Hippolyte Fizeau

Armand Hippolyte Louis Fizeau FRS FRSE MIF (23 September 1819 – 18 September 1896) was a French physicist, best known for measuring the speed of light in the namesake Fizeau experiment.

Hippolyte Fizeau
Armand Hippolyte Louis Fizeau by Eugène Pirou - Original
Hippolyte Fizeau in 1883 by Eugène Pirou
Born23 September 1819
Died18 September 1896 (aged 76)
Known forDoppler effect
Fizeau–Foucault apparatus
AwardsRumford Medal (1866)
Scientific career


Fizeau was born in Paris to Louis and Beatrice Fizeau.[1] He married into the de Jussieu botanical family. His earliest work was concerned with improvements in photographic processes.[2] Following suggestions by François Arago, Léon Foucault and Fizeau collaborated in a series of investigations on the interference of light and heat.[3] In 1848, he predicted the redshifting of electromagnetic waves.[4]

In 1849, Fizeau calculated a value for the speed of light to a better precision than the previous value determined by Ole Rømer in 1676. He used a beam of light reflected from a mirror 8 kilometers away. The beam passed through the gaps between teeth of a rapidly rotating wheel. The speed of the wheel was increased until the returning light passed through the next gap and could be seen.

Fizeau calculated the speed of light to be 313,300 kilometres per second (194,700 mi/s), which was within 5% of the correct value (299,792.458 kilometers per second). Fizeau published the first results obtained by his method for determining the speed of light in 1849. (See Fizeau–Foucault apparatus.)[5] Fizeau made the first suggestion in 1864 that the "speed of a light wave be used as a length standard".[6]

Fizeau was involved in the discovery of the Doppler effect,[7] which is known in French as the Doppler–Fizeau effect.

In 1853, Fizeau described the use of the capacitor (sometimes called a "condenser") as a means to increase the efficiency of the induction coil. Later on, he studied the thermal expansion of solids and applied the phenomenon of interference of light to the measurement of the dilatations of crystals. He became a member of the Académie des Sciences in 1860 and a member of the Bureau des Longitudes in 1878. He died at Venteuil on 18 September 1896.[3]

"Fizeau" is one of the 72 names inscribed at the base of Eiffel Tower, and of the 72 scientists and engineers listed on the tower, Fizeau is the only one who was still alive when the tower was opened to the public for the 1889 World's Fair. The crater Fizeau on the far side of the Moon is named after him.[8]

See also


  1. ^ Hockey, Thomas (2009). The Biographical Encyclopedia of Astronomers. Springer Publishing. ISBN 978-0-387-31022-0. Retrieved August 22, 2012.
  2. ^ Solbert, Oscar N.; Newhall, Beaumont; Card, James g., eds. (May 1952). "Hippolyte-Louis Fizeau (1819–1896)" (PDF). Image, Journal of Photography of George Eastman House. Rochester, N.Y.: International Museum of Photography at George Eastman House Inc. 1 (5): 3–4. Archived from the original (PDF) on 14 July 2014. Retrieved 22 June 2014.
  3. ^ a b  One or more of the preceding sentences incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). "Fizeau, Armand Hippolyte Louis" . Encyclopædia Britannica. 10 (11th ed.). Cambridge University Press. p. 452.
  4. ^ Hellemans, Alexander; Bryan Bunch (1988). The Timetables of Science. New York City: Simon and Schuster. p. 317. ISBN 0-671-62130-0.
  5. ^ Poincaré, H. (1904). "Experiments of MM. Fizeau and Gounelle". Maxwell's Theory and Wireless Telegraphy: Part 1. New York: McGraw Publishing Co. pp. 52–55.
  6. ^ Physics part 1 Resnick/Halliday p. 5.
  7. ^ Houdas, Y. (April 1991). "Doppler, Buys-Ballot, Fizeau. Historical note on the discovery of the Doppler's effect". Annales de cardiologie et d'angéiologie (in French). 40 (4): 209–13. PMID 2053764.
  8. ^ "Fizeau on Moon". Gazetteer of Planetary Nomenclature. United States Geological Survey. Retrieved 21 September 2018.

External links



was a common year starting on Friday of the Gregorian calendar and a common year starting on Wednesday of the Julian calendar, the 1819th year of the Common Era (CE) and Anno Domini (AD) designations, the 819th year of the 2nd millennium, the 19th year of the 19th century, and the 10th and last year of the 1810s decade. As of the start of 1819, the Gregorian calendar was

12 days ahead of the Julian calendar, which remained in localized use until 1923.

1819 in France

Events from the year 1819 in France.

1819 in science

The year 1819 in science and technology involved some significant events, listed below.

1848 in science

The year 1848 in science and technology involved some significant events, listed below.

1849 in science

The year 1849 in science and technology involved some significant events, listed below.

1850 in science

The year 1850 in science and technology involved some significant events, listed below.

1851 in science

The year 1851 in science and technology involved some significant events, listed below.

1896 in France

Events from the year 1896 in France.

1896 in science

The year 1896 in science and technology involved some significant events, listed below.

Fast Fourier Transform Telescope

Fast Fourier Transform Telescope is Tegmark and Zaldarriaga's name for a design for an all-digital synthetic-aperture telescope. It is a type of interferometer designed to be cheaper than standard telescope interferometers currently in use.

In 1868, Hippolyte Fizeau realized that the lenses and mirrors in a telescope perform a physical approximation of a Fourier transform. He noted that by using an array of small instruments it would be possible to measure the diameter of a star with the same precision as a single telescope which was as large as the whole array — a technique which later became known as astronomical interferometry. See History of astronomical interferometry.

In a 2008 paper, Tegmark and Zaldarriaga proposed a telescope design that dispenses altogether with the lenses and mirrors, relying instead on computers fast enough to perform all the necessary transforms. The concept is an all-digital telescope with an antenna consisting of a rectangular grid. Building radio telescopes this way should become feasible within a few years if Moore's law continues to hold. Eventually optical telescopes could also be built this way. This technique is already being used in radar applications.

This paper refers to an earlier telescope design from 1993 which took direct images of the Crab nebula at radio wavelengths using an eight-by-eight-pixel two-dimensional spatial FFT processor.

Fizeau experiment

The Fizeau experiment was carried out by Hippolyte Fizeau in 1851 to measure the relative speeds of light in moving water. Fizeau used a special interferometer arrangement to measure the effect of movement of a medium upon the speed of light.

According to the theories prevailing at the time, light traveling through a moving medium would be dragged along by the medium, so that the measured speed of the light would be a simple sum of its speed through the medium plus the speed of the medium. Fizeau indeed detected a dragging effect, but the magnitude of the effect that he observed was far lower than expected. His results seemingly supported the partial aether-drag hypothesis of Fresnel, a situation that was disconcerting to most physicists. Over half a century passed before a satisfactory explanation of Fizeau's unexpected measurement was developed with the advent of Albert Einstein's theory of special relativity. Einstein later pointed out the importance of the experiment for special relativity, in which it corresponds to the relativistic velocity-addition formula when restricted to small velocities.

Although it is referred to as the Fizeau experiment, Fizeau was an active experimenter who carried out a wide variety of different experiments involving measuring the speed of light in various situations.

Fizeau interferometer

A Fizeau interferometer is an interferometric arrangement whereby two reflecting surfaces are placed facing each other. As seen in Fig 1, the rear-surface reflected light from the transparent first reflector is combined with front-surface reflected light from the second reflector to form interference fringes.

The term Fizeau interferometer also refers to an interferometric arrangement used by Hippolyte Fizeau in a famous 1851 experiment that seemingly supported the partial ether-drag hypothesis of Augustin Jean Fresnel, but which ultimately played an instrumental role in bringing about a crisis in physics that led to Einstein's development of the theory of special relativity. See Fizeau experiment.

Fizeau–Foucault apparatus

The Fizeau–Foucault apparatus is either of two types of instrument historically used to measure the speed of light. The conflation of the two instrument types arises in part because Hippolyte Fizeau and Léon Foucault had originally been friends and collaborators. They worked together on such projects as using the Daguerreotype process to take images of the Sun between 1843 and 1845 and characterizing absorption bands in the infrared spectrum of sunlight in 1847.In 1834, Charles Wheatstone developed a method of using a rapidly rotating mirror to study transient phenomena, and applied this method to measure the velocity of electricity in a wire and the duration of an electric spark. He communicated to François Arago the idea that his method could be adapted to a study of the speed of light. Arago expanded upon Wheatstone's concept in an 1838 publication, emphasizing the possibility that a test of the relative speed of light in air versus water could be used to distinguish between the particle and wave theories of light.

In 1845, Arago suggested to Fizeau and Foucault that they attempt to measure the speed of light. Sometime in 1849, however, it appears that the two had a falling out, and they parted ways pursuing separate means of performing this experiment. In 1848−49, Fizeau used, not a rotating mirror, but a toothed wheel apparatus to perform an absolute measurement of the speed of light in air. In 1850, Fizeau and Foucault both used rotating mirror devices to perform relative measures of the speed of light in air versus water. Foucault used a scaled-up version of the rotating mirror apparatus to perform an absolute measurement of the speed of light in 1862. Subsequent experiments performed by Marie Alfred Cornu in 1872–76 and by Albert A. Michelson in 1877–1931 used improved versions of the toothed wheel and rotating mirror experiments to make steadily more accurate estimates of the speed of light.

List of the 72 names on the Eiffel Tower

On the Eiffel Tower, seventy-two names of French scientists, engineers, and mathematicians are engraved in recognition of their contributions. Gustave Eiffel chose this "invocation of science" because of his concern over the protests against the tower. The engravings are found on the sides of the tower under the first balcony, in letters about 60 cm high, and originally painted in gold.

The engraving was painted over at the beginning of the twentieth century and restored in 1986–1987 by Société Nouvelle d'exploitation de la Tour Eiffel, the company contracted by the city of Paris to operate the Tower. The repainting of 2010–2011 restored the letters to their original gold colour.

There are also names of the engineers who helped build the tower and design its architecture on the top of the tower on a plaque, where a laboratory was built as well.

Louis-François-Clement Breguet

Louis François Clément Breguet (22 December 1804 – 27 October 1883), was a French physicist and watchmaker, noted for his work in the early days of telegraphy.

Educated in Switzerland, Breguet was the grandson of Abraham-Louis Breguet, founder of the watch manufacturing company Breguet. He became manager of Breguet et Fils watchmakers in 1833 after his father Louis Antoine Breguet retired.

Between 1835 and 1840 he standardized the company product line of watches, then making 350 watches per year, and diversified into scientific instruments, electrical devices, recording instruments, an electric thermometer, telegraph instruments and electrically synchronized clocks. With Alphonse Foy, in 1842 he developed an electrical needle telegraph to replace the optical telegraph system then in use. and a later step-by-step telegraph system (1847) was applied to French railways and exported to Japan. He observed in 1847 that small wires could be used to protect telegraph installations from lightning, the ancestor of the fuse.

He also manufactured the rotating mirror Fizeau–Foucault apparatus, used by Léon Foucault and Hippolyte Fizeau to measure the speed of light (1850). In 1856 he designed a public network of synchronized electric clocks for the center of Lyon. In 1866 he patented an electric clock controlled by a 100 Hz tuning fork.In 1870 he transferred the leadership of the company to Edward Brown. Breguet then focused entirely on the telegraph and the nascent field of telecommunications. He collaborated in the development of an induction coil, later improved by Heinrich Ruhmkorff.

In terms of honors, in 1843 he was appointed to the Bureau of Longitudes. In 1845 Breguet was awarded the Legion d'Honneur. He was made a member of the French Academy of Sciences in 1874, and was elevated to Officer of the Legion d'Honneur in 1877. He is one of the 72 French scientists whose names are written around the base of the Eiffel Tower.Breguet was married and had one son Antoine (1851–1882) who also joined the family electrical business. With his son, he met Alexander Graham Bell and obtained a license to manufacture Bell telephones for the French market. Grandfather of Louis Charles Breguet, aviation pioneer and aircraft manufacturer.

Michel Eugène Chevreul

Michel Eugène Chevreul (31 August 1786 – 9 April 1889) was a French chemist whose work with fatty acids led to early applications in the fields of art and science. He is credited with the discovery of margaric acid, creatine, and designing an early form of soap made from animal fats and salt. He lived to 102 and was a pioneer in the field of gerontology. He is also one of the 72 people whose names are inscribed on the Eiffel Tower; of those 72 scientists and engineers, Chevreul was one of only two who were still alive when Gustave Eiffel planted the French Tricolor on the top of the tower on 31 March 1889 (the other being Hippolyte Fizeau) and was the last living individual born before the French Revolution.

Michelson stellar interferometer

The Michelson stellar interferometer is one of the earliest astronomical interferometers built and used. The interferometer was proposed by Albert A. Michelson in 1890, following a suggestion by Hippolyte Fizeau.

The first such interferometer built was at the Mount Wilson observatory, making use of its 100-inch (~250 centimeters) mirror. It was used to make the first-ever measurement of a stellar diameter, by Michelson and Francis G. Pease, when the diameter of Betelgeuse was measured in December 1920. The diameter was found to be 240 million miles (~380 million kilometers), about the size of the orbit of Mars, or about 300 times larger than the Sun.

On Physical Lines of Force

"On Physical Lines of Force" is a famous four-part paper written by James Clerk Maxwell published between 1861 and 1862. In it, Maxwell derived the equations of electromagnetism in conjunction with a "sea" of "molecular vortices" which he used to model Faraday's lines of force. Maxwell had studied and commented on the field of electricity and magnetism as early as 1855/6 when "On Faraday's Lines of Force" was read to the Cambridge Philosophical Society. Maxwell made an analogy between the density of this medium and the magnetic permeability, as well as an analogy between the transverse elasticity and the dielectric constant, and using the results of a prior experiment by Wilhelm Eduard Weber and Rudolf Kohlrausch performed in 1856, he established a connection between the speed of light and the speed of propagation of waves in this medium.

The paper ushered in a new era of classical electrodynamics and catalyzed further progress in the mathematical field of vector calculus. Because of this, it is considered one of the most historically significant publications in the field of physics and of science in general, comparable with Einstein's Annus Mirabilis papers and Newton's Principia Mathematica.

Optical chopper

An optical chopper is a device which periodically interrupts a light beam. Three types are available: variable frequency rotating disc choppers, fixed frequency tuning fork choppers, and optical shutters. A rotating disc chopper was famously used in 1849 by Hippolyte Fizeau in the first non-astronomical measurement of the speed of light.

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