Some scientists think that we already understand consciousness or that it’s just an illusion. But it seems to many others that we haven’t even gotten close to the essence of consciousness at all. A long-standing puzzle called “consciousness” has even led some scientists to try to explain it using quantum physics. But their zeal was met with a fair amount of skepticism, and this is not surprising: it seems unwise to explain one mystery with the help of another. But such ideas have never been absurd, and they didn’t even come from the ceiling. On the one hand, to the great annoyance of physicists, the mind initially refuses to comprehend the early quantum theory. Moreover, quantum computers are predicted to be capable of things that conventional computers are not capable of. This reminds us that our brains are still capable of feats beyond the reach of artificial intelligence. “Quantum consciousness” is widely ridiculed as mystical nonsense, but no one has been able to completely dispel it.   Quantum mechanics is the best theory we have that can describe the world at the level of atoms and subatomic particles. Perhaps the most famous of her mysteries is the fact that the result of a quantum experiment can vary depending on whether we decide to measure the properties of the particles involved or not. When the pioneers of quantum theory first discovered this “observer effect,” they were seriously alarmed. It seemed to undermine the assumption underlying all of science: that there is an objective world out there, independent of us. If the world really behaves depending on how—or if—we look at it, what would “reality” really mean? Some scientists have been forced to conclude that objectivity is an illusion, and that consciousness should play an active role in quantum theory. Others simply didn’t see any common sense in it. For example, Albert Einstein was annoyed: does the moon really exist only when you look at it? Today, some physicists suspect that the point is not that consciousness influences quantum mechanics… but that it appeared at all, thanks to it. They believe that we may need quantum theory to understand how the brain works at all. Could it be that just as quantum objects can be in two places at the same time, so a quantum brain can simultaneously mean two mutually exclusive things? These ideas are controversial. It may turn out that quantum physics has nothing to do with the workings of consciousness. But at least they demonstrate that the strange quantum theory makes us think about strange things.   The best way quantum mechanics makes its way into human consciousness is through a double slit experiment. Imagine a ray of light falling on a screen with two closely spaced parallel slits. Some of the light passes through the slits and falls on another screen. You can represent light as a wave. When waves pass through two slits, as in the experiment, they collide — interfere — with each other. If their peaks coincide, they enhance each other, resulting in a series of black-and-white streaks of light on the second black screen. This experiment was used to show the wave nature of light for more than 200 years, until quantum theory appeared. Then the double slit experiment was conducted with quantum particles — electrons. These are tiny charged particles, the components of an atom. Inexplicably, these particles can behave like waves. That is, they are diffracted when a stream of particles passes through two slits, producing an interference pattern. Now let’s assume that quantum particles pass through the slits one after the other and their arrival on the screen will also be observed step by step. Now there is nothing obvious that would cause a particle to interfere in its path. But the pattern of particle hits will still show interference fringes. Everything indicates that each particle simultaneously passes through both slits and interferes with itself. This combination of the two paths is known as the superposition state. But here’s what’s weird.   If we place the detector in one of the slits or behind it, we could find out whether particles pass through it or not. But in this case, the interference disappears. The simple fact of observing the path of a particle — even if this observation should not interfere with the movement of the particle — changes the result. Physicist Pascual Jordan, who worked with quantum guru Niels Bohr in Copenhagen in the 1920s, put it this way: “Observations not only disrupt what needs to be measured, they define it.”… We are forcing a quantum particle to choose a certain position.” In other words, Jordan says that “we produce the measurement results ourselves.” If that’s the case, objective reality can just be thrown out the window. But the oddities don’t end there.   If nature changes its behavior depending on whether we look or not, we could try to trick it. To do this, we could measure which path the particle chose when passing through the double slit, but only after passing through it. By that time, she should have already “decided” whether to go through one path or both. Such an experiment was proposed by the American physicist John Wheeler in the 1970s, and in the next ten years an experiment with a “delayed choice” was conducted. It uses clever methods to measure the paths of quantum particles (typically light particles called photons) after they choose one path or a superposition of two.   It turned out that, as Bohr predicted, there is no difference whether we delay measurements or not. As long as we measure the path of the photon before it hits and registers in the detector, there is no interference. It seems that nature “knows” not only when we peek, but also when we plan to peek.   Eugene Wigner Whenever we discover the path of a quantum particle in these experiments, its cloud of possible routes is “compressed” into a single well-defined state. Moreover, the delayed experiment suggests that the very act of observation, without any physical intervention caused by measurement, can cause a collapse. Does this mean that true collapse occurs only when the result of the measurement reaches our consciousness? This possibility was proposed in the 1930s by the Hungarian physicist Eugene Wigner. “It follows that the quantum description of objects is influenced by impressions entering my consciousness,” he wrote. “Solipsism can be logically consistent with quantum mechanics.” Wheeler was even amused by the idea that the presence of living beings capable of “observing” transformed what had previously been a multitude of possible quantum pasts into one specific story. In this sense, Wheeler says, we become participants in the evolution of the universe from its very beginning. According to him, we live in a “complicit universe.” Physicists still cannot choose the best interpretation of these quantum experiments, and to some extent you have the right to do so. But, one way or another, the subtext is obvious: consciousness and quantum mechanics are somehow connected. Starting in the 1980s, English physicist Roger Penrose suggested that this connection could work in a different direction. He said that regardless of whether consciousness influences quantum mechanics or not, perhaps quantum mechanics is involved in consciousness.   Physicist and mathematician Roger Penrose Penrose also asked: what if there are molecular structures in our brain that can change their state in response to a single quantum event? Can these structures assume a superposition state, like the particles in the double slit experiment? Could these quantum superpositions then manifest themselves in how neurons communicate via electrical signals? Perhaps, Penrose said, our ability to maintain seemingly incompatible mental states is not a quirk of perception, but a real quantum effect? After all, the human brain seems to be able to process cognitive processes that are still far superior to digital computing machines. We may even be able to perform computational tasks that cannot be performed on ordinary computers using classical digital logic. Penrose first suggested that quantum effects are present in human consciousness in his 1989 book The Emperor’s New Mind. His main idea was “orchestrated objective reduction.” Objective reduction, according to Penrose, means that the collapse of quantum interference and superposition is a real physical process, like a bursting bubble. Orchestrated objective reduction relies on Penrose’s assumption that gravity, which affects everyday objects, chairs, or planets, does not exhibit quantum effects. Penrose believes that quantum superposition becomes impossible for objects larger than atoms, because their gravitational influence in this case would lead to the existence of two incompatible versions of space-time. Penrose further developed this idea with the American physician Stuart Hameroff. In his book Shadows of the Mind (1994), he suggested that the structures involved in this quantum cognition may be protein filaments called microtubules. They are present in most of our cells, including the neurons of the brain. Penrose and Hameroff argued that microtubules can assume a state of quantum superposition during the oscillation process. But there is nothing to support that this is even possible. It was assumed that the idea of quantum superpositions in microtubules would be supported by experiments proposed in 2013, but in fact, these studies did not mention quantum effects. In addition, most researchers believe that the idea of orchestrated objective reductions was debunked by a study published in 2000. Physicist Max Tegmark calculated that quantum superpositions of molecules involved in neural signals would not be able to exist even for a moment of the time needed to transmit the signal. Quantum effects, including superposition, are very fragile and break down in the process of so-called decoherence. This process is caused by the interactions of a quantum object with its environment, as its “quantality” leaks away. Decoherence was thought to occur extremely rapidly in warm and humid environments such as living cells. Nerve signals are electrical impulses caused by the passage of electrically charged atoms through the walls of nerve cells. If one of these atoms was in a superposition and then collided with a neuron, Tegmark showed that the superposition should decay in less than one billionth of a billionth of a second. It takes ten thousand trillion times longer for a neuron to release a signal. This is why ideas about quantum effects in the brain are not tested by skeptics. But Penrose inexorably insists on the OOR hypothesis. And despite the prediction of ultrafast Tegmark decoherence in cells, other scientists have found manifestations of quantum effects in living beings. Some argue that quantum mechanics is used by migratory birds that use magnetic navigation, and by green plants when they use sunlight to produce sugar during photosynthesis. At the same time, the idea that the brain can use quantum tricks refuses to go away forever. Because they found another argument in her favor.   Can phosphorus maintain a quantum state? In a 2015 study, physicist Matthew Fisher of the University of California, Santa Barbara, argued that the brain may contain molecules capable of withstanding more powerful quantum superpositions. In particular, he believes that the nuclei of phosphorus atoms may have this ability. Phosphorus atoms are found everywhere in living cells. They often take the form of phosphate ions, in which one phosphorus atom combines with four oxygen atoms. Such ions are the basic unit of energy in cells. Most of the cell’s energy is stored in ATP molecules, which contain a sequence of three phosphate groups connected to an organic molecule. When one of the phosphates is cut off, energy is released, which is used by the cell. Cells have molecular machines for assembling phosphate ions into groups and for splitting them. Fischer proposed a scheme in which two phosphate ions can be placed in a certain type of superposition: in an entangled state. Phosphorus nuclei have a quantum property — spin — that makes them look like small magnets with poles pointing in certain directions. In the entangled state, the spin of one phosphorus nucleus depends on the other. In other words, entangled states are superposition states involving more than one quantum particle. Fischer says that the quantum mechanical behavior of these nuclear spins can resist decoherence. He agrees with Tegmark that the quantum vibrations mentioned by Penrose and Hameroff will be highly dependent on their environment and “decode almost immediately.” But the spins of the nuclei do not interact so much with their surroundings. Nevertheless, the quantum behavior of the spins of phosphorus nuclei must be “protected” from decoherence.   Quantum particles can have different spins. This can happen, Fischer says, if phosphorus atoms are incorporated into larger objects called “Posner molecules.” They are clusters of six phosphate ions combined with nine calcium ions. There are definite indications that such molecules may be present in living cells, but so far they are not very convincing. In Posner’s molecules, Fischer argues, phosphorus spins can resist decoherence for a day or so, even in living cells. Therefore, they can also affect brain function. The idea is that Posner molecules can be absorbed by neurons. Once inside, the molecules will activate a signal to another neuron, breaking up and releasing calcium ions. Due to the entanglement in Posner’s molecules, two such signals can become entangled in turn: in a way, it will be a quantum superposition of “thought”. “If nuclear-spin quantum processing is actually present in the brain, it would be an extremely common phenomenon that happens all the time,” says Fisher. The idea first came to him when he was thinking about mental illness. Lithium Carbonate Capsule “My introduction to the biochemistry of the brain began when I decided three or four years ago to investigate how and why lithium ion has such a radical effect in the treatment of mental disorders,” says Fisher. Lithium drugs are widely used to treat bipolar disorder. They work, but no one really knows why. “I wasn’t looking for a quantum explanation,” says Fischer. But then he came across a paper that described how lithium preparations had different effects on rat behavior, depending on which form—or “isotope”—of lithium was used. At first, this puzzled scientists. From a chemical point of view, different isotopes behave almost identically, so if lithium worked like a regular drug, the isotopes should have had the same effect.   Nerve cells are connected to synapses But Fischer realized that the nuclei of atoms of different lithium isotopes can have different spins. This quantum property may influence how lithium-based drugs work. For example, if lithium replaces calcium in Posner molecules, lithium spins can have an effect on phosphorus atoms and prevent them from entangling. If this is true, it could also explain why lithium can treat bipolar disorder. At the moment, Fischer’s suggestion is nothing more than an intriguing idea. But there are several ways to check it. For example, that phosphorus spins in Posner molecules can maintain quantum coherence for a long time. This is what Fischer plans to check further. Nevertheless, he fears being associated with earlier ideas about “quantum consciousness,” which he considers speculative at best.   Consciousness is a deep mystery Physicists don’t really like being inside their own theories. Many of them hope that consciousness and the brain can be extracted from quantum theory, or maybe vice versa. But we don’t know what consciousness is, let alone that we don’t have a theory that describes it. Moreover, there are occasional loud shouts that quantum mechanics will allow us to master telepathy and telekinesis (and although this may be true somewhere deep in the concepts, people take everything too literally). That’s why physicists are generally afraid to mention the words “quantum” and “consciousness” in the same sentence. In 2016, Adrian Kent of the University of Cambridge in the UK, one of the most respected “quantum philosophers”, suggested that consciousness can change the behavior of quantum systems in subtle but quite detectable ways. Kent is very careful in his statements. “There is no convincing reason to believe that quantum theory is a suitable theory from which to extract a theory of consciousness, or that the problems of quantum theory should somehow overlap with the problem of consciousness,” he admits. But he adds that it is completely unclear how a description of consciousness can be derived based solely on pre-quantum physics, how to describe all its properties and features.   We don’t understand how thoughts work. One particularly exciting question is how our conscious minds can experience unique sensations like the color red or the smell of frying meat. Except for people with visual impairments, we all know what red looks like, but we can’t convey that feeling, and there’s nothing in physics that can tell us what it looks like. Feelings like these are called “qualia.” We perceive them as unified properties of the external world, but in fact they are products of our consciousness — and it is difficult to explain this. In 1995, the philosopher David Chalmers called this the “grave problem” of consciousness. “Any thought chain about the connection of consciousness with physics leads to serious problems,” says Kent. This led him to suggest that “we could make some progress in understanding the problem of the evolution of consciousness if we allowed (at least just allowed) that consciousness changes quantum probabilities.”   In other words, the brain can actually influence the measurement results. From this point of view, he does not define “what is real.” But it can influence the probability that each of the possible realities imposed by quantum mechanics will be observed. Even quantum theory itself cannot predict this. And Kent believes that we could look for such manifestations experimentally. He even boldly estimates the chances of finding them. “I would assume with 15 percent certainty that consciousness causes deviations from quantum theory; and another 3 percent certainty that we will experimentally confirm this in the next 50 years,” he says. If that happens, the world won’t be the same anymore. And it’s worth exploring for that. Author: Ilya Khel.