Nikolay Alekseevich Umov (; January 23, 1846 – January 15, 1915) was a
Russian physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate cau ...
and
mathematician
A mathematician is someone who uses an extensive knowledge of mathematics in their work, typically to solve mathematical problems. Mathematicians are concerned with numbers, data, quantity, mathematical structure, structure, space, Mathematica ...
known for discovering the concept of
Umov-Poynting vector and
Umov effect.
Biography
Umov was born in 1846 in
Simbirsk (present-day Ulyanovsk) in the family of a military doctor. He graduated from the Physics and Mathematics department of
Moscow State University
Moscow State University (MSU), officially M. V. Lomonosov Moscow State University,. is a public university, public research university in Moscow, Russia. The university includes 15 research institutes, 43 faculties, more than 300 departments, a ...
in 1867 and became a Professor of Physics in 1875. He studied theoretical physics by reading works of
Gabriel Lamé
Gabriel Lamé (22 July 1795 – 1 May 1870) was a French mathematician who contributed to the theory of partial differential equations by the use of curvilinear coordinates, and the mathematical theory of elasticity (for which linear elasticity ...
,
Clebsch and
Clausius
Rudolf Julius Emanuel Clausius (; 2 January 1822 – 24 August 1888) was a German physicist and mathematician and is considered one of the central founding fathers of the science of thermodynamics. By his restatement of Nicolas Léonard Sadi Ca ...
, that made a significant impact on the originality of his later ideas in physics.
Umov became the head of the Physics department of Moscow State University (MSU) after
Aleksandr Stoletov died in 1896. Together with
Pyotr Lebedev
Pyotr Nikolaevich Lebedev (; 24 February 1866 – 1 March 1912) was a Russian physicist. His name was also transliterated as Peter Lebedew and Peter Lebedev. Lebedev was the creator of the first scientific school in Russia.
Career
Lebedev made hi ...
, Umov actively participated in founding the Physical Institute at the MSU.
He organized several educational societies. He was the president of the Moscow Society of Nature Explorers for 17 years. He was among the first Russian scientists who acknowledged the importance of the
theory of relativity
The theory of relativity usually encompasses two interrelated physics theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical ph ...
. In 1911, along with a group of leading professors, he left Moscow University in protest of reactionary actions of the government. Umov died in 1915 in Moscow.
Contribution to physics
Umov was the first who introduced in physics such basic concepts as speed and direction of movement of
energy
Energy () is the physical quantity, quantitative physical property, property that is transferred to a physical body, body or to a physical system, recognizable in the performance of Work (thermodynamics), work and in the form of heat and l ...
, which are now associated with
Umov-Poynting vector, and density of energy in a given point of space. During his work in
Odessa
ODESSA is an American codename (from the German language, German: ''Organisation der ehemaligen SS-Angehörigen'', meaning: Organization of Former SS Members) coined in 1946 to cover Ratlines (World War II aftermath), Nazi underground escape-pl ...
from 1873 to 1874, Umov published first papers containing the major ideas of energy movement. In his first works of this period, Umov considered
potential energy
In physics, potential energy is the energy of an object or system due to the body's position relative to other objects, or the configuration of its particles. The energy is equal to the work done against any restoring forces, such as gravity ...
as
kinetic energy
In physics, the kinetic energy of an object is the form of energy that it possesses due to its motion.
In classical mechanics, the kinetic energy of a non-rotating object of mass ''m'' traveling at a speed ''v'' is \fracmv^2.Resnick, Rober ...
of some environments "imperceptible for us". From this hypothesis, he made a conclusion: it is always possible to specify a place where the energy is in. Therefore, it is natural to raise the question about movement of energy. In his following works, Umov did not bind himself to this hypothesis about the nature of potential energy, but was guided by the principle of energy conservation only. After formulating the concept of density and movement of energy, he wrote differential equations for energy movement in the elastic media and in the fluid. The authoritative
''Encyklopädie der mathematischen Wissenschaften'' states:
He was the first scientist to indicate interrelation between mass and energy proposing the formula
''E = kmc2'' with 0,5 ≤ k ≤ 1 as early as in 1873.
[''Умов Н. А. Избранные сочинения'' .A. Umov. Selected Works М. — Л., 1950.] In 1875, Umov solved a general problem of distribution of electric currents in conducting surfaces of any kind. Between 1888 and 1891, he investigated experimentally the diffusion in water solutions, the
polarization of light in opaque media, and discovered the effect of chromatic depolarization of light. In 1900, he conducted a thorough analysis of many
Gauss
Johann Carl Friedrich Gauss (; ; ; 30 April 177723 February 1855) was a German mathematician, astronomer, Geodesy, geodesist, and physicist, who contributed to many fields in mathematics and science. He was director of the Göttingen Observat ...
formulae regarding
terrestrial magnetism, which allowed the definition of secular changes of the Earth's magnetic field.
References
External links
Umov's works review
{{DEFAULTSORT:Umov, Nikolay
Physicists from the Russian Empire
Mathematicians from the Russian Empire
Moscow State University alumni
1846 births
1915 deaths