- Person
- Vitaly Ginzburg
- Lived
- 1916–2009
- Field
- Theoretical physics
- From
- Russian
The story
Superconductivity, the complete loss of electrical resistance in certain materials cooled close to absolute zero, was discovered in 1911. Such materials also push magnetic fields out of their interior. Decades later there was still no satisfactory theory explaining how superconductors behave, especially in magnetic fields.
In 1950, in Moscow, Vitaly Ginzburg of the Lebedev Physical Institute and Lev Landau took a new approach. Landau had already built a general theory of phase transitions, and had worked for years on quantum fluids such as liquid helium. Rather than starting from the behaviour of individual electrons, which nobody yet understood, the two described the superconducting state with a single quantity, a complex order parameter whose size measures the density of superconducting electrons. They then wrote equations for how this quantity varies in space and how it interacts with magnetic fields.
Their paper appeared in 1950 in the Soviet Journal of Experimental and Theoretical Physics, only in Russian. It defined two characteristic lengths: the coherence length, over which the order parameter changes, and the penetration depth, over which a magnetic field dies away inside the material. Their ratio, now called the Ginzburg–Landau parameter, separates two kinds of superconductor. Below a value of one over the square root of two a material is type I; above it, type II.
The theory proved remarkably powerful. In 1957 Alexei Abrikosov used it to show that magnetic fields enter type-II superconductors as a lattice of tiny quantised whirlpools, or vortices. In 1959 Lev Gor'kov derived the Ginzburg–Landau equations from the new microscopic theory of superconductivity, showing that they emerge as a limiting case and giving their parameters a precise meaning. The same mathematical approach spread into the study of phase transitions and even into quantum field theory and string theory.
In 2003 Ginzburg, then 87, shared the Nobel Prize in Physics with Abrikosov and Anthony Leggett for pioneering contributions to the theory of superconductors and superfluids. Landau had received his own Nobel Prize in 1962. Ginzburg noted with amusement that the 1950 paper was cited so often that people usually mentioned it without even listing the reference.
Why it matters
The Ginzburg–Landau theory is taught to every student of condensed-matter physics and remains a working tool for designing superconducting materials, magnets and devices.
About Vitaly Ginzburg
Soviet-Jewish physicist whose Ginzburg–Landau theory of superconductivity won the 2003 Nobel Prize, and who survived Stalin’s antisemitic purges to become a fearless public voice.
More about Vitaly Ginzburg
- Vitaly Ginzburg founded a department to train physicistsIn 1968 Vitaly Ginzburg founded the Department of Problems of Physics and Astrophysics at the Moscow Institute of Physics and Technology, which he headed for decades.
- Vitaly Ginzburg helped bring genetics back to the USSRVitaly Ginzburg was among the scientists who helped end the dominance of Trofim Lysenko, the politically connected opponent of genetics, allowing modern genetic science to return to the Soviet Union.
- Vitaly Ginzburg kept a famous list of physics' big questionsFor three decades Vitaly Ginzburg compiled and updated a list of the most important unsolved problems in physics, publishing 30 problems for the 21st century in 1999.
- Vitaly Ginzburg developed a theory of cosmic ray originsVitaly Ginzburg developed a theory of the origin of cosmic rays, the high-energy particles that rain on Earth from space, work honoured by the cosmic ray physicists' Ó Ceallaigh Medal.
- Vitaly Ginzburg explained how radio waves cross the skyDuring the Second World War and after, Vitaly Ginzburg developed the theory of how electromagnetic waves travel through plasmas such as the ionosphere, vital for long-distance radio.
- Vitaly Ginzburg's theory underpins MRI magnetsSuperconducting magnets in hospital MRI scanners and particle accelerators rely on type-II superconductors, whose behaviour is described by the theory Vitaly Ginzburg helped create.
- Vitaly Ginzburg ran a physics seminar for 1,700 sessionsFrom the mid-1950s Vitaly Ginzburg ran a weekly Wednesday physics seminar in Moscow that drew scientists from across the city and beyond, closing it at its 1,700th session in November 2001.
Sources
- Vitaly Ginzburg Wikipedia
- The Nobel Prize in Physics 2003, Press release NobelPrize.org
- Ginzburg–Landau theory Wikipedia
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