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Quantum mechanics and the puzzle of human consciousness

Exploring how quantum processes in the brain might shape our experiences.

Graphic of a brain surrounded by a network of interconnected lines and nodes that suggest neural activity or connections. The background is filled with mathematical equations and formulas in white against a blue digital space, conveying a theme of intelligence, data processing, or scientific analysis.

Deep down, your brain is an ensemble of the smallest bits of matter in the universe.

These subatomic particles don’t play by the rules of the everyday world. They obey quantum physics—the mind-bending theory that posits objects can exist in multiple states at once and entangled atoms can instantaneously interact across vast distances.

Some scientists speculate that the strange happenings in this microscopic realm may hold the key to understanding consciousness. But scant evidence has left the majority skeptical.

That includes Christof Koch, Ph.D., meritorious investigator at the Allen Institute. As he wrote in his recent book, Then I am myself the world, “the brain is wet and warm, hardly conducive to subtle quantum interactions.”

But despite his skepticism, Koch is collaborating with scientists at Google Quantum AI and universities worldwide to explore the role quantum mechanics might play in shaping consciousness. A paper published in Entropy offers their novel theory on the links between quantum mechanics and consciousness and details a series of experiments to test it.

Some of those experiments—like linking a human brain to a quantum processor—are currently impossible. But other studies are actively pursuing signs of quantum activity within the brain, with results expected within the next few years.

Koch, who has spent decades studying the link between the physical matter in our brains and our conscious minds, remains open to unexpected discoveries.

“Anything that isn’t ruled out by the laws of physics can be exploited by evolution,” Koch said. “Evolution is very clever and has had the entire planet to play with for 4.5 billion years, so it’s possible.”

Clues of quantum minds?

Various theories have tried to explain how quantum physics might play a role in consciousness. Most hinge on the idea of superposition, where particles like electrons, photons, or maybe even the cat of the physicist Erwin Schrödinger, of the eponymous equation, can be in two or more states or positions at the same time. When observed, the state or position of these particle “collapses” and the system is in one definite state or location.

Christof Koch standing in building

Despite his skepticism, Koch is collaborating with scientists at Google Quantum AI and universities worldwide to explore the role quantum mechanics might play in shaping consciousness. Photo by Erik Dinnel / Allen Institute

Roger Penrose, a Nobel Prize winning cosmologist, has suggested that each collapse of a quantum superposition creates a moment of “proto-conscious.” Penrose, together with the anesthesiologist Stuart Hameroff, posit that small structures in our neurons (and other cells), called microtubules, might weave these moments together into full consciousness.

Koch and team drew upon Penrose’s theory but propose the opposite—that conscious experience arises whenever a quantum superposition forms. That avoids the possibility of faster-than-light travel implied in the original theory, Koch said.

It also implies a graded model of consciousness, where the complexity of consciousness correlates with the number of potential states in a superposition. Which isn’t surprising, Koch said; we’ve all observed the development of consciousness from infancy to adulthood. What is perhaps more surprising is that this also implies that at least simple forms of consciousness are far more widespread than conventionally assumed.

Other consequences are even harder to digest.

“It’s total science fiction right now, but if you could couple your brain with a quantum computer, achieving entanglement between the brain and the computer, you could expand your consciousness,” Koch said.

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What makes science uniquely powerful is that you can have strongly held opinions, but you can test things by asking Nature a question.

That experiment is on the team’s proposed to-do list, though Koch says it’s unlikely in his lifetime. Instead, they are starting a bit smaller.

In a 2018 study, researchers in China explored how four forms of xenon, a noble gas with known anesthetic properties, affected consciousness. These forms or isotopes of xenon, were chemically identical but differed in their “spin,” a quantum property tied to particle momentum.

Intriguingly, the researchers observed different anesthetic effects in mice. The finding suggested a link between quantum processes and the modulation of consciousness.

Koch and his collaborators hypothesize that the xenon form with a larger “spin” value might create larger superpositions, correlating with more complex conscious experiences. This could counteract anesthetic effects, explaining the observed differences. They are now trying to replicate the 2018 results in flies and lab-grown human brain cells. If they do, the results just might shatter Koch’s skepticism.

Those are big ifs. Koch notes the profound differences between the frigid conditions necessary for today’s quantum computers—colder than the vacuum of outer space—and the brain’s warm, wet environment. Many believe that setting simply can’t sustain quantum processes, let alone those related to consciousness.

Still, he says, “what makes science uniquely powerful is that you can have strongly held opinions, but you can test things by asking Nature a question.”

Lead image created by AI using Image Creator from Microsoft Designer.

About the Allen Institute

The Allen Institute is an independent, 501(c)(3) nonprofit research organization founded by philanthropist and visionary, the late Paul G. Allen. The Allen Institute is dedicated to answering some of the biggest questions in bioscience and accelerating research worldwide. The Institute is a recognized leader in large-scale research with a commitment to an open science model. Its research institutes and programs include the Allen Institute for Brain Science, launched in 2003; the Allen Institute for Cell Science, launched in 2014; the Allen Institute for Immunology, launched in 2018; and the Allen Institute for Neural Dynamics, launched in 2021. In 2016, the Allen Institute expanded its reach with the launch of The Paul G. Allen Frontiers Group, which identifies pioneers with new ideas to expand the boundaries of knowledge and make the world better. For more information, visit alleninstitute.org.

Science Programs at Allen Institute