Justin-Mirande René Benoit or Jean-René Benoit (29 November 1844 – 5 May 1922) was a French physicist who was involved in establishing metric standards as director of the

International Bureau of Weights and Measures The International Bureau of Weights and Measures (, BIPM) is an List of intergovernmental organizations, intergovernmental organisation, through which its 64 member-states act on measurement standards in areas including chemistry, ionising radi ...

(Bureau International des Poids et Mesures) from 1889 to 1915. He was involved in moving from a physical definition of the unit of length to one based on the wavelength of light. Benoit was born in

Montpellier Montpellier (; ) is a city in southern France near the Mediterranean Sea. One of the largest urban centres in the region of Occitania (administrative region), Occitania, Montpellier is the prefecture of the Departments of France, department of ...

where his father, Justin Benoit, was dean of the medicine school. He too studied medicine but moved to study physics at the École des Hautes Études, examining electrical resistance and temperature for his doctorate which he received in 1873. He worked in the industry before joining the International Bureau of Weights and Measures. He worked along with

Albert A. Michelson Albert Abraham Michelson ( ; December 19, 1852 – May 9, 1931) was an American physicist known for his work on measuring the speed of light and especially for the Michelson–Morley experiment. In 1907, he received the Nobel Prize in Physics, ...

and based on their findings, Benoit suggested using the light wave as a unit for defining length. They established a definition based on the wavelength determined through interferometry and based on the red spectral line of cadmium.

References

{{DEFAULTSORT:Benoit, Justin-Mirande René 1844 births 1922 deaths 19th-century French physicists