Saturday, August 21, 2010


What is Science?

The other day I listened as the speaker at the breakfast meeting of the service organization I belong to delivered a rather long speech about "science." He spoke about astronomy, about Darwin's theory of evolution, and other things. I couldn't tell for sure whether he was for or against "science." I'll assume for the present that he was for it. At any rate his speech prompted me to think about what I would say about science. I was, after all, a scientist with a Ph.D. degree in physics from a good university.

Since I'm rather long-winded myself, I would start with the history of human attempts to understand and predict certain events that occur with some regularity. A good example is the attempt to predict eclipses of the sun and the moon. Thousands of years ago humans built simple observatories to enable them to observe the exact locations of sunrise and moonrise. One of these observatories exists at Stonehenge in England. By observing and recording (or memorizing) the dates and positions of the sun and moon when they rose and then correlating this information with eclipses of the moon and the sun eventually the observers (we might call them early astronomers) discovered a pattern that enabled them to predict dates on which such eclipses were likely to occur.

For a long time scientific inquiry consisted of observing and recording and collecting data. Mathematics was not highly developed in those days. Explanations of the "cause" of the observations were stories that we today dismiss as quaint fairy tales or superstitions. For example, the Greeks believed that the sun rose every morning because the god Apollo hitlched his horses to his chariot and drove it along an invisible highway in the sky. The god and the chariot were very bright, so bright that they formed the sun. They were so bright that the horses became invisible. Other cultures had other explanations.

Finally, a clever technician invented the telescope and the microscope. Now it was possible to study the stars in the sky in much more detail. It was also possible to observe and study various microbes. New observations were made and recorded. The moving stars or planets could be observed as orbs of finite size rather than points of light.

At this point I shall back up to an explanation of the motion of the planets by a Greek savant named Ptolomey. Ptolomey knew that the earth was round because he had measured its circumference. Hence, the sun, the stars, and the planets appeared to rotate around the earth. He looked for a mechanical explanation for their motions (rather than the fairy tale about Apollo's chariot) and devised a scheme of cycles and epicycles. Cycles were circular paths around the earth. Epicycles were circular paths around imaginary points on the radii of the cycles. And so on. It was an explanation but not a theory. We'll see why it wasn't a theory in a moment. It wasn't a satisfactory explanation either because no one could explain why the planets had to behave as though they were at the ends of imaginary rods rotating around the ends of other rods, etc.

A very smart Pole named Nicholas Copernicus (educated people wrote in latin and latinized their names) figured out that he could do away with all the cycles and epicycles if he assumed that the earth and all the planets rotated around the sun in circular orbits. He was also smart enough not to publish his explanation during his lifetime, to avoid getting in trouble with the Catholic Church. Circular orbits provided a simpler explanation than the epicycles of Ptolomey. They provided a fairly simple way of predicting the motions of new planets that were being discovered by astronomers using the newly invented telescope. However, a Danish astronomer, Tyge Brahe, found that circular orbits could not explain exactly the orbits of some of the planets. One of his students, a German named Johannes Kepler, discovered that if one assumed elliptical orbits instead of circular ones, Tyge Brahe's observations could be exactly confirmed by calculation. Kepler had no explanation as to why the orbits should be elliptical rather than circular.

That explanation was left to Isaac Newton. Newton used some new developments in mathematics, specifically the discovery of calculus, and an idea called gravity to explain and calculate the orbits of planets. His theory of universal gravitation also explained why apples fall from trees and why we humans are so strongly attracted to the earth that we never fall off or fly into space. His theory satisfied two philosophical requirements of any scientific theory: (1) it involved the fewest assumptions; (2) it was constructed in a way that it could be tested and disproved if wrong.

Let's think about Darwin for a bit. It is customary to say that Darwin proposed the "theory of evolution." I think that's a poor name for his theory. Evolution is an observed fact. Millions of years ago there were species of animals and plants who left fossilized remains but who no longer exist. At the same time, may species that exist today didn't exist millions of years ago. New species come into being and old ones die out. Darwin proposed a mechanism that involved the least number of assumptions. Characteristics of living things change because of random mutations. Some of these mutations allow species to inhabit new conditions of environment or to survive better in a changed environment. Hence, the new species thrives and prospers. Darwin had to assume that (1) environments change with time and (2) mutations occur randomly. From the fossil record we know that environments have changed. There have been several ice ages in the past million years. Darwin didn't know the mechanism by which mutations occur. Today we know that in reproduction, the DNA molecule is never replicated exactly. Some of the changes have no effect. Some of them produce mutations in the form of the organism. This is the scientific theory of why evolution occurs.

So, what is science? Science is a process of studying and trying to understand the nature of the universe. The process involves observation, recording the results of observation, and constructing theories to explain or predict the results. The theories must satisfy the two philosopohical requirements of simplicity and verifiability.

What is the value of science? Science allows us to see the world as it is, not as we believe it to be. It is a human tendency to acquire certain beliefs about the world from our parents, then to cling to these beliefs even though observation tends to contradict them. I've told this story about myself before, but it is a good example. As a child I learned that the "southern" dialect in the United States came about because the white children of southern planters were cared for by negro nannies. The negro nannies had peculiar tongues. They were thick and prevented the nannies from pronouncing some words correctly. It was this strange way of speaking English that the children learned from their nannies and carried into adulthood. In college I met and talked and argued with a black student from Haiti. He didn't speak with a southern accent; his accent was French. I argued with him that as a negro, he had a thick tongue and couldn't pronounce English words correctly. This in spite of the fact that he had a French, not a Southern accent. He must have thought I was the dumbest bigot he'd ever met. Later I learned that there is nothing wrong with the negro tongue and that the Southern accent in the United States originated in England. If I had seriously practiced being a scientist I would not have made such a fool of myself in front of my Haitian friend, Berthony Vieux.


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