PERSPECTIVE

The dilemma of attribution

H. David Politzer* California Institute of Technology, Pasadena, CA 91125

suspected that there were some compress and simplify all of the devel- notables included Dick Feynman, Shelly members of the live audience who opments that have come before. We Glashow, Abdus Salam, and Steve were somewhat apprehensive about want to bring our students as quickly as Weinberg.) And now it seemed that no sitting through the morning’s phys- possible to the frontier of current un- senior physicist wanted to discuss them; icsI lectures. After all, there were three derstanding. From this perspective, the their ignorance and confusion were too guys there to talk about one minus sign. actual history, which involves many vari- embarrassing. If it were just two people and a plus ants and many missteps, is only a hin- (While delivering my talk live in sign, ϩ, one could talk about the ͉ and drance. And the neat, linear progress, as Stockholm, it occurred to me I should the other about the –. However, to my outlined by the sequence of gleaming have had a little light or a bell that went mind, this year’s awards represent or gems recognized by Nobel prizes, is a off when I mentioned a Nobel laure- symbolize not just a minus sign, but a useful fiction. But a fiction it is. The ate—because part of my point is to try large body of significant advances in our truth is often far more complicated. Of to understand who is and who isn’t. The understanding of fundamental physics, course, there are the oft-told priority relevant names are already familiar to and are the work of not just three peo- disputes, bickering over who is responsi- the physicist segment of the audience, ple but a great many scientists, stretch- ble for some particular idea. But those but for the sake of the general audience, ing out over many years and many questions are not only often unresolv- I just raised my finger discretely. Here countries. This is really a prize for that able, they are often rather meaningless. I’ll use a superscript N. So far, there’s whole community. Genuinely independent discovery is not YangN, FeynmanN, GlashowN, SalamN, Sidney Coleman, my beloved teacher only possible, it occurs all of the time. Steve WeinbergN, but not Coleman or from graduate school, referred to this Sometimes a yet harder problem in the Erick Weinberg.) community as i fratelli fisici, by which he prize selection process is to identify It turns out there was one brave soul, meant the brotherhood of physicists. what is the essential or most important Tini VeltmanN, who never gave up on Most of us spoke at least a bit of broken idea in some particular, broader context. Yang–Mills theory, and, with his best- Italian, a legacy of the grand and highly So, it’s not just a question of who did it, ever grad student, Gerard ’t HooftN, influential summer schools organized by i.e., who is responsible for the work, but cracked the case in 1971. I think it Nino Zichichi in Erice, Sicily. Indeed, what ‘‘it’’ is. In other words, what is the worth noting that I, personally, know of one of my fondest reflections on my significant ‘‘it’’ that should stand as a no one who claimed to understand the particle physics career is having been symbol for a particularly important details of ‘t Hooft’s paper. Rather, we able to arrive at a train station, virtually advance. all learned it from Ben Lee, who com- anywhere in the world, and be greeted I’ve no interest in recounting my bined insights from his own work (that by a total stranger who immediately whole life’s story or even my physics renormalization constants are indepen- treated me like an old friend. career. Rather, I want to focus on the dent of the choice of ground state in I’d love to tell you all their stories, context of the particular work cited in such theories), from hitherto unnoticed but I certainly don’t know them all, nor this year’s awards. So, I begin this saga work from Russia (Fadde’ev and Popov do I have time (or space) even for those with a trip I took with Erick Weinberg, on quantization and Feynman rules), that I do. So I’ve chosen a few of the a fellow graduate student, friend, and and from the simple encouragement people and a few of the stories with something of a mentor (he was a year from ’t Hooft’s paper that it was possi- which to make a particular point. You ahead of me) from Cambridge, Massa- ble. (It is amazing how much easier it can judge for yourself at the end how chusetts to Hoboken, New Jersey (I can be to solve a problem once you are well I’ve succeeded. And I’ll deal mostly think it was 1970) to a conference to assured that a solution exists!) with theorists because I know them hear our teacher, Sidney Coleman, The bit of physics I remember best best—although I must say that I do re- speak. He was delivering a paper titled from the Hoboken conference was from gard theoretical physics as a fundamen- ‘‘Why Dilatation Generators Don’t Gen- a talk by T. D. LeeN. He spoke with tally parasitic profession, living off the erate Dilatations.’’ We had read a writ- confidence that the weak interactions labors of the real physicists. ten version, but hoped that his talk were mediated by a heavy bosonic parti- I’d like to address one particular as- would help us understand it better. It cle that carried the force, and he gave pect of the impact of these prizes. To a was a several-hour drive. Somewhere its mass. (Several years later, he was considerable extent, they have come to along the way, I asked Erick to explain proven right.) The clearest version of represent milestones in the progress of to me a bit about what were called science. And it is a testament to the Yang–Mills or non-Abelian gauge theo- care and wisdom exercised in the selec- ries. I had heard the name but was oth- *E-mail: [email protected]. tion process just how important the erwise ignorant. They’d been invented in Adapted from Les Prix Nobel, 2004. © 2004 by the Nobel prizes have become. To the public, they 1954 and were the last and least under- Foundation spark continued interest in science’s stood entry in a short list of what came Editor’s Note: This article is a version of H. David Politzer’s most important advances. But even to be considered the only possible de- Nobel Lecture, ‘‘The Dilemma of Attribution.’’ The 2004 within the world of the scientific ex- scriptions of fundamental particle inter- Nobel Prize in Physics was awarded to Drs. Politzer, Frank Wilczek, and David J. Gross for their discovery of asymptotic perts, the prizes likewise serve as mark- actions. Erick explained the defining freedom in the theory of the strong interaction. The Nobel ers of this progress. The use of history basics, but told me that nothing was Foundation graciously has granted us permission to reprint in science education may be a contribut- known about their consequences and this article. The Nobel Lectures provide examples of success- ing factor to why this is so and how it that many of the most famous senior ful approaches to major scientific problems. However, in recent years, these lectures have rarely been read, perhaps works. As teachers of the next genera- particle theorists had gotten seriously because of the difficulty in obtaining the collections. By tion of scientists, we always seek to confused about them. (The list of such reprinting this lecture, we hope to broaden their exposure.

www.pnas.org͞cgi͞doi͞10.1073͞pnas.0501644102 PNAS ͉ May 31, 2005 ͉ vol. 102 ͉ no. 22 ͉ 7789–7793 Downloaded by guest on September 26, 2021 that theory had been written down by that prize, was all done in collaboration HeisenbergN) for solving [at least in the Steve WeinbergN in 1967. But no one in with Michael Fisher; we should remem- simplest approximation (what’s called that period ever referred to Weinberg’s ber that the basic, formal work was 1͞N)] what came later to be known as paper. For example, I don’t think that done independently and published ear- the Gross–Neveu model. Weinberg’s paper had any influence on lier by Wegner and Houghton; and we Coleman took a leave of absence T. D. Lee’s thinking. In fact, when what should remember that the essential from Harvard, taking his sabbatical at is now known as the Weinberg–Salam physical ideas were articulated indepen- Princeton. At that point, I decided I model was recognized by the Nobel dently and earlier by Leo Kadanoff. needed a research program on which I Foundation, Sidney Coleman published Furthermore, the renormalization group could proceed on my own—something in Science magazine in 1979 a citation was actually invented in 1954 by Murray that might not meet Coleman’s high search he did documenting that essen- Gell-MannN and Francis Low. But even standards but on which I might have tially no one paid any attention to that formulation of the renormalization some chance of success. I decided to Weinberg’s Nobel prize winning paper group appeared in an earlier, independent look into whether the renormalization until the work of ‘t HooftN (as expli- paper of Stueckelberg and Petermann. group had anything to say about the cated by Ben Lee). In 1971, interest in In the early days following the tri- low-energy (or ground state) behavior Weinberg’s paper exploded. I had a par- umph of the Weinberg–Salam model, at of Yang–Mills theory. An analogous allel personal experience: I took a one- one point GlashowN asked Coleman a analysis for electrodynamics appeared in year course on weak interactions from practical question that came up in his the classic textbook of Bogoliubov and Shelly GlashowN in 1970, and he never own work. (The specific technical ques- Shirkov, although Coleman character- even mentioned the Weinberg–Salam tion was ‘‘What happens if the whole ized the relevant chapter there as ‘‘mys- model or his own contributions to the theory has less symmetry than the classi- terious.’’ This was a possible approach theory (for which he shared that Nobel cal scalar (spin zero) sector?’’) And to the question I articulated regarding prize; by the way, his contribution to Coleman answered the question, but he no scalar fields, but I thought I might be that theory was largely his Ph.D. thesis also recognized that the answer was able to follow the steps of Bogoliubov work, done under the direction of Julian worthy of a deeper, clearer understand- and Shirkov explicitly as a guide. SchwingerN, who had already published ing. So, he embarked on its study, in the A key first step was to know the papers on the non-Abelian gauge bosons simplest possible contexts, with my Yang–Mills beta function. [I assumed as carriers of the weak force in the mid- buddy Erick Weinberg. I tagged along in (correctly) in my live talk that its defini- 1960s.) I note again that I also don’t this effort and occasionally made some tion had been made clear in the earlier personally know anyone who ever read contribution. remarks of my corecipients; it is, after Salam’s work on the subject either, ex- (Here’s an anecdote of my first meet- all, the minus sign to which I first al- cept for John Ward, and he was actually ing with Niccolo Cabbibo, a charming luded.] By the way, Erick Weinberg was the coauthor on the relevant papers (he man responsible for a monumental con- supposed to compute it for an appendix is not a Nobel Laureate). tribution to our understanding of the of his thesis, to carry out a generaliza- A further aside on the work of ’t HooftN weak interactions and their relation to tion of a renormalization group flow and VeltmanN, whose contributions the strong interactions, which is now argument that appears in the Coleman– were enormously profound and influen- largely overlooked because of the tele- Weinberg paper, except for a realistic, tial, albeit really rather difficult to char- scoping of history into a compact intro- non-Abelian weak interaction theory. acterize for a lay audience. One of their duction to the present. We were both But, in the end, I guess he figured he many contributions (called, in the busi- visiting the University of Chicago, staying had enough stuff to get his degree, and ness, dimensional regularization) is a at the Windemere Hotel. We chatted it was time for him to move on to some- tool of essential significance, both for over dinner and after as rats scurried thing new. I had actually hoped we’d settling issues of principle and for doing between our feet. He is the only person compare notes, but he never attempted explicit calculations. Dimensional regular- who ever mentioned to me noticing my the calculation. ization also was invented independently name in the acknowledgments of I visited Coleman a couple of times in for the same purposes and appeared in an Coleman and Weinberg’s classic paper.) Princeton. When I described to him my earlier paper, now mostly forgotten, by During this work with Coleman and new, specific research program, I asked Bollini and Giambiaggi. Weinberg, one day I wondered and then if he knew whether the beta function Coleman’s talk in Hoboken was about asked Coleman, ‘‘What happens if there had already been computed. He thought his then-early understanding of what are no scalar fields (spin zero particles) not, but said we should ask David came to be known as the renormaliza- in the first place?’’ It was an innocent Gross, who was down the hall. David tion group. His thinking was very much but inordinately profound question said no, and we discussed briefly then influenced by the independent work of which occupied us both quite intensively that, while the calculation may have Kurt Symanzik and Curt Callan. How- for the next several months. I learned seemed to some to be daunting, it ever, the undisputed champion of the an enormous amount just working on it. would, in fact, be straightforward. renormalization group was Ken WilsonN And I benefited from far closer and Fortunately for both of us—and for (one of my all-time, absolute heroes), more extensive interactions with Frank, too—he was probably wrong, for which he received Nobel recognition. Coleman than he awarded to most of although this episode is fraught with That a prize was given to WilsonN and his students—because he was actively ambiguity. To my knowledge, there are WilsonN alone in 1982 perhaps reflects working on the problem with me. How- no relevant printed records of the cru- the depth of his understanding, the pre- ever, I never made what Coleman cial bits of the story, which have been cision of his detailed physical predictions, considered substantial ‘‘progress’’ as handed down only as folklore, existing and his evangelical zeal. We should measured by his standards. On the other in a variety of variant versions. remember, however, that the renormal- hand, I did many things that, in retro- At a major particle physics meeting in ization group work that lead to experi- spect, would have been publishable on Marseilles the previous year, attended mentally confirmed predictions, which their own. For example, I was very by many particle physics luminaries, were in the field of phase transitions proud of a trick I invented (only to be Symanzik gave a talk precisely about and are the substance of the citation for told later that it was first done by what came to be known as asymptotic

7790 ͉ www.pnas.org͞cgi͞doi͞10.1073͞pnas.0501644102 Politzer Downloaded by guest on September 26, 2021 freedom. He described how it could ac- text per page. His handwriting was typi- beta function, was the clincher. I’d only count for the otherwise mysterious re- cal German: undecipherable, at least to heard of Gell-MannN and Fritzsch’s sults from SLAC on electron-proton Americans, looking like endless up- work second hand, from Shelly scattering. Symanzik knew that the beta down-up-down-up-down. The clincher, GlashowN, and he seemed think it functions for other theories were all though, was when an equation on one shouldn’t be taken too seriously. I only positive. In fact, many wise people page referred to an equation on an- later realized it was more Glashow’s thought there was a general, model- other. He’d slap the second slide on top mode of communication than his serious independent argument for positivity. For of the first, off-set the two by half a assessment of the plausibility of the pro- example, SchwingerN later asked me line, and point to both. posal. In any case, I had completely lost after hearing me speak on the subject, I slowly and carefully completed a track of Gell-MannN and Fritzsch’s ‘‘What about the positivity of the spec- calculation of the Yang–Mills beta func- QCD. tral function?’’ In other words, interme- tion. I happen to be ambidextrous and After the first seminar I ever gave on diate, physical states come with positive mildly dyslexic. So I have trouble with this subject (it was at MIT), I was ap- probabilities. (This refers to an argu- left͞right, in͞out, forward͞backward, proached by Ken Johnson (who, himself ment that is, indeed, relevant to other etc. Hence, I derived each partial result had done pioneering work on the renor- theories.) Symanzik said it would be from scratch, paying special attention to malization group years earlier) and interesting to know the answer for signs and conventions. It did not take Vicki Weisskopf. ‘‘Very nice,’’ they said. Yang–Mills theory, and then ‘t HooftN long to go from dismay over the final ‘‘Too bad that it is in glaring contradic- announced that it was negative. In some minus sign (it was indeed useless for tion to at least two important classes of versions of the story, ’t HooftN spoke studying low energy phenomena) to ex- experiments.’’ One problem was the up at the question and answer period citement over the possibilities. I phoned electron–positron cross section, which following Symanzik’s talk. However, Sidney Coleman. He listened patiently had only gotten much worse since Gell- N there are attendees of the meeting who and said it was interesting. But, accord- Mann and Fritzsch’s proposal of QCD, have no such recollection. In other ver- ing to Coleman, I had apparently made and the other was the issue of large an- sions, it was a private exchange between an error because David Gross and his gle products in proton–proton collisions. ’t HooftN and Symanzik. student had completed the same calcula- There were many more energetic parti- There are a variety of first-, second-, tion, and they found it was plus. cles produced than expected (naively) and third-hand accounts of why nothing Coleman seemed to have more faith in from QCD. By the way, this second is- further was heard on this subject from ‘t the reliability of a team of two, which sue attracted Dick Feynman’s attention. HooftN. I won’t repeat them here.† But included a seasoned theorist, than in a And it wasn’t until a couple of years single, young student. I said I’d check it later and his careful analysis with Rick I’d like to speculate a complementary yet once more. I called again about a Field that QCD was reconciled with perspective as to why no one else at the week later to say I could find nothing those experiments. Only then did Feyn- meeting got wind of it or otherwise took wrong with my first calculation. manN join the ranks of the believers. any notice. (Admittedly, I wasn’t there. Coleman said yes, he knew because the The experimentally measured So this is pure speculation.) Most theo- Princeton team had found a mistake, electron–positron cross section (as a rists’ attention then was on weak inter- corrected it, and already submitted a function of increasing collision energy) actions, and this is a strong interaction paper to Physical Review Letters. had leveled off—instead of continuing issue. But that’s not a good enough ex- On learning of the Gross–Wilczek– to drop steeply, which was thought to be cuse. People did, after all, talk a lot Politzer result, Ken WilsonN, who might a QCD prediction. In Aspen, Colorado, about the scaling of the Stanford elec- have thought of its impossibility along in the summer of 1974, I crossed paths tron–proton experiments. Rather, I the same lines as I attributed to with Ken WilsonN, who, characteristi- think Symanzik’s speaking style played a SchwingerN, above, knew who to call to cally succinct, said, ‘‘It’s charm, and it’s crucial role. He was a charming, intense, check to result. He realized that there not short distance.’’ Tom Appelquist sweet, and brilliant man, but his live de- were actually several people around the and I made it our task to understand livery left something to be desired. I world who had done the calculation, en those oracular comments and flesh out remember a different talk I heard him passant as it were, as part of their work their consequences. By the end of the give on a somewhat related subject. He on radiative corrections to weak interac- summer, the reconciliation of QCD with used hand-written slides for an overhead tions in the newly popular Weinberg– the experimental measurements was projector (which were the industry stan- Salam model. They just never thought to pretty clear to us. Tom toured the coun- dard at the time for technical presenta- focus particularly on this aspect. But try explaining our work. His seminars tions). However, he obviously wrote out they could quickly confirm for WilsonN included a sketch of what the cross sec- his slides with lined paper underneath as by looking in their notebooks that the tion really was, as opposed to what the a guide, using every line. So he ended claimed result was, indeed, correct. experimentalists reported and an esti- up with over 25 lines of equations and Steve WeinbergN and Murray Gell- mate, albeit technically an upper bound, MannN were among those to instantly on the astoundingly long lifetime of a embrace non-Abelian color SU(3) gauge particle that was being produced and † I will add one conjecture to the list, although it is not theory as the theory of the strong inter- decaying as yet unnoticed. Many people something I ever confirmed with ‘t HooftN. It is possible that at that time ’t HooftN knew the sign of the beta actions. In Gell-Mann’s case, it was in heard those talks and remember them, function but not its coefficient. His calculations used di- no small part because he had already and there is at least one objective writ- mensional regularization and dimensional subtraction. invented it (!) with Harald Fritzsch and ten record of their existence: Sid Drell From these, he would have known the sign of the renor- christened it QCD. He had previously gave an account in a piece he wrote malization constants. However, the fundamental defini- tion of the beta function makes reference to the response articulated three solid arguments for subsequently for Scientific American of the theory to scale transformations. Dimensional regu- choosing this particular theory. (For the about charm. At the time, there were larization introduces a scale in a subtle way—when one physicists, those arguments were: baryon already many what-proved-to-be wrong analytically continues away from the superficially scale statistics, ␲ 3 2␥, and the electron– papers trying to interpret the electron– invariant dimensions. How the traditional renormalization group is represented in this context is something that was positron annihilation cross section). And positron experiments, and the SLAC worked out only a couple of years later. asymptotic freedom, i.e., the negative experiment leader, Burt RichterN, was

Politzer PNAS ͉ May 31, 2005 ͉ vol. 102 ͉ no. 22 ͉ 7791 Downloaded by guest on September 26, 2021 touring the country explaining that he that the consensus on this issue was a thought. What Isgur and Wise noted had made the monumental discovery major contributing factor to the Swedish was that in a world with more than one that the electron was actually a little Royal Academy’s recognition within just type of heavy quark, this gives rise to hadron, i.e., a strongly interacting parti- a couple of years of RichterN and Ting’s symmetries of monumentally useful im- cle like the proton, only much smaller in discovery. portance. (The second heavy quark, the diameter. (This discovery, or at least I hope you all now understand why I so-called bottom quark, was identified the same experimental results, had been owe Tom Appelquist a huge, profound, only several years after the first, i.e., the observed a few years earlier at the Cam- and public apology. We certainly could charmed quark.) bridge Electron Accelerator, a joint have submitted for publication in Sep- The establishment by the mid-1970’s Harvard–MIT venture. But no one be- tember substantially the same paper we of QCD as the correct theory of the lieved it, and the machine was decom- ultimately wrote 2 months later. strong interactions completed what is missioned.) Appelquist and I were Now, somewhat out of chronological now known prosaically as the Standard drafting a paper. But I was the conser- order, I’d like to express my thanks to Model. It offers a description of all vative one, perhaps overly influenced, I my old friend and collaborator Howard known fundamental physics except for later realized, by a talk that I had heard Georgi. After the calculation of the beta gravity, and gravity is something that by Steve Adler as to how large the dis- function, it was fairly obvious what has no discernible effect when particles crepancy between naive QCD calcula- should be done next. One had to redo are studied a few at a time. However, tion and experimental measurements some calculations that had been done the situation is a bit like the way that could be before the theory was in defi- earlier by Norman Christ, Brosl Hassla- the Navier–Stokes equation accounts nite trouble. I focused on the things we cher, and Al Mueller, but in the context for the flow of water. The equations are could most reliably compute and did not of what was now, obviously, the right at some level obviously correct, but appreciate the correctness of Tom’s theory. Here, again, a missing name there are only a few, limited circum- more general arguments. from that collaboration but who had a stances in which their consequences can In November came the experimental major impact was Georgio Parisi. Well, be worked out in any detail. Neverthe- announcements. SLAC observed a parti- Howard Georgi checked up periodically ␺ less, many leading physicists were in- cle (they called it the ) and ultimately on my progress, and I admitted having clined to conclude in the late 1970’s that observed a whole cross section just as some technical trouble. So he volun- the task of basic physics was nearly predicted by Appelquist. And observa- teered to help, and we went on to do complete, and we’d soon be out of jobs. tion was simultaneously announced by an enormous number of clever things A famous example was the inaugural Sam TingN, in an experiment that together. lecture of Stephen Hawking as Lucasian identified a pimple, which TingN epony- Apropos clever, there are some ad- Professor of Mathematics, a chair first mously titled the J (a reasonable ap- vances that require considerable mental held by Isaac Barrow at Cambridge Uni- proximation to the relevant Chinese struggle and lengthy argumentation, versity. Hawking titled his lecture, ‘‘Is character), on what had been known as only to virtually disappear as nonissues, the End in Sight for Theoretical Phys- Lederman’s Shoulder. (That’s Leon because they’re simply obvious from a ics?’’ And he argued strongly for ‘‘Yes.’’ LedermanN.) That is to say that Ting’s newer perspective. For example, the fact But more recent observations of as- experiment had actually been done ear- that quarks could have a mass, some- lier by LedermanN. The earlier experi- thing unambiguously quantifiable and tronomers have turned things on their ment had cruder resolution, but it measured in grams—despite their never heads. Recall, if you will, that among clearly indicated that there was some- existing as isolated particles—was one the many stupendous insights of Isaac thing anomalous at just that energy. such issue on which I battled with many Newton, the second Lucasian Professor, Appelquist and I hurriedly dashed off physicists, including, for example, Gell- were the idea that the stuff of the heav- a short version of our work to Physical MannN and Steve WeinbergN. The ens was the same stuff as matter here Review Letters, where it was immediately heavy charm quark gave impetus to on Earth. This was revolutionary. And and unequivocally rejected by senior those considerations, but there was a he asserted that the laws that governed editor Sy Pasternak. It was against that conceptual battle that had to be fought the motion of stuff in the heavens were journal’s policy to let authors engage in against older prejudices formed in the the same laws as applied to matter on the coining of frivolous, new terminol- limited context of the ‘‘light’’ quarks. Earth. (That there are laws at all may ogy. In the case at hand, our friend and Younger physicists today can’t even be his most profound insight. It is cer- colleague Alvaro De Ru´jula, on hearing imagine that there was ever an issue. tainly what came to define the whole of our work, had coined the term ‘‘char- Heavy quarks appeared once again in discipline of physics.) For three centu- monium,’’ which in a single word was my research life. Joe Polchinski asked ries, we accumulated stunning detailed able to transmit the central new idea of Mark Wise, a colleague of mine at confirmation of these of Newton’s asser- the paper to any serious particle physics Caltech, a question about heavy quark tions. But in a very fundamental way, reader. Ultimately, Shelly GlashowN calculations, which Mark and I pro- both of these ideas now appear to be brokered a compromise with Pasternak. ceeded to answer. It was again a case about as wrong as they possibly could We could use ‘‘charmonium’’ in the text, where, unbeknownst to us, the work had be—at least that’s the simplest interpre- but not in the title. The negotiations already been done, this time by Misha tation of our current large-scale astro- caused a delay of a couple of weeks—a Shiffman and Mike Voloshin in the So- physical observations. It turns out that long time in those heady days. As a con- viet Union. Furthermore, I again missed we haven’t a clue what virtually all of sequence, publication came along side the most important phenomenological the matter in the universe consists of— several other long-since-forgotten pa- consequences of that line of thought. except that it’s not made of the particles pers, instead of being hard on the heals Those had to wait for the collaboration that make up matter on earth or in the of the experimental discovery. of Mark Wise with Nathan Isgur. That stars. Furthermore, the force which gov- That our explanation was correct was heavy quark physics depends only trivi- erns the largest scale motions in the uni- soon widely appreciated, and it con- ally on the actual value of the heavy verse has nothing to do with the forces vinced almost all of the remaining skep- quark mass was obvious to me and of the Standard Model or with gravity tics of the validity of QCD. I suspect probably most anyone else who gave it a as it is familiar here on Earth.

7792 ͉ www.pnas.org͞cgi͞doi͞10.1073͞pnas.0501644102 Politzer Downloaded by guest on September 26, 2021 There is a very active field of theoret- day. The reality of the actual progress of The first is colorful in its rendition of ical research which seeks to go beyond science is, however, often very compli- the personalities, rather accurate in its the Standard Model. Success in these cated, as I hope I have conveyed from physics, and totally accessible to the in- endeavors would mean explaining the my few examples. The committees of the terested layman. The second is a more apparently arbitrary aspects of the Stan- Academy know this full well, but their scholarly endeavor. Pickering began his dard Model; success would mean bring- deliberations are confidential. I felt career as a particle theorist, a contem- ing an account of gravity into the strongly that more of the public should porary of mine. He includes consider- picture; and success would mean illumi- contemplate these matters if they wish able scientific detail but still aims at a nating the previously mentioned issues to understand not just the ideas of sci- nontechnical audience. in astrophysics. However, we now face a ence but also how they have developed. Two marvelous books on 20th century very serious problem in advancing the I also hope that more of the scientific physics for the interested layman which experimental frontier, a problem which community would remember them, too. focus more on scientific substance few people like to discuss. It seems to My presentation in Stockholm ended rather than historical process are The me that, ever since Leeuwenhoek, ad- at this point, but, in the days that fol- Cosmic Code and Perfect Symmetry, both vances in the resolving power of our lowed, it prompted a variety of com- by Heinz Pagels, something of a self- ‘‘microscopes’’ have come with similar ments, questions, and exchanges. I’d like styled New York City dandy, but as investments of capital and manpower. In to add here a brief version of one of charming a person as could be. He died other words, an increase by an order of them. I was asked, point blank, what I young but just as he dreamed it would magnitude in the one required an in- actually thought of the 2004 Nobel be. The Cosmic Code is about quantum crease by roughly an order of magnitude Prizes in Physics, aside from the obvious mechanics, and Perfect Symmetry covers of the other—at least once we average personal considerations. And this is a more of the sweep of particle physics and cosmology. over fits and starts and brilliant insights. distilled version of my reply. Recogni- I have not sought out the actual pub- The last big machine planned and can- tion of the theory of the strong interac- lished references for the relevant points celed in the U.S. was to cost about $10 tions is an obvious choice—for all the in my narrative. They’re not hard to billion. (That’s $1010.) That would have reasons that have been discussed in my find, but Les Prix Nobel is not a refer- allowed us to reach distances small corecipients’ lectures, in the presenta- reed journal. And yet, there is a poten- enough to study the interactions of weak tion speech in Stockholm by Lars Brink, tially enlightening aspect to my having bosons directly. The realm of the con- in the assembled material of the Nobel put this together purely from memory in jectured ‘‘unification’’ of the forces of Foundation, and in the wide coverage October and November of 2004. While the Standard Model, the realm of their elsewhere. However, in my view, getting standard references are unequivocally possible unification with gravity, and the to our current level of understanding available in the published record, what basic physics of String Theory, the most has been a rich and complex story. Nev- actually transpired, leading to those widely pursued approach to a physics ertheless, I believe that it is the over- publications, is not. We rely on people’s more fundamental than the Standard whelming consensus (but by no means personal accounts. And now we enter Model, are all more than a dozen orders unanimous) opinion of researchers in the interesting realm where participants of magnitude further away. However, the field—and I personally agree—that in the same event may have very differ- $1022 is simply not available for this line the discovery of asymptotic freedom was ent and mutually contradictory percep- of research (or anything else for that a genuinely crucial event. For some, it tions of what transpired, and those matter). made everything clear. For others, it perceptions may shift as time passes. The question of the benefit of this was only the beginning. And for yet oth- While intentional deception is not an work incurred on mankind, an aspect ers, it was the beginning of the final unheard of phenomenon, these phenom- stipulated in Mr. Nobel’s will, is a whole chapter. But in any case, it was key. ena effect the reports of people with the other topic. But, as I said at the outset, The two books I would recommend highest integrity. Although evaluating I certainly appreciate the care and wis- first which give excellent accounts of the accuracy of my personal recollec- dom invested by the Royal Academy in this epoch in particle physics (and more) tions may be very difficult, at least it identifying noteworthy advances in fun- are The Second Creation, by Robert would be possible to see how good my damental physics—and in identifying the Crease and Charles Mann, and Con- memory is with respect to items that can particular advance that we celebrate to- structing Quarks, by Andrew Pickering. be confirmed or refuted.

Politzer PNAS ͉ May 31, 2005 ͉ vol. 102 ͉ no. 22 ͉ 7793 Downloaded by guest on September 26, 2021