Pendulum : Leon Foucault and the Triumph of Science

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Summary: Physical Evidence Of The Unobvious Truth
Review: "You are invited to come to see the Earth turn, tomorrow, from three to five, at Meridian Hall ..." This curious invitation was sent on cards to all the known scientists in Paris on 2 February 1851. The physicist who issued them was convinced that at last he was going to be established as a scientist of repute; he had other discoveries and inventions to his name, but had garnered little official acknowledgement. In _Pendulum: Léon Foucault and the Triumph of Science_ (Atria Books), Amir Aczel, one of our best explicators of science themes, gives a remarkable account of just how it was physically demonstrated that we are not the center of everything. The book takes in a good deal of history of the ideas of astronomical movements, and nicely places Foucault's invention within his society and time.

Aczel rightly gives a history of the idea that the Earth turned, an idea that was at one time dangerous to hold because of religious implications. But the only thing the heliocentric model really had going for it was that the mathematical calculations for understanding and predicting celestial motion were simpler. That made it a good model, but still, you could sit on a hill and night and watch as the heavens moved, and feel no spin of the Earth. Foucault enabled us to see and feel a bit more accurately. He was a brilliant engineer, and an even better tinkerer with gadgets at his disposal. He had worked with electric lighting, microscopy, and photography, and turned his attention to the movement of the Earth. Mathematicians and physicists had said that such motion could never be observed, but Foucault worked in his cellar for months, perfecting his experiment, which seems so very simple in retrospect. He designed a series of larger pendulums. A pendulum swings in its own plane; on a moving Earth, the pendulum seems to shift around, depending on where the pendulum is located. People loved the huge pendulums and the clear demonstration.

Foucault was thereafter a celebrity, a status that he enjoyed. But it did not help him with the members of the Academy of Sciences. They were angry. He was not a trained scientist. He was not a trained mathematician. He had scooped them all with a simple experiment that had a universal appeal. It was not until three years before his death in 1865 that he was elected a member of the Academy, although he had gained many honors by that time. One of his further inventions was the gyroscope, which he invented specifically to see in another way the turning of the Earth (his word for it, "gyroscope", means literally "turn see"). Once again, he demonstrated the truth that the calculations had shown, but in a physical way. Aczel's book clearly shows how Foucault's ideas fit into the progression of our better understanding (and acceptance) of celestial movements. There are clear explanations here as well of how Coriolis force, a force Foucault knew nothing about, acts on pendulums, cannonballs, and storms, as well as how Foucault and his idea fit into the religious and political times. This is a readable tribute to a remarkable thinker. Come see the Earth turn.

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Summary: Foucault fools hackwriter Aczel
Review: Aczel doesn't get it and furthers the claim originally made by Foucault that his free-swinging pendulum stays in the same plane as the earth rotates, which is plain (pun intended) nonsense. If it did, then 12 hours later at Paris, the free-swinging pendulum, having knocked out the sidewall, would be swinging out of the side of the building. During the next 12 hours, it would de-levitate to be seen swinging at about right angles to the plane of its motion in which, 24 hours earlier, it started. This is so as the clockwise precession of the pendulum in Paris is about 11 degrees per hour. Which means that the pendulum lags the earth's real rotation by 4 degrees an hour. So after 24 hours, when the orientation and place of the earth is as it was when the pendulum was set going, the plane in which the pendulum is swinging is at 96 degrees to the direction that it originally had. So much for the lie that the pendulum stays in the same plane. The actual strange behavior was not understood by Foucault, nor has it been good to continue to champion his ridiculous claim that the complex phenomenon, which is observed, clearly demonstrates that the earth rotates.

To add insult to injury Aczel writes:

"On January 6, 1680, Hooke wrote to Newton:"

"'In the mean time I must acquaint you that I have (with as much care as I could) made 3 tryalls of the experiment of the falling body, in every of which the ball fell towards the south-east of the perpendicular, and that very considerably, the last being above a quarter of an inch, but because they were not all the same I know not which was true.'"

"Hooke's experiments with falling objects thus revealed not only the correct deviation east, but also a smaller deviation to the south, now known to be spurious. These results were seen as inconclusive."

But the result is not spurious. At the moment of its release, the object would no longer be forced to rotate in a due east direction, which is a small-circle parallel the equator, but like a ball from a whirled sling it would begin to fall in the plane of a great-circle tangent to the small-circle through the point of release and centered on the center of the earth. As a result, in England, the falling object would fall south of east of the vertical through the point of release. This is what careful Hooke observed and, although the savants of the day may not have been convinced by three trials, the free fall of an object is the only simple-to-understand method to give proof of the earth's rotation. The complex behavior of the Foucault pendulum anywhere but precisely at the north or south pole provides for no clear proof. And that demonstration has never been done. The supposed mathematical "QED" explanation of the motion of the Foucault pendulum (at a latitude other than 90 degrees north or south) offered at the end of the book by Aczel is so nonsensical that it should be seen as laughable but not everyone will have the math to get the joke.

Save your sanity and your money and wait for someone to write a better and more informed book...

Rating:
Summary: Marvelous Discovery
Review: Aczel tells a wonderful story in this new book: about the discovery of a proof of the rotation of the Earth by Leon Foucault 150 years ago. Foucault was an untrained scientist who became one of the greatest physicists of his time by being able to use a pendulum to demonstrate that the Earth rotates on its axis--despite what the mathematicians and physicists of the day were saying: that it was impossible! The author did a very nice job combining the history of France during the Second Empire with advances in technology and science at that time and Foucault great odyssey of discovery and triumph in the face of great adversity.

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Summary: A Gem of a Book!
Review: Amir Aczel has outdone himself, yet again, with another book that simply cannot be put down. Not only does he describe the life of a perhaps little-known-to-some but most important scientist, but he also goes off on tangents to give the reader a true flavor of the times in which Foucault was living, as well as including mini biographies of people who influenced Foucault's life in various ways. I believe that these tangents are a credit to the book and contribute to its uncommonly exciting nature. Aczel's writing style is as clear as a bell - especially on the scientific explanations that are given. A true credit to popular science writing!

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Summary: History of science at its best
Review: Amir Aczel's "Pendulum: Leon Foucault and the Triumph of Science" artfully combines history, biography, and science in a way that captures the human drama behind Foucault's demonstration--as irrefutable as it was ingenious--of the earth's rotation in the 1850s. Before reading "Pendulum" I had thought that after the work of Galileo, Kepler, Copernicus, Newton, it was commonly accepted by all that the earth rotated on its axis. Apparently I was wrong: all accepted this proposition save the Catholic Church, who held fast to the believe that the earth stood fixed and motionless, while all the heavens revolved around it. Curiously, while the Church persecuted (indeed, killed) anyone who maintained that the earth rotated, even as early as 1615, Cardinal Bellarmine articulated the position that if an irrefutable proof could be given of the earth's rotation, the Church would change its view.

Aczel recounts how Foucault, an outsider to the world of the French academy, without the benefit of rigorous university training in mathematics and science, devised his demonstration, proved a surprising relationship between the behavior of the pendulum and the lattitude of the location of the pendulum, and finally overcame systematic discrimination by the reigning authorities of the French academy and was finally recognized for his achievements.

Foucault enjoyed the support of the emperor Louis Napoleon, who himself had dabbled with science during his time in prison, years before. Louis Napoleon arranged for a public viewing of Foucault's elegant pendulum demonstration in the Pantheon in Paris, which provided a great forum for the Parisian public to see science in action and history in the making.

Aczel is a master of relating episodes in the history of science and mathematics to a general audience. As in his earlier books, Aczel deftly sketches relevant biographical detail of the major dramatis personae and the historical context of the story. His explanations of the underlying scientific and mathematical principles are notably clear and jargon-free. "Pendulum" weaves Church history, French political and social history, biography, and science into a cohesive narrative that highlights, above all else, the human drama of scientific discovery. This is the history of science at its best.

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Summary: An informationally rich coverage
Review: This account of Leon Foucault and his dramatic scientific inside the Pantheon in Paris tells of his experiment revolving and the pendulum's path - offering proof that the earth revolves on its axis. Author Amir Aczel uses primary research to reveal the life and background of a physicist who had almost o former education in science. The pendulum wasn't his only amazing discovery - he invented the modern compass, devised an electric microscope, and invented photography. This informationally rich coverage blends his life and science in an intriguing survey.