The origin of consciousness is one of the greatest mysteries of science. A proposed solution, first proposed by Nobel laureate and mathematician Roger Penrose of Oxford and anesthetist Stuart Hammeroff of Arizona State University in Tucson, attributes consciousness to quantum computations in the brain. This, in turn, depends on the idea that gravity could play a role in how quantum effects disappear or “collapse.” But a series of experiments in a lab deep beneath the Gran Sasso Mountains, in Italy, have found no evidence to support a gravity-related model for quantum collapse, undermining the feasibility of this explanation for consciousness. The result is reported in the journal Physics of Life Reviews†
“How consciousness arises in the brain is a huge puzzle,” said Catalina Curceanu, a member of the physics think tank, the Foundational Questions Institute, FQXi, and the lead physicist of experiments at INFN in Frascati, Italy. “There are many competing ideas, but few that can be tested experimentally.”
Quantum physics famously tells us that cats can be alive and dead at the same time, at least in theory. But in practice, we never see cats cooped up in such an unfortunate limbo state. A popular explanation for why not is that a system’s “wave function” – the quantum nature that makes it in two conflicting states at the same time – is more likely to “collapse” or be destroyed if it is more massive, leaving it in a defined state, either dead or alive, shall we say, but not both at the same time. This model of collapse, related to the gravity acting on heavy objects such as cats, was invoked by Penrose and Hammeroff when developing their consciousness model, ‘Orch OR theory’ (the Orchestrated Objective Reduction theory), in the 1990s.
Quantum calculations in the brain
Curceanu first became interested in Orch OR theory when she met Penrose, also an FQXi member, at a conference several years ago. Consciousness is not usually associated with quantum properties because quantum effects are fragile and difficult to maintain, even under highly controlled conditions and cold temperatures in the lab. So it was long believed that the warm and wet environment of the brain would be too disruptive for quantum effects to survive. But Penrose explained that he and Hammeroff have identified tiny structures called microtubules in neurons in the brain that could potentially sustain quantum effects for short periods of time — just long enough to perform quantum computations. Orch OR theory attributes consciousness to quantum computations that are orchestrated (“Orch”) by electrical oscillations in these microtubules. “What I liked about this theory was that it’s basically testable, and I decided to look for evidence that could help confirm or falsify it,” Curceanu says.
“What I liked about this theory was that it’s basically testable and I decided to look for evidence that could help confirm or falsify it.”
The core of the theory is the idea that gravity is related to the collapse of the quantum wave function and that this collapse is faster in systems with more mass. This concept was developed in a number of models by various physicists in the 1980s. One of them was Lajos Diósi, affiliated with the Wigner Research Center for Physics and Eötvös Loránd University in Budapest, Hungary, who, together with Curceanu, Maaneli Derakhshani of Rutgers University in New Brunswick, New Jersey, and Matthias Laubenstein, developed the new article wrote. also at INFN, and Kristian Piscicchia of CREF and INFN. Penrose independently approached this idea a few years later and it became the core of his theory of consciousness with Hammeroff.
The two theories are often referred to by the umbrella term, the ‘Diósi-Penrose theory’. But there’s an important difference behind the joint name, Curceanu notes. Diósi’s approach predicts that collapse would involve the spontaneous emission of a small amount of radiation, just large enough to be detected by advanced experiments.
The Curceanu Underground Laboratory is located in the Gran Sasso National Laboratory, 1.4 km below Italy’s Gran Sasso mountains. The lab is on one side of the 10km highway tunnel that crosses the Gran Sasso massif, connecting L’Aquila to Teramo. “The location was chosen because it is basically free of radiation sources of cosmic rays above the ground, which could interfere with the experiment,” said Curceanu. The experiment uses a highly sensitive cylindrical detector, not much larger than a mug, made of high-purity germanium. It is surrounded by a shield, made of layers of ultra-pure lead and copper, to protect it from background radiation coming from the rocks. After running the experiment for two months, the team measured no spontaneous radiation signals, limiting the feasibility of gravity-related collapse. In 2020, the team reported in Nature physics that their negative result had helped them rule out the simplest version of the Diósi-Penrose model.
In their new paper, they explicitly explored the implications of their finding for Penrose and Hammeroff’s Orch OR theory of consciousness. After a re-analysis of Hammeroff and Penrose’s most plausible scenarios, in light of their recent experimental limitations on quantum collapse, they concluded that almost none of the scenarios are plausible. “This is the first experimental investigation of the gravity-related quantum collapse pillar of the Orch OR consciousness model, which we hope will be followed by many others,” said Curceanu. “I am very proud of our achievement.”
The experiments and analysis are funded in part by a grant from the Foundational Questions Institute, FQXi. “Without it, it would not have been possible to achieve this result,” says Curceanu. “It’s hard to get funding for projects like this otherwise, because of their interdisciplinary characteristics.”
“It’s really exciting to link what you can do in the lab with perhaps the greatest mystery in the universe: consciousness.”
But all is not lost for Orch Or, Curceanu adds. “Actually, the real work is just getting started.” she says. In fact, unlike Diósi’s, Penrose’s original collapse model did not predict spontaneous radiation, so it cannot be ruled out. The new article also briefly discusses how to realistically adjust a gravity-related collapse model. “Such a revised model, which we are working on within the FQXi-funded project, could open the door to the Orch OR theory,” said Curceanu.
Meanwhile, the team is preparing to test these sophisticated new collapse models, to further explore their implications for the Orch OR model. “It’s really exciting to link what you can do in the lab with perhaps the greatest mystery in the universe: consciousness,” Curceanu says.
Deconstructing Schrödinger’s Cat
Maaneli Derakhshani et al, At the intersection of the search for spontaneous radiation and the Orch OR theory of consciousness, Physics of Life Reviews (2022). DOI: 10.116/j.plrev.2022.05.004
Provided by Foundational Questions Institute
Quote: The Collapse of a Leading Theory for the Quantum Origin of Consciousness (2022, June 13) retrieved June 13, 2022 from https://phys.org/news/2022-06-collapsing-theory-quantum-consciousness.html
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