Most scientists regard quantum mechanics as irrelevant to our understanding of how the brain works. Still, it’s not hard to see why Penrose’s theory has gained attention. Artificial intelligence experts have been predicting some sort of computer brain for decades, with little to show so far. And for all the recent advances in neurobiology, we seem no closer to solving the mind-brain problem than we were a century ago. Even if the human brain’s neurons, synapses and neurotransmitters could be completely mapped—which would be one of the great triumphs in the history of science—it’s not clear that we’d be any closer to explaining how this 3-pound mass of wet tissue generates the immaterial world of our thoughts and feelings. Something seems to be missing in current theories of consciousness. The philosopher David Chalmers has speculated that consciousness may be a fundamental property of nature existing outside the known laws of physics. Others—often branded “mysterians”—claim that subjective experience is simply beyond the capacity of science to explain.[...]
Still, you’d need more than just a continuous flood of random moments of quantum coherence to have any impact on consciousness. The process would need to be structured, or orchestrated, in some way so we can make conscious choices. In the Penrose-Hameroff theory of Orchestrated Objective Reduction, known as Orch-OR, these moments of conscious awareness are orchestrated by the microtubules in our brains, which—they believe—have the capacity to store and process information and memory. [...]
This is a heady brew, but unconvincing to critics. Most scientists believe the brain is too warm and wet for quantum states to have any influence on neuronal activity because quantum coherence only seems possible in highly protected and frigid environments. The most damning critique has come from Max Tegmark, a professor of physics at the Massachusetts Institute of Technology, who calculated that any quantum effects within microtubules would break down after 100 quadrillionths of a second. “For my thoughts to correspond to a quantum computation, they’d need to finish before decoherence kicked in, so I’d need to be able to think fast enough to have 10,000,000,000,000 thoughts each second,” Tegmark writes in his 2014 book Our Mathematical Universe: My Quest for the Ultimate Nature of Reality. “Perhaps Roger Penrose can think that fast, but I sure can’t.” Even Penrose’s old collaborator Stephen Hawking is dubious. “I get uneasy when people, especially theoretical physicists, talk about consciousness,” he’s written. “His argument seemed to be that consciousness is a mystery and quantum gravity is another mystery so they must be related.” Penrose dismisses Hawking’s criticism, saying their disagreement is really about the nature of quantum mechanics.
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