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Pendulum: Leon Foucault and the Triumph of Science

Pendulum: Leon Foucault and the Triumph of Science

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by Amir D. Aczel

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He was neither a mathematician nor a trained physicist and yet Léon Foucault always knew that a mysterious force of nature was among us. Like Newton, Galileo, Copernicus, and others before him, Foucault sensed a dramatic relationship between the rotating skies above and the seemingly motionless ground beneath our feet. But it wasn't until 1851 — in Paris,


He was neither a mathematician nor a trained physicist and yet Léon Foucault always knew that a mysterious force of nature was among us. Like Newton, Galileo, Copernicus, and others before him, Foucault sensed a dramatic relationship between the rotating skies above and the seemingly motionless ground beneath our feet. But it wasn't until 1851 — in Paris, inside the Panthéon, and in the company of fellow amateur scientist Napoleon III — that Foucault swung a pendulum and demonstrated an extraordinary truth about the world: that it turns on its axis.
Pendulum is a fascinating journey through the mind and findings of one of the most important and lesser-known characters in the history of science. Through careful research and lively anecdotes, world-renowned author Amir D. Aczel reveals the astonishing range and breadth of Foucault's discoveries. For, in addition to offering the first unequivocal proof of Earth's rotation, Foucault gave us the modern electric compass and microscope, was a pioneer in photographic technology, and made remarkable deductions about color theory, heat waves, and the speed of light.
At its heart, Pendulum is a story about the illustrious period in France during the Second Empire; the crucial triumph of science over religion; and, most compelling, the life of a struggling, self-made man whose pursuit of knowledge continues to inform our notions about the universe today.

Editorial Reviews

From the Publisher
The Christian Science Monitor This intriguing account...exemplifies a lesson that humanity seems forever reluctant to learn: How the world appears depends on your frame of reference.

Simon Winchester author of The Professor and the Madman [S]eductively captivating....With all the clarity and narrative brilliance that has become [Aczel's] hallmark.

Publishers Weekly
Aczel, one of our best science popularizers (Fermat's Last Theorem; The Mystery of the Aleph; etc.), now recounts the triumphs and struggles of the French physicist L on Foucault (1819-1868), whose eponymous pendulum presented the first tangible proof of the earth's rotation. Aczel follows Foucault from his beginnings as a medical student and a science journalist covering the meetings of the august French Academy of Sciences to his installation as the official physicist attached to the Imperial Observatory in Paris and his belated election to the Academy of Sciences, finally overcoming the resistance of those who saw as an outsider this genius with no formal academic training. Foucault is portrayed as a wide-ranging thinker, fascinated with questions from the speed of light to the construction of the first gyroscope, but at the center of this account is his 1851 invention and demonstration of his famed pendulum. The author's transitions from narrative to scientific exposition can be a bit rough, but every time the pace begins to drag, he veers off in a new direction, drawing connections between Foucault's work and broader scientific, political and philosophical trends and themes. Aczel's material is so intriguing that one is inclined to forgive his habit of pursuing tangents. The reader is left with a choppy yet fascinating survey of Parisian science during the Second Empire and L on Foucault's grudgingly rewarded place in it. Illus. (Aug. 19) Copyright 2003 Reed Business Information.
Library Journal
The notion that the earth rotates had been advanced centuries earlier, but in the mid-19th century, physicists and mathematicians remained frustrated by their failure to find clear proof. Leon Foucault had been a frail child and an indifferent student, but by the time he was a young man, he displayed a keen mind and the skilled hands of an inventor. Snubbed by the prestigious but snooty French Academy of Sciences because he lacked a university degree, Foucault persevered with hard work, a little luck, and fortuitous encounters with influential individuals. In 1853, at the Parthenon in Paris, he rocked the scientific community by proving with a pendulum that the earth rotated on its axis. Mathematician Aczel (Fermat's Last Theorum) has crafted a terrific page-turner that captures the essence of the personalities of the story while clearly expounding on the scientific principles. With rich detail, he evokes the spirit of France during the Second Empire, weaving a tale of political intrigue, scientific discovery, and personal triumph. Highly recommended for all public and small academic libraries.-Denise Hamilton, Franklin Pierce Coll. Lib., Rindge, NH Copyright 2003 Reed Business Information.
Kirkus Reviews
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 toprovide 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.

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Washington Square Press
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5.31(w) x 8.25(h) x 0.80(d)

Read an Excerpt

Chapter One: A Stunning Discovery in the Cellar

From his journal, we know that he made the discovery at exactly two o'clock in the morning on January 6, 1851. He was down in the cellar of the house he shared with his mother, located at the corner of the rue de Vaugirard and rue d'Assas — in the heart of the intellectual Left Bank of Paris and within the immediate area in which Gertrude Stein and Picasso would live during the next century. He had been working feverishly in the cellar for weeks, but no one walking on the fashionable street above could suspect that down below an experiment was being prepared — one that would forever change the way we view the world.

Jean Bernard Léon Foucault (Léon Foucault to all who knew him) was thirty-two years old. He was not a trained scientist, but he already had a few scientific achievements to his credit, including a clever experiment to measure the speed of light. And he could claim credit for some inventions as well, including a design for light in microscopy and a way of regulating theatrical lighting. But during the last few months of 1850 and into 1851, Léon Foucault had been concentrating all his efforts on a different kind of problem. He was attempting to solve the most persistent scientific problem of all time: one that had plagued Copernicus, Kepler, Descartes, Galileo, and Newton in the sixteenth to the eighteenth centuries, and that — surprisingly — remained unresolved as late as Foucault's own time.

He had prepared his experiment carefully, perfecting it during long hours of concentrated work in his cellar over a period of months. Foucault's remaining problems with the experiment were technical ones, and he was an expert at doing precision work with his hands. He worked with wires, metal cutters, measuring devices, and weights. He finally secured one end of a 2-meter long steel wire to the ceiling of the cellar in a way that allowed it to rotate freely without resulting torque. At the other end of the wire, he attached a 5-kilogram bob made of brass. Foucault had thus created a free-swinging pendulum, suspended from the ceiling.

Once the pendulum was set in motion, the plane in which it oscillated back and forth could change in any direction. Designing a mechanism that would secure this property was the hardest part of his preparations. And the pendulum had to be perfectly symmetric: Any imperfection in its shape or distribution of weight could skew the results of the experiment, denying Foucault the proof he desired. Finally, the pendulum's swing had to be initiated in such a way that it would not favor any particular direction because a hand pushed it slightly in one direction or another. The initial conditions of the pendulum's motion had to be perfectly controlled.

Since such a pendulum had never been made before, the process of building it also required much trial and error, and Foucault had been experimenting with the mechanism for a month. Finally, he got it right. His pendulum could swing in any direction without hindrance.

On January 3, 1851, Foucault's apparatus was ready, and he set the device in motion. He held his breath as the pendulum began to swing. Suddenly the wire snapped, and the bob fell heavily to the ground. Three days later, he was ready to try again. He carefully set the pendulum in motion and waited. The bob swung slowly in front of his eyes, and Foucault attentively followed every oscillation.

Finally, he saw it. He detected the slight but clearly perceptible change he was looking for in the plane of the swing of the pendulum. The pendulum's plane of oscillation had moved away from its initial position, as if a magic hand had intervened and pushed it slowly but steadily away from him. Foucault knew he had just observed the impossible. The mathematicians — and among them France's greatest names: Laplace, Cauchy, and Poisson — had all said that such motion could not occur or, if it did, could never be detected. Yet he, not a mathematician and not a trained physicist, somehow always knew that the mysterious force would be there. And now, he finally found it. He saw a clear shift in the plane of the swing of the pendulum. Léon Foucault had just seen the Earth turn.

Copyright © 2003 by Amir D. Aczel

Meet the Author

Amir D. Aczel is the bestselling author of ten books, including Entanglement, The Riddle of the Compass, The Mystery of the Aleph, and Fermat's Last Theorem. He lives in Brookline, Massachusetts.

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Pendulum: Leon Foucault and the Triumph of Science 3.5 out of 5 based on 0 ratings. 4 reviews.
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Plodding, padded, and repetitious. It's a tough job to fold any science at all into a pop narrative, but I thought this book to be so awkward that I looked to see if it was a translation. Seemingly, there is very little material on Foucault himself, so the book consists of background and tangential stuff that tends to repeat, and has the feel of entries in a juvenile encyclopedia. The science - all of it - is either missing or not meaningfully interpreted for lay readers. The major theme, of rejection by the establishment, isn't particularly supported by the (few) quotations, so it seems weak as well. It's a shame, since the pendulum is such an accessible and dramatic demonstration.