Vitaly Ginzburg was an outstanding Russian (formerly Soviet) scientist. A theoretical physicist and astrophysicist, he was a member of the Russian Academy of Sciences and head of the Department of Theoretical Physics at the Academy’s P. N. Lebedev Physical Institute in Moscow.

Ginzburg is best known for his contribution to the theory of superconductivity, for which he was awarded the 2003 Nobel Prize in Physics; for the theory of electromagnetic wave propagation in plasmas (such as the ionosphere); and for a theory of the origin of cosmic radiation. He also made a fundamental contribution to the development of the Soviet thermonuclear (hydrogen) weapon.

The world of very small things, like electrons and other particles, atoms, and so on, is controlled by quantum physics. Many spectacular effects occur in the micro-world that do not normally occur in our ordinary world — the macro-world.

One example of many is the uncertainty principle. This states that it is not possible to know accurately both the position and velocity of a particle. This is counterintuitive. In our world, we can know accurately the velocity of, say, a motor car as it passes a certain location. There are, however, certain situations in the macro-world to which quantum physics does apply. One of them is superconductivity.

The electrical resistance of a metallic conductor decreases as the temperature of the conductor falls. However, in ordinary conductors such as copper and silver, impurities, for example, limit the effect. Even at a temperature near absolute zero (minus 273.15 centigrade), the lowest possible temperature, they have some electrical resistance.

It was discovered in 1911 that when mercury was cooled by liquid helium, to a temperature of about minus 200C, its electrical resistance vanished altogether. This phenomenon was called superconductivity.

Many people are familiar with the concept of superconductivity because it is a popular device in science fiction, movies and computer games. The complete absence of electrical resistance provides the producers of such entertainment with abundant technological possibilities.

Superconductivity occurs in a wide variety of materials, including simple elements such as tin and aluminium and various metallic alloys. But it does not occur in, for example, noble metals such as gold and silver.

The resistance of a superconductor drops sharply to zero when the material is cooled below a “critical temperature”, typically about minus 253C. An electrical current flowing in a loop of wire made from a superconductor will continue indefinitely without an applied voltage. Currents flowing in coils made of superconducting material can persist for years. Experimental evidence suggests that such currents last for at least 100,000 years.

After superconductivity was discovered, great efforts were made to find out how and why it happens. But it was 40 years before a theory of superconductivity was elaborated. In 1950 Lev Davidovich Landau and Vitaly Ginzburg published one. Landau died in 1968 but Ginzburg was awarded the Nobel Prize — Aleksei Abrikosov and Anthony Leggett were also recipients in 2003 — for his contribution to developing the theory.

The work of Landau and Ginzburg helped to make possible the development of important applications of superconductivity. In 1962 the first commercial superconducting wire was made using a niobium-titanium alloy.

The fact that an electrical current will continue to flow in a superconductor indefinitely is exploited in superconducting electromagnets. Some of the most powerful electromagnets known to man are made from superconductors, such as the magnets used in magnetic resonance imaging (MRI) machines, used in hospitals to scan patients. Superconductors have also been used to make digital circuits and microwave filters used in the base stations for mobile phones.