Thursday, January 19, 2006

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.

13 Comments:

At 10:35 AM, Blogger Evgueni Naverniouk said...

Reminds me of J. Michael Straczynski
"We are star-stuff. The Universe made manifest trying to figure itself out. And sometimes the Universe requires a change of perspective. At the right moment we are in the right place. The Universe puts us in places we can learn. Where ever we are is the right place at the right time and the pain is part of the process of being born. The Universe knows what it is doing."

 
At 11:20 AM, Blogger Kurt said...

This should be part 5, no?

You are far too gentle on Penrose and Hameroff. I've started watching the Consciousness DVD that you mentioned at the beginning of your blog, and it seems that whenever people discuss the Penrose/Hameroff theory, the conversation quickly descends into new-age silliness. As David Chalmers pointed out, whether or not quantum effects turn out to significant in the workings of the brain (beyond being a source of randomness), it's still a mechanistic process. All the other stuff about universal consciousness, etc., is just empty speculation which is not supported by the science.

 
At 11:40 AM, Blogger Abednego said...

Opps. It should be 5, yes. Fixed.

You are right - I decided not to be too critical of the theory. The reason is that I have tried very hard to defend materialism in Part 4, and I want to give each theory a fair introduction, without too much critique. I think it is important to realise that at this point, we know so little about consciousness that any original idea, no matter how ridiculous, should be given a chance to explain itself.

Personally, I don't believe at all in Penrose-Hameroff, but the idea upon which it is based is cute - maybe there is indeed some connection with the quantum stuff, even if it turns out to be completely materialistic in the end. The whole discussion of consciousness is one big brainstorm at this point.

 
At 3:41 AM, Blogger JeremyHussell said...

I have some serious problems with the way quantum physics is usually described. When you dig down into the details of what they're talking about, there's always a common sense explanation of what's going on. For example, in the case of "quantum superposition", one of the prerequisites is that the system have no contact with the rest of the universe. In other words, there must be no possible way to observe the system. As far as I'm concerned, the system is in one state or the other, not both. The only thing that's in a state of superposition is the physicist's internal model of what's happening, and when an observation is made, the only thing that collapses into a single state is that model inside the physicist's head.

So, I'm not just critical of Penrose and Hameroff's theory, I'm critical of the whole system used to describe quantum mechanics to those who don't understand the details (namely, us).

I'll probably write about this subject more extensively on my own blog, as it isn't really relevant here.

 
At 6:34 AM, Blogger Harrison said...

Hello, Im Harrison, Harvard Student in Philosophy. I am not a quantum physcist, nor do I have any significant depth in science. I have read your article, which has evoked my imagination from past philosophical work in which I have done.

However, my true passion lies in psychology, and I am currently working on my doctorate in Neuroscience. What has always fascinated me though is the nature of intelligence.

I have led research projects in these areas before, but it is my studies in philosophy that gives such a realization to me after reading your explanation of quantum mechanics.

Last year, two other students and I worked on a purely philosophical project. The question was: "How can a God with omniscience exist, yet humans can still have free will?".

After several months of research, debates within the philosophy panel, and returning to the very foundations of philosophy, a theory that fit within the boundaries of logic was found by my group:

Before a person makes a choice, the outcome of his decision is already existing, but cannot be expressed within the bounds of reality; therefore, either choice is possible within our logical perception. When a choice is finally made, the predetermined outcome is forced and 'converges' with the outcome that has already been made, but only from our point of view, becuase we did not know what it was originally. Ultimately, the outcome is predetermined. Furthermore, the system relies on the fact that the person that is deciding cannot in any way get knowledge of the predetermined outcome.

Neither I nor my colleagues know anything of quantum physics. When I read your report, I was instantly reminded of this project. To me they sound very much alike, yet both theories are made from completely different points of view.

I realize that what I wrote is extremely abstract, but I think that philosophy and psychology are more closely related then most people believe. I have read some of your other articles and, at least, I feel that they are very insightful, raising questions in which may be fundamental in the possible development of a true ai.

I would like to hear from you. We both share passion in the possibilities of AI, and, as both doctorate students, we may even be the future of such technologies.

 
At 9:02 AM, Blogger Abednego said...

Hello Harrison. Please note that none of these ideas are mine. I'm just summarizing other people's work. I have some thoughts of my own, and I will get to them soon.

About your paragraph on free will, I have a question. What is the meanning of "cannot be expressed within the bounds of reality"? Can you give an example of something that "cannot be expressed within the bounds of reality"? It sounds to me like an artificial concept invented to protect a belief in God rather than explain what free will is. After reading some of Daniel Dennett's work, I became a firm believer that he is right, and everyone else is wrong because his arguments make a lot of sense without the need to invent non-existent concepts. Have a look at my post on free will and tell me what you think.

 
At 6:13 AM, Blogger Harrison said...

This comment has been removed by a blog administrator.

 
At 9:16 AM, Blogger Harrison said...

My work in philosophy is very philosophical; thought used for further thought, and I just mentioned it to point out what I feel is similarity with this quantum theory I havent heard about before. And realize that it was based on the assumption that there is a god. With that assumption, the 'theory' would be the most simple explanation, unless you propose that God can exist outside of logic.

I do believe in free will, and I support the neural network theory. I believe free will deeply related to consciousness, and there would be no reason for consciousness if free will did not exist. That is one basis.

Anyone, tell me: what do you define as consciousness?

 
At 7:22 AM, Blogger James said...

This theory doesn't ring any bells in me. And it is not because of the quantum mechanic think.

He might be true or not ... I have the feeling that it doesn't matter. At a decision point, I see several path in front of me. I choose one. I don't see how quantum mechanics helps me in making my decision. At least it doesn't explain why a path is chosen over the other, which is what I want to know to be able to replicate it.

 
At 4:34 PM, Blogger santi said...

This comment has been removed by the author.

 
At 4:35 PM, Blogger Abednego said...

That experiment is called the Double Slit experiment. There's a pretty good write-up of it on wikipedia.

 
At 9:55 AM, Blogger cease ill said...

Until the atom could be observed, it was mere speculation, for how else can one know? It's just an idea until it's witnessed in experiments.
Pure science has been occurring without witnesses and continues to do so. We're aware there continue to be levels of matter as yet undefined by a human element to wade through the raw data.

So---how can one say that universal consciousness is just "mere speculation" with certainty? We experience consciousness in signs every day---so there consciousness is, in different degrees.
Some of those signs might very well co-exist, as when separate parties come up with the same theory without collaborating directly (for example, Darwin was not alone).

If there's a way to detect the mechanistic unit, we might discover an objective field of being, capable of encompassing that expansive state.

Why consciousness should exist at all might one day prove, instead of an accepted mystery, a solvable problem.

Cecil and Angela

 
At 2:50 PM, Blogger Abednego said...

Can you define what you mean by "consciousness"? You seem very sure that it exists.

 

Post a Comment

Links to this post:

Create a Link

<< Home