Gerard 't Hooft

Gerardus (Gerard) ’t Hooft (born July 5, 1946) is a Dutch theoretical physicist and professor at Utrecht University, the Netherlands.

Gerard ’t Hooft was born in Den Helder on July 5, 1946, but grew up in The Hague.

He was the middle child of a family of three.

He comes from a family of scholars.

His great uncle was Nobel prize laureate Frits Zernike, and his grandmother was married to Pieter Nicolaas van Kampen, a professor of zoology at Leiden University.

His uncle Nico van Kampen was an (emeritus) professor of theoretical physics at Utrecht University, and his mother married a maritime engineer.

Following his family's footsteps, he showed interest in science at an early age.

When his primary school teacher asked him what he wanted to be when he grew up, he replied, "a man who knows everything."

After primary school Gerard attended the Dalton Lyceum, a school that applied the ideas of the Dalton Plan, an educational method that suited him well.

He excelled at science and mathematics courses.

At the age of sixteen he won a silver medal in the second Dutch Math Olympiad.

After Gerard ’t Hooft passed his high school exams in 1964, he enrolled in the physics program at Utrecht University.

He opted for Utrecht instead of the much closer Leiden, because his uncle was a professor there and he wanted to attend his lectures.

Because he was so focused on science, his father insisted that he join the Utrechtsch Studenten Corps, a student association, in the hope that he would do something else besides studying.

This worked to some extent; during his studies he was a coxswain with their rowing club "Triton" and organized a national congress for science students with their science discussion club "Christiaan Huygens".

In the course of his studies he decided he wanted to go into what he perceived as the heart of theoretical physics, elementary particles.

His uncle had grown to dislike the subject and in particular its practitioners, so when it became time to write his doctoraalscriptie (former name of the Dutch equivalent of a master's thesis) in 1968, ’t Hooft turned to the newly appointed professor Martinus Veltman, who specialized in Yang–Mills theory, a relatively fringe subject at the time because it was thought that these could not be renormalized.

His assignment was to study the Adler–Bell–Jackiw anomaly, a mismatch in the theory of the decay of neutral pions; formal arguments forbid the decay into photons, whereas practical calculations and experiments showed that this was the primary form of decay.

The resolution of the problem was completely unknown at the time, and ’t Hooft was unable to provide one.

In 1969, ’t Hooft started on his doctoral research with Martinus Veltman as his advisor.

He would work on the same subject Veltman was working on, the renormalization of Yang–Mills theories.

In 1971 his first paper was published.

In it he showed how to renormalize massless Yang–Mills fields, and was able to derive relations between amplitudes, which would be generalized by Andrei Slavnov and John C. Taylor, and become known as the Slavnov–Taylor identities.

The world took little notice, but Veltman was excited because he saw that the problem he had been working on was solved.

A period of intense collaboration followed in which they developed the technique of dimensional regularization.

Soon ’t Hooft's second paper was ready to be published, in which he showed that Yang–Mills theories with massive fields due to spontaneous symmetry breaking could be renormalized.

These two papers formed the basis of ’t Hooft's dissertation, The Renormalization procedure for Yang–Mills Fields, and he obtained his PhD degree in 1972.

In the same year he married his wife, Albertha A. Schik, a student of medicine in Utrecht.

After obtaining his doctorate ’t Hooft went to CERN in Geneva, where he had a fellowship.

He further refined his methods for Yang–Mills theories with Veltman (who went back to Geneva).

In this time he became interested in the possibility that the strong interaction could be described as a massless Yang–Mills theory, i.e. one of a type that he had just proved to be renormalizable and hence be susceptible to detailed calculation and comparison with experiment.

According to ’t Hooft's calculations, this type of theory possessed just the right kind of scaling properties (asymptotic freedom) that this theory should have according to deep inelastic scattering experiments.

This was contrary to popular perception of Yang–Mills theories at the time, that like gravitation and electrodynamics, their intensity should decrease with increasing distance between the interacting particles; such conventional behaviour with distance was unable to explain the results of deep inelastic scattering, whereas ’t Hooft's calculations could.

When ’t Hooft mentioned his results at a small conference at Marseilles in 1972, Kurt Symanzik urged him to publish this result; but ’t Hooft did not, and the result was eventually rediscovered and published by Hugh David Politzer, David Gross, and Frank Wilczek in 1973, which led to their earning the 2004 Nobel Prize in Physics.

In 1974, ’t Hooft returned to Utrecht where he became assistant professor.

In 1976, he was invited for a guest position at Stanford and a position at Harvard as Morris Loeb lecturer.

He shared the 1999 Nobel Prize in Physics with his thesis advisor Martinus J. G. Veltman "for elucidating the quantum structure of electroweak interactions".

His work concentrates on gauge theory, black holes, quantum gravity and fundamental aspects of quantum mechanics.

His contributions to physics include a proof that gauge theories are renormalizable, dimensional regularization and the holographic principle.

This paper earned them worldwide recognition, and would ultimately earn the pair the 1999 Nobel Prize in Physics.