Friday, February 13, 2009

What is Life?

That's the title of a book based on some lectures physicist Erwin Schrödinger gave back in February of 1943. Imagine this. Fermi had just got his atomic reactor going in Chicago a couple of months earlier, Britain's been devastated by bombing, America has entered the war but it still looks like Hitler just might end up ruling the world, and in the midst of this chaos, Erwin Schrödinger is pondering the nature of life by thinking about how cells work.

Remember that this is well before Watson and Crick, and though funny-looking things called chromosomes had been located inside cells, nobody (let alone a physicist) really knew where the genetics were, where the cell was hiding those traits that could almost magically be passed down from one generation to another. It was a perfect opportunity for Schrödinger to make a bunch of prognostications that would soon prove foolish. But he really didn't -- he was amazingly prescient in his analysis of the nature of life.

Hands Off My Gene Splicer!

Physicists are almost irresistibly attracted to biology. Leo Szilárd, co-patenter of the nuclear reactor and the guy who got the Manhattan Project going by warning Roosevelt about nuclear fission, eventually switched to biology, and designed the radiation treatment he used to successfully treat his own bladder cancer. Richard Feynman dabbled briefly in biology just for fun. Roger Penrose tries to find quantum spookiness in the brain that will keep us from just being meat machines.

I think physicists are attracted to biology because there is a great race going on, much like the building of the Transcontinental Railroad. Physicists are exploring reality from the bottom (particle physics) up, while biologists are driving from the top (living tissue) down. Sooner or later, they are going to meet somewhere in the middle, and physicists really would rather not see biologists be the ones to drive that golden spike in to nail down our understanding of how life works.

Like the Second Coming of Christ, it's hard to prove this momentous event might not be just around the corner, so periodically physicists will make a little run at the problem just to keep their team in the game. And the 1940's were heady times for physicists -- they were bustin' atoms apart for the first time in human history! So it's entirely understandable that Schrödinger, sensing we were close to big progress in understanding cells, would want to take a hard look to see what physics could say about the situation. (His little essay would end up influencing both Watson and Crick in their search for the genetic code less than a decade later.)

Enter Psychology

How did writing a book on psychology and programming lead me to reading 60-year-old physics lectures? It's because my book starts by trying to understand the fundamental nature of what computer programming is, and how it fits into human history. Martin Seligman, founder of the Positive Psychology movement wrote a comment about a book by Robert Wright, called "Nonzero: The Logic of Human Destiny" that piqued my interest. In that book, as he considers human history from the perspective of energy usage, Wright refers back to Schrödinger's essay. And since I have the luxury of writing a book with no deadline, I cannot resist hopping the bus to the University of Washington to read Schrödinger's own words. What do I find there? Descartes once more.

I was just writing about Descartes and his pesky question: is the mind something separate from the body? After pondering the nature of cellular life, Schrödinger eventually cannot avoid making his own pronouncement on Descartes' question. To understand why anyone would care, you have to remember who this particular physicist was.

Schrödinger almost single-handedly put the "spooky" into quantum physics. With one relatively simple equation, he both explained observed results and, like Descartes, raised philosophical questions that remain unanswered today. What Schrödinger offered was an equation that both explained available data stunningly well, but did it by describing matter as a wave. What does it mean that matter can be described by a "wave"? That is still being argued today, but it certainly means that spooky stuff we can't really grasp happens when you get down to the tiny world of sub-atomic particles. One extreme extrapolation of Schrödinger's useful, accurate, but spooky wave equation is the idea that every little thing that can happen, does -- and causes yet another split into an infinite number of parallel universes. Some grown men believe this could be true. Honest.

For the holdouts who still hope that the brain isn't just a meat machine, that there is something special about "consciousness" (as though anyone agrees on what that word actually means!) that will make it impossible to create machines that are "alive", quantum spookiness is one of their last, best hopes. Schrödinger's physics offers a spookiness so rich, and full of bizarre possibiities, that it's hard to absolutely rule out (though most physicists think it bunkum) the possibility that "consciousness" (whatever that is!) is some special phenomenon woven into the very nature of reality, and therefore not something we will be able to recreate by simply reverse-engineering the neurons of the brain. What would Schrödinger have said about this? Fortunately, we don't have to wonder because he had already pondered the question more than 60 years ago. Here's exactly what he said:

According to the evidence put forward in the preceding pages the space-time events in the body of a living being which correspond to the activity of its mind, to its self-conscious or any other actions, are (considering also their complex structure and the accepted statistical explanation of physico-chemistry) if not strictly deterministic at any rate statistico-deterministic. To the physicist I wish to ephasize that in my opinion, and contrary to the opinion upheld in some quarters, quantum indeterminacy plays no biologically relevant role in them, except perhaps by enhancing their purely accidental character in such events as meiosis, natural and X-ray-induced mutation and so on -- and this is in any case obvious and well recognized.

So the very father of quantum spookiness got his vote in early: there is no quantum spookiness involved in consciousness, we are just deterministic machines and we would admit it, in his words, "if there were not the well-known, unpleasant feeling about 'declaring oneself to be a pure mechanism'."

And yet, if you read the epilogue of "What is Life?", which is titled "On Determinism and Free Will", you'll see that, just as his famous equation encompasses the contradition of matter being both a particle and a wave, Schrödinger's personal philosophy embraced the contradiction of being a purely mechanical mechanism but still having the powerful feeling of personal free will. Those who accuse Schrödinger of turning to mysticism are, I think, correct. But we all have to do something with the big, blank page labelled Currently Unknowable, and it's not clear to me that carrying it in a bag marked Mysticism is any worse that carrying it anywhere else.

The Hook

Little to none of this discussion is in my book. The real reason Robert Wright refers to Schrödinger's essay is his observation that the nature of life is to create a temporary island of decreasing entropy, though the 2nd law of thermodynamics is preserved because life emits a waste stream of increased entropy. Therein lies a key to understanding the fundamental nature of computer programming. But you'll have to wait for the book to read about that.

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