PENDULUM

Everyone knows about Foucault’s pendulum, but who knows anything about the man himself?

Mathematician Aczel (The Riddle of the Compass, 2001, etc.) offers a corrective with the story of Léon Foucault (1819–68), whose famous experiment gave the first proof of Earth’s rotation. Aczel begins in 1851, when Foucault set up a pendulum in the cellar of the house he shared with his mother, then jumps back to establish a historical framework. The medieval church adopted the Ptolemaic theory of the cosmos because it agreed with biblical texts implying that Earth is the unmoving center of the universe. When Copernicus and later scientists challenged Ptolemy’s theory, one rejoinder was that no one could detect the Earth’s rotation. Aczel summarizes the arguments up until the 19th century, then switches to Foucault’s early years. The son of a Parisian publisher, Léon suffered from poor health. He left medical school because the sight of blood sickened him, but his professors encouraged him to apply his talents to research, and he became a consummate scientific generalist. Foucault made the first photographs of microscopic objects and of the sun through a telescope. Later, he measured the speed of light with high accuracy. But his lack of formal scientific training held him back. For years he worked as science reporter for a prominent daily newspaper, and even after his 1851 pendulum experiment he fought for recognition. His prime ally was Napoleon III, science-loving Emperor of France, who secured for Foucault the honors the scientific establishment had refused him, including a Ph.D. and membership in the Academy of Science shortly before his premature death. Aczel effectively uses Foucault’s story to provide a vivid panorama of Second Empire Paris, although occasionally the transitions are a bit rough.

A good summary of an important era in science and one of its underrated stars.