Chapter
Five
The theatre
a controlled way. This kind of stable isolation is normally
possible only at extremely low temperatures.
Where in the brain could such a process, requiring such
particular conditions of stability, be going on? Penrose
builds on the suggestion first made by American anaesthe-
siologist Stuart Hameroff that consciousness emerges from
quantum coherence in the microtubules. Microtubules are,
as their name suggests, tiny tube-like proteins found in
almost all cells of the body. They are involved in support-
ing the cell’s structure, in cell division, and in transporting
organelles within the cell. Hameroff and Penrose propose
them as the site of non-algorithmic quantum computing
because of their shape and the spiral structure of their
walls, and because any quantum-coherent effect within
them could be kept reasonably isolated from the outside.
Why is this relevant to consciousness? Hameroff argues that
the real problems for understanding consciousness include
the unitary sense of self, free will, and the effects of anaes-
thesia, as well as non-algorithmic, intuitive processing. All these, he claims, can be
explained by quantum coherence in the microtubules. Nonlocality can bring about
the unity of consciousness, quantum indeterminacy accounts for free will, and
non-algorithmic processing, or quantum computing, is done by quantum superpo-
sition. So, it is in the microtubules that not only your experience of the traffic light on
red is generated, but also your sense that it is ‘you’ who experiences the red, and you
who freely decide to stop the car when you see it.
In 2014, Hameroff and Penrose published new evidence in support of the theory,
including a claim to have identified microtubule ‘quantum channels’ in which
anesthetics erase consciousness, as well as warm quantum vibrations in brain
microtubules, and links between the ‘beat frequencies’ of microtubules and the
gamma synchrony found in EEG. Among many commentators on the 2014 paper,
Deepak Chopra contrasts mind-first theories that have trouble explaining matter
against matter-first theories (including this one) that struggle to explain mind.
Hameroff and Penrose respond that quantum events indicate an ‘invisible agency
(consciousness)’ (p. 96) producing intelligent activity at the interface where
space-time emerges. Responding to others, they agree that the current model
of neuronal functions is inadequate, that parts of the human mind are non-com-
putable, and that without an account of consciousness, the universe remains ‘as
mysterious as ever’ (p. 98).
A sticking point has always been whether quantum coherence could survive in
a warm, wet brain. Hameroff and Penrose argue that biology can use thermal
energy to drive coherence, while physicist Matthew Fisher (2015) has proposed
that the nuclear spins of phosphorus atoms in the brain could allow it to function
as a quantum computer. But if the brain is a quantum computer, does this tell us
anything about consciousness?
More generally, we might question whether this quantum theory doesn’t just
replace one mystery (subjective experience) with another (quantum coherence
‘consciousness depends
on biologically
“orchestrated” coherent
quantum processes
in collections of
microtubules within
brain neurons’(Hameroff and Penrose, 2014, p. 39)FIGURE 5.8 • Penrose and Hameroff argue
that consciousness emerges
from quantum coherence in the
microtubules. Microtubules are
structural proteins in cell walls.
They are shaped like a hollow tube
with a spiral structure in their walls
(Penrose, 1994b).