Loránd Eötvös

Loránd Eötvös

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Baron Loránd Eötvös de Vásárosnamény ( or Loránd Eötvös, ˈloraːnd ˈøtvøʃ; 27 July 1848 – 8 April 1919), more commonly called Baron Roland von Eötvös in English literature, was a Hungarian physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...

. He is remembered today largely for his work on gravitation and surface tension
Surface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...

.

Life


Born in 1848, the year of the Hungarian revolution
Hungarian Revolution of 1848
The Hungarian Revolution of 1848 was one of many of the European Revolutions of 1848 and closely linked to other revolutions of 1848 in the Habsburg areas...

, Eötvös was the son of József Eötvös
József Eötvös
József baron Eötvös de Vásárosnamény was a Hungarian writer and statesman, the son of Ignacz baron Eötvös de Vásárosnamény and Anna von Lilien, who stemmed from an Erbsälzer family of Werl in Germany....

, 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.

Loránd Eötvös first studied law, but soon switched to physics and went abroad to study in Heidelberg
Heidelberg
-Early history:Between 600,000 and 200,000 years ago, "Heidelberg Man" died at nearby Mauer. His jaw bone was discovered in 1907; with scientific dating, his remains were determined to be the earliest evidence of human life in Europe. In the 5th century BC, a Celtic fortress of refuge and place of...

 and Königsberg
Königsberg
Königsberg was the capital of East Prussia from the Late Middle Ages until 1945 as well as the northernmost and easternmost German city with 286,666 inhabitants . Due to the multicultural society in and around the city, there are several local names for it...

. After earning his doctorate, he became a university professor in Budapest
Budapest
Budapest is the capital of Hungary. As the largest city of Hungary, it is the country's principal political, cultural, commercial, industrial, and transportation centre. In 2011, Budapest had 1,733,685 inhabitants, down from its 1989 peak of 2,113,645 due to suburbanization. The Budapest Commuter...

 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.

Eötvös is remembered today for his experimental work on gravity, in particular his study of the equivalence of gravitational and inertial mass
Mass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...

 (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 Eötvös experiment
Eötvös experiment
The Eötvös experiment was a famous physics experiment that measured the correlation between inertial mass and gravitational mass, demonstrating that the two were one and the same, something that had long been suspected but never demonstrated with the same accuracy. The earliest experiments were...

 was cited by Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 in his 1916 paper The Foundation of the General Theory of Relativity. Measurements of the gravitational gradient are important in applied geophysics
Geophysics
Geophysics is the physics of the Earth and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and...

, such as the location of petroleum deposits. The CGS unit for gravitational gradient is named the eotvos
Eotvos (unit)
The eotvos is a unit of acceleration divided by distance that was used in conjunction with the older centimeter-gram-second system of units. The eotvos is defined as 1/1,000,000,000 galileo per centimetre...

 in his honor.

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

Eötvös is buried in the Kerepesi Cemetery
Kerepesi Cemetery
Kerepesi Cemetery is the most famous cemetery in Budapest...

 in Budapest, Hungary.

Torsion balance


A variation of the earlier invention, the Torsion balance, the Eötvös pendulum, designed by Hungarian Baron Loránd Eötvös, 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 horizontal plane. It determines the distribution of masses in the Earth's crust. The Eötvös 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 Eötvös 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 Eötvös' Pendulum. The Eötvös 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 was used later by Albert Einstein
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of general relativity, effecting a revolution in physics. For this achievement, Einstein is often regarded as the father of modern physics and one of the most prolific intellects in human history...

 as aid in setting out the theory of general relativity
General relativity
General relativity or the general theory of relativity is the geometric theory of gravitation published by Albert Einstein in 1916. It is the current description of gravitation in modern physics...

.

This is how Eötvös 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 (Cited from the Hungarian Wikipedia)


One of Eötvös' assistants who later became famous was Radó von Kövesligethy.

Eötvös' law of capillarity (weak equivalence principle) served as a basis for Einstein's theory of relativity.
(Capillarity: the property or exertion of capillary attraction of repulsion, a force that is the resultant of adhesion, cohesion, and surface tension in liquids which are in contact with solids, causing the liquid surface to rise – or be depressed...)

See also

  • eotvos
    Eotvos (unit)
    The eotvos is a unit of acceleration divided by distance that was used in conjunction with the older centimeter-gram-second system of units. The eotvos is defined as 1/1,000,000,000 galileo per centimetre...

    , a unit of gravitational gradient
  • Eötvös effect
    Eötvös effect
    The Eötvös effect is the change in perceived gravitational force caused by the change in centrifugal acceleration resulting from eastbound or westbound velocity...

    , a concept in geodesy
    Geodesy
    Geodesy , also named geodetics, a branch of earth sciences, is the scientific discipline that deals with the measurement and representation of the Earth, including its gravitational field, in a three-dimensional time-varying space. Geodesists also study geodynamical phenomena such as crustal...

  • Eötvös number
    Eötvös number
    In fluid dynamics the Eötvös number is a dimensionless number named after Hungarian physicist Loránd Eötvös . It is also known as the Bond number...

    , a concept in fluid dynamics
    Fluid dynamics
    In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...

  • Eötvös (crater)
    Eötvös (crater)
    Eötvös is the remains of a lunar crater on the far side of the Moon. It lies to the north-northwest of the walled plain Roche, and east-southeast of the equally ruined Bolyai....

     on the moon
  • Eötvös rule
    Eötvös rule
    The Eötvös rule, named after the Hungarian physicist Loránd Eötvös enables the prediction of the surface tension of an arbitrary liquid pure substance at all temperatures. The density, molar mass and the critical temperature of the liquid have to be known. At the critical point the surface...

     for predicting surface tension
    Surface tension
    Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...

     dependent on temperature
  • List of geophysicists
  • Lorandite
    Lorandite
    Lorandite is a thallium arsenic sulfosalt with the chemical formula: TlAsS2. Though rare, it is the most common thallium-bearing mineral. Lorandite occurs in low-temperature hydrothermal associations and in gold and mercury ore deposits...

    , a mineral named after Loránd Eötvös

External links