Russian and 2 Americans Win Nobel Prize Physics Honors (The New York Times)
Russian and 2 Americans Win Nobel Prize Physics Honors
A Russian and two Americans, one originally from Russia and one from England, won the Nobel Prize in Physics yesterday for their insights on how electricity can flow through some materials without resistance and some fluids can flow without friction.
The winners are Dr. Alexei A. Abrikosov, 75, of Argonne National Laboratory in Illinois; Dr. Vitaly L. Ginzburg, 87, of the P. N. Lebedev Physical Institute in Moscow; and Dr. Anthony J. Leggett, 65, of the University of Illinois at Urbana-Champaign.
All three were recognized for work done decades ago . Dr. Abrikosov and Dr. Ginzburg for theoretical research in the early 1950's, when physicists were struggling to figure out the nature of superconductivity, and Dr. Leggett for explanations of strange properties of liquid helium in the 1970's.
"They have been nominating me for about 30 years, so in that sense it didn't come out of the blue," Dr. Ginzburg told The Associated Press. "But I thought, `Well, they're not giving it to me, I guess that's it.' After all, there are a lot of contenders. So, you know, I had long ago forgotten to think about this."
Superconductors are materials that lose all resistance to electrical currents at ultracold temperatures. Wound into magnets, they have found uses like magnetic resonance imaging machines and a new magnetically levitating train in Shanghai that can travel 250 miles per hour.
In the late 1950's, three physicists . Dr. John Bardeen, Dr. Leon N. Cooper and Dr. John R. Schrieffer solved the underlying physical mechanisms that give rise to superconductivity. That work is known as B.C.S. theory, after the scientists' surnames. (They won the Nobel Prize in 1972.)
This year's prize recognizes even earlier theoretical work. Without knowing the behavior of electrons and atoms in a superconductor, Dr. Ginzburg, along with Dr. Lev Landau, another Russian physicist, devised a set of equations in 1950 that describe the behavior of a superconductor near the temperature at which electrical resistance falls to zero. Those Ginzburg-Landau equations correctly predicted a superconductor's tolerance to magnetic fields and its capacity for electrical current.
Dr. Vladimir Kogan, a physicist at Ames Laboratory in Iowa, described the equation as "a brilliant tour de force guess."
"Ginzburg-Landau gave people a relatively simple tool to address actual effects they can measure in the lab," Dr. Kogan said. "It is correct, and people use it up to today."
Dr. Landau, who won the 1962 Nobel Prize in Physics for other research, died in 1968.
Dr. Abrikosov began his work soon after Dr. Ginzburg and Dr. Landau published their equation when physicists discovered that some materials could maintain their superconductivity at much higher magnetic fields, a property essential for applications like magnets and motors.
"These experimentalists, they found something they couldn't explain, so they asked me to help them with the explanation," Dr. Abrikosov said in a telephone interview.
In 1953, Dr. Abrikosov, then at the Kapitsa Institute for Physical Problems in Moscow, extended the Ginzburg-Landau equations to show that with the new superconductors, magnetic fields did not immediately destroy superconductivity, but instead passed through the material in cylindrical vortices, preserving superconductivity outside of the vortices.
Because of the cold war, the Ginzburg-Landau equations did not receive much attention from Western scientists, who focused on B.C.S. theory. Scientists later showed that the two theories were compatible, that the general Ginzburg-Landau equations could be derived from the more specific B.C.S. theory. Western scientists also had little knowledge of Dr. Abrikosov's work until the 1960's.
Just as superconductors conduct without resistance, superfluids flow without friction or viscosity, leading to unusual behavior. When poured in a beaker, a superfluid will flow up the sides and out.
Three scientists won the Nobel Prize in Physics in 1996 for discovering in 1972 that the rare, lighter version of helium with two protons and a single neutron in its nucleus turns into a superfluid at a few thousandths of a degree above absolute zero. (Absolute zero is the coldest possible temperature, about minus 459 degrees Fahrenheit, where motion comes to an almost complete stop.)
Using the same B.C.S. theory that underlies superconductivity, Dr. Leggett described why light helium behaves as a superfluid.
In their experiments, the Cornell researchers also observed some strange properties in the helium superfluid when it was placed in magnetic fields. When they finished a draft of the scientific paper describing their experiment, they sent copies to other physicists, including Dr. Leggett, who was then at the University of Sussex in England. Less than a month later, Dr. Leggett had worked out an explanation for the strange properties.
"That must not have taken more than three weeks to do," said Dr. Douglas D. Osheroff, one of the three Cornell researchers, now a professor at Stanford. "That was really a key piece."
Dr. Leggett expanded his calculations and worked out properties of the superfluid. Dr. Osheroff said that several times after they observed new effects in the superfluid, "Sure enough, Tony had predicted it."
The three winners will split $1.3 million in prize money.
"In a Communist country, nobody could save any money," said Dr. Abrikosov, who emigrated from Russia in 1991. "I think this money, it solves my problems."
He also said he had not yet retired. For one thing, he said he could explain the workings of high-temperature superconductors, a class discovered in the 1980's that defy B.C.S. theory.
"I know the answer," Dr. Abrikosov said, "and one day I will write a book."