Wednesday, September 21, 2005

Einstein and Lamarck, or, Being Right for the Wrong Reasons

It is a peculiar thing about scientific progress that it often seems to depend entirely on the imaginative scope of its practitioners. At first one might wonder where there is room for creativity in the study of our actual-factual surroundings, but as it becomes clear that for every answer we find, any number of questions might have produced it, one begins to wonder how there is room for anything else. Science often finds itself in a rather universal dilemma: you may identify exactly forty-two species of beetle in your backyard, but why not more or less, or a different combination of species; how did they get there and when there are forty-four next year, what does it mean? What we would really like to have is the exact question that generated our empirically derived answer of forty-two, something like:

In year [ ] after the Big Bang, when the planet Earth has been going on for [ ] years, [ ] years after the first beetle evolved, if the solar irradiance on this speck of Earth's crust has changed according to the following graph . . . and a small marmoset once chewed on a piece of paper that was blown into the compost heap and the nutrients of the marmoset's spittle were absorbed by the large citrus tree in the backyard . . . how many species of beetles would inhabit this precise area?

After all, most people are capable of counting up forty-two species of beetles. Which leads me to the following Deep Thought: Although Nature can be observed by all of humanity, it can be interpreted only by some fraction thereof. And of these interpretations, how many are correct, only time and further observations can tell.

Historians are continually arguing whether men make history, or history makes men. If Alexander the Great, Emperor Meiji, or George Washington had not existed, would the history of our world have been unimaginably different? Or were the times in which they lived such that other men, whose names are unknown to us today, would have risen in their places and brought about similar change? I find the debate alternately intriguing and utterly vacuous, depending on my mood, but there is no doubt that whatever their usefulness, the same questions can be asked of the Newtons and Curies of science.

In this light, the unique imagination of individual scientists gains particular interest. The human imagination breeds fancies, conceits, and occasionally, deep and abiding truths. The difficulty lies in identifying which of these imaginative productions each idea is--the distinction is often easier a year or two hundred in the future.

The reason, I think, it is so difficult to tell good ideas from bad, or rather, potentially true explanations from the truly ridiculous, is that for any given natural phenomenon, there are often so many potentially true explanations. Galileo wrote of a man who studied birdsong, and became a master of understanding the way in which music is formed from a bird's throat. One day he happened upon a boy playing a flute, and his mind was boggled by this entirely unforeseen manner of producing music. He continued to travel, and learned about stringed instruments, grasshoppers, and cicadas. (He never did figure out the cicada.)

The moral of the story is that, when it comes to Nature, it's almost impossible for the human imagination to come up with an idea so outlandish that she has not, in fact, already implemented it. (Galileo was actually discussing the infinite creativity of God, as expressed in Nature.)

But I didn't want to talk about Galileo, man of great imagination though he was. At least not until a few paragraphs later. Right now I want to talk about two other great men of science whom one might accuse of being ahead of their times.

Being "ahead of one's time" is certainly a vacuous concept, at least in a worldview which excludes time travel. However, it seems a good phrase to apply to scientists who had astonishingly correct ideas that were patently false, before they were proven true some time after those scientists' deaths and in ways the scientists themselves probably could not have imagined.

The first of these is Lamarck, who, when I was first learning biology, was still being ridiculed for his ideas about the evolution of giraffes. He proposed that a short-necked animal had at one point stretched and stretched to reach high leaves, and lengthened its neck by some incremental amount. This increment of neck length was passed onto the animal's children, who continued the family tradition of stretching to reach high leaves, thereby lengthening their necks further . . .

Once genetics was understood, this "inheritance of acquired traits" was justly considered balderdash. Only traits encoded in genes can be passed on from parent to child, and no amount of effort during your lifetime can alter your genetic material. And thus, despite Lamarck's other, rarely remembered but not insignificant, contributions to early evolutionary thought, he went down in biological history as the father of a nonsensical theory.

However, fairly recent (actually sometime in the nineties--I worry that I might always consider the nineties "recent") discoveries of unusual methods of inheritance may be lending some credence to Lamarckian thought, after all. It turns out that bare DNA isn't all it takes to make an organism--it's only the beginning. Many genes have to be turned on, most are turned off, and if a gene is turned on due to the environmental condition of a parent, that activation may be maintained in the child. Furthermore, parents deliver more to their children than pure DNA. There are proteins in those gametes too, and aggregated infectious proteins, or prions, are known to transferred vertically (parent to child) in at least some cases. Not that Lamarck knew about prions, but to be fair, he didn't even know about DNA. Nobody did. His hypothesis seemed perfectly reasonable at the time.

On to my second scientist. Unlike Lamarck, Einstein certainly hasn't spent most of his posthumous years being considered an embarrassment to his field. However, as revered as he is, his career certainly was not without mistakes, as he himself noted. The "greatest blunder of his career", in the physicist's own words, was his introduction of the fudge factor lambda into his equations, to prevent the universe from expanding. (More mundanely though more accurately, to prevent his equations from predicting expansion.) Of course, the universe is expanding, and Einstein was pleased to remove the inelegant lambda from his model.

But as cosmologists have turned a more and more critical eye on the cosmos, further discoveries have come. And in recent years (nineties again), it was found that the world is more than expanding--it is accelerating. In looking for the energy the fuel this acceleration, theoreticians have dusted off the good old cosmological fudge factor, lambda. Of course, Einstein was still wrong about putting it into his equations to stabilize the universe--as well he knew.

We can all sympathize with him, though. There is a great temptation, when one is faced with an extremely elegant model, to introduce just about anything to defend it or make it work. Even when the model is not of one's own creation, it can still have great logical and intuitive attraction, as the Copernican model did for Galileo. While the great Italian mathematician crafted numerous well-reasoned and accurate defenses of Copernicus, he was not immune to error. In fact, he wrote an entire treatise attempted to show the movement of the Earth based on the tides, likening the Earth to a basin of water, in which the water sloshes back and forth when the basin is moved.

Living in a world without gravity, Galileo may perhaps be forgiven for attempting to explain the tides in this way--except that he was well aware that if the Earth were moving, it could not be accelerating, and would therefore exert no force on its seas. In fact, Galileo spent considerable time and energy responding to critics who asked why, if the earth is moving, birds in the air are not left behind, nor does a falling object fall at an angle. Galileo described to them a man in the cabin of a continuously moving, non-accelerating boat, who drips water into a basin, watches birds and insects fly around the room, tosses a ball to his friend, and finds no evidence of the boat's motion in any of these events. One would think, given this argument, that he would see its contradiction with his tide treatise . . .

And in fact, there were even some people at the time who had noticed a correlation between the phases of the moon and the tides of the seas, and spoke of some "attractive power" by which the moon acts upon the water. However, this explanation no doubt reeked of the occult, and would have been repugnant to Galileo's logical mind.*

Guess those moon-philosophers were just ahead of their time.

* Most of my Galileo information is from this awesome book, although I would like to take full credit for pointing out G.G.'s inconsistency.

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