Seeing and Believing: How the Telescope Opened Our Eyes and Minds to the Heavens by Richard Panek. Viking, $21.95, 198 pages.

The Chapel Hill News

June 12, 2002

Why Science Moves Slowly

By Phillip Manning

Research scientists generate new ideas that advance our understanding of the physical world. However, those same scientists can be surprisingly reluctant to accept someone else's new ideas, especially big ones. In his smoothly written history of astronomy, "Seeing and Believing: How the Telescope Opened Our Eyes and Minds to the Heavens" (Viking, $21.95), science writer Richard Panek vividly illustrates an early example of this reluctance. But as we shall see, scientists have a reason for resisting new ideas.

According to Aristotle, the stars and planets were made of a perfect "celestial" substance, and they rotated in perfect spheres around the center of the universe, the stationary Earth. Unfortunately, they did not rotate as perfectly as Aristotle claimed, so in the 2nd century A.D. Ptolemy introduced epicycles (circles within circles) to account for the motions of the planets. So complicated did these circles become that by the 16th century the system was ridiculously unwieldy.

Copernicus simplified Ptolomey's system by proposing that the Earth (and the other planets) revolved around the sun. However, his new system did not predict the positions of the planets much better than the old one, so it was still possible to believe that the Earth was stationary - as our senses tell us it is. Then, in November of 1609, an ambitious Italian professor of mathematics, Galileo Galilei, aimed a newly invented telescope at the moon, and astronomy suddenly got less sensible.

Instead of Aristotle's perfect celestial sphere, Galileo saw mountains and valleys marring the moon's surface. Later, he spotted four moons revolving around Jupiter, exactly as our own moon revolves around the Earth. He observed the phases of Venus, proving that it does not produce its own light but is illuminated by the sun - and orbits it. Galileo published his conclusions in 1613, "An understanding of what Copernicus wrote suffices . . . astronomers to ascertain that Venus revolves around the sun, as well as to verify the rest of his system."

Panek recounts what happened next. One man said that Galileo and his telescope had "overthrown all former astronomy," but many astronomers had their doubts. One argued that "these satellites of Jupiter are invisible to the naked eye, and therefore exercise no influence on the earth, and therefore would be useless, and therefore do not exist." Panek says that this reaction was to be expected. After all, the telescope "revealed evidence that was different from what the naked eye could see, evidence that wasn't otherwise there." His point is well taken. The evidence gathered through the telescope was difficult for 17th-century Europeans to believe because it contradicted almost everything that they knew. Drop a rock, and it falls straight down, not at the angle you might expect if the Earth were moving. It would be another 75 years before Isaac Newton would provide the theoretical framework for the Copernican theory that Galileo was confirming with his telescope.

But I have a bone to pick with Panek's interpretation of why astronomers were slow in accepting Galileo's ideas; more is at work here than just a difficulty in believing what the telescope revealed. History is full of scientists who refused to accept new theories. And scientists' stick-in-the-mud posture toward new ideas is just as prevalent today as it was in Galileo's time. Einstein, for example, was skeptical of the full implications of quantum mechanics. "I shall never believe that God plays dice with the world," he famously said. Yet that is precisely the conclusion that most physicists now accept.

I suspect it was this same skeptical attitude toward new ideas that caused many 17th-century scientists to reject the evidence Galileo collected, evidence that turned astronomy upside down. The old saw that new theories are only accepted after the people who developed the old ones die is all too true. It also the reason that most great leaps forward in science are made by men and women under age 30, people who do not have big investments of time and energy in older theories.

Why don't scientists buy into new ideas more quickly? The main reason is that most new ideas are wrong. One recent example was the cold fusion results reported by two chemists at the University of Utah in 1989. Naive journalists jumped all over the story. An unlimited, nonpolluting, cheap source of power was at hand trumpeted the headlines. Few scientists believed it. Were the results reproducible, they huffed. Why was the announcement made at a news conference rather than in a scientific journal, they grumbled. It turns out the scientists were right; the results were not reproducible, and cold fusion was quickly forgotten. So, it is easy to understand why Galileo's peers did not all immediately jump on the heliocentric bandwagon. Eventually, of course, Galileo's ideas prevailed. But only because better telescopes allowed other astronomers to see what he saw. His results were reproducible.
####