Part 5: Quantum epiphanies
One of the most famous theories of consciousness is that of Sir Roger Penrose and Dr. Stuart Hameroff - a mathematical physicist and an anesthesiologist. As their theory is at best revolutionary and at worst crazy, I will approach the fascinating subject from afar.
Quantum mechanics. Often regarded as the most successful development in all of modern physics, quantum mechanics is basically a theory that explains how the elementary particles (electrons, protons, neutrons, photons, etc.) behave. At the turn of the 20th century, a new theory was needed, as classical physics would fail on the very small scale of electrons and photons. Through the work of Bohr, Heisenberg, Schrödinger, Pauli and others, the theory of quantum mechanics was born. This theory is able to predict with incredible accuracy the outcomes of numerous physical experiments that cannot be explained by classical physics. Quantum mechanics is correct; it is tried and tested. The only situations where it gets into trouble are inside black holes and during the first fractions of a second after the Big Bang, neither of which have much to do with our study of consciousness.
As successful as it is, quantum mechanics is very strange. First of all, it is entirely based on probability - a dubious mathematical concept. (When asked to define "probability", mathematicians often quote the Law of Large Numbers, which, of course, "defines" probability in terms of itself.) Albert Einsten, often quoted as saying, "[God] does not throw dice," was an early opponent of quantum mechanics because of its basis in probability.
However, probability is just the beginning of the weirdness that is quantum mechanics. The core principle behind the Penrose-Hameroff theory of consciousness is a phenomenon called quantum superposition. The mathematics behind quantum mechanics says that if a particle (for example, a photon) has a probability of being in one of two distinct states, then in some cases, it can be in the two states simultaneously. For example, we can set up a laser and aim it at a half-silvered mirror. Half the light beam will be reflected by the mirror at a 90-degree angle, and half the beam will pass through the mirror. We can then dim down the laser to a point when it starts shooting single photons, say, one per second. Each photon will have a 50% probability of being reflected and a 50% probability of passing through the mirror. Quantum superposition says that, under certain conditions, it is possible for the photon to be both reflected and not reflected at the same time. As long as there is no interaction between the photon and the outside world, the two states can exist at the same time - a phenomenon called quantum entanglement. However, as soon as we attempt to detect whether the photon went through the mirror or got reflected, quantum entanglement is broken, and the photon collapses to one of the two states.
To illustrate how weird this theory is, Erwin Schrödinger described his famous Schrödinger's cat thought experiment. Suppose that we put the laser and the mirror into a box with two holes - one for each of the possible exit paths of the photon. To one of the holes, we attach a device that fires a gun whenever a photon is detected. The gun is pointed at a cat. Now, whenever a photon is fired from the laser, quantum entanglement says that it is both reflected and not reflected, which means that the gun both fires and does not fire, which, in turn, means that the cat is both dead and alive. Eventually, a physicist comes into the room and looks at the cat, at which point the quantum state collapses into one of the two possibilities, and the physicist either sees a dead cat or a happy cat. There are some technical details; for example, the whole contraption has to be isolated from the outside environment so that the quantum entanglement can be preserved, but the point of the thought experiment is to illustrate the inherently weird nature of quantum mechanics.
One of the most interesting and puzzling properties of quantum superposition is that an observer causes the quantum state to collapse. In a sense, superposition is an "undecided state", and the observer causes a decision to be made. There is that word again - decision. Perhaps there is a connection between consciousness and quantum superposition collapse. What is it inside our neurons that causes consciousness? And what is so special about neurons anyway, especially if we assume that bugs and bacteria are conscious, too? What if consciousness is really a quantum mechanical property, and biology is simply a "bridge" between the strange microscopic quantum world and the macroscopic world of classical physics? Electrons and photons in superposition states make decisions all the time, but we do not see any of their effects because they cannot create a noticeable change in the macroscopic world. Biology, however, has found a way to build an amplification device - life - that allows microscopic events to have large-scale consequences. For example, when I think of lifting my arm, there is a decision being made at the quantum level, and through the electro-chemical signals, that decision has an enormous (compared to the quantum scale) effect - my muscles contract and lift my arm.
What if the cat's life or death is a decision made by the photon after it has passed through the half-mirror? For a certain short period of time, the photon is in superposition - the undecided state. Then, an observer opens the box, and the decision is made - superposition collapses to one of the two possibilities. Perhaps it is not the photon itself that makes the decision, but the observer, or the cat. In any case, the two spooky notions - consciousness and superposition - seem to have something in common. Opponents of the Penrose-Hameroff theory dismiss it as simply replacing one weird concept (consciousness) by another (quantum mechanics) without explaining anything. That is not true; we know quite a bit about quantum mechanics. For one, we can make predictions and devise experiments to test them. So far, however, no one has come up with a way to definitively prove or disprove the existence of a connection between decision making and quantum superposition.
Is such a thing even possible - maintaining a superposition state in the brain? Superposition requires complete isolation from the outside environment and extremely low temperatures. Nevertheless, Hameroff claims that there is a place in the brain where superposition is possible for periods of time on the order of milliseconds, which is about the right time it takes humans to make a decision. That place is inside microtubules - tiny pipes inside a neuron that are made of proteins. Anesthetics (drugs that make you "lose consciousness") act on the microtubules in neurons.
In essense, the Penrose-Hameroff theory says that consciousness is everywhere. It is a fundamental physical property. Biological organisms are not the source of consciousness; they are merely nature's attempt at understanding itself by providing a bridge between the quantum world and the macroscopic world. The universe itself is conscious. In fact, one of the most fascinating unanswered questions in physics is the question of why we have asymmetry in the world. Why is all of the known universe made of matter and not anti-matter? Why do we have stars, galaxies and black holes - clumps - instead of a uniformly smeared cloud of "stuff" everywhere? One hypothesis is that just after the Big Bang, the whole universe was in quantum superposition - everything existed at once. But then at some point there was a collapse - the Big Wow - that moment when the Universe became aware of itself.
Perhaps the Universe has been trying to understand itself ever since, and through evolution, it has developed us - humans - as one of the tools for self-understanding. As far as theories go, in my view, this one is remarkable. On the one hand, it is tied into the core of physics, yet it says nothing of the existence of "true" free will and even leaves open the possibility of a God, a supreme being in the form of the very Universe. There is great debate about the assumptions at the foundation of the theory, as there should be. There are scientists trying hard to find experimental evidence for or against it, and there are those who outright dismiss it as complete rubbish, claiming that it resolves nothing. I hope that you can find a corner in your mind for this piece of the puzzle. Maybe it will fit into place later, maybe not.