Physics Folklore

By Lynne Zielinski


Sometime after World War II physicists began to change their way of giving names to theoretical ideas. Before then, new ideas were given titles such as "special relativity theory" or "neutrons." A precursor of the new kinds of names came in 1953 when Murray Gell-Mann and Kazuhiko Hishijima decided to name one of the properties of subatomic particles "strangeness." Gell-Mann accelerated the trend in 1961 by calling his group-theoretic way of explaining the properties of particles "The Eightfold Way." Gell-Mann's crazy names finally reached the consciousness of the general public in 1964 when he described the particles involved in the next stage of his thinking as "quarks." p. 508, source B

Where did the names of the particles come from? Often times physicists are whimsical in naming things, as termed by Chuck Brown, "they are random and poetic in nature." So, below, in alphabetical order, I've done my best to try to give you the true origin of the various particle names.

Troubled by the apparent "chaos" of the everyday world, ancient Greek philosophers sought an underlying order, or "cosmos," in Nature. Leucippus and Democritus viewed the world as composed of tiny particles, or "atoms" – from the Greek word "atomos" for "uncuttable" or "indivisible."

Baryon number is something that only heavy particles could have; therefore, baryon was taken from the Greeks because baros means "heavy."

Particles that obey the statistical system set up by an Indian physicist, Satyendranath Bose, were originally called "Bose particles," and the name was later shortened to "boson."

cascade particle (Ξ)
This particle, denoted by the Greek letter "xi," was called the "cascade" because it decayed into a cascade of lighter fragments. p. 64, source D

In 1964, Sheldon L. Glashow had written an article with James Bjorken suggesting a possible fourth quark. "We called our construct the 'charmed quark,'" recalled Glashow, "for we were fascinated and pleased by the symmetry it brought to the subnuclear world." Later in 1974 Glashow was pushing scientists to find the charm. In doing so, he stated at a conference that there were three possibilities: "One, charm is not found, and I eat my hat. Two, charm is found by spectroscopists, and we celebrate. Three, charm is found by 'outlanders' (other kinds of physicists who did neutrino scattering or measured electron-positron collisions in storage rings), and you eat your hats." p. 210, source D

In 1976, charm was found by "outlanders", and a year later Glashow gave a rabble-rousing talk titled "Charm Is Not Enough." Then they all had a big laugh as the spectroscopists present finally ate their hats – Mexican candy hats were supplied by the organizers. p. 321, source D

In the autumn of 1971, Murray Gell-Mann and Harald Fritszch began trying to understand how neutral pions decayed. However, these particles decayed nine times too quickly. On the other hand, this small problem would not occur if each quark came in three different kinds, increasing the decay rate ninefold. In this picture, each quark had to have some new physical property, something that made them in fact different, which Gell-Mann with characteristic aplomb dubbed merely color. "It was a natural choice," he recalled. With Richard P. Feynman in the late 1950s, he had advocated "red" and "blue" neutrinos to distinguish two different kinds of these ghosts, names that never caught on. Now he resurrected the old terminology and applied it to quarks, which henceforth came in red, white, and blue varieties. He did not mean that quarks actually had visible colors; that was absurd. "Color" was just another name among many, plucked from everyday discourse to help physicists communicate. Next, it was found that the grouping of quarks had to combine so that they became "colorless" – that is, have zero net color. Because of this, physicists later adopted a new terminology of red, green, and blue quarks over Gell-Mann's original, more patriotic choice because red, green, and blue light can add up neatly to give white, colorless light. pp. 228-229, source D

Eightfold Way
In 1961, Murray Gell-Mann reached into Chinese literature to christen his classification scheme the "Eightfold Way," a name that soon captured the imagination of physicists around the world. The phrase comes from an aphorism attributed to Buddha, about the appropriate path to Nirvana:

Now this, O monks, is noble truth that leads to the cessation of pain; this is the noble Eightfold Way: namely, right views, right intention, right speech, right action, right living, right effort, right mindfulness, right concentration.

pp. 90-91, source D; p. 508, source B; p. 106, source C

Particles that obey the statistical system set up by Enrico Fermi were originally called "Fermi particles" and later shortened to "fermions".

Although the names used currently for the original three quarks are only a little peculiar – up, down, and strange – they also were known at one time as vanilla, chocolate, and strawberry. This accounts for the different kinds of quarks being called different flavors of quark.

Gluons are the "glue" that holds the partons together in the nucleons. p. 508, source B

Hadron comes from the Greek word hadros, meaning "thick" or "heavy." p. 54, source C

The implication here is that it is a "strong particle," and these particles are thus named because they interact strongly. p. 12, source C

The word isospin is a combination of isotope, meaning "same form," and spin. p. 54, source C

J/Ψ particle
The J/Ψ particle is a combination of two names. J was the name given to the particle by Samuel Ting's group from MIT and Brookhaven. Ψ was the name given to the particle by Burton Richter's group at SLAC. Each group had found the particle independently and almost simultaneously. As the story goes. . .

On Sunday, November 10, 1974, after searching for the charm quark around 3 GeV, Richter's group found a peak at 3.105 GeV. Richter called one of his friends, James Bjorken, just as he had sat down to dinner and gave him the startling news. "I couldn't believe such a crazy thing was so low in mass, was so narrow, and had such a high peak cross-section," Bjorken recalled. "It was sensational." He returned to the table a few minutes later, seemingly in a daze. His wife and children then watched open-mouthed as he unthinkingly heaped a large tablespoon of horseradish onto his baked potato and quietly began munching away, staring absentmindedly off into space. "BJ," his wife finally counseled, "I think you'd better go down to the lab now."

As the word of the fantastic discovery leaked out into the SLAC community, a crowd of happy onlookers began to gather in the SPEAR control room. Somehow amid the euphoria, the physicists remembered the champagne. It ran low very fast, and there was a shortage of glasses. Recruits departed for more supplies. Meanwhile, Gerson Goldhaber's original draft of the discovery paper had been made a shambles by more recent data, so Richter began writing another version. The new particle needed a name, and he first tried calling it the "SP" after the first two letters of SPEAR. But nobody liked that very much, so Richter went over to Leo Resvanais, a Greek physicist with the University of Pennsylvania, and asked him what Greek letters were still unused. Resvanais went down the list alphabetically, until he came to iota, but Richter didn't like that very much because it also meant something small, which this discovery was clearly not. The next available letter was psi, or Ψ, which Richter thought might be confused with the Greek symbol for the wave function, but Resvanais told him that psi was a good choice because this discovery was certainly something big (psi's meaning). Most of the others liked the name, especially after Goldhaber pointed out that it contained the letters s and p in reverse order.

Meanwhile, Ting from MIT, who was part of an experiment at Brookhaven, was unaware of the rumors circulating there about the particles's discovery. His own discovery of the same particle had been achieved on October 31. On November 4 or 5, Ting showed his results to Victor Weisskopf, who told him he was crazy not to publish immediately. Ting, however, wanted to be very careful and make certain that he wasn't in error. By coincidence, on November 10, Ting was headed for SLAC for a scheduled meeting. Unaware of the rumors circulating at Brookhaven, Ted Kycia asked Ting if he had discovered anything yet. Ting replied no. Little did Ting know then of the rude shock awaiting him in California. While Ting was in flight, his group at Brookhaven heard the news. Ting called in at 1 a.m., and his experimenters had convinced themselves that this was just a lousy practical joke being played on them. Ting, however, agreed to check it out anyway when he got to SLAC the next day. But immediately after he arrived at his motel, Ting received a call that SLAC had indeed discovered a resonance. Worried now, Ting called Stanley Brodsky, a SLAC theorist he knew, and learned that yes, indeed, there had been a big discovery that would be announced tomorrow. For Ting, it was the moment of truth. He was about to be scooped on the greatest discovery of the year, if not the decade. His weeks of cautious silence now had to be undone overnight. The battle began, each group trying to get the paper in first. By the time Ting's paper was written, Ting had dubbed his particle the "J," a letter that closely resembled the Chinese ideogram for Ting. pp. 276-289, source D

The touchy issue of what to call the first particle, J or psi, had been smoldering ever since it became obvious that each group was sticking by its own name. So physicists began deliberately using the dual label J/Ψ in their talks and papers, to avoid getting caught in the crossfire. This was the label that stuck.

Just as a side note, in the first few months, the contest over which name to use seemed to be fairly good-natured. Ting's troops began to offer and wear T-shirts with "J-3.1 GeV" emblazoned on the front. SLAC-LBL physicists kidded that "the particles themselves preferred the Ψ label." To prove their point, they passed around photos of a computer display showing a Ψ disintegrating into two pions and the two muons. The four visible tracks had arranged themselves neatly into the four arms of a near-perfect letter psi. pp. 311-313, source D

Lepton comes from the Greek word meaning "light" (opposite of heavy) or "small." It was originally the name of a small Greek coin. p. 53, source E; p. 183, source A

The meson was originally called the "X-particle" by Carl Anderson and Seth Neddermeyer. Eventually it was found to be a middleweight particle, or "middle particles" between the light lepton and the heavy baryon. The Caltech group promoted the name "mesotron" for it, from the Greek "mesos" for "intermediate" or "middle." This was the name generally used, although the particle was also called the "meson" or "heavy electron" in Europe. pp. 50-51, source D; p. 183, source A

Cecil Powell used the nomenclature more common to Europe to name the light particle the "mu-meson" or "μ-meson" from the Greek letter "mu" or "μ." Today the name has been shortened to "muon." p. 52, source D

In 1930, Wolfgang Pauli postulated that an invisible particle was emitted during radioactive beta decay along with the electron, which carries off missing energy and angular momentum. The original reaction conserved electric charge, so the new particle must be neutral. On the strength of this, Enrico Fermi called it the neutrino. Neutrino is the Italian word for "little neutral one" and is denoted by the Greek letter "nu" or "ν." p. 67, source D; p. 40, source A

omega particle (Ω)
If the Eightfold Way were true, then theory suggested that there had to be a tenth baryon resonance since nine had been previously found. The Greek letter omega (Ω) seemed an appropriate choice by Murray Gell-Mann for this final member of the baryon decimet because it was the last letter in the Greek alphabet.

Parton means "partial particles." Richard P. Feynmam called them partons because the hadron was made of many particles.

Cecil Powell used the nomenclature more common to Europe to name this heavy particle the "pi-meson" or "π". Today, the name has been shortened to pion. p. 52, source D

Carl Anderson, a postdoc under Robert Millikan, had been working alone, taking photographs of cosmic ray tracks at Caltech. Anderson showed a curious photo to Millikan, who agreed with Anderson that the track shown could only be positive. They dubbed the particle the "positron," for "positive electron."

The quark model was introduced independently by Murray Gell-Mann and George Zweig in 1964. Gell-Mann called the triplet of the new particles "quarks," and Zweig called them "aces," like the aces in playing cards. p. 104, source C

Gell-Mann's crazy names finally reached the consciousness of the general public in 1964 when he described the particles involved in the next stage of his thinking as "quarks." Gell-Mann and Zweig pointed out that the representations of SU(3) [Special Unitary group of transformations of dimension 3], which were occupied by particles, could be chosen from among all those mathematically possible by assuming them to be generated by just two combinations of the fundamental representation. p. 57, source A; p. 508, source B

Gell-Mann called the entities in the fundamental representation quarks. This is the rather idiosyncratic use of a German word meaning curds or slop (abstracted for this purpose from the novel Finnegan's Wake by James Joyce). And this is how it all began.

Gell-Mann had a luncheon conversation with Columbia theorist Robert Serber, Tsung Dao Lee, and others. While they were eating, Serber mentioned why a fundamental triplet did not appear in Nature. According to Serber, Gell-Mann's immediate reply was, "That would be a funny quirk!" Tsung Dao Lee chimed in, calling it "a terrible idea." Pulling out pen and napkin, Gell-Mann showed Serber why. Such a triplet, if it existed at all, had to have fractional charges of 2/3, -1/3, and -1/3. Serber had to agree that these were odd birds, indeed; ever since Robert Millikan's famous oil-drop experiment, nothing but whole-number charges had ever been observed.

While a visiting lecturer at MIT that year, Gell-Mann had been seeking a simple basis for the Eightfold Way. He knew about triplets but always passed them over without much thought because of the fractional charges involved. Serber's offhand query now catalyzed his thinking. Later that evening and the following morning, Gell-Mann began to realize that fractional charges were not completely absurd – as long as they could never appear in Nature. Gell-Mann began calling these whimsical motes quorks, a nonsense word he had used previously, in the spirit of Lewis Caroll, to mean "those funny little things." Serber thought it was a play on the word quirk used at lunch. Whatever the case, Gell-Mann mentioned these quorks in his next lecture, giving Serber credit for proposing the fundamental triplet. Although he quickly moved on to other topics, quorks were a favorite subject of discussion at the subsequent coffee hour. Gell-Mann was in no great hurry to publish the quork idea. There were a number of puzzles to resolve, and he had other commitments demanding his attention. Back at Caltech that fall, he began working out the details in earnest. In a phone call to his old MIT thesis adviser, Victor Weisskopf, Gell-Mann mentioned he was working on a new and exciting idea: that baryons and mesons were composed of three fractionally charged entities. "Please, Murray, let's be serious," came Weisskopf's reply. "This is an international call."

By then the widely read theorist had found a telltale passage in James Joyce's enigmatic novel, Finnegan's Wake:

Three quarks for Muster Mark!
Sure he hasn't got much of a bark
And sure any he has it's all beside the mark.
But O, Wreneagle Almighty, wouldn't un be a sky of a lark
To see that old buzzard whooping about for uns shirt in the dark.
And he hunting round for uns speckled trousers around by Palmerston Park?

This poem is the drunken dream of Humphrey Chimpden Earwicker as he lies passed out on the floor of his Dublin tavern. Gell-Mann happily borrowed the quark spelling for his imaginary triplet. No doubt he also enjoyed the irony of the last few lines. There is an obvious parallel between the trials of Muster Mark and the seemingly hopeless plight of eager experimenters who would inevitably go searching for motes they could never possibly find.

Meanwhile at Caltech, Zweig was reading publications of bubble chamber experiments in 1963 and was puzzled as to why some particles elected to decay by the most difficult path available. He first guessed that a conservation law was at work because it was the only one allowed. While fiddling with group theories, Zweig inadvertently discovered that he could get collections of particles if baryons were built from three constituents with fractional charges.

At first, it seemed an artificial solution. Then things began to fall into place. That fall at CERN, Zweig wrote up his discoveries for publication, calling his fractionally charged particles aces. Mesons, which were built from pairs of these aces, formed the deuces and baryons the treys in his deck of cards. Just cut the deck, shuffle the cards, and you could deal all kinds of poker hands. pp. 102-104, source D

Just so I don't leave you hanging, I don't know the reason why the name quark beat out the name aces. But I do know that while the two theories were essentially the same physics, stylistically they were poles apart. Sorry! (If you do find out, please tell me.)

In 1947, the English physicists George D. Rochester and Clifford C. Butler observed new particles which were a thousand times more massive than the electron. These particles were often associated with V-shaped tracks; they were at first called V particles. Their origin and purpose were an entire mystery. For the following six years, the V particles were observed, and two kinds became apparent. Those whose decay products always include a proton are called hyperons or Lambda particles, and those whose decay products consist only of mesons are called K mesons or kaons. The hyperons and kaons soon became known as the strange particles because of their anomalous (strange) behavior. pp. 49-50, source A

Originally, strangeness was introduced to explain why some hadrons decay quickly by the strong nuclear force while others decay slowly by the weak force. p. 185, source A

Strange came from the fact that something "strange" was going on with a third particle that was neither an up nor a down quark. (Drasko Jovanovic) Lacking any good explanation, theorists simply dubbed them "strange" particles, a name that has survived to this day as the label for a completely new property of matter. The quark that all strange particles contain is known as the strange quark, and it is this quark that gives them their property of "strangeness."

"Strangeness" is a term, a name, for a property of matter seen only in violent collisions of subatomic particles; it has no corresponding meaning in the everyday world of our senses that language was originally developed to describe. Physicists have had to create a new nomenclature in order to begin talking with each other about the weird subatomic landscape. One way they do so is to borrow words from everyday language and use them in entirely new ways. In this case, "strangeness" is a property found in particles containing the strange quark.

top/bottom or truth/beauty
As two more quarks came to be required in 1978 and following years, it was no longer surprising that some physicists would call the new ones beauty and truth. Theorists had predicted the quarks long before they were found, naming them the "t" and "b" quarks for top and bottom -- varients of the labels "up" and "down." Top and bottom came from the fact that there had to be a pair of particles, heavier in nature, with up and down spins also. (Drasko Jovanovic)

The more whimsically inclined favored "truth" and "beauty," so that experimenters might begin the search for naked truth and beauty. However, at this point, more prosaic imaginations prevailed, so most physicists call beauty "bottom "and truth "top." In any case, when physicists searched for the existence of the last two quarks to be named, they had an interesting choice as to how to describe their work to outsiders. Since the object was to find the beauty or bottom quark in undisguised form, they could choose to say they were looking for either "bare bottom" or "naked beauty." The search was serious, even if the names were playful. p. 508, source B; p. 331, source D

In 1975, Leon Lederman and his group finally began searching for particles like the J/Ψ with masses above 5 GeV. In 1976, they thought they had found one. Observing electron-positron pairs produced in the collisions of 400 GeV protons with beryllium nuclei, they found only twenty-seven at high mass. But twelve of these pairs clustered around a mass of 6 GeV, suggesting the existence of a neutral, spin-1 particle. Lederman and company published their find, dubbing their particle the Υ. Upsilon was determined when Leon Letterman and his group at Fermi were in a portacamp. Around 3 a.m. they tried to write down all the Greek letters that hadn't been used before. (Chuck Brown)

When they repeated the experiment that summer, however, the peak withered away. The peak must have been just a statistical fluctuation that had fooled the group. Jokes began to circulate around Fermilab that they had only discovered the "oops Leon." Not long after this, experimenters noticed another small bump. Once burned and twice shy, they checked their analysis and began preparing yet another experiment. In August 1977, Lederman presented the combined data revealing three peaks. He recommended calling these particles Υ, Υ', and Υ" as this label was obviously no longer needed for the 6 GeV peak. pp. 329-330, source D

Originally, depending on whether the spin of the nucleon (this is the quark part of the nucleon) was parallel or anti-parallel to the direction of the angular momentum, it was called up or down respectively. (Drasko Jovanovic)

W particle
The W stands for "weak."

Z particle
The Z means that there is "zero" charge.


Dodd, J.E. The Ideas of Particle Physics: An Introduction for Scientists. Cambridge University Press: Cambridge, 1984.

Bunch, Bryan, ed. The Science Almanac. Anchor Books: Garden City, New York, 1984.

Nambu, Y. Quarks: Frontiers in Elementary Particle Physics. World Scientific: Philadelphia, 1985.

Riordan, Michael. The Hunting of the Quark. Touchstone Books: New York, 1987.

Close, Frank. The Cosmic Onion. Heinemann Educational Books: London, 1983.

Many of the stories were confirmed or told by the following people:
Chuck Brown
Drasko Jovanovic
Leon Lederman