousness in the universe: A review of the
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Hameroff, S., & Penrose, R. (2014b). Reply to criticism of the “Orch OR qubit” -
“Orchestrated objective reduction” is scientifically justified. Physics of Life Reviews.
Hameroff, S., & Penrose, R. (2014c). Reply to seven commentaries on “Consciousness in
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Retrieved from
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