Lorand Eotvos
Eotvos in 1912
Born	27 July 1848 Buda , Kingdom of Hungary
Died	8 April 1919 (1919-04-08) (aged 70) Budapest , Hungarian Soviet Republic
Nationality	Hungarian
Alma mater	University of Heidelberg
Known for	Eotvos effect Eotvos experiment Eotvos number Eotvos rule
Spouse	Gizella Horvat
Children	Jolan Rolanda Ilona
Parent(s)	Jozsef Eotvos Agnes Rosty de Barkocz
Scientific career
Fields	Physics
Institutions	University of Budapest
Doctoral advisor	Hermann Helmholtz [1]

Baron Lorand Eotvos de Vasarosnameny (or Lorand Eotvos, pronounced [?loraːnd ?øtvø?] , Hungarian : vasarosnamenyi baro Eotvos Lorand Agoston ; 27 July 1848 ? 8 April 1919), also called Baron Roland von Eotvos in English literature, ^[2] was a Hungarian physicist . He is remembered today largely for his work on gravitation and surface tension , and the invention of the torsion pendulum .

In addition to Eotvos Lorand University ^[3] and the Eotvos Lorand Institute of Geophysics in Hungary, the Eotvos crater on the Moon, ^[4] the asteroid 12301 Eotvos and the mineral lorandite also bear his name, as well as a peak (Cima Eotvos) in the Dolomites .

Life [ edit ]

Born in 1848, the year of the Hungarian revolution , Eotvos was the son of the Baron Jozsef Eotvos de Vasarosnameny (1813?1871), a well-known poet, writer, and liberal politician, who was cabinet minister at the time, and played an important part in 19th century Hungarian intellectual and political life. His mother was the Hungarian noble lady Agnes Rosty de Barkocz (1825?1913), member of the illustrious noble family Rosty de Barkocz  [ hu ] that originally hailed from the Vas county , and through this, he descended from the ancient medieval Hungarian noble Perneszy family , which died out in the 18th century. Lorand's uncle was Pal Rosty de Barkocz (1830?1874) was a Hungarian nobleman , photographer, and explorer, who visited Texas , New Mexico , Mexico, Cuba and Venezuela between 1857 and 1859.

Lorand Eotvos first studied law, but soon switched to physics and went abroad to study in Heidelberg and Konigsberg . After earning his doctorate, he became a university professor in Budapest and played a leading part in Hungarian science for almost half a century. He gained international recognition first by his innovative work on capillarity , then by his refined experimental methods and extensive field studies in gravity.

Eotvos is remembered today for his experimental work on gravity , in particular his study of the equivalence of gravitational and inertial mass (the so-called weak equivalence principle ) and his study of the gravitational gradient on the Earth's surface. The weak equivalence principle plays a prominent role in relativity theory and the Eotvos experiment was cited by Albert Einstein in his 1916 paper The Foundation of the General Theory of Relativity . Measurements of the gravitational gradient are important in applied geophysics , such as the location of petroleum deposits. The CGS unit for gravitational gradient is named the eotvos in his honor.

From 1886 until his death, Lorand Eotvos researched and taught in the University of Budapest , which in 1950 was renamed after him ( Eotvos Lorand University ) .

Eotvos is buried in the Kerepesi Cemetery in Budapest, Hungary. ^[5]

Torsion balance [ edit ]

A variation of the earlier invention, the torsion balance in the Eotvos experiment , the Eotvos pendulum , designed by Hungarian Baron Lorand Eotvos, is a sensitive instrument for measuring the density of underlying rock strata. The device measures not only the direction of force of gravity, but the change in the force of gravity's extent in the horizontal plane. It determines the distribution of masses in the Earth's crust. The Eotvos torsion balance, an important instrument of geodesy and geophysics throughout the whole world, studies the Earth's physical properties. It is used for mine exploration, and also in the search for minerals, such as oil, coal and ores. The Eotvos pendulum was never patented, but after the demonstration of its accuracy and numerous visits to Hungary from abroad, several instruments were exported worldwide, and the richest oilfields in the United States were discovered by using it. The Eotvos pendulum was used to prove the equivalence of the inertial mass and the gravitational mass accurately, as a response to the offer of a prize. This equivalence was used later by Albert Einstein in setting out the theory of general relativity .

This is how Eotvos describes his balance:

It was just a simple, straight stick that I used as instrument, specially loaded at both ends, enclosed into a metal sheath to protect it from the wind and temperature changes. Upon this stick every single mass, be it near or far, exerts a directing force; but the wire upon which it hangs resists, and whilst resisting it twists, with the degree of this twist showing us the exact magnitude of the forces acting upon the stick. This is a Coulomb balance, and that is all there is to it. It is simple, like the flute of Hamlet, you only have to know how to play on it, and just like the musician who can delight you with splendid variations, the physicist can, on this balance, with no less delight determine the finest variations of gravity. This way we can peer into such depth of the crust of the Earth, that neither our eyes, nor our longest drills could reach. ^{[6] [7]}

One of Eotvos' assistants who later became a noted scientist was Rado von Kovesligethy .

Honors [ edit ]

To honor Eotvos, a postage stamp was issued by Hungary on 1 July 1932. ^[8] Another stamp was issued on 27 July 1948 to commemorate the centenary of the birth of the physicist. ^[9] Hungary issued a postage stamp on 31 January 1991. ^[10]

See also [ edit ]

• Eotvos , a unit of gravitational gradient
• List of geophysicists
• Lorandite , a mineral named after Lorand Eotvos

References [ edit ]

Further reading [ edit ]

• Antall, J. (1971), "The Pest School of Medicine and the health policy of the Centralists. On the centenary of the death of Jozsef Eotvos", Orvosi Hetilap , vol. 112, no. 19 (published 9 May 1971), pp. 1083?9, PMID   4932574

External links [ edit ]

• Media related to Lorand Eotvos at Wikimedia Commons
• Eotvos and STEP (biographical remarks and a summary of his research)
• Eotvos Lorand Virtual Museum