Léon Foucault was born on September 18, 1819, the son of a publisher in Paris and attended the Stanislas College there from 1829 . He received his training from a private teacher , since he had been advised to leave school for lack of diligence and good behavior. He began studying medicine , but had to break it off because he couldn't get over the disgust when dissecting . Through the influence of the physicist Hippolyte Fizeau of the same age , he found interest in and access to physics and astronomy. Without a university degree, he devoted himself to physics and acquired extensive knowledge and skills on an autodidactic basis .
In the 1840s he contributed to the scientific journal Comptes rendus de l ' Académie des sciences, describing an electromagnetic regulator for the electric arc lamp , and published a paper on binocular vision with Henri Victor Regnault . Furthermore, in 1845 he succeeded in creating the first usable daguerreotype of the sun, which was an extremely important contribution to further astrophotography at that time. In 1851 he presented the Foucault pendulum named after him to the public. After several attempts in the Paris observatory, he fastened a 67 meter long rope with a weight of 28 kg in the dome of the Pantheon in Paris. Under the tip of the pendulum, he marked the stand on the floor at rest. But since a pendulum, according to his thoughts, maintains the plane of oscillation, the position of the pendulum above the marking changes due to the rotation of the earth. The result was visible after just a few minutes of the experiment. The presentation of this experiment, carried out by Vincenzo Viviani in 1661, illustrated the earth's rotation .
In the years 1850–1851, with the help of the rotating mirror method he developed, he succeeded in measuring the speed of light very precisely , which he determined to be 298,000 km / s - five percent lower than Hippolyte Fizeau's result in 1849. He used a rotating mirror which resembled that of Sir Charles Wheatstone . In his experimental set-up, he let a thin bundle of light hit a rapidly rotating mirror, the light being deflected by a certain angle. From this, Foucault calculated the speed of light. In addition, he proved in 1853, also with the rotating mirror method, that the speed of light in water is lower than in air , which at the same time confirmed the hypothesis of the wave nature of light. In optics , the Foucault cutting edge method he developed is still used today to test optical surfaces or entire optical systems. Foucault also studied eddy currents in metals, for which he received the Copley Medal in 1855 . In the same year he became an employee of the Paris observatory. He developed a powerful telescope and, based on Johann Gottlieb Friedrich von beans Bergers gyroscope of 1810, in the years 1851-1852 the gyrocompass .
In 1862 he published various results of his long-term research. He was admitted to the French Academy of Sciences in 1865 .
At the age of 48, Foucault suffered a serious illness from which he first felt numbness in his hands in October 1867. It progressed rapidly until he died, almost blind and mute, on February 11, 1868 in Paris . The exact cause of death is unclear, although a rapidly progressing case of multiple sclerosis , a stroke or the aftereffects of his long-term experiments with chemicals, especially mercury , are assumed.
Together with 71 other scientists, he is immortalized by name on the Eiffel Tower ( The 72 names on the Eiffel Tower ).
Effect and honors
- 1855: Winner of the Copley Medal
- 1860: Foreign corresponding member of the Imperial Russian Academy of Sciences in St. Petersburg
- 1862: Member of the Presidium of the Bureau des Longitudes in Paris
- 1862: Order of Merit Legion of Honor (officer)
- 1864: Foreign member of the Royal Society in London
- 1864: Honorary Fellow of the Royal Society of Edinburgh
- 1865: Member of the Académie des Sciences
- 1865: Corresponding member of the Prussian Academy of Sciences
- Foucault and his pendulum play an important role in the novel Foucault's Pendulum by Umberto Eco
- The Bouguer-Foucault photometer was named after Pierre Bouguer and Foucault
- The Glan-Foucault prism was named after Paul Glan and Foucault
- The submarine Foucault of the Brumaire class was named after Foucault
- His name is immortalized on the Eiffel Tower (southeast side), see: The 72 names on the Eiffel Tower
- In 1935 the Foucault crater was named after him
- In 1997 the asteroid (5668) Foucault was named after him
- Street names Rue Foucault in 16th arrondissement (Paris) , Clichy and Québec
- Léon Foucault High School, Hoyerswerda
- The painter and sculptor Gerhard Richter (born 1932) created his work of art Two gray double mirrors for a pendulum for the Foucault pendulum in Münster, which has been on view in the Dominican Church there since June 17, 2018 .
- Amir D. Aczel: Pendulum. Léon Foucault and the Triumph of Science. Washington Square Press, New York NY et al. 2003, ISBN 0-7434-6478-8 .
- William Tobin: Evolution of the Foucault-Secretan Reflecting Telescope. In: Journal of Astronomical History and Heritage. Volume 19, No. 2, 2016, pp. 106-184 , No. 3, 361-362 , (Errata and Addenda).
- William Tobin: Léon Foucault. In: Scientific American. Volume 279, No. 1, July 1998, pp. 70-77, JSTOR 26057851 .
- William Tobin: The Life and Science of Léon Foucault. The Man who Proved the Earth Rotates. Cambridge University Press, Cambridge et al. 2003, ISBN 0-521-80855-3 .
- Literature by and about Léon Foucault in the catalog of the German National Library
- Digitized works by Foucault ( Memento of February 9, 2012 in the Internet Archive ) - SICD of the Universities of Strasbourg
- Bernd Wolfram, University of Hamburg: Jean Bernard Léon Foucault (PDF, 265 KiB)
- Foucault pendulum of the KIP of Heidelberg University with live webcam (left)
- Article by / about Léon Foucault in the Polytechnic Journal
- Léon Foucault in the nndb (English)
- Biography Léon Foucault - St. Andrews School of Mathematics and Statistics
- Note also Foucaultstrom, engl. Foucault's current
- Members of the previous academies. Jean Bernard Léon Foucault. Berlin-Brandenburg Academy of Sciences and Humanities , accessed on March 24, 2015 .
- Sketch of the Bouguer-Foucault photometer
|ALTERNATIVE NAMES||Foucault, Jean Bernard Léon (full name)|
|BRIEF DESCRIPTION||French physicist|
|DATE OF BIRTH||September 18, 1819|
|PLACE OF BIRTH||Paris , France|
|DATE OF DEATH||February 11, 1868|
|Place of death||Paris , France|