Nobody understands what consciousness is and how it works. Nobody understands quantum mechanics either. Could this be more than just a coincidence? "I cannot identify the real problem, so I suspect there is no real problem, but I am not sure there is no real problem." American physicist Richard Feynman said this about the mysterious paradoxes of quantum mechanics. Today physicists use this theory to describe the smallest objects in the universe. But he could say the same about the intricate problem of consciousness.
Some scientists think that we already understand consciousness or that it is just an illusion. But many others think that we have not even gotten close to the essence of consciousness.
A perennial 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 unreasonable to explain one riddle with another.
But such ideas are never absurd and not even from the ceiling.
On the one hand, much to the dismay 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 cannot. 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 for describing the world at the level of atoms and subatomic particles. Perhaps the most famous of its mysteries is the fact that the result of a quantum experiment can change depending on whether we decide to measure the properties of the particles involved in it or not.
When the pioneers of quantum theory first discovered this "observer effect," they were alarmed in earnest. It seemed to undermine the assumption underlying all science: that there is an objective world out there, independent of us. If the world does behave depending on how - or if - we look at it, what would "reality" really mean?
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Some scientists have been forced to conclude that objectivity is an illusion and that consciousness must play an active role in quantum theory. Others simply did not see any common sense in this. For example, Albert Einstein was annoyed: does the moon exist only when you look at it?
Today, some physicists suspect that it is not that consciousness affects quantum mechanics … but that it even came about 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 weird quantum theory makes us think weird things.
Best of all, quantum mechanics makes its way into human consciousness through a double-slit experiment. Imagine a beam of light striking a screen with two closely spaced parallel slits. Some of the light passes through the slits and falls on another screen.
You can think of light as a wave. When waves pass through two slits, as in an experiment, they collide - interfere - with each other. If their peaks match, they reinforce each other, resulting in a series of black and white streaks of light on a second black screen.
This experiment was used to show the wave nature of light for over 200 years before quantum theory emerged. Then the experiment with a double slit was carried out with quantum particles - electrons. These are tiny charged particles, components of an atom. In an incomprehensible way, but 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 suppose that quantum particles pass through the slits one by one and their arrival on the screen will also be observed step by step. Now there is nothing obvious that would cause the particle to interfere in its path. But the picture of the particles hitting will still show 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 state of superposition.
But here's what's strange.
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 mere 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 violate what should be measured, they determine it … We force the quantum particle to choose a certain position." In other words, Jordan says that "we make our own measurements."
If so, objective reality can simply be thrown out the window.
But the oddities don't end there.
If nature changes its behavior depending on whether we are looking or not, we could try to twist it around our fingers. To do this, we could measure which path the particle took when passing through the double slit, but only after passing through it. By that time, she should already "decide" whether to go through one path or through both.
An American physicist John Wheeler proposed such an experiment in the 1970s, and over the next ten years, an experiment with "delayed choice" was carried out. It uses clever methods to measure the paths of quantum particles (usually light particles - photons) after they choose one path, or a superposition of two.
It turned out that, as Bohr predicted, it makes no difference whether we delay the measurements or not. As long as we measure the path of the photon before it hits and register in the detector, there is no interference. It seems that nature "knows" not only when we are peeping, but also when we are planning to peep.
Eugene Wigner
Whenever in these experiments we discover the path of a quantum particle, its cloud of possible routes "shrinks" into a single well-defined state. Moreover, a delayed experiment suggests that the very act of observing, without any physical intervention caused by the measurement, can cause collapse. Does this mean that true collapse occurs only when the measurement result reaches our consciousness?
This possibility was proposed in the 1930s by the Hungarian physicist Eugene Wigner. "It follows from this that the quantum description of objects is influenced by the 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 things capable of "observing" transformed what was previously a multitude of possible quantum past into one concrete story. In this sense, Wheeler says, we become participants in the evolution of the universe from the 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 are entitled to do so. But one way or another, the subtext is obvious: consciousness and quantum mechanics are somehow connected.
Beginning in the 1980s, English physicist Roger Penrose suggested that this connection might work in a different direction. He said that whether consciousness affects quantum mechanics or not, perhaps quantum mechanics is involved in consciousness.
Physicist and mathematician Roger Penrose
And Penrose also asked: what if there are molecular structures in our brain that can change their state in response to one quantum event? Can these structures take on a superposition state, like the particles in the double slit experiment? Could these quantum superpositions then manifest themselves in the way neurons communicate through electrical signals?
Maybe, Penrose said, our ability to maintain seemingly incompatible mental states is not a perceptual quirk, 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 computers in capabilities. 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 the human mind 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 that 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 would then lead to the existence of two incompatible versions of spacetime.
Then Penrose 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 could be protein filaments - microtubules. They are found in most of our cells, including the neurons of the brain. Penrose and Hameroff argued that during the oscillation process, microtubules can assume a state of quantum superposition.
But there is nothing to suggest that this is possible at all.
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 the moment required for signal transmission.
Quantum effects, including superposition, are very fragile and are destroyed in a process called decoherence. This process is due to the interactions of a quantum object with its environment, since its "quantum" is leaking out.
Decoherence was believed to be extremely fast 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 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 emit a signal.
This is why ideas about quantum effects in the brain are not being tested by skeptics.
But Penrose relentlessly insists on the OER hypothesis. And despite the prediction of Tegmark's ultrafast decoherence in cells, other scientists have found manifestations of quantum effects in living things. Some argue that quantum mechanics is used by migratory birds, which use magnetic navigation, and green plants, when they use sunlight to make sugar through photosynthesis.
That said, the idea that the brain can use quantum tricks refuses to go away. Because they found another argument in its 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 that can withstand 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 main unit of energy in cells. Most of the cell's energy is stored in ATP molecules, which contain a sequence of three phosphate groups attached to an organic molecule. When one of the phosphates is cut off, energy is released that is used by the cell.
Cells have molecular machines for assembling phosphate ions into clusters and breaking them down. Fisher proposed a scheme in which two phosphate ions can be placed in a superposition of a certain kind: in an entangled state.
Phosphorus nuclei have a quantum property - spin - that makes them look like little magnets with poles pointing in certain directions. In an 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.
Fisher says the quantum mechanical behavior of these nuclear spins can counter decoherence. He agrees with Tegmark that the quantum vibrations that Penrose and Hameroff talked about will be highly dependent on their environment and "decohere almost immediately." But the spins of the nuclei do not interact so strongly with their environment.
And yet, the quantum behavior of the spins of phosphorus nuclei must be "protected" from decoherence.
Quantum particles can have different spin
This could happen, says Fischer, if the phosphorus atoms are incorporated into larger objects called "Posner molecules." They are clusters of six phosphate ions combined with nine calcium ions. There are some indications that such molecules can be in living cells, but so far they are not very convincing.
In Posner molecules, Fischer argues, the spins of phosphorus can resist decoherence for a day or so, even in living cells. Therefore, they can also affect the functioning of the brain.
The idea is that Posner's molecules can be taken up by neurons. Once inside, the molecules will activate a signal to another neuron, decaying and releasing calcium ions. Due to the entanglement in Posner's molecules, two of these signals can become entangled in turn: in some way, it will be a quantum superposition of "thought." “If quantum processing with nuclear spins is actually present in the brain, it would be extremely common, happening all the time,” says Fisher.
This idea first came to him when he was thinking about mental illness.
Lithium Carbonate Capsule
“My introduction to brain biochemistry began when I decided three to four years ago to investigate how and why lithium ion has such a radical effect in treating mental health problems,” says Fisher.
Lithium medications are widely used to treat bipolar disorder. They work, but no one really knows why.
“I wasn't looking for a quantum explanation,” says Fisher. But then he came across a paper that described how lithium preparations had different effects on the behavior of rats depending on which form - or "isotope" - of lithium was used.
This puzzled scientists at first. Chemically, different isotopes behave in much the same way, so if lithium worked like a common drug, the isotopes must 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 can influence how lithium-based drugs work. For example, if lithium replaces calcium in Posner molecules, the spins of lithium 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 this point, Fischer's guess is nothing more than an intriguing idea. But there are several ways to check it. For example, that the spins of phosphorus in Posner molecules can maintain quantum coherence for a long time. This is Fisher and plans to check further.
Yet he is wary of being associated with earlier concepts of "quantum consciousness," which he considers speculative at best.
Consciousness is a deep mystery
Physicists are not very fond of being inside their own theories. Many of them hope that consciousness and the brain can be extracted from quantum theory, and maybe vice versa. But we do not know what consciousness is, let alone the fact that we do not have a theory that describes it.
Moreover, occasionally there are loud exclamations that quantum mechanics will allow us to master telepathy and telekinesis (and although somewhere in the depth of concepts this may be so, people take everything too literally). Therefore, physicists are generally afraid to mention the words "quantum" and "consciousness" in one 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 a subtle but detectable way. Kent is very careful in his statements. “There is no compelling reason to believe that quantum theory is a suitable theory from which to draw a theory of consciousness, or that the problems of quantum theory must somehow overlap with the problem of consciousness,” he admits.
But he adds that it is completely incomprehensible how you can deduce a description of consciousness, based solely on pre-quantum physics, how to describe all its properties and features.
We don't understand how thoughts work
One particularly troubling question is how our conscious mind can experience unique sensations such as red or the smell of roasting meat. Apart from people with visual impairments, we all know what red looks like, but we cannot convey this feeling, and in physics there is nothing that can tell us what it looks like.
Feelings like these are called qualia. We perceive them as uniform properties of the external world, but in reality they are products of our consciousness - and this is difficult to explain. In 1995, philosopher David Chalmers called this the "hard problem" of consciousness.
“Any thought chain about the connection between consciousness and physics leads to serious problems,” says Kent.
This prompted him to suggest that "we could make some progress in understanding the problem of the evolution of consciousness, if we admitted (at least just admitted) that consciousness changes quantum probabilities."
In other words, the brain can actually influence the measurement results.
From this point of view, it does not define "what is real." But it can affect the likelihood that each of the possible realities imposed by quantum mechanics will be observed. Even quantum theory itself cannot predict this. And Kent thinks we could look for such manifestations experimentally. Even boldly assesses the chances of finding them.
“I would assume with 15 percent certainty that consciousness causes deviations from quantum theory; and another 3 percent that we will experimentally confirm this in the next 50 years,”he says.
If this happens, the world will not be the same. It's worth exploring for that.
ILYA KHEL
