Roger Penrose On Why Consciousness Does Not Compute

[Note:  This item comes from friend Robert Berger.  DLH]

Roger Penrose On Why Consciousness Does Not Compute
The emperor of physics defends his controversial theory of mind.
May 4 2017

Once you start poking around in the muck of consciousness studies, you will soon encounter the specter of Sir Roger Penrose, the renowned Oxford physicist with an audacious—and quite possibly crackpot—theory about the quantum origins of consciousness. He believes we must go beyond neuroscience and into the mysterious world of quantum mechanics to explain our rich mental life. No one quite knows what to make of this theory, developed with the American anesthesiologist Stuart Hameroff, but conventional wisdom goes something like this: Their theory is almost certainly wrong, but since Penrose is so brilliant (“One of the very few people I’ve met in my life who, without reservation, I call a genius,” physicist Lee Smolin has said), we’d be foolish to dismiss their theory out of hand.

Penrose, 85, is a mathematical physicist who made his name decades ago with groundbreaking work in general relativity and then, working with Stephen Hawking, helped conceptualize black holes and gravitational singularities, a point of infinite density out of which the universe may have formed. He also invented “twistor theory,” a new way to connect quantum mechanics with the structure of spacetime. His discovery of certain geometric forms known as “Penrose tiles”—an ingenious design of non-repeating patterns—led to new directions of study in mathematics and crystallography.

The breadth of Penrose’s interests is extraordinary, which is evident in his recent book Fashion, Faith and Fantasy in the New Physics of the Universe—a dense 500-page tome that challenges some of the trendiest but still unproven theories in physics, from the multiple dimensions of string theory to cosmic inflation in the first moment of the Big Bang. He considers these theories to be fanciful and implausible.

Penrose doesn’t seem to mind being branded a maverick, though he disputes the label in regard to his work in physics. But his theory of consciousness pushes the edges of what’s considered plausible science and has left critics wondering why he embraces a theory based on so little evidence.

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.

Penrose’s theory promises a deeper level of explanation. He starts with the premise that consciousness is not computational, and it’s beyond anything that neuroscience, biology, or physics can now explain. “We need a major revolution in our understanding of the physical world in order to accommodate consciousness,” Penrose told me in a recent interview. “The most likely place, if we’re not going to go outside physics altogether, is in this big unknown—namely, making sense of quantum mechanics.”

He draws on the basic properties of quantum computing, in which bits (qubits) of information can be in multiple states—for instance, in the “on” or “off” position—at the same time. These quantum states exist simultaneously—the “superposition”—before coalescing into a single, almost instantaneous, calculation. Quantum coherence occurs when a huge number of things—say, a whole system of electrons—act together in one quantum state.

It was Hameroff’s idea that quantum coherence happens in microtubules, protein structures inside the brain’s neurons. And what are microtubules, you ask? They are tubular structures inside eukaryotic cells (part of the cytoskeleton) that play a role in determining the cell’s shape, as well as its movements, which includes cell division—separation of chromosomes during mitosis. Hameroff suggests that microtubules are the quantum device that Penrose had been looking for in his theory. In neurons, microtubules help control the strength of synaptic connections, and their tube-like shape might protect them from the surrounding noise of the larger neuron. The microtubules’ symmetry and lattice structure are of particular interest to Penrose. He believes “this reeks of something quantum mechanical.”



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