Gerard 't Hooft

This is a Dutch name; the family name is 't Hooft, notHooft.

Gerardus (Gerard) 't Hooft (Dutch: [errt t oft];born July 5, 1946) is a Dutch theoretical physicist andprofessor at Utrecht University, the Netherlands. Heshared the 1999 Nobel Prize in Physics with his thesisadvisor Martinus J. G. Veltman for elucidating the quan-tum structure of electroweak interactions".His work concentrates on gauge theory, black holes,quantum gravity and fundamental aspects of quantummechanics. His contributions to physics include a proofthat gauge theories are renormalizable, dimensional reg-ularization, and the holographic principle.

1 Personal lifeHe is married to Albertha Schik (Betteke) and has twodaughters, Saskia and Ellen. Saskia has translated one ofher fathers popular Dutch ction books Planetenbiljartinto English. The books title is Playing with Planets andwas launched in Singapore in November 2008.

2 Biography

2.1 Early lifeGerard 't Hooft was born in Den Helder on July 5, 1946,but grew up in The Hague, the seat of government ofthe Netherlands. He was the middle child of a familyof three. He comes from a family of scholars. His grand-mother was a sister of Nobel prize laureate Frits Zernike,and wasmarried to Pieter Nicolaas vanKampen, whowasa well-known professor of zoology at Leiden University.His uncle Nico van Kampen is an (emeritus) professorof theoretical physics at Utrecht University, and while hismother did not opt for a scientic career because she wasfemale,[1] she did marry a maritime engineer.[1] Follow-ing his familys footsteps, he showed interest in scienceat an early age. When his primary school teacher askedhim what he wanted to be when he grew up, he boldlydeclared, a man who knows everything.[1]

After primary school Gerard attended the DaltonLyceum, a school that applied the ideas of the DaltonPlan, an educational method that suited him well. He eas-ily passed his science and mathematics courses, but strug-

gled with his language courses. Nonetheless, he passedhis classes in English, French, German, classical Greekand Latin. At the age of sixteen he earned a silver medalin the second Dutch Math Olympiad. [1]

2.2 Education

After Gerard 't Hooft passed his high school exams in1964, he enrolled in the physics program at Utrecht Uni-versity. He opted for Utrecht instead of the much closerLeiden, because his uncle was a professor there and hewanted to attend his lectures. Because he was so fo-cused on science, his father insisted that he join theUtrechtsch Studenten Corps, an elite student association,in the hope that he would do something else besides study-ing. This worked to some extent, during his studies hewas a coxswain with their rowing club Triton and orga-nized a national congress for science students with theirscience discussion club Christiaan Huygens.In the course of his studies he decided he wanted to gointo what he perceived as the heart of theoretical physics,elementary particles. His uncle had grown to dislike thesubject and in particular its practitioners, so when it be-came time to write his 'doctoraalscriptie' (Dutch equiva-lent of a masters thesis) in 1968, 't Hooft turned to thenewly appointed professor Martinus Veltman, who spe-cialized in YangMills theory, a relatively fringe subjectat the time because it was thought that these could notbe renormalized. His assignment was to study the AdlerBellJackiw anomaly, a mismatch in the theory of the de-cay of neutral pions; formal arguments forbid the decayinto photons, whereas practical calculations and experi-ments showed that this was the primary form of decay.The resolution of the problem was completely unknownat the time, and 't Hooft was unable to provide one.In 1969, 't Hooft started on his PhD with Martinus Velt-man as his advisor. He would work on the same subjectVeltman was working on, the renormalization of YangMills theories. In 1971 his rst paper was published.[2]In it he showed how to renormalize massless YangMillselds, and was able to derive relations between ampli-tudes, which would be generalized by Andrei Slavnov andJ.C. Taylor, and become known as the SlavnovTayloridentities.The world took little notice, but Veltman was excited be-cause he saw that the problem he had been working onwas solved. A period of intense collaboration followed inwhich they developed the technique of dimensional reg-

1

2 4 RESEARCH

ularization. Soon 't Hoofts second paper was ready to bepublished,[3] in which he showed that YangMills theorieswith massive elds due to spontaneous symmetry break-ing could be renormalized. This paper earned themworldwide recognition, and would ultimately earn the pair the1999 Nobel Prize in Physics.These two papers formed the basis of 't Hoofts dis-sertation, The Renormalization procedure for YangMillsFields, and he obtained in his PhD in 1972. In the sameyear he married his wife, Albertha A. Schik, a student ofmedicine in Utrecht.[1]

2.3 Career

Gerardus 't Hooft at Harvard

After obtaining his doctorate 't Hooft went to CERN inGeneva, where he had a fellowship. He further renedhis methods for YangMills theories with Veltman (whowent back to Geneva). In this time he became interestedin the possibility that the strong interaction could be de-scribed as a massless YangMills theory, i.e. one of atype that he had just proved to be renormalizable andhence be susceptible to detailed calculation and compar-ison with experiment. According to his calculations, thistype of theory possessed just the right kind of scalingproperties (asymptotic freedom) that this theory shouldhave according to deep inelastic scattering experiments.This was contrary to popular perception of YangMillstheories at the time, that like gravitation and electrody-namics, their intensity should decrease with increasingdistance between the interacting particles; such conven-

tional behaviour with distance was unable to explain theresults of deep inelastic scattering, whereas 't Hoofts cal-culations could. When he mentioned his results at a smallconference at Marseilles in 1972, Kurt Symanzik urgedhim to publish this result.[1] He did not, and the result waseventually rediscovered and published by Hugh DavidPolitzer, David Gross, and FrankWilczek in 1973, whichled to them earning the 2004 Nobel Prize in Physics.[4][5]

In 1974, 't Hooft returned to Utrecht where he becameassistant professor. In 1976, he was invited for a guestposition at Stanford and a position at Harvard as Mor-ris Loeb lecturer. His eldest daughter, Saskia Anne, wasborn in Boston, while his second daughter, Ellen Marga,was born in 1978 after he returned to Utrecht, where hewas made full professor.[1] On July 1, 2011 he was ap-pointed Distinguished professor by Utrecht University.[6]

3 HonorsIn 1999 't Hooft shared the Nobel prize in Physics withhis thesis adviser Veltman for elucidating the quantumstructure of the electroweak interactions in physics.[7]Before that time his work had already been recognized byother notable awards. In 1981, he was awarded the WolfPrize,[8] possibly the most prestigious prize in physicsafter the Nobel prize. Five years later he received theLorentz Medal, awarded every four years in recogni-tion of the most important contributions in theoreticalphysics.[9] In 1995, he was one of the rst recipients ofthe Spinozapremie, the highest award available to scien-tists in the Netherlands.[10] In the same year he was alsohonoured with a Franklin Medal[11]

Since his Nobel Prize, 't Hooft has received aslew of awards, honorary doctorates and honoraryprofessorships.[12] He was knighted commander in theOrder of the Netherlands Lion, and ocer in the FrenchLegion of Honor. The asteroid 9491 Thooft has beennamed in his honor,[13] and he has written a constitutionfor its future inhabitants.[14]

He is a member of the Royal Netherlands Academyof Arts and Sciences (KNAW),[15] where he was madeacademy professor in 2003.[16] He is also a foreign mem-ber of many other science academies, including theFrench Acadmie des Sciences, the American NationalAcademy of Sciences and American Academy of Artsand Sciences and the Britain and Ireland based Instituteof Physics.[12]

4 Research't Hoofts research interest can be divided in three maindirections: 'gauge theories in elementary particle physics,'quantum gravity and black holes, and 'foundational as-pects of quantum mechanics.[17]

4.3 Fundamental aspects of quantum mechanics 3

4.1 Gauge theories in elementary particlephysics

't Hooft is most famous for his contributions to the de-velopment of gauge theories in particle physics. The bestknown of these is the proof in his PhD thesis that YangMills theories are renormalizable, for which he shared the1999Nobel Prize in Physics. For this proof he introduced(with his adviser Veltman) the technique of dimensionalregularization.After his PhD, he became interested in the role of gaugetheories in the strong interaction,[1] the leading theory ofwhich is called quantum chromodynamics or QCD.Muchof his research focused on the problem of colour conne-ment in QCD, i.e. the observational fact that only colourneutral particles are observed at low energies. This ledhim to the discovery that SU(N) gauge theories simplifyin the large N limit,[18] a fact which has proved importantin the examination of the conjectured correspondencebetween string theories in an Anti-de Sitter space andconformal eld theories in one lower dimension. By solv-ing the theory in one space and one time dimension, 'tHooft was able to derive a formula for the masses ofmesons.[19]

He also studied the role of so-called instanton contribu-tions in QCD. His calculation showed that these contri-butions lead to an interaction between light quarks at lowenergies not present in the normal theory.[20] Studyinginstanton solutions of YangMills theories, 't Hooft dis-covered that spontaneously breaking a theory with SU(N)symmetry to a U(1) symmetry will lead to the existenceof magnetic monopoles.[21] These monopoles are called't HooftPolyakov monopoles, after Alexander Polyakov,who independently obtained the same result.[22]

As another piece in the colour connement puzzle 'tHooft introduced 't Hooft operators, which are themagnetic dual of Wilson loops.[23] Using these operatorshe was able to classify dierent phases of QCD, whichform the basis of the QCD phase diagram.In 1986, he was nally able to show that instanton contri-butions solve the AdlerBellJackiw anomaly, the topicof his masters thesis.[24]

4.2 Quantum gravity and black holesWhen Veltman and 't Hooft moved to CERN after 'tHooft obtained his PhD, Veltmans attention was drawnto the possibility of using their dimensional regulariza-tion techniques to the problem of quantizing gravity. Al-though it was known that perturbative quantum gravitywas not completely renormalizible, they felt importantlessons were to be learned by studying the formal renor-malization of the theory order by order. This work wouldbe continued by Stanley Deser and another PhD studentof Veltman, Peter van Nieuwenhuizen, who later foundpatterns in the renormalization counter terms, which led

to the discovery of supergravity.[1]

In the 1980s, 't Hoofts attention was drawn to the sub-ject of gravity in 3 spacetime dimensions. Together withDeser and Jackiw he published an article in 1984 describ-ing the dynamics of at space where the only local de-grees of freedom were propagating point defects.[25] Hisattention returned to this model at various points in time,showing that Gott pairs would not cause causality violat-ing timelike loops,[26] and showing how the model couldbe quantized.[27] More recently he proposed generaliz-ing this piecewise at model of gravity to 4 spacetimedimensions.[28]

With Stephen Hawking's discovery of Hawking radiationof black holes, it appeared that the evaporation of theseobjects violated a fundamental property of quantum me-chanics, unitarity. 't Hooft refused to accept this prob-lem, known as the black hole information paradox, andassumed that this must be the result of the semi-classicaltreatment of Hawking, and that it should not appear in afull theory of quantum gravity. He proposed that it mightbe possible to study some of the properties of such a the-ory, by assuming that such a theory was unitary.Using this approach he has argued that near a black hole,quantum elds could be described by a theory in a lowerdimension.[29] This led to introduction of the holographicprinciple by him and Leonard Susskind.[30]

4.3 Fundamental aspects of quantum me-chanics

't Hooft has deviating views on the physicalinterpretation of quantum theory".[17] He believesthat there should be a deterministic theory underlyingquantum mechanics.[31] Using a toy model he has arguedthat such a theory could avoid the usual Bell inequalityarguments that would disallow such a local hiddenvariable theory.[32]

5 See also

Anomaly matching condition

Feynman't Hooft gauge

Minimal subtraction scheme

Naturalness (physics)

Renormalon

't Hooft symbol

Mars One (Gerard 't Hooft is a main supporter ofthe project)

4 7 EXTERNAL LINKS

6 References[1] 't Hooft, G. (1999). Gerardus 't Hooft - Autobiography.

Nobel web. Retrieved 06-10-2010. Check date values in:|accessdate= (help)

[2] 't Hooft, G. . (1971). Renormalization of mass-less Yang-Mills elds. Nuclear Physics B 33: 173177. Bibcode:1971NuPhB..33..173T. doi:10.1016/0550-3213(71)90395-6.

[3] 't Hooft, G. . (1971). Renormalizable Lagrangians formassive Yang-Mills elds. Nuclear Physics B 35: 167188. Bibcode:1971NuPhB..35..167T. doi:10.1016/0550-3213(71)90139-8.

[4] The Nobel Prize in Physics 2004. Nobel Web. 2004.Retrieved 2010-10-24.

[5] Politzer, H. David (2004). The Dilemma of Attribution(PDF). Nobel Web. Retrieved 2010-10-24.

[6] Prof. dr. Gerard t Hooft has been appointed Distin-guished Professor. Utrecht University. Archived fromthe original on 2012-04-19. Retrieved 2012-04-19.

[7] The Nobel Prize in Physics 1999. Nobel web.

[8] The 1981 Wolf Foundation Prize in Physics. WolfFoundation.

[9] Lorentz medal. Leiden University.

[10] NWO/Spinoza Prizes 1995-2000. The Netherlands Or-ganisation for Scientic Research (NWO).

[11] Franklin Laureate Database. The Franklin Institute..

[12] Curriculum Vitae Gerard 't Hooft. G. 't Hooft.

[13] JPL Small-Body Database Browser. NASA.

[14] 9491 THOOFT - Constitution and Bylaws. G. 't Hooft.

[15] KNAW - Organisatie - Leden. Royal NetherlandsAcademy of Arts and Sciences. (in Dutch)

[16] Academy Professorships Programme - 2003. RoyalNetherlands Academy of Arts and Sciences.

[17] 't Hooft, G. Gerard 't Hooft. Retrieved 24-20-2010.Check date values in: |accessdate= (help)

[18] 't Hooft, G. (1974). A planar diagram theory forstrong interactions. Nuclear Physics B 72 (3): 461470. Bibcode:1974NuPhB..72..461T. doi:10.1016/0550-3213(74)90154-0.

[19] 't Hooft, G. (1974). A two-dimensional modelfor mesons. Nuclear Physics B 75 (3): 461863. Bibcode:1974NuPhB..75..461T. doi:10.1016/0550-3213(74)90088-1.

[20] 't Hooft, G. (1976). Computation of the quantum eectsdue to a four-dimensional pseudoparticle. Physical Re-view D 14 (12): 3432. Bibcode:1976PhRvD..14.3432T.doi:10.1103/PhysRevD.14.3432.

[21] 't Hooft, G. (1974). Magnetic monopoles in uni-ed gauge theories. Nuclear Physics B 79 (2): 276284. Bibcode:1974NuPhB..79..276T. doi:10.1016/0550-3213(74)90486-6.

[22] Polyakov, A.M. (1974). Particle spectrum in quantumeld theory. Journal of Experimental and TheoreticalPhysics Letters 20: 194. Bibcode:1974JETPL..20..194P.

[23] 't Hooft, G. (1978). On the phase transition towardspermanent quark connement. Nuclear Physics B 138:12. Bibcode:1978NuPhB.138....1T. doi:10.1016/0550-3213(78)90153-0.

[24] 't Hooft, G. (1986). How instantons solve theU(1) problem. Physics Reports 142 (6): 357712. Bibcode:1986PhR...142..357T. doi:10.1016/0370-1573(86)90117-1.

[25] Deser, S.; Jackiw, R.; 't Hooft, G. (1984).Three-dimensional Einstein gravity: Dynam-ics of at space. Annals of Physics 152: 220.Bibcode:1984AnPhy.152..220D. doi:10.1016/0003-4916(84)90085-X.

[26] 't Hooft, G. (1992). Causality in (2+1)-dimensionalgravity. Classical and Quantum Gravity 9 (5): 1335.Bibcode:1992CQGra...9.1335T. doi:10.1088/0264-9381/9/5/015.

[27] Hooft, G. 'T. (1993). Canonical quantization of gravi-tating point particles in 2+1 dimensions. Classical andQuantum Gravity 10 (8): 1653. arXiv:gr-qc/9305008.Bibcode:1993CQGra..10.1653T. doi:10.1088/0264-9381/10/8/022.

[28] 't Hooft, G. (2008). A Locally Finite Model forGravity. Foundations of Physics 38 (8): 733757. arXiv:0804.0328. Bibcode:2008FoPh...38..733T.doi:10.1007/s10701-008-9231-3.

[29] Stephens, C. R.; 't Hooft, G.; Whiting, B. F.(1994). Black hole evaporation without informationloss. Classical and Quantum Gravity 11 (3): 621.arXiv:gr-qc/9310006. Bibcode:1994CQGra..11..621S.doi:10.1088/0264-9381/11/3/014.

[30] Susskind, L. (1995). The world as a hologram.Journal of Mathematical Physics 36 (11): 63776371.arXiv:hep-th/9409089. Bibcode:1995JMP....36.6377S.doi:10.1063/1.531249.

[31] Hooft, G. 'T. (2007). A mathematical theory fordeterministic quantum mechanics. Journal of Physics:Conference Series 67: 012015. arXiv:quant-ph/0604008.Bibcode:2007JPhCS..67a2015T. doi:10.1088/1742-6596/67/1/012015.

[32] Gerard 't Hooft (2009). Entangled quantum states in alocal deterministic theory. arXiv:0908.3408 [quant-ph].

7 External links Gerard 't Hooft (homepage)

5 How To Become a Good Theoretical Physicist The Nobel Prize in Physics 1999 A Confrontation with Innity, Nobel Lecture Publications from Google Scholar Publications on the Arxiv TVO.org video - Gerard t'Hooft lectures on Science

Fiction and Reality Lecture delivered at the Perime-ter Institute inWaterloo, Ontario, Canada onMay 7,2008

6 8 TEXT AND IMAGE SOURCES, CONTRIBUTORS, AND LICENSES

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Gerard 't Hooft Source: http://en.wikipedia.org/wiki/Gerard_'t_Hooft?oldid=660751604 Contributors: AxelBoldt, XJaM, Rsabbatini,Mic, Ellywa, Andres, Wik, Maximus Rex, Secretlondon, Gidonb, Timrollpickering, Ancheta Wis, Giftlite, Everyking, Jdavidb, Wmahan,ChicXulub, Tothebarricades.tk, Pethan, Lumidek, Robin klein, D6, Pjacobi, Aris Katsaris, Kwamikagami, Mairi, Bill Thayer, SamRushing,Nk, Physicistjedi, A2Kar, Guy Harris, Eric Kvaalen, Crazyjoe, Snowolf, Ksnow, Aegis Maelstrom, Ilse@, Gene Nygaard, RyanGerbil10,Pierremenard, JarlaxleArtemis, Etacar11, GregorB, Emerson7, Kbdank71, Koavf, Harro5, The wub, FlaBot, Srleer, Valentinian, CJLLWright, Roboto de Ajvol, Kummi, RobotE, Bhny, Salsb, JocK, Zwobot, Reyk, GrinBot~enwiki, SmackBot, YellowMonkey, InverseHyper-cube, Jprg1966, Afasmit, Josteinn, Colonies Chris, Yelm, Acepectif, Andrei Stroe, SashatoBot, John, Cesium 133, JorisvS, JdH, Joseph So-lis in Australia, IvanLanin, Sophomoric, Geremia, Drinibot, Ksoileau, Cydebot, Slp1, WISo, Studerby, Arb, Thijs!bot, Headbomb, SecondQuantization, MassimoMacconi, Bunzil, RobotG, Gcm, MER-C, Christopher Cooper, Magioladitis, T@nn, Waacstats, Jvhertum, Drdavid-hill, Kraxler, Lijnema, Poikilothron, R'n'B, Kentucho, Hans Dunkelberg, VolkovBot, TXiKiBoT, Jalwikip, Jimmyeatskids, Sk741~enwiki,Moose-32, Rtol, SieBot, Cb77305, Arjen Dijksman, RS1900, Binksternet, PipepBot, Worobiew, Auntof6, Rozth, DragonBot, Eustress,Cardinalem, TimothyRias, MystBot, Kbdankbot, Addbot, MrOllie, Taketa, Wammes Waggel, Zorrobot, Ben Ben, Luckas-bot, Yobot,Amirobot, ErwinsMoggie, Joan kingston, Galoubet, Ulric1313, ArthurBot, LilHelpa, Xqbot, Stsang, GrouchoBot, Omnipaedista, Mn-mngb, Sthooft, Aliotra, Citation bot 2, Horst-schlaemma, Lightlowemon, TobeBot, Badger M., DixonDBot, RjwilmsiBot, EmausBot,WikitanvirBot, Dewritech, Somerwind, ZroBot, Lemeza Kosugi, Ystalyfera, JasperFan, Mythio, Editr, AMH2326, Ttoptommy, Asal-rifai, FiveColourMap, Brad7777, BattyBot, ParottaBeefFry, Arcandam, JYBot, Logosun, Logi553, VIAFbot, DennisLMay, Bibliophilen,RaphaelQS, Jonarnold1985, Peter238, Broido, KasparBot and Anonymous: 62

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Personal lifeBiographyEarly lifeEducationCareer

HonorsResearchGauge theories in elementary particle physicsQuantum gravity and black holesFundamental aspects of quantum mechanics

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