...1940's.
Lawrence's 184 inch Cyclotron, the biggest synchrocyclotron ever built, was originally conceived as a giant mass spectrometer for separating the isotopes of uranium for the first fission bomb; however, a far more efficient method was invented soon after it was built, and ``the 184'' went into service as a pion and muon producer. Many Ph.D. theses (including my own in 1972) were written on experiments performed at the 184 until it was dismantled in the 1980's to make room for the world's most intense Synchrotron Light Source on the same site at what has been called the Lawrence Berkeley Laboratory (LBL) since the end of the 1960's. [Before that it was called the Lawrence Radiation Laboratory (LRL); the name was changed partly to avoid association with the other LRL branch in Livermore (now known as LLL, the Lawrence Livermore Laboratory) where weapons research is conducted, and psrtly to expunge that fearsome word ``Radiation.'' It is still know as ``the Rad Lab'' to Berkeleyans.]
...femtoseconds.
I refer, of course, to the `` big bang'' scenario, which is almost universally regarded as the best model of cosmogony [a fancy word for Creation].
...field.
Just to give a hint of how this works, "psi" is now composed of some complex exponential wave functions multiplied by creation and annihilation operators that respectively increase and decrease the number of particles of that species by one. The creation and annihilation operators obey an algebra that corresponds to the statistical properties of the particle - e.g. for fermions no two can be in the same state. I will resist the temptation to show any of the equations, which are actually very compact but (as one might expect) have an extremely high ``interpretation density.''
...rays,
Muons are the main component of cosmic rays that make it to the Earth's surface - all the more strongly interacting particles are absorbed or re-scattered in the atmosphere, which makes a pretty good shield. In fact, if you take a transcontinental trip at 30,000 feet altitude, you pick up about 50 mR of ionizing radiation from cosmic rays that are not absorbed because you are above most of the shield! Recall the Radiation Hazards handout.
...strongly).
In case you wondered, I am skipping over a lot of agonizing reevaluation and painstaking experiments that led to the discoveries that justify using the ``modern'' names for all these particles; the muon was called a ``mesotron'' for years and is still sometimes referred to as a ``mu meson'' in Russia. But why sacrifice simplicity for mere historical accuracy?
...pairs.
I haven't bothered to label all the particles; see if you can find any violations of local conservation laws.
...recently
Well, it seems recent to me!
...lifetime.
This theory now forms the core of what is known as `` the Standard Model'' of elementary particles - a name which reveals a certain disaffection, since no one is particularly excited at the prospect of serving the Establishment prejudices connoted by a ``standard model.'' Particle physicists, like most free thinkers, prefer to think of themselves as romantic revolutionaries challenging established conventions and ``standard models'' everywhere. Not surprisingly, a great deal of experimental effort goes into ``tests of the Standard Model'' which the experimenters openly hope will throw a monkey wrench into the works.
...again.
There is an even more dramatic consequence in the neighbourhood of a very small black hole whose tidal forces (the gradient of the gravitational field between one place and another) is so intense that one of the virtual particles of a pair can fall into the black hole while the other is ejected and becomes a ``real'' particle - leading to intense radiation that can be described as the explosive annihilation of the miniature black hole. This explains why there are no small black holes around any more, only big ones whose gravitational gradient is very gentle at the Schwartzschild radius. [Recall discussions on general relativity.]
...``superweak''
The ``superweak'' force is a name coined to describe a really esoteric interaction which appears to affect only the decays of strange neutral mesons (if it exists at all).
...matter.
Neutral particles either convert into charged particles (which do ionize the medium) or else are conspicuous in their invisibility!
...light.
One example is old-fashioned ``moth balls'' - if you take a handful of mothballs into a very dark closet (you must get rid of all ambient light!) and wait for your eyes to adjust, you should be able to see tiny flashes of light every few seconds as cosmic ray muons zap the mothballs. There are many apocryphal stories about graduate students in closets with mothballs and manual counters in the early days of nuclear physics....
...chamber.
Probably this was a bar frequented by many HEP types, so such behaviour went unremarked.
...first.
If you have access to a microwave oven, you can observe this effect for yourself: take a cup of cold water and slowly increase the cooking time (replacing it with new cold water each time) until it is just starting to boil as the timer runs out. Then do one more with a slightly decreased cooking time, take out the cup and drop in a few grains of sugar or salt - the dissolved gases will abruptly come out of solution around these ``nucleation centres'' to make a stream of bubbles for a short time.
...information;
For decades, HEP has ``driven'' the leading edge of supercomputer hardware and software development. Today's computing environment is rapidly becoming more driven by the personal workstation, which is probably a more healthy arrangement, but it is certainly true that we would not have the computer technology we do without the demand created by HEP from about 1950 to about 1980.
...number.
It just barely makes it, mass-wise, which partly accounts for the slowness of the decay.
...photon?
As a matter of fact, this is still an open question - experiments have recently pushed the upper limit on the ``branching ratio'' for radiative muon decay (i.e. the fraction of the time muons decay into electrons and photons) to less than one part in ??? and more experiments are underway, because several theories demand that such ``flavour-violating'' decays must exist at some level.
...flavour
No, I'm not kidding, the official name for the difference between muons and electrons (and, later on, tau leptons) is ``lepton flavour.''
...sentence.
Kirk: ``Boy, this particle sure looks strange.'' Spock: ``Not at all, Captain. If you look more closely, I believe you'll find it's charmed.''
...shape!
The shapes are a little crooked in this representation. The hypercharge Y and isospin I (whose ``projection'' I3 along some ``axis'' in ``isospace'' is the same as its charge Q, within a constant) were invented partly to make the diagrams nicely symmetric with the origin at the centre of each arrangement. I haven't bothered.
...dimensions
Honest, we don't have the faintest idea whether there is actually some space in which isospin actually refers to rotations about some axis, we only know that isospin transforms that way. If there is such a space, none of its dimensions are our familiar x, y or z directions. Very weird.
...quarks.''
See James Joyce's Finnegan's Wake for the origin of the term ``quark'' - it was originally a nonsense syllable, which makes it a pretty good choice for its present application. At least the commandeering of the word ``quark'' by particle physics did not inconvenience any users of the English language.
...miserably.
Unfortunatly, the genuinely new paradigms that were springing up to deal with this crisis (Geoffrey Chew's bootstrap theory, in which each hadron is composed of small amounts of all the others [think about it!]) have been neglected since the development of QCD.
...mathematics,
Of course, energy is ``just a cute mnemonic metaphor for some esoteric mathematics,'' if we think back to classical mechanics; but we have gotten so used to energy that we don't think of it that way any more, whereas quarks are still... well, weird.
...versa.
The SUSY partner of the photon is the photino, the SUSY partner of the graviton is the gravitino, the SUSY partner of the W boson is (I am not making this up!) the wino, and so on. This is not a joke, but no one knows if it is ``real'' either. That is, we do not yet know if Nature contains phenomena for which there is no other known explanation.
...debates).
My personal opinion is that such extravagant claims miss the point of Physics almost entirely - we know that the ordinary properties of solids are governed completely by QED, the most perfectly understood physical theory in the history of humanity, but we are still discovering unexpected qualitative behaviour of solids as we explore the seemingly endless variety of ways that large numbers of simple units (like electrons) can interact collectively with other simple units (like phonons or positive ions). To understand the components out of which things are built is not the same as understanding the things! So-called ``naive Reductionism'' is alive and well in certain overly arrogant elementary particle physicists....