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George Zweig and Leon van Hove


Writing up the quarks. Real, mathematical or fictitious particles
Murray Gell-Mann Scientist
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I wrote up the quarks in a very tentative manner. I also included in the letter the possibility of integrally charged... of an integrally charge triple together with a fourth particle; the… the thing I had mentioned at MIT in my lectures that spring. But I said that the quarks, I implied that the quarks were a neater solution. But I did something that has caused problems ever since. I needed a word to describe particles that actually came out and could be seen and used in the laboratory and used for industrial purposes and so on and so on. And I chose the word 'real' for that, reserving ‘mathematical’ or ‘fictitious’ for a particle that couldn't be directly, singly observed in the laboratory, utilized for industrial purposes and so forth. Well, this was a huge mistake. The reason I did it was that I imagined myself in a debate with philosophers, who would ask, 'If this particle doesn't come out to be seen singly by itself and so on, how can you say it's there? How can you say it's real?' And in fact people said that kind of thing. There's a historian of science–he must be a very silly person–called Pickering, Andy Pickering, who wrote something called Constructing Quarks. He's one of these 'social construction of science' people, I guess, or is close to it anyway. And he said in this book, written many years later, that he doesn't think quarks are part of the furniture of the universe. Anyway, it was that kind of thing that I was thinking of when I used this word 'real'. So then I said, well of course, the quarks are less likely to be real than if we have the other scheme with the three particles with integral charges and the fourth one… fourth one as a singlet. I didn't mean that the quarks were less likely to be the right solution, but they were… if they were the solution, they were more likely to be trapped inside because that would account for nobody ever having seen a fractionally charged particle, and so on and so forth. Of course, if they were very heavy, they wouldn't have been seen anyway. But then I had to have some way to describe to people what I meant by their being mathematical, so in that letter I said well, imagine the mass of the quark goes to infinity, that's the kind of thing I mean by mathematical. They're in there all right but mass being infinite they can't come out. They can be in there only bound together, they can't come out.

In 1966, to jump ahead a bit, when I was invited to give the introductory talk to the International Conference on Particle Physics at Berkeley, I used a different description of what I meant. Instead of talking about infinite mass, I said that if the quarks were not real they would… it would be like a situation in which they were trapped in a infinitely high potential barrier and couldn't get out. Well, that's exactly what we believe today to be the case, so my unreal or mathematical or fictitious quarks were precisely the kinds of quarks we believe in today. But many people have alleged that that isn't what I meant at all, that I meant I didn't believe the quarks, that they were a dumb idea and so on and so on, which was not at all the case.

New York-born physicist Murray Gell-Mann (1929-2019) was known for his creation of the eightfold way, an ordering system for subatomic particles, comparable to the periodic table. His discovery of the omega-minus particle filled a gap in the system, brought the theory wide acceptance and led to Gell-Mann's winning the Nobel Prize in Physics in 1969.

Listeners: Geoffrey West

Geoffrey West is a Staff Member, Fellow, and Program Manager for High Energy Physics at Los Alamos National Laboratory. He is also a member of The Santa Fe Institute. He is a native of England and was educated at Cambridge University (B.A. 1961). He received his Ph.D. from Stanford University in 1966 followed by post-doctoral appointments at Cornell and Harvard Universities. He returned to Stanford as a faculty member in 1970. He left to build and lead the Theoretical High Energy Physics Group at Los Alamos. He has numerous scientific publications including the editing of three books. His primary interest has been in fundamental questions in Physics, especially those concerning the elementary particles and their interactions. His long-term fascination in general scaling phenomena grew out of his work on scaling in quantum chromodynamics and the unification of all forces of nature. In 1996 this evolved into the highly productive collaboration with James Brown and Brian Enquist on the origin of allometric scaling laws in biology and the development of realistic quantitative models that analyse the influence of size on the structural and functional design of organisms.

Tags: MIT, Constructing Quarks, International Conference on Particle Physics, Berkeley, Andy Pickering

Duration: 3 minutes, 34 seconds

Date story recorded: October 1997

Date story went live: 24 January 2008