I just finished reading Roger Penrose's "The Emperor's New Mind" a few days ago. I think it took me seven or eight years to get through it, but I finally did it. From the cover of the book, Penrose seems to be implying that he will explain "computers, minds and the laws of physics". While he does an adequate job on computers and physics, his conclusion on the minds is rather disapointing, concluding with "It probably has something to do with quantum gravity."

The book assumes you have an understanding of simple arithmatic (addition, substraction, multiplication, division), the English language, and basic concepts of classical physics (e.g. that gravity pulls objects together, or that billiard balls bounce when they strike a surface). In other words, not much more than a high school education. From there, he explains everything you need to know to understand why he believes the mind uses some aspect of quantum physics. That means that of the 466 pages that comprise this book, about 400 pages are used to explain the Artificial Intelligence and the Turing Test, what algorithms are, how to count in Binary, set theory, computability theory, countability of natural and real numbers, what complex numbers are, what fractals are, the concept of Platonic Reality, Gödel's Theorem, complexity theory, non-Euclidean geometry, hamiltonian mechnaics, phase space, Maxwell's electromagnetic theory, wave equations, Lorentz equations, special relativity, general relativity, quantum physics, uncertainty principles, Hilbert space, particle spin, Riemann spheres of state, Schrödinger's equation, Dirac's equation, Quantum field theory, entropy, thermodynamics, cosmology and the big bang, black holes, space-time singularities, Weyl curvature hypothesis, split-brain experiments, information processing in the visual cortex, nerve signals, brain plasticity, and so on.

I actually started reading this book in high school, and got about as far as complexity theory, computability theory and Turing machines. Fascinating stuff for me. But I couldn't get through it. It wasn't that there were words or concepts I didn't understand, but I just couldn't put the concepts together to form a bigger understanding of everything that I had read. And so I'd put down the book for a few months, and came back to it again later. By the time I was in Cegep, I made it through the section on Gödel and fractals, but got caught up in the physics stuff.

Surprisingly enough, I don't think I picked the book up again over the four years I spent in university. Maybe I was just too damn busy. But a few months after graduating, I did pick it up again, and this time I was surprised at how far I made it before I got confused. In fact, I finished the book (though I did give up after re-reading the some sections of quantum physics four or five times, and just went ahead, accepting Penrose's conclusions, rather than logically convincing myself that they were true).

As I mentioned earlier, the conclusion was rather disapointing, and for those who don't mind the "spoiler", I'll summarize it here. Given that the human mind is made up of particles, and physics can understand particles very well, the brain should be "deterministic". But if your brain is deterministic, you could predict what your future action will be, and then just decide to do the opposite, thus creating a paradox. Therefore, Penrose concludes that the brain is deterministic, but non-computable. Some portions of quantum physics also show properties of being deterministic but non-computable, and so the brain probably uses one of these. Nothing we can think of might apply to brains, but we don't have a theory for Quantum Gravity yet, so that's probably the portion of quantum physics which gives the human mind the power of non-computability. Obviously, this summary isn't as eloquently put as Penrose might want, so for the full argument, please read his book.

Since 1989, the year in which this book was written, Penrose wrote (at least) two other books on the topic. Hopefully, he will have gathered a better understanding of quantum gravity by then and have been better able to explain the human mind (but probably not, or else I would have heard more about quantum gravity from other sources).

In case you haven't heard of him, Penrose is a brilliant mathematician who dabbles in theoretical physics. His contribution to physics is right up there with Einstein, Newton and Hawking. From my understanding, Hawking and Penrose are "friendly rivals", like Kilree and I, each jokingly (?) boasting that he is smarter than the other, and arguing about various details like how black holes really behave and such.