Landau, Lev Davidovich (physicist)


(1908-1968) Russian Low-Temperature, Atomic, Nuclear, Plasma, Solid State, and Quantum Physicist; Relativist

Lev Davidovich Landau was a brilliant theorist whose research and teaching raised theoretical physics in the Soviet Union to new levels. The range of his discoveries influenced all branches of theoretical physics, from fluid mechanics to quantum field theory. His theoretical explanation of why liquid helium is a superfluid earned him the 1962 Nobel Prize in physics.

Landau was born in Baku, Azerbaijan, Russian Empire, on January 22, 1908, into a scientifically oriented Jewish family. His father was an engineer, who worked in the Baku oil industry; his mother, a physician, who did research in physiology. Lev was a mathematical prodigy and finished his secondary studies at age 13. Too young to attend university, he studied physics and chemistry at the Baku Economical Technical School for a year before enrolling in Leningrad State University. After graduating in 1927, at the age of 19, he worked at the Leningrad Physico-Technical Institute (known as Phystech). At that time, the most exciting work in physics was being done in Europe, and Landau had the opportunity to interact with it firsthand. Between 1929 and 1931, he traveled to Gottingen, Leipzig, Zurich, and Cambridge. But his most formative stay was in Copenhagen, where he worked at niels henrik david bohr’s Institute of Theoretical Physics, developing the new quantum mechanics. From then on he became a disciple of Bohr, whose work would have a powerful impact on his subsequent research, which involved applying the quantum paradigm to all realms of theoretical physics.

In 1930, Landau published a quantum theoretical study on the behavior of free electrons in a magnetic field that drew him instant international recognition. It proved essential to an understanding of the properties of metals. Working in collaboration with his students, after he returned to the Soviet Union, he was able to uncover important new theoretical results about the structure of magnetic substances and superconductors and new insights into the quantum theory of phase transformations and thermodynamical fluctuations. In 1932, he became the head of the Theory Division of the Ukrainian Physical-Technical Institute in Kharkov, Ukraine. Under his leadership, it became the center of theoretical physics in the Soviet Union. Three years later, he became head physicist at the Kharkov Gorky State University and began collaboration with E. M. Lifshits on classic texts on theoretical physics. Studying under Landau was no small achievement: to be accepted a student had to master what Landau called “the theoretical minimum,” which meant basic knowledge of all fields of theoretical physics.

In 1937, Landau left Kharkov for Moscow to become head of the Theory Division of pyotr leonidovich kapitsa’s Institute of Physical Problems and teach at Moscow University. That year he married K. T. Drobanzeva, with whom he would have a son, Igor, who would become an experimental physicist. The late 1930s, however, was the height of the Stalinist purges, known as the Terror, and Landau soon became one of its victims. Swept up in the dragnet of random, groundless arrests, in April 1938, he was taken into custody and convicted of being a “German spy.” After a year in prison, he was seriously ill, and Kapitsa, whose work on behalf of Soviet physics was much valued by Stalin, was determined to save him. He handed the dictator a desperate ultimatum, saying that he, Kapitsa, would resign all his posts if Landau was not released immediately. Kapitsa won his gamble and Stalin assented. Although Landau would later be honored as a Hero of Socialist Labor, his youthful devotion to Communism did not survive this episode.

Lev Davidovich Landau was a Russian physicist whose discoveries influenced all branches of theoretical physics, from fluid mechanics to quantum field theory.

Lev Davidovich Landau was a Russian physicist whose discoveries influenced all branches of theoretical physics, from fluid mechanics to quantum field theory.

After Kapitsa’s discovery, in 1938, of the superfluidity of liquid helium II, Landau began research that would lead him to a complete theory of the “quantum liquids” at temperatures near absolute zero. Helium gas had previously been liquefied by cooling to about 4 K above absolute zero. However, subsequent experiments by Kapitsa indicated that when cooled another 2 K, liquid helium was transformed into a new state, called liquid helium II, whose high thermal conductivity allowed it to flow without friction through very fine capillaries and slits that almost completely prevent the flow of all other liquids. Kapitsa invented the term superfluid to describe the physical flow properties of liquid helium II. On the basis of these experiments Landau set out to explain superfluidity in terms not of single atoms, but of the quantized states of motion of the whole liquid. He began by looking at the fluid in its ground state of absolute zero temperature. He theoretically described the excited states of the superfluid in terms of quantum states that he called quasi particles. He then used Kapitsa’s experimental results to deduce the quantum mechanical properties of the quasi particles. Landau’s theory, from which the properties of the superfluid could be calculated, was later confirmed in 1957 by studies of the scattering of neutrons in liquid helium II and earned him the Nobel Prize in physics in 1962.

His papers of 1941-1947 are devoted to the theory of the quantum liquids of the Bose type, to which the superfluid liquid helium (the usual isotope 4He) belongs. Between 1956 and 1958, he formulated the theory of the quantum liquids of the Fermi type, among which liquid helium or isotope 3He belongs.

In 1962, the year he won the Nobel Prize, Landau was in a car accident that left him unconscious for six weeks. Several times doctors declared him clinically dead. Although he did regain consciousness and lived for another six years, he was never again capable of creative work. He died in Moscow on April 1, 1968.

Landau is famous for the major discoveries he made in low-temperature, atomic, nuclear, and plasma physics. He will always be remembered for his uncanny ability to see to the core of a physical problem with a unique physical intuition that he was able to apply to almost all areas of theoretical physics.

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