Nikolay Umov
Encyclopedia
Nikolay Alekseevich Umov (January 23, 1846 – January 15, 1915) was a Russian
physicist
and mathematician
known for discovering the concept of Umov-Poynting vector and Umov effect
.
in 1867 and became a Professor of Physics in 1875. He studied theoretical physics by reading works of Gabriel Lamé
, Clebsch and Clausius, 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, 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
. 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.
, which are now associated with Umov-Poynting vector, and density of energy in a given point of space. During his work in Odessa
in 1873—1874, Umov published first papers containing the major ideas of energy movement. In his first works of this period, Umov considered potential energy
as kinetic energy
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: "N. Umov in 1874 had already solved a problem of the movement of energy in liquid and elastic media in completely generalized view. However, the intense attention to this view has been attracted only after Poynting
had presented a stream of electromagnetic energy based on Maxwell equations" ten years later than Umov's publications.
He was the first scientist to indicate interrelation between mass and energy proposing the formula
with 0,5 =< k =< 1 as early as in 1873. In 1875, Umov solved a general problem of distribution of electric currents in conducting surfaces of any kind. In 1888—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
formulae regarding terrestrial magnetism, which allowed the definition of secular changes of the Earth's magnetic field.
Russians
The Russian people are an East Slavic ethnic group native to Russia, speaking the Russian language and primarily living in Russia and neighboring countries....
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...
and mathematician
Mathematician
A mathematician is a person whose primary area of study is the field of mathematics. Mathematicians are concerned with quantity, structure, space, and change....
known for discovering the concept of Umov-Poynting vector and Umov effect
Umov effect
The Umov effect, also known as Umov's law, is a relationship between the albedo of an astronomical object, and the degree of polarization of light reflecting off it...
.
Biography
Umov was born in 1846 in Simbirsk (nowadays Ulyanovsk) in the family of a military doctor. He graduated from the Physics and Mathematics department of Moscow State UniversityMoscow State University
Lomonosov Moscow State University , previously known as Lomonosov University or MSU , is the largest university in Russia. Founded in 1755, it also claims to be one of the oldest university in Russia and to have the tallest educational building in the world. Its current rector is Viktor Sadovnichiy...
in 1867 and became a Professor of Physics in 1875. He studied theoretical physics by reading works of Gabriel Lamé
Gabriel Lamé
Gabriel Léon Jean Baptiste Lamé was a French mathematician.-Biography:Lamé was born in Tours, in today's département of Indre-et-Loire....
, Clebsch and Clausius, 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
Aleksandr Stoletov
Aleksandr Grigorievich Stoletov was a Russian physicist, founder of electrical engineering, and professor in Moscow University. He was the brother of general Nikolai Stoletov.-Biography:...
died in 1896. Together with Pyotr Lebedev, 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
Theory of relativity
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word relativity is sometimes used in reference to Galilean invariance....
. 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 energyEnergy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
, which are now associated with Umov-Poynting vector, and density of energy in a given point of space. During his work in Odessa
Odessa
Odessa or Odesa is the administrative center of the Odessa Oblast located in southern Ukraine. The city is a major seaport located on the northwest shore of the Black Sea and the fourth largest city in Ukraine with a population of 1,029,000 .The predecessor of Odessa, a small Tatar settlement,...
in 1873—1874, Umov published first papers containing the major ideas of energy movement. In his first works of this period, Umov considered potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...
as kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
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
Klein's encyclopedia
In mathematics, Klein’s encyclopedia refers to a German mathematical encyclopedia published in six volumes from 1898 to 1933. Felix Klein and Wilhelm Meyer were organizers of the encyclopedia. Its title in English is "Encyclopedia of mathematical sciences including their applications", which is...
states: "N. Umov in 1874 had already solved a problem of the movement of energy in liquid and elastic media in completely generalized view. However, the intense attention to this view has been attracted only after Poynting
Poynting
Poynting may refer to:* John Henry Poynting , a British physicist** Poynting vector, a representation of the energy flux of an electromagnetic field** Poynting's theorem on conservation of energy in electromagnetic field...
had presented a stream of electromagnetic energy based on Maxwell equations" ten years later than Umov's publications.
He was the first scientist to indicate interrelation between mass and energy proposing the formula
with 0,5 =< k =< 1 as early as in 1873. In 1875, Umov solved a general problem of distribution of electric currents in conducting surfaces of any kind. In 1888—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 GaussGauss
Gauss may refer to:*Carl Friedrich Gauss, German mathematician and physicist*Gauss , a unit of magnetic flux density or magnetic induction*GAUSS , a software package*Gauss , a crater on the moon...
formulae regarding terrestrial magnetism, which allowed the definition of secular changes of the Earth's magnetic field.