Gerardus (Gerard) 't Hooft (; born July 5, 1946) is a Dutch
theoretical physicist
Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experim ...
and professor at
Utrecht University
Utrecht University (UU; nl, Universiteit Utrecht, formerly ''Rijksuniversiteit Utrecht'') is a public research university in Utrecht, Netherlands. Established , it is one of the oldest universities in the Netherlands. In 2018, it had an enrollm ...
, the Netherlands. He shared the 1999
Nobel Prize in Physics
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
with his thesis advisor
Martinus J. G. Veltman "for elucidating the quantum structure of
electroweak interaction
In particle physics, the electroweak interaction or electroweak force is the unified description of two of the four known fundamental interactions of nature: electromagnetism and the weak interaction. Although these two forces appear very diff ...
s".
His work concentrates on
gauge theory
In physics, a gauge theory is a type of field theory in which the Lagrangian (and hence the dynamics of the system itself) does not change (is invariant) under local transformations according to certain smooth families of operations (Lie groups ...
,
black hole
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...
s,
quantum gravity
Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics; it deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the v ...
and fundamental aspects of quantum mechanics. His contributions to physics include a proof that gauge theories are
renormalizable,
dimensional regularization and the
holographic principle.
Personal life
He is married to Albertha Schik (Betteke) and has two daughters, Saskia and Ellen.
Biography
Early life
Gerard 't Hooft was born in
Den Helder on July 5, 1946, but grew up in
The Hague
The Hague ( ; nl, Den Haag or ) is a list of cities in the Netherlands by province, city and municipalities of the Netherlands, municipality of the Netherlands, situated on the west coast facing the North Sea. The Hague is the country's ad ...
. 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
Pieter Nicolaas van Kampen (30 June 1878, Amsterdam – 3 July 1937, Leiden) was a Dutch zoologist.
In 1904 he received his PhD from the University of Amsterdam, where he was a student and assistant to Max Carl Wilhelm Weber. From 1905 to 191 ...
, a professor of
zoology
Zoology ()The pronunciation of zoology as is usually regarded as nonstandard, though it is not uncommon. is the branch of biology that studies the animal kingdom, including the structure, embryology, evolution, classification, habits, and ...
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.
Education
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
The coxswain ( , or ) is the person in charge of a boat, particularly its navigation and steering. The etymology of the word gives a literal meaning of "boat servant" since it comes from ''cock'', referring to the cockboat, a type of ship's boa ...
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
In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. Particles currently thought to be elementary include electrons, the fundamental fermions (quarks, leptons, an ...
. 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
A thesis ( : theses), or dissertation (abbreviated diss.), is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings.International Standard ISO 7144 ...
) in 1968, 't Hooft turned to the newly appointed professor
Martinus Veltman, who specialized in
Yang–Mills theory
In mathematical physics, Yang–Mills theory is a gauge theory based on a special unitary group SU(''N''), or more generally any compact, reductive Lie algebra. Yang–Mills theory seeks to describe the behavior of elementary particles using ...
, 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
pion
In particle physics, a pion (or a pi meson, denoted with the Greek letter pi: ) is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the lightest mesons and, more gen ...
s; formal arguments forbid the decay into
photon
A photon () is an elementary particle that is a quantum of the electromagnetic field, including electromagnetic radiation such as light and radio waves, and the force carrier for the electromagnetic force. Photons are Massless particle, massless ...
s, 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
John Clarence Taylor, (March 2, 1890 – March 25, 1983) was elected to the U.S. House of Representatives for South Carolina's 3rd congressional district. He served for three terms from 1933 to 1939.
Biography
John Clarence was born in Honea ...
, 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. This paper earned them worldwide recognition, and would ultimately earn the pair the 1999 Nobel Prize in Physics.
These two papers formed the basis of 't Hooft's
dissertation, ''The Renormalization procedure for Yang–Mills Fields'', and he obtained his
PhD PHD or PhD may refer to:
* Doctor of Philosophy (PhD), an academic qualification
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degree in 1972. In the same year he married his wife, Albertha A. Schik, a student of
medicine
Medicine is the science and Praxis (process), practice of caring for a patient, managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, and Health promotion ...
in Utrecht.
[
]
Career
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
The strong interaction or strong force is a fundamental interaction that confines quarks into proton, neutron, and other hadron particles. The strong interaction also binds neutrons and protons to create atomic nuclei, where it is called th ...
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
)
, image = Nobel Prize.png
, alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...
.
In 1974, 't Hooft returned to Utrecht where he became assistant professor. In 1976, he was invited for a guest position at Stanford
Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...
and a position at Harvard as Morris Loeb lecturer. His eldest daughter, Saskia Anne, was born in Boston
Boston (), officially the City of Boston, is the capital city, state capital and List of municipalities in Massachusetts, most populous city of the Commonwealth (U.S. state), Commonwealth of Massachusetts, as well as the cultural and financ ...
, while his second daughter, Ellen Marga, was born in 1978 after he returned to Utrecht, where he was made full professor.[ In the academic year 1987-1988 't Hooft spent a sabbatical in the Boston University Physics Department along with Howard Georgi, Robert Jaffe and others arranged by the then new Department chair ]Lawrence Sulak
Lawrence Sulak (born August 29, 1944) is an American physicist, currently the David M. Myers Distinguished Professor at Boston University. Some of Sulak's research has included Higgs detection at the Compact Muon Solenoid in the Large Hadron Collid ...
.
In 2007 't Hooft became editor-in-chief for '' Foundations of Physics'', where he sought to distance the journal from the controversy of ECE theory
Ece () is a Turkish word meaning queen and may refer to:
* Umay, also known as Ece, the Turkic earth goddess
Given names
* Ece Ayhan Çağlar (1931–2002), Turkish poet
* Ece Ege (born 1963), Turkish fashion designer
* Ece Erken (born 1978), Tur ...
. 't Hooft held the position until 2016.
On July 1, 2011 he was appointed Distinguished professor by Utrecht University.
Honors
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". Before that time his work had already been recognized by other notable awards. In 1981, he was awarded the Wolf Prize
The Wolf Prize is an international award granted in Israel, that has been presented most years since 1978 to living scientists and artists for ''"achievements in the interest of mankind and friendly relations among people ... irrespective of natio ...
, possibly the most prestigious prize in physics after the Nobel prize. Five years later he received the Lorentz Medal, awarded every four years in recognition of the most important contributions in theoretical physics. In 1995, he was one of the first recipients of the Spinozapremie, the highest award available to scientists in the Netherlands. In the same year he was also honoured with a Franklin Medal. In 2000, 't Hooft received the Golden Plate Award of the American Academy of Achievement
The American Academy of Achievement, colloquially known as the Academy of Achievement, is a non-profit educational organization that recognizes some of the highest achieving individuals in diverse fields and gives them the opportunity to meet o ...
.
Since his Nobel Prize, 't Hooft has received a slew of awards, honorary doctorates and honorary professorships. He was knighted commander in the Order of the Netherlands Lion, and officer in the French Legion of Honor. The asteroid 9491 Thooft has been named in his honor, and he has written a constitution for its future inhabitants.
He is a member of the Royal Netherlands Academy of Arts and Sciences
The Royal Netherlands Academy of Arts and Sciences ( nl, Koninklijke Nederlandse Akademie van Wetenschappen, abbreviated: KNAW) is an organization dedicated to the advancement of science and literature in the Netherlands. The academy is housed ...
(KNAW) since 1982, where he was made academy professor in 2003. He is also a foreign member of many other science academies, including the French Académie des Sciences
The French Academy of Sciences (French: ''Académie des sciences'') is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French scientific research. It was at the ...
, the American National Academy of Sciences
The National Academy of Sciences (NAS) is a United States nonprofit, non-governmental organization. NAS is part of the National Academies of Sciences, Engineering, and Medicine, along with the National Academy of Engineering (NAE) and the Nat ...
and American Academy of Arts and Sciences
The American Academy of Arts and Sciences (abbreviation: AAA&S) is one of the oldest learned societies in the United States. It was founded in 1780 during the American Revolution by John Adams, John Hancock, James Bowdoin, Andrew Oliver, ...
and the Britain and Ireland based Institute of Physics
The Institute of Physics (IOP) is a UK-based learned society and professional body that works to advance physics education, research and application.
It was founded in 1874 and has a worldwide membership of over 20,000. The IOP is the Physica ...
.
't Hooft has appeared in season 3 of ''Through the Wormhole
''Through the Wormhole'' is an American science documentary television series narrated and hosted by American actor Morgan Freeman. It began airing on Science Channel in the United States on June 9, 2010. The series concluded its run on May 16 ...
'' with Morgan Freeman.
Research
'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'.
Gauge theories in elementary particle physics
'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 of dimensional regularization.
After his PhD, he became interested in the role of gauge theories in the strong interaction, the leading theory of which is called quantum chromodynamics
In theoretical physics, quantum chromodynamics (QCD) is the theory of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a ty ...
or QCD. Much of his research focused on the problem of color confinement in QCD, i.e. the observational fact that only color neutral particles are observed at low energies. This led him to the discovery that SU(N) gauge theories simplify in the large ''N'' limit, a fact which has proved important in the examination of the conjectured correspondence between string theories in an Anti-de Sitter space
In mathematics and physics, ''n''-dimensional anti-de Sitter space (AdS''n'') is a maximally symmetric Lorentzian manifold with constant negative scalar curvature. Anti-de Sitter space and de Sitter space are named after Willem de Sitter (18 ...
and conformal 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 of meson
In particle physics, a meson ( or ) is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks, usually one of each, bound together by the strong interaction. Because mesons are composed of quark subparticle ...
s.
He also studied the role of so-called instanton
An instanton (or pseudoparticle) is a notion appearing in theoretical and mathematical physics. An instanton is a classical solution to equations of motion with a finite, non-zero action, either in quantum mechanics or in quantum field theory. M ...
contributions in QCD. His calculation showed that these contributions lead to an interaction between light quark
A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All common ...
s at low energies not present in the normal theory. Studying instanton solutions of Yang–Mills theories, 't Hooft discovered that spontaneously breaking a theory with SU(N) symmetry to a U(1) symmetry will lead to the existence of magnetic monopoles. These monopoles are called 't Hooft–Polyakov monopole __NOTOC__
In theoretical physics, the t Hooft–Polyakov monopole is a topological soliton similar to the Dirac monopole but without the Dirac string. It arises in the case of a Yang–Mills theory with a gauge group G, coupled to a Higgs field whi ...
s, after Alexander Polyakov, who independently obtained the same result.
As another piece in the color confinement puzzle 't Hooft introduced 't Hooft loop
In quantum field theory, the 't Hooft loop is a magnetic analogue of the Wilson loop for which spatial loops give rise to thin loops of magnetic flux associated with magnetic vortices. They play the role of a disorder parameter for the Higgs pha ...
s, which are the magnetic dual of Wilson loops. Using these operators he was able to classify different phases of QCD, which form the basis of the QCD phase diagram.
In 1986, he was finally able to show that instanton contributions solve the Adler–Bell–Jackiw anomaly, the topic of his master's thesis.
Quantum gravity and black holes
When Veltman and 't Hooft moved to CERN after 't Hooft obtained his PhD, Veltman's attention was drawn to the possibility of using their dimensional regularization techniques to the problem of quantizing gravity. Although it was known that perturbative quantum gravity
Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics; it deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the v ...
was not completely 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 by Stanley Deser and another PhD student of Veltman, Peter van Nieuwenhuizen, who later found patterns in the renormalization counter term
Counter may refer to:
Mathematics and computing
* Counter machine, a subclass of register machines
* Counter (digital), an electronic device, mechanical device, or computer program for counting
* Loop counter, the variable that controls the iter ...
s, which led to the discovery of supergravity
In theoretical physics, supergravity (supergravity theory; SUGRA for short) is a modern field theory that combines the principles of supersymmetry and general relativity; this is in contrast to non-gravitational supersymmetric theories such as ...
.
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. His attention returned to this model at various points in time, showing that Gott pair
Gott (german: God, link=no) may refer to:
* Gott (surname) Gott is a surname. Notable people with the name include:
* Benjamin Gott (1762–1840), British textile manufacturer
* Daniel Gott (1794–1864), U.S. Representative from New York
* He ...
s would not cause causality
Causality (also referred to as causation, or cause and effect) is influence by which one event, process, state, or object (''a'' ''cause'') contributes to the production of another event, process, state, or object (an ''effect'') where the ca ...
violating timelike loop
In mathematical physics, a closed timelike curve (CTC) is a world line in a Lorentzian manifold, of a material particle in spacetime, that is "closed", returning to its starting point. This possibility was first discovered by Willem Jacob van St ...
s, and showing how the model could be quantized. More recently he proposed generalizing this piecewise flat model of gravity to 4 spacetime dimensions.
With Stephen Hawking's discovery of Hawking radiation of black hole
A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can defo ...
s, 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 the black 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. This led to the introduction of the holographic principle by him and Leonard Susskind.
Fundamental aspects of quantum mechanics
't Hooft has "deviating views on the physical interpretation
Interpretation may refer to:
Culture
* Aesthetic interpretation, an explanation of the meaning of a work of art
* Allegorical interpretation, an approach that assumes a text should not be interpreted literally
* Dramatic Interpretation, an event ...
of quantum theory". He believes that there could be a deterministic explanation underlying quantum mechanics. Using a speculative model he has argued that such a theory could avoid the usual Bell inequality arguments that would disallow such a local hidden-variable theory. In 2016 he published a book length exposition of his ideas which, according to 't Hooft, has encountered mixed reactions.
Popular publications
*
*
*
See also
* Asymptotic freedom
* Center vortex
* Naturalness (physics)
* Pauli–Villars regularization
__NOTOC__
In theoretical physics, Pauli–Villars regularization (P–V) is a procedure that isolates divergent terms from finite parts in loop calculations in field theory in order to renormalize the theory. Wolfgang Pauli and Felix Villars p ...
* Slavnov–Taylor identities
* Superdeterminism
* Mars One (Gerard 't Hooft is a main supporter of the project)
References
External links
Gerard 't Hooft
(homepage)
* including the Nobel Lecture ''A Confrontation with Infinity''
Publications
from Google Scholar
Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Released in beta in November 2004, the Google Scholar index includes p ...
Publications
on the arXiv
arXiv (pronounced " archive"—the X represents the Greek letter chi ⟨χ⟩) is an open-access repository of electronic preprints and postprints (known as e-prints) approved for posting after moderation, but not peer review. It consists o ...
TVO.org video - Gerard t'Hooft lectures on Science Fiction and Reality
Lecture delivered at the Perimeter Institute in Waterloo, Ontario, Canada on May 7, 2008
*
{{DEFAULTSORT:Hooft, Gerardus t
1946 births
Living people
20th-century Dutch physicists
Members of the Royal Netherlands Academy of Arts and Sciences
Foreign associates of the National Academy of Sciences
Foreign Members of the Russian Academy of Sciences
Nobel laureates in Physics
Dutch Nobel laureates
Utrecht University alumni
Utrecht University faculty
Wolf Prize in Physics laureates
Commanders of the Order of the Netherlands Lion
Officiers of the Légion d'honneur
Lorentz Medal winners
Recipients of the Lomonosov Gold Medal
People from Den Helder
Scientists from Utrecht (city)
Members of the French Academy of Sciences
Institute for Advanced Study visiting scholars
Spinoza Prize winners
Theoretical physicists
Mars One
People associated with CERN
21st-century Dutch physicists