The Physics of Silly Names

Physicists are a silly lot, especially when it comes to naming things. Given some of the humdingers that they have come up with, you might think that they might have their very own Ministry of Silly Names (MoSN), something like the Ministry of Silly Walks, featured in a 1970 sketch from the "Monty Python's Flying Circus" television show.

Take, for example, the names given to the various types of quarks, those reclusive, fractionally-charged, point-like particles that are the building blocks of protons and neutrons. First, it would have to be conceded that the name quark, itself, is pretty silly - not surprising, given that it was selected because it sounds like the call of a duck. This silliness is only compounded when one notes that quarks don't come in types, they come in flavors - as though specifying a fundamental characteristic of some of the tiniest bits of matter was akin to ordering an ice cream cone at the neighborhood Baskin Robbins.

A little dignity is restored by the fact that the two "original" quark flavors have the unremarkable names up and down. To a good approximation, protons are constructed from 2 up quarks, designated, conventionally, by the letter 'u', and one down quark, designated by 'd'; neutrons, likewise, from 2 down quarks and one up quark.

The second generation of quarks flavors - more massive than up and down, so it took collisions created by high-energy particle accelerators to produce them in abundance - were given the apparently silly names, strange ('s') and charm ('c').

Strange, it turned out, was not all that silly a choice. When particles called K-mesons, or kaons, were first created, they were observed to decay into a triplet of garden-variety pions, but they took their good time doing so. Something "strange" was keeping them from decaying as quickly as had been expected. A special property was proposed, strangeness, to account for the kaon's longevity. Such a property, called a conserved quantity, is difficult, if not impossible, to shed - sort of like a bad cosmological penny. Thus, the kaon is stymied in its routine attempts to self-destruct, and must resort to slow-as-molasses assistance from the feeble weak interaction to get the job done. You see, the weak interaction doesn't hold strangeness in any special regard and would just as soon eradicate it as keep it around, of course taking in its own sweet time.

I wish I could say that there was a similarly dignified story to account for the origin of the designation charm as a quark flavor, but, to be frank, once strange found its way into the particle physics lexicon, a kind of silliness mania took hold. Indeed, the flavors of the third generation of quarks, then yet to be discovered, were christened beauty and truth by some silly researchers. There were fears - smirking hopes in some quarters, actually - that it would just be a matter of time before newspaper headlines would appear proclaiming such things as: "Beauty Revealed by Fermilab Scientists" or "Particle Physicists Seek Truth with New Accelerator". Something had to be done.

As a result, the Ministry of Silly Names put its foot down and a silly-name reformation was launched. When the quark dust settled, charm, old enough to sound quaint, was, graciously, grandfathered in, but beauty and truth were sent packing, replaced with the names bottom ('b')and top ('t'). How the silly how fallen!

Not going down without a fight, the forces of silliness mounted a rear guard action, so to speak. When the b quark was first created in particle collisions, it was always produced in conjunction with its antimatter counterpart, the b antiquark. So, given the way matter and antimatter cancel each other out, the particle that they formed possessed no net "bottomness". This was just the kind of opening that the silliness resistance needed. The search was on for creating a so-called B meson, a particle containing a single, unbalanced b antiquark, one that would brazenly show its "bare bottom". It was a last hurrah for quark name silliness.

Well, silly or not, the sextet of quarks - up, down, strange, charm, bottom, and top - have now all been detected, advancing the cause of the Standard Model of elementary particles, if not the cause of respectable physics names, considerably. This is as close as physicists have come so far to a long-sought theory of everything (ToE), and by that I mean a comprehensive theory of matter and energy and (most of) the forces of nature that has undergone rigorous experimental tests.

There is, though, one important piece still missing from from the Standard Model puzzle and it is called the Higgs particle, an eponym, named for the theoretician Peter Higgs, so hardly a silly name. Unfortunately, because of the pivotal role the Higgs plays in bestowing mass on other particles in the Standard Model, Leon Lederman, who, it turns out, was a co-discoverer of the b quark, nick-named it the God Particle. No doubt this nickname will be the inspiration for silly headlines when the Higgs is detected, as is likely to be the case, in the next couple of years. There's not much that can be done to avoid this embarrassment. Particle nicknames - much like Bush-era financial markets - are pretty much unregulated.

To put things in perspective, and to give the silly physicists their due, let's turn to the book of Genesis for some guidance about the challenge posed by naming things.

In the creation myth of the first chapter, after creating man in His image, God grants him dominion over every living thing. And in the creation tale of chapter 2, immediately after fashioning Adam out of dust,

the Lord God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what he would call them: and whatsoever Adam called every living creature, that was the name thereof.

How formidable a task for Adam - himself just now created - to be called upon to name things, things not only unfamiliar to him, but things entirely new to the world!

I imagine that Adam, struggled and stumbled, yet persevered, and came up with names for the animals, as commanded. No doubt, some of these names were fitting and clever, while others were out-and-out silly. But, what choice did Adam have? To have dominion over a thing means you have to call it by name.

To the list of attributes that have been used to characterize to our species - "thinker", "tool maker", "culture bearer" - perhaps, "namer" should be added. Physicists, as scientists, have taken on the task of discovering things entirely new to the world and, with that assignment, they have taken on the responsibility of giving names to the things they discover. We can hardly fault them for struggling and stumbling. We can hardly fault them, now and then, for coming up with silly names.

The Physics of Unwelcome Surprises

"Who ordered that?" This was the flustered response of physicist Isidor Isaac Rabi when he was told that a new elementary particle, one that would eventually be named the muon, had just been observed.

The year was 1936, and the world of 20th century physics, rocked by three decades of disorienting discoveries, was in need of a breather, a bit of time to take stock, to consolidate the mind-bending theories that had been cobbled together at an unprecedented pace.

This roller coaster ride of surprises was set in motion in 1900 with Max Planck's quantum hypothesis. It turned out, to Planck's despair, that the the elegant mathematical models of the physical world, painstakingly developed over the preceding three centuries, failed abjectly when scrutinized at extreme microscopic levels. Graceful, continuously-varying classical arcs gave way to jagged, stair-stepped quantum diagrams when atoms were the object of investigation. It was as though a mischief-maker had stolen into the Louvre one night and had replaced Leonardo's "Mona Lisa" with Braque's "Woman with a Guitar". Planck, crestfallen, soldiered on.

Only five years later Albert Einstein, exploiting Planck's conjecture about the particle nature of light to solve, virtually en passant, the problem of the photoelectric effect, proposed his theory of special relativity, demolishing the heretofore unquestioned notion that measurements of space and time were absolute. Astonishingly, distances shortened and clocks ticked more slowly as observers moved relative to one another - the closer their difference in speed to the unassailable speed of light, the more dramatic the distortion. Ever the iconoclast, Einstein forged ahead with his assault on Newton's theory of gravitation while the rest of the world was still reeling from his recent revelations.

Ironically, the troubled time after the Great War and the early years of the decade of the roaring twenties provided physicists an opportunity to recover their bearings. The early quantum musings of Planck and Einstein, followed soon by those of Niels Bohr, found rigorous mathematical expression with the so-called matrix mechanics of Werner Heisenberg and in Erwin Schrödinger's eponymous wave equation. The structure of the hydrogen atom could now be calculated to impressive precision. A tentative understanding of the universe - at least one consisting of protons, electrons and photons (quanta of light) - appeared to be within reach.

Forging ahead, in 1928, Paul Dirac advanced a formulation of quantum mechanics, which explicitly took into account Einstein's special relativity, and, in doing so, predicted the existence of antimatter. According to Dirac, every elementary particle possessed a negative-image twin of sorts. For the neutral photon, this turned out to be the photon itself. But, for the electron and the proton, Dirac's equations demanded the existence of, yet-unobserved, particles of identical mass and opposite charge. Dirac was serenely confident in the implications of his mathematically elegant theory. Other physicists, though, awaiting experimental confirmation, were skeptical. Four years later, the discovery of the positron, the electron's antimatter doppelgänger laid their doubts to rest.

At about the time of the positron's debut, the existence of another, apparently fundamental, particle was being established. The neutron, a sister particle to the proton - a little heavier but possessing no electrical charge - was, in many ways, a welcome addition to the particle family. Its discovery led to the understanding that the atomic nucleus was composed of an unimaginably compact knot of protons and neutrons, bound together by a hypothetical "strong" force.

The behavior of the electrons orbiting this nuclear droplet, in accordance with now established quantum theory, explained the chemical activity of the elements, while the numbers of protons and neutrons within their nuclei accounted for their atomic weights. At long last an explanation for the organization and the particulars of the periodic table of elements, devised by Dmitri Mendeleev in 1867, had been provided, and with it came the first comprehensive understanding of ordinary matter in the history of the world.

But, to everyone's surprise, the neutron itself proved to be anything but ordinary. Unlike the other elementary particles, neutrons were not immortal. Within an atomic nucleus their lifetimes varied widely, but left to fend for themselves they survived, on average, a little less than 15 minutes, decaying spontaneously into a proton and electron.

To make matters worse, when the momenta of the proton and the electron resulting from the neutron's decay were tallied, it turned out that energy accounts did not balance. Either the supposedly inviolable law of the conservation of energy had to be jettisoned, or a new particle had to be called into existence, one that fled the neutron's self-destruction unobserved, stealing away with the unaccounted for missing energy. This placeholder, promissory note of a particle, conjured into being by Wolfgang Pauli and christened the neutrino by Enrico Fermi escaped detection for another quarter century, owing to the fact that it felt the push and pull of only the aptly-named "weak" interaction. In the meantime, the hypothesis of the neutrino, a ghost of a particle bullet, allowed physics to dodge another, much more potentially damaging, one.

By the mid-1930s a family portrait of elementary particles looked like it was coming into focus. There were the "adults", the neutron and the proton: the heavy-set neutral momma and positive poppa particles, bound in enduring strong-force matrimony, comfortably ensconced in their nuclear home. Then there were the "kids": the bantam-weight, negatively-charged electron, a mercurial and rambunctious boy-child, hovering close by when mindful of his father's tugs, but venturing beyond the atomic neighborhood when overly stimulated, and the neutrino, an alienated and asthenic teenage daughter, resembling her brother in outline, but drained entirely of charge and heft, a Garbo manqué, withdrawn and in perpetual flight.

Of course, there was Planck's voluble particle of light, around from the beginning, less a full-fledged blood relation than a domesticated sprite, a restless go-between, bounding from electrical lap to electrical lap. There were rumors circulating, though, that the photon had relatives of her own, answerable to the commands of the strong force and weak force, the way she obeyed the beck and call of electricity and magnetism. Physicists were on the lookout for them.

That's about the time that, to Rabi's feigned consternation, the muon showed up, unsummoned. At first it appeared that it might be the strong-force cousin of the photon forecast by Hideki Yukawa only a year before. That turned out not to be the case. Instead, the muon was the harbinger of a wave of particle discoveries to come.

By the time the "unwelcome" muon arrived on the scene, the enterprise of physics had been transformed in a fundamental way by the philosophical buffeting of the preceding 30 years. Grudgingly, physicists had come to appreciate that the universe was such a strange and marvelous place, that their understanding of it was, in a profound way, destined to be forever provisional, and that any charter for their investigations required that they not only seek answers to long-standing questions, but also be prepared to wrestle with unexpected - even confounding - surprises.

This intellectual no man's land, bounded on one side by time-tested facts and theories and on the other by ever-restless skepticism and doubt, was both a precarious and a wondrous territory. Nevertheless, it was, and remains, the quintessential realm of all scientific discovery.