't Hooft was born inDen Helder on July 5, 1946,[2] to Hendrik 't Hooft and Margaretha Agnes 'Peggy' van Kampen, but grew up inThe Hague. He was the middle child in a family of three. He comes from a family of scholars. His great-uncle was Nobel Prize laureateFrits Zernike; his maternal grandfather wasPieter Nicolaas van Kampen, a professor ofzoology atLeiden University; his uncleNico van Kampen was a professor emeritus of theoretical physics at Utrecht University, and his father was a maritime engineer.[3] Following his family's footsteps, he showed an 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."[4]
After primary school Gerard attended the Dalton Lyceum, a school that implemented theDalton Plan, an educational method that suited him well. He excelled in science and mathematics. At the age of sixteen, he won a silver medal in the second DutchMath Olympiad.[4]
After 't Hooft passed his secondary-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. Since Gerard focused solely on science, his father insisted he join the Utrechtsch Studenten Corps, a student association, in the hope that he would engage in activities outside of studying. To some extent this worked: During his studies he was acoxswain with the rowing club "Triton" and organized a national congress for science students with the science discussion club "Christiaan Huygens".
In the course of his studies, he decided to delve 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. When it became time to write hisdoctoraalscriptie (former name of the Dutch equivalent of a master'sthesis) in 1968, 't Hooft turned toMartinus Veltman, the newly appointed professor who specialized inYang–Mills theory. At the time, this subject was considered relatively fringe, because it was thought that it could not berenormalized. His assignment was to study theAdler–Bell–Jackiw anomaly, a mismatch in the theory of the decay of neutralpions; formal arguments forbid the decay intophotons, 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 began his doctoral research under the guidance of Martinus Veltman. He worked on the same subject as Veltman: the renormalization of Yang–Mills theories. In 1971 his first paper was published.[5] In it he demonstrated how to renormalize massless Yang–Mills fields, and was able to derive relations between amplitudes. These relations would later be generalized byAndrei Slavnov andJohn C. Taylor and become known as theSlavnov–Taylor identities.
The world took little notice, but Veltman was excited because he realized that the problem he had been working on had been solved. A period of intense collaboration followed, during which they developed the technique ofdimensional regularization. Soon, 't Hooft's second paper was ready to be published,[6] in which he showed that Yang–Mills theories with massive fields due to spontaneous symmetry breaking could be renormalized. This paper earned them worldwide recognition and ultimately won them the 1999 Nobel Prize in Physics.
These two papers formed the basis of 't Hooft's 1972Ph.D.dissertationThe Renormalization Procedure for Yang–Mills Fields. That same year he married Albertha A. Schik, a medical student in Utrecht.[4]
After obtaining his doctorate 't Hooft went toCERN inGeneva, where he held a fellowship. There, he further refined his methods for Yang–Mills theories with Veltman (who had returned to Geneva). During this time, he became interested in the possibility that thestrong interaction could be described as a massless Yang–Mills theory. This type of theory he had just proven to be renormalizable, making it susceptible to detailed calculation and comparison with experiments.
According to 't Hooft's calculations, this type of theory possesses just the right kind of scaling properties (asymptotic freedom) thatdeep inelastic scattering experiments suggest it should have. This was contrary to the popular perception ofYang–Mills theories at the time. Like gravitation and electrodynamics, it was thought that their intensity would decrease with increasing distance between the interacting particles. However, such conventional behavior could not explain the results of deep inelastic scattering, whereas 't Hooft's calculations could.
In 1974, 't Hooft returned to Utrecht where he became an assistant professor. In 1976, he was invited to take on a guest position atStanford and a position atHarvard as Morris Loeb Lecturer. His eldest daughter, Saskia Anne, was born inBoston, while his second daughter, Ellen Marga, was born in 1978 after he returned to Utrecht, where he was made full professor.[4] In the 1987–1988 academic year 't Hooft spent a sabbatical in the Boston University Physics Department along withHoward Georgi,Robert Jaffe and others arranged by the then new department chairLawrence Sulak.
In 2007 't Hooft became the editor-in-chief ofFoundations of Physics, where he sought to distance the journal from the controversy ofECE theory[9] and held the position until 2016.
On July 1, 2011 Utrecht University appointed him distinguished professor.[10]
He is married to Albertha A. Schik (Betteke), MD, former anaesthesiologist, Arbo-arts (medical doctor for company personnel), now retired.He has two daughters; Saskia A. Eisberg - ’t Hooft. Labyrinth Risk Consulting, Now living in Zeist (NL), and Ellen M. ’t Hooft. Veterinary Surgeon at Hopmans Diergeneeskundig Centrum, Roden, Drenthe (NL) .[11]
In 1999 't Hooft shared the Nobel prize in Physics with his thesis adviser Veltman for "elucidating the quantum structure of the electroweak interactions in physics".[12] Before that time his work had already been recognized by other notable awards. In 1981, he was awarded theWolf Prize,[13] possibly the most prestigious prize in physics after the Nobel prize. Five years later he received theLorentz Medal, awarded every four years in recognition of the most important contributions in theoretical physics.[14] In 1995, he was one of the first recipients of theSpinozapremie, the highest award available to scientists in the Netherlands.[15] In the same year he was also honoured with aFranklin Medal.[16] In 2000, 't Hooft received the Golden Plate Award of theAmerican Academy of Achievement.[17] He was awarded a Special Breakthrough Prize in April 2025 in recognition of his contributions to Fundamental Physics across his career.[1]
't Hooft's research interest can be divided in three main directions: 'gauge theories in elementary particle physics', 'quantum gravity and black holes', and 'foundational aspects of quantum mechanics'.[23]
't Hooft is most famous for his contributions to the development of gauge theories in particle physics. The best known of these is the proof in his PhD thesis that Yang–Mills theories are renormalizable, for which he shared the 1999 Nobel Prize in Physics. For this proof he introduced (with his adviser Veltman) the technique ofdimensional regularization.
After receiving his PhD, he became interested in the role of gauge theories in the strong interaction,[4] the leading theory of which is calledquantum chromodynamics or QCD. He focused much of his research on the problem ofcolor confinement in QCD, i.e. the observational fact that only color-neutral particles are observed at low energies. This led him to the discovery thatSU(N) gauge theories simplify in thelargeN limit,[24] a fact that has proven important in examining the conjecturedcorrespondence betweenstring theories in anAnti-de Sitter space andconformal field theories in one lower dimension. By solving the theory in one space and one time dimension, 't Hooft was able to derive a formula for the masses ofmesons.[25]
He also studied the role of so-calledinstanton contributions in QCD. His calculations showed that these contributions lead to an interaction between lightquarks at low energies that is not present in the standard theory.[26] Studying instanton solutions of Yang–Mills theories, 't Hooft discovered thatspontaneously breaking a theory with SU(N) symmetry to aU(1) symmetry leads to the existence ofmagnetic monopoles.[27] These monopoles are called't Hooft–Polyakov monopoles, afterAlexander Polyakov, who obtained the same result independently.[28]
When Veltman and 't Hooft moved to CERN after 't Hooft obtained his PhD, Veltman's attention was drawn to the possibility of applying their dimensional regularization techniques to the problem of quantizing gravity. Although it was known that perturbativequantum gravity was not fully renormalizible, they felt important lessons were to be learned by studying the formal renormalization of the theory order by order. This work would be continued byStanley Deser and another PhD student of Veltman,Peter van Nieuwenhuizen, who later found patterns in the renormalizationcounter terms, which led to the discovery ofsupergravity.[4]
In the 1980s, 't Hooft's attention was drawn to the subject of gravity in 3 spacetime dimensions. Together with Deser and Jackiw he published an article in 1984 describing the dynamics of flat space where the only local degrees of freedom were propagating point defects.[31] His attention returned to this model at various points in time, showing thatGott pairs would not causecausality violatingtimelike loops,[32] and showing how the model could be quantized.[33] More recently he proposed generalizing this piecewise flat model of gravity to 4 spacetime dimensions.[34]
WithStephen Hawking's discovery ofHawking radiation ofblack holes, it appeared that the evaporation of these objects violated a fundamental property of quantum mechanics,unitarity. 't Hooft refused to accept this problem, known as theblack hole information paradox, and assumed that this must be the result of the semi-classical treatment of Hawking, and that it should not appear in a full theory of quantum gravity. He proposed that it might be possible to study some of the properties of such a theory, by assuming that such a theory was unitary.
Using this approach he has argued that near a black hole, quantum fields could be described by a theory in a lower dimension.[35] This led to the introduction of theholographic principle by him andLeonard Susskind.[36]
't Hooft has "deviating views on the physicalinterpretation ofquantum theory".[23] He believes that there could be adeterministic explanation underlying quantum mechanics.[37] Using a speculative model he has argued that such a theory could avoid the usualBell inequality arguments that would disallow such alocal hidden-variable theory.[38] In 2016 he published a book length exposition of his ideas[39] which, according to 't Hooft, has encountered mixed reactions.[40] In 2025, speaking in his often-times plainspoken manner, he was quoted in Scientific American, "Quantum mechanics is the possibility that you can consider superpositions of states. That's really all there is to it."[41]
Billings, Lee, "Quantum Physics Is Nonsense: Theoretical physicist Gerard 't Hooft reflects on the future" (interview with Gerard 't Hooft),Scientific American, vol. 333, no. 1 (July/August 2025), pp. 104–108. "Quantum mechanics is the possibility that you can considersuperpositions of states. That's really all there is to it. And I'd argue that superpositions of states are not real." (p. 106.)
Curt Jaimungal, 2025 interview with Gerard 't Hooft, "The Nobel Laureate Who (Also) Says Quantum Theory Is 'Totally Wrong'"[2]
^"NWO Spinoza Prize 1995". Netherlands Organisation for Scientific Research. 3 September 2014. Archived fromthe original on 2015-06-29. Retrieved2016-01-30.
