Note 6 — IV BASAL CONCEPTS AS THOUGHT-MATERIAL

“Johannes Kepler (1571-1630) was at one time in Prague assistant to the Danish astronomer Tycho Brahe. Unlike Tycho, Kepler had no talent for observation and experimentation. But he was a great thinker, and excelled as a mathematician. He absorbed Copernican ideas, and early grappled with the problem of determining the real paths of the planets. In his first attempts he worked on the dreams of the Pythagoreans concerning figure and number. Intercourse with Tycho led him to reject such mysticism and to study on the planets recorded by his master. He took the planet Mars, and found that no combinations of circles would give a path which could be reconciled with the observations. In one case the difference between the observed and his computed values was eight minutes, and he knew that so accurate an observer as Tycho could not make an error so great. He tried an oval orbit for Mars, and rejected it; he tried an ellipse, and it fitted. Thus, after more than four years of assiduous computation, and after trying nineteen imaginary paths, and rejecting each because it was inconsistent with observation, Kepler in 1618 discovered the truth. An ellipse! Why did he not think of it before? What a simple matter—after the puzzle is once solved! He worked out what are known as Kepler’s laws, which accorded with observation, but conflicted with the Ptolemaic hypothesis. Thus the old system was logically overthrown. But not until after a bitter struggle between science and theology did the new system find general acceptation.”—Cajori’s “History of Physics,” pages 29, 30.