Elementary, My Dear Watson

The publication of data by a team at CERN† brought into focus, once again, the delightful parts of physics, thus the elementary particles, the neutrino specifically. The team clocked neutrinos travelling a distance of 732 km underground, at a depth, at the maximum of the path 11.4 km underground, faster than the speed of light by 60.7 nanoseconds. These particles came into view in the twentieth century, perhaps a time when physicists were tiring of the old-fashioned naming conventions. Hence we have quarks—with first names like Up, Down, and Top and colors—and neutrinos (first hypothesized by Wolfgang Pauli in 1930); neutrinos come in three flavors.

Both belong to the category of elementary particles, and those are defined as particles not known to have any deeper structure, thus not known to be built up from yet smaller particles. These are the smallest things we know to exist as definable entities. Here, in effect, are what the ancients (in the West fifth century BC) called “atoms.” Who knows. Our elementary particles may someday also turn out to be yet smaller empires of yet smaller things, but at the present Western Culture has done enough. Just yesterday came news that Fermilab is closing down its large hadron collider. Exhausted. The next great push is in some nebulous future; we’re resting on our laurels. And lovely, cute things they are. Here is a picture of them all:

The oldest, by discovery, are the leptons (from the Greek for slight, slender, delicate), and the first lepton was the electron, which dates to 1897. Our neutrino belongs to this category too. The quarks (we owe that name to one of James Joyce’s nonsense words used in Finnegans Wake) date to the 1960s. These two categories are known as fermions, that name derived from the statistics developed by Fermi and Dirac. Thus they obey Fermi-Dirac statistics.

The red particles are force carriers described by gauge theory; that theory deals certain kinds of fields. They’re usually just called bosons, and that name we owe to the Bose-Einstein statistics, which in turn describes their behavior. The Bose in that composite was one Satyendra Nath Bose (1894-1974).

But what is missing from this picture? Two bosons, of course. There should be six of them, shouldn’t there? Just for parity with leptons and with quarks! Let’s have some equality around here. Well, there are—two more. One of them is the graviton (in theory mediating the force of gravity) and the Higgs boson. That last one is quite beyond me; evidently the Standard Model of particle interactions requires yet another particle that Higgs and others simultaneously proposed from the Standard Model math. Neither of these missing two have made themselves visible to science—although the graviton is alive and well in science fiction.

The interesting feature of the Standard Model for me—its absolutely fundamental underlying structural assumption—is that nothing happens in physical reality, nothing, without the mediation of some kind of particle. One of those shown above—plus the two that we’ve still not managed to capture in a bubble chamber. Gravity is the elephant in this room: it is the most commonly experienced aspect of physical reality—but its little magic mediator has remained entirely elusive. Therefore, of course, we also still lack a comprehensive Grand Unifying Theory (GUT).

Having refreshed my memories of the neutrino, tracing its family lineage, I planned to write a post and prominently feature John Updike’s wonderful poem, Cosmic Gall. Alas! Still copyrighted. Therefore I provide this link. But for the lazy I will herewith present something of my own. It arises from two urges that ever battle within me. One is a wonder at humanity’s scientific achievements; the other is a dark urge always to deny. The first urge tends on the whole to triumph—and here is why:

Beta-Decay Believer

In neutrinos I have faith
Otherwise I’d not be wise.
Appearing thinner than all wraiths

They seem to lack all size.

Even in their bubble chambers,

To be seen for a brief time,

To display what we call flavors,

They must collide with nuclei.

And particles that even poets
Like Mr. Updike sometimes tease,
Must surely be as sweet as suet,
Fly fast as lightning dipped in grease

Thus faster than Sir Albert’s light—

To cognoscenti’s consternation

And ordinary fools’ delight—

As news break of the demonstration

Of such-like heresies. Indeed,

I say, tomorrow it might be Okay   

To say that light can violate the speed

Limit that Einstein posted yesterday.

But to doubt neutrinos would be rash

For Richard Feynman is a man

With whom I’d never dream to clash.

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†Conseil Européen pour la Recherche Nucléaire
Picture credit is Wikipedia (link).