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**Isaak Markovich Khalatnikov** (Russian : Исаак Маркович Халатников; born 17 October 1919) is a Soviet-born physicist known for his role in developing the BKL conjecture in general relativity.

**Russian** is an East Slavic language, which is official in the Russian Federation, Belarus, Kazakhstan and Kyrgyzstan, as well as being widely used throughout Eastern Europe, the Baltic states, the Caucasus and Central Asia. It was the *de facto* language of the Soviet Union until its dissolution on 25 December 1991. Although, nowadays, nearly three decades after the breakup of the Soviet Union, Russian is used in official capacity or in public life in all the post-Soviet nation-states, as well as in Israel and Mongolia, the rise of state-specific varieties of this language tends to be strongly denied in Russia, in line with the Russian World ideology.

The **Soviet Union**, officially the **Union of Soviet Socialist Republics** (**USSR**), was a socialist state in Eurasia that existed from 30 December 1922 to 26 December 1991. Nominally a union of multiple national Soviet republics, its government and economy were highly centralized. The country was a one-party state, governed by the Communist Party with Moscow as its capital in its largest republic, the Russian Soviet Federative Socialist Republic. Other major urban centres were Leningrad, Kiev, Minsk, Alma-Ata, and Novosibirsk.

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 causes of phenomena, and usually frame their understanding in mathematical terms. Physicists work across a wide range of research fields, spanning all length scales: from sub-atomic and particle physics, through biological physics, to cosmological length scales encompassing the universe as a whole. The field generally includes two types of physicists: experimental physicists who specialize in the observation of physical phenomena and the analysis of experiments, and theoretical physicists who specialize in mathematical modeling of physical systems to rationalize, explain and predict natural phenomena. Physicists can apply their knowledge towards solving practical problems or to developing new technologies.

Khalatnikov was born into a Jewish family in Dnipropetrovsk and graduated from Dnipropetrovsk State University with a degree in Physics in 1941. He had been a member of the Communist Party since 1944. He earned his doctorate in 1952. His wife Valentina was the daughter of Revolutionary hero Nikolay Shchors.

The **Communist Party of the Soviet Union** (**CPSU**) was the founding and ruling political party of the Soviet Union. The CPSU was the sole governing party of the Soviet Union until 1990, when the Congress of People's Deputies modified Article 6 of the most recent 1977 Soviet constitution, which had granted the CPSU a monopoly over the political system.

**Mykola Oleksandrovich Shchors** was a Red Army commander, member of the Russian Communist Party, renowned for his personal courage during the Russian Civil War and sometimes being called the Ukrainian Chapayev. In 1918–1919 he fought against the new established Ukrainian government of the Ukrainian People's Republic. Later he commanded the Bohunsky regiment, brigade, 1st Soviet Ukrainian division and 44th rifle division against head of the Ukrainian People's Republic Symon Petliura and his Polish allies. Shchors was slain in battle.

Much of Khalatnikov's research has been a collaboration with, or inspired by, Lev Landau, including the *Landau-Khalatnikov theory* of superfluidity.

**Lev Davidovich Landau** was a Soviet physicist who made fundamental contributions to many areas of theoretical physics.

**Superfluidity** is the characteristic property of a fluid with zero viscosity which therefore flows without loss of kinetic energy. When stirred, a superfluid forms cellular vortices that continue to rotate indefinitely. Superfluidity occurs in two isotopes of helium when they are liquified by cooling to cryogenic temperatures. It is also a property of various other exotic states of matter theorized to exist in astrophysics, high-energy physics, and theories of quantum gravity. The phenomenon is related to Bose–Einstein condensation, but neither is a specific type of the other: not all Bose-Einstein condensates can be regarded as superfluids, and not all superfluids are Bose–Einstein condensates. The theory of superfluidity was developed by Lev Landau.

In 1970, inspired by the mixmaster model introduced by Charles W. Misner, then at Princeton University, Khalatnikov, together with Vladimir A. Belinsky and Evgeny Mikhailovich Lifshitz, introduced what has become known as the BKL conjecture, which is widely regarded as one of the most outstanding open problems in the classical theory of gravitation.

The **Mixmaster universe** is a solution to Einstein field equations of general relativity studied by Charles Misner in an effort to better understand the dynamics of the early universe. He hoped to solve the horizon problem in a natural way by showing that the early universe underwent an oscillatory, chaotic epoch.

**Charles W. Misner** is an American physicist and one of the authors of *Gravitation*. His specialties include general relativity and cosmology. His work has also provided early foundations for studies of quantum gravity and numerical relativity.

**Princeton University ** is a private Ivy League research university in Princeton, New Jersey. Founded in 1746 in Elizabeth as the **College of New Jersey**, Princeton is the fourth-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution. The institution moved to Newark in 1747, then to the current site nine years later, and renamed itself Princeton University in 1896.

Khalatnikov directed the Landau Institute for Theoretical Physics in Moscow from 1965 to 1992. He was elected to the Soviet Academy of Sciences in 1984. He has been awarded the Landau Prize and the Alexander von Humboldt Award, and he is a foreign member of the Royal Society of London.

The **L. D. Landau Institute for Theoretical Physics** of the Russian Academy of Sciences is a research institution, located in the small town of Chernogolovka near Moscow. Its main fields of research are

**Moscow** is the capital and most populous city of Russia, with 13.2 million residents within the city limits, 17 million within the urban area and 20 million within the metropolitan area. Moscow is one of Russia's federal cities.

He is portrayed by Georg Nikoloff in * The Theory of Everything *.

* The Theory of Everything* is a 2014 biographical romantic drama film which is set at Cambridge University and details the life of the theoretical physicist Stephen Hawking. It was directed by James Marsh and adapted by Anthony McCarten from the memoir

- Order of Merit for the Fatherland, 3rd class
- Order of the October Revolution
- Order of the Patriotic War, 2nd class
- Order of the Red Banner of Labour, three times
- Order of Friendship of Peoples
- Order of the Badge of Honour
- Stalin Prize (1953)
- Marcel Grossmann Award (2012) "For the discovery of a general solution of the Einstein equations with a cosmological singularity of an oscillatory chaotic character known as the BKL singularity"

In physical cosmology, **cosmic inflation**, **cosmological inflation**, or just **inflation**, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10^{−36} seconds after the conjectured Big Bang singularity to sometime between 10^{−33} and 10^{−32} seconds after the singularity. Following the inflationary period, the universe continues to expand, but at a less rapid rate.

**Sir Roger Penrose** is an English mathematical physicist, mathematician and philosopher of science. He is Emeritus Rouse Ball Professor of Mathematics in the University of Oxford and Emeritus Fellow of Wadham College, Oxford.

The **Big Bounce** is a hypothetical cosmological model for the origin of the known universe. It was originally suggested as a phase of the *cyclic model* or *oscillatory universe* interpretation of the Big Bang, where the first cosmological event was the result of the collapse of a previous universe. It receded from serious consideration in the early 1980s after inflation theory emerged as a solution to the horizon problem, which had arisen from advances in observations revealing the large-scale structure of the universe. In the early 2000s, inflation was found by some theorists to be problematic and unfalsifiable in that its various parameters could be adjusted to fit any observations, so that the properties of the observable universe are a matter of chance. Alternative pictures including a Big Bounce may provide a predictive and falsifiable possible solution to the horizon problem, and are under active investigation as of 2017.

**Sergei Petrovich Novikov** is a Soviet and Russian mathematician, noted for work in both algebraic topology and soliton theory. In 1970, he won the Fields Medal.

In physics, the **Landau pole** is the momentum scale at which the coupling constant of a quantum field theory becomes infinite. Such a possibility was pointed out by the physicist Lev Landau and his colleagues. The fact that couplings depend on the momentum scale is the central idea behind the renormalization group.

**Evgeny Mikhailovich Lifshitz** was a leading Soviet physicist and brother of the physicist Ilya Lifshitz.

**Hagen Kleinert** is Professor of Theoretical Physics at the Free University of Berlin, Germany , Honorary Doctor at the West University of Timişoara, and at the Kyrgyz-Russian Slavic University in Bishkek. He is also Honorary Member of the Russian Academy of Creative Endeavors. For his contributions to particle and solid state physics he was awarded the Max Born Prize 2008 with Medal. His contribution to the memorial volume celebrating the 100th birthday of Lev Davidovich Landau earned him the Majorana Prize 2008 with Medal. He is married to Dr. Annemarie Kleinert since 1974 with whom he has a son Michael Kleinert.

**Dimitri V. Nanopoulos** is a Greek physicist. He is one of the most regularly cited researchers in the world, cited more than 48,500 times over across a number of separate branches of science.

A **Belinskii-Khalatnikov-Lifshitz (BKL) singularity** is a model of the dynamic evolution of the Universe near the initial singularity, described by an anisotropic, chaotic solutions of the Einstein field equations of gravitation. According to this model, the Universe is chaotically oscillating around a gravitational singularity in which time and space become equal to zero. This singularity is physically real in the sense that it is a necessary property of the solution, and will appear also in the exact solution of those equations. The singularity is not artificially created by the assumptions and simplifications made by the other special solutions such as the Friedmann–Lemaître–Robertson–Walker, quasi-isotropic, and Kasner solutions.

**Valery Leonidovich Pokrovsky** is a Soviet and Russian physicist. He is a member of the Landau Institute in Chernogolovka near Moscow in Russia and a professor for Theoretical Physics at Texas A&M University.

**Alexander Zakharovich Patashinski** is a Research Professor at Northwestern University in Evanston, Illinois. He is known for his contributions in many parts of the theoretical physics, including phase transition and critical phenomena, high energy physics, general relativity, amorphous materials. The announcement for the 1982 Nobel Prize in Physics, which was awarded to Kenneth G. Wilson, acknowledges Patashinski, along with B. Widom, Michael Fisher, Valery Pokrovsky, and Leo Kadanoff, for important contributions to the theory of critical phenomena and renormalization group. In 1983, Patashinski and Pokrovsky received the Landau Prize of the Academy of Sciences of USSR for these contributions

In a quantum field theory, charge screening can restrict the value of the observable "renormalized" charge of a classical theory. If the only resulting value of the renormalized charge is zero, the theory is said to be "trivial" or noninteracting. Thus, surprisingly, a classical theory that appears to describe interacting particles can, when realized as a quantum field theory, become a "trivial" theory of noninteracting free particles. This phenomenon is referred to as **quantum triviality**. Strong evidence supports the idea that a field theory involving only a scalar Higgs boson is trivial in four spacetime dimensions, but the situation for realistic models including other particles in addition to the Higgs boson is not known in general. Nevertheless, because the Higgs boson plays a central role in the Standard Model of particle physics, the question of triviality in Higgs models is of great importance.

**Vladimir Alekseevich Belinski** is a Russian and Italian theoretical physicist involved in research in cosmology and general relativity. He worked at Landau Institute for Theoretical Physics from 1968 to 1989 and got his Habilitation degree at this Institute in 1980. As of 2016, he holds the permanent professor position at International Network of the Centers for Relativistic Astrophysics (ICRANet), Italy.

**Solomon Isaakovich Pekar**, a Soviet theoretical physicist, born in Kiev, Ukraine. He was a full Member of the Ukrainian Academy of Sciences and is known for his fundamental contributions to condensed matter physics, especially for introducing and advancing the concept of polaron as a charge carrier in solids.

**Alexei Alexandrovich Starobinsky** is a Soviet and Russian astrophysicist and cosmologist. He received the Kavli Prize in Astrophysics “for pioneering the theory of cosmic inflation", together with Alan Guth and Andrei Linde in 2014.

**Alexander Nikolaevich Varchenko** is a Soviet and Russian mathematician working in geometry, topology, combinatorics and mathematical physics.

**Vadim L'vovich Berezinskii** was a Soviet physicist. He was born in Kiev, graduated from Moscow State University in 1959, and worked in Moscow and the Landau Institute for Theoretical Physics. He is famous for having identified the role played by topological defects in the low-temperature phase of two-dimensional systems with a continuous symmetry. His work led to the discovery of the Berezinskii–Kosterlitz–Thouless transition, for which John M. Kosterlitz and David J. Thouless were awarded the Nobel Prize in 2016. He also developed a technique for treating electrons in one-dimensional disordered systems and provided first consistent proof of one-dimensional localization. and predicted negative-gap superconductivity.

- "Khalatnikov's C.V." Retrieved August 11, 2005.
- Belinskii, V.; Khalatnikov, I.; Lifschitz, E. (1970). "Oscillatory approach to a singular point in the relativistic cosmology".
*Adv. Phys*.**19**(80): 525–573. Bibcode:1970AdPhy..19..525B. doi:10.1080/00018737000101171.

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