The 1991 Nobel Prize in Physics was awarded to Pierre-Gilles de Gennes “for discovering that methods developed for studying order phenomena in simple systems can be generalized to more complex forms of matter, in particular to liquid crystals and polymers.”
The Science: Order in Matter
The physical structure of molecules and molecule chains within physical matter can have consequences on the macroscopic properties of the object, such as during the phase transition of an object from one state of matter to another.
In addition to the state of the matter, other properties can be determined from the physical structure of the atoms, such as by the orientation of the magnetic dipoles created by the atoms.
One of the most obvious examples of this phenomena is in a traditional iron bar magnet. The individual iron atoms each have a magnetic field from their magnetic dipole, and the atoms are physically structured within the magnet so that they are oriented in the same direction. This produces the net magnetic field from the bar magnet. When the iron magnet is heated, however, this ordered structure of the iron atoms degenerates, with the atoms transitioning into a disordered state with each of the individual atoms randomly oriented … and, as a consequence, there is no net magnetic field produced by the piece of metal. (See: How Magnets Work) For magnets, the temperature of this phase transition is known as the Curie temperature.
The physical structure of molecules of various phenomena are complex enough that many physicists had studied them but been unable to determine general rules governing their transition from ordered to disordered states.
French physicist Pierre-Gilles de Gennes, however, determined the mathematical relationships governing these sorts of transitions. Instead of needing a unique approach to each of these sorts of transition, Pierre-Gilles de Gennes showed that the same mathematical principles were applicable as a broad generalization for these transitions. Some examples include:
- Liquid crystals
- Transition to superconducting states
- Geometric arrangement and movement in polymer chains
- Stability conditions in micro-emulsions
The Science: Liquid Crystals
Liquid crystals had been known about for more than a century. (See images of liquid crystals here, here, and here.) Professor Wilhelm Oseen had begun studying how such crystals flowed as early as the 1920s, but it would take decades for them to come into practical use in electronics such as wristwatches and calculators (and even more decades before they would find use in liquid crystal display, or LCD, screens).
Dr. de Gennes formed a research group to focus on liquid crystal research in the late 1960s, including a combination of theorists and experimenters within the team. This group, led by de Gennes, was able to explain light scattering from liquid crystals and how the liquid crystals transitioned in response to a weak alternating electric field. His 1974 book The Physics of Liquid Crystals helped to define the field.
Pierre-Gilles de Gennes
Pierre-Gilles de Gennes was born in Paris, France, on October 24, 1932. He graduated from the Ecole Normale in 1955, then went on to work with the Atomic Energy Center from 1955 to 1959 (earning his PhD along the way in 1957). After some time at Berkeley and then in the French Navy, he went on to become an assistant professor in Orsay. He started a research group on superconductors initially, but then in 1968 switched his research emphasis to liquid crystals … the beginning of the work for which he is largely recognized with this award.
In 1971, de Gennes became a professor at the College de France in Paris and participated in the STRASACOL research group on polymer physics, where he continued his work in identifying mathematical descriptions of the physical structure of matter.
From 1976 to 2002, de Gennes was director of the Ecole de Physique et Chimie, in Paris, which focused on the education of research engineers in the fields of physics, chemistry, and (later) biology. He proceeded to study a number of unusual physical states of matter, such as gels, porous materials, and other “soft systems,” including a study of the “dynamics of wetting” and the physical chemistry of adhesion. Following the receipt of the Nobel Prize, de Gennes used it as an opportunity to speak to over 200 high schools from 1992 through 1994 on the subject of science, innovation, and common sense, ultimately writing a book (in French) on the subject.
He spent the last years of his life doing interdisciplinary research at the Institut Curie in Paris, which emphasizes cancer research. His work was focused on cellular adhesion and brain function. Dr. Pierre-Gilles de Gennes died on May 18, 2007, in Orsay, France.