Quarks and Leptons and Bosons, Oh My!

The following is an article from the book Uncle John's Bathroom Reader Plunges Into the Universe.

Let's get really, really, really small...

In the fourth century B.C. a Greek named Democritus (known as the "laughing philosopher" because he was always making fun of people) proposed a theory of matter that remained uncontested well into the 19th century. (This was before he went mad and blinded himself with hot glass in an effort to heighten his intellectual acuity.)

Anyway, Democritus suggested that all matter is made up of tiny indestructible pieces that he named atomos, meaning undivided. Today it's known that atoms can certainly be broken up into subatomic particles, and those particles can be broken into more particles, and so on. (Image credit: Flickr user edgeplot)


For about 2,200 years, scientists were happy enough with the idea that matter was made up of atoms. This all changed in 1886 when E. Goldstein discovered the positively charged particle that he named "proton", after the Greek root proto, meaning "first", since it was the first subatomic particle ever to be discovered.

Shortly after that, in 1897, the English physicist J.J. Thomson (who also only used his initials -is it some sort of club?) discovered negatively charged particles that he called "corpuscles," which today are known as electrons.

In 1932, English scientist Sir James Chadwick (finally, a man with a real name!) discovered the neutron, the subatomic particle that lacks a charge.


Of course, scientists were not content to stop at having three subatomic particles -they're funny that way- so they feverishly looked for more. And sure enough, by splitting a proton or a neutron, smaller subatomic particle were created. These particle were named "quarks" in 1964 by scientist Murray Gell-Mann, who got the name from the following quote in James Joyce's 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."

(Image credit: Wikimedia user MissMJ)

The names of the six "flavors," or types of quarks, are more down to earth. They are: up, down, strange, charmed, top, and bottom.Two "up" quarks and one "down" quark make a proton, and two "down" quarks and one "up" quark make a neutron.


In the world of science, you are either an elementary particle or you are a hadron. An elementary particle is one that can't be broken down (yet) into smaller particles. Scientists refer to elementary particles as "fundamental." There are three types of elementary particles: quarks, leptons, and bosons. hadrons are made of quarks and therefore are not fundamental. Got it?


(Image credit: The NeatoShop)

The fundamental members of the boson family include photons, gravitons, and gluons. Photons are little packets of electromagnetic radiation, that is, light; gravitons are presumed to be responsible for gravitational force; and gluons are responsible (you may have guessed this one) gluing and holding together other fundamental particles that comprise hadrons.

The most famous lepton is the electron, from which we get electricity. The other members are the muon (pronounced mew-on, like a cat), tau, electron neutrino, muon neutrino, and tau neautrino. Whew!


There are two main families of hadrons: the baryons and the mesons. Protons and neutrons are part of the baryon family. In the meson family there are several hadrons named mostly after the Greek alphabet (a grudging nod to the laughing philosopher) such as omega, eta, chi, and psi. Mesons are also made up of various combinations of quarks. (Image credit: Wikimedia user Army1987)


How can a teensy-weensy particle be split, anyway? This is not a dumb question. The answer is by using a particle accelerator, of course. A particle accelerator shoots a beam of particles through a closed track. These high-energy beams, along with powerful magnets, cause the particles to move along almost as fast as the speed of light. When the particles finally reach top speed, they're slammed into another particle, causing them to break apart into pieces- thus creating new particles that scientists can thn name with one of those "on" endings.

There are particle accelerators everywhere (really!), but the largest, called Tevatron, is over four miles (6.4 km) long and can be found at Fermilab in Batavia, Illinois. [Ed: since this book was published, the CERN Large Hadron Collider opened as the largest particle accelerator in the world, at 17 miles (27km) in length.]


In addition to all the particles that make up matter, there also exists particles of antimatter. For instance, the antiparticle of the negatively charged electron would be a similar particle with a positive charge, called a positron. There are also antiprotons, antineautrons, and anti almost anything else (thought there don't seem to be any antiphotons, but what do you want to bet they turn up someday?). Antimatter was predicted in 1928 by physicist Paul Durac and later confirmed in 1932.

Matter and antimatter are thought to destroy each other, and scientists believe the universe existing today is made from the remnants of excess matter that was not annihilated by its antimatter counterpart. A stroke of luck for us!


It's invisible. It makes up at least 90 percent of the universe. It is... drum roll, please ...dark matter.

See, scientists are still trying to explain the theory that the universe is constantly expanding. If it continues to expand, then there must be a lot of unseen stuff that comprises it. Enter the concept of dark matter.

There are several types of dark matter. And it's here that you begin to notice, hey, scientists are getting much better at naming things. MACHO, for instance, stands for MAssive Compact Halo Object. Scientists witness this form of dark matter by observing the halos that surround stars. WIMP stands for Weakly Interactive Massive Particles, which have yet to actually be discovered but are thought to be the skinny guys at the beach who have sand kicked at them by the MACHO dark matter. There's also hot and cold dark matter, so named for how fast the particles move (the hot ones move faster), and neutrinos, which are the most prolific particles: one billion exist for every single proton and electron.


The article above was reprinted with permission from Uncle John's Bathroom Reader Plunges Into the Universe.

Since 1988, the Bathroom Reader Institute had published a series of popular books containing irresistible bits of trivia and obscure yet fascinating facts.

If you like Neatorama, you'll love the Bathroom Reader Institute's books - go ahead and check 'em out!

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There are several things wrong with the science here. All the stuff on dark matter is very wrong. The masses of the quarks are not known nearly as precisely as they are in that table. There's the antiphoton thing that James White mentioned. And you don't get quarks by splitting protons and neutrons - quarks are never observed alone, only as parts of mesons and baryons.
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Antiphotons will never exist. Or they always have. An antiparticle is just the same particle with the opposite charge on it - a negative charge instead of a positive, or vice versa. Photons (as well as gluons and a few other force-carriers) are electrically neutral. And I'm sure we can agree that -0 is the same as +0, so an antiphoton is the same thing as a photon.

"splitting a proton or a neutron" - it's not quite as simple as that, as quarks cannot exist on their own, but that's perhaps a chat for another day...
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