Orch-OR
Orchestrated objective reduction
The quantum brain hypothesis à la Penrose & Hameroff
Christopher B. Germann (Marie Curie Alumnus / Ph.D., M.Sc., B.Sc.)
2019
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”
1
(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)
2
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).
1
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).
2
In a Hegelian fashion, Chalmers argues that “the thesis is materialism, the antithesis is dualism, and the
synthesis is panpsychism” (Chalmers, 2016).