Cautionary Tales from the Front Lines of Science

A review of On Fact and Fraud: Cautionary Tales from the Front Lines of Science by David Goodstein. This review appeared in the American Journal of Physics on July 14, 2010.

In 1609 Galileo turned toward the heavens a modified version of the telescope first invented by the Dutch spectaclemaker Hans Lippershey, and there he observed that satellites were orbiting Jupiter, that Venus had phases, and that there were mountains on the moon and spots on the sun. His claims challenged Aristotelian cosmology, which held that all objects in space must be perfectly round and perfectly smooth. After observing Saturn, however, Galileo wrote to Johannes Kepler, “Altissimum planetam tergeminum observavi” (“I have observed that the farthest planet is threefold”). He continued: “This is to say that to my very great amazement Saturn was seen to me to be not a single star, but three together, which almost touch each other.” Galileo saw Saturn not as a planet with rings as we see it today in even the tiniest of home telescopes, but as one large sphere surrounded by two smaller spheres.

Why did Galileo make this mistake? Two reasons: (1) Data—Saturn is twice as far away as Jupiter; thus what few photons of light there were streaming through the cloudy glass in his little tube made resolution of the rings problematic at best; and (2) theory—there was no theory of planetary rings. It is at this intersection of nonexistent theory and nebulous data that the power of belief is at its zenith and the mind fills in the blanks. (continue reading…)