‘T Hooft, Gerardus (1946-) a Dutch physicist, developed a mathematical method to predict the properties of subatomic particles and forces. He won the 1999 Nobel Prize in physics with Martinus J. G. Veltman for his work on the structure of the electroweak interaction.

‘T Hooft's granduncle, Frits Zernike, won a Nobel Prize in physics in 1953 for his invention of a phase contrast microscope. His grandfather was Peiter Nicolaas van Kampen, a famous zoologist, and his uncle, Nicolaas Godfried van Kampen, was a theoretical physics professor at the State University of Utrecht.

‘T Hooft's father was a naval engineer, and his mother held a degree in French. ‘T Hooft grew up in The Hague, where his father worked in the dockyards that served as a home to the big cruise ships. For 10 months, when ‘t Hooft was eight, the family lived in London, England.

After returning to The Hague, ‘t Hooft completed his primary schooling and then attended the Dalton Lyceum. He chose to pursue a classical studies curriculum, which included ancient Greek and Latin and required an additional year of schooling. In addition to the classical languages and Dutch, ‘t Hooft studied English, French, and German.

At age 16, ‘t Hooft placed second in a Dutch National Math Olympiad and took home a two-volume math book, which included Euler's theorems for polygons in three-dimensional space. This type of mathematics would prove useful later in ‘t Hooft's career.

‘T Hooft often questioned the accuracy of his textbooks. In one case, he argued with his teacher about a statement in a physics book regarding the number of photons per second that a light bulb emits. To settle the matter, ‘t Hooft called upon the aid of his uncle, a physics professor. ‘T Hooft claimed that throughout his high-school years, teachers and examiners gave him higher grades than he deserved in biology because his grandfather was a well-known zoologist.

Following graduation, ‘t Hooft attended the State University of Utrecht, where he met Martinus J. G. Veltman, a professor of theoretical physics. Veltman supervised ‘t Hooft's undergraduate thesis. While ‘t Hooft focused much of his time in college on physics, he also had nonscientific interests. At the urging of his father, he participated in a student association, where he joined a science discussion club and helped organize a national congress for science students. He also was the coxswain on a rowing team. As a child, ‘t Hooft had taken up piano playing and drawing, and he has continued to play the piano throughout his life.

As a graduate student in 1969, ‘t Hooft collaborated with Veltman to develop a reliable mathematical model for the electroweak theory, which had been developed by three Nobel prize-winning scientists. In the early 1960s, Sheldon Lee Glashow, Steven Weinberg, and Abdus Salam created the theory of electroweak interaction, which synthesized theories of the electromagnetic force and the weak force. The weak force is involved in high-energy reactions where new particles are created and is responsible for nuclear decay. The electroweak theory predicted new particles, called W+, W-, and Z. But when scientists tried to use the electroweak theory to calculate the masses of the particles, they came up with nonsensical answers, such as infinity.

The electromagnetic force was itself a synthesis of electric and magnetic forces. Because these two forces are so closely related, they had been brought together in one new theory. In the late 1940's, Richard Phillips Feynman, Julian Seymour Schwinger, and Sin-Itiro Tomonaga independently came up with a process, called renormalization, which canceled out the infinite terms. All three scientists shared the 1965 Nobel Prize in physics. The electromagnetic renormalization process creates measurement results so exact that they match calculated results exactly.

Just as the electromagnetic theory had been renormalized, ‘t Hooft and Veltman set out to do the same for the electroweak theory. To accomplish this, they created a method that replaced infinite values with numbers that had been derived from experiments. They tested these various mathematical values using a computer program that Veltman had created in the 1960's. By the early 1970's, they had managed to successfully renormalize the electroweak theory by developing a method for measuring the precise characteristics of W and Z particles.

Although ‘t Hooft and Veltman's technique fails to yield the precise results of the renormalized electromagnetic theory, it has proven to be extremely accurate. In 1983, scientists at the European Organization of Nuclear Research (CERN), the European particle laboratory in Geneva, detected the W and Z particles, with results nearly the same as those predicted by ‘t Hooft and Veltman. In 1995, experiments at Fermi National Laboratory near Chicago produced a particle called the top quark, whose mass was in close agreement with calculations by ‘t Hooft and Veltman. The Higgs particle, a particle predicted by the electroweak theory, remains elusive. Scientists hope to secure this particle in testing with an accelerator called the Large Hadron Collider (LHC). The LHC is scheduled to be completed at CERN in 2005.

In 1981, Veltman accepted a position in the United States at the University of Michigan, where he is now emeritus professor. ‘T Hooft continues to teach at Utrecht. He is studying quantum gravity and black holes, trying to unlock the exact nature of black holes and the laws of physics that govern them. Another area of interest is gauge theories in elementary particle physics. Gauge fields mediate forces among elementary particles. ‘T Hooft also has written about the fundamental aspects of quantum physics and its implications for the big bang theories of the universe.

‘T Hooft and Albertha A. Schik, an anesthesiologist, married in 1972. They have two daughters.