Carnival of the
© 2007 N. David Mermin
I. Everything is made of Atoms
Democritus, an ancient Greek
Philosopher, once tried to seek
The answer to a vexing riddle:
Break a stick right down the middle,
Giving you two little sticks.
Now, if you enjoy such tricks,
Then repeat the whole procedure
With one small stick. You may need your
Sharpest knife to make the slice,
But now you will have done it twice!
Will the process never cease?
Or must there be a smallest piece
Which can't be cut up into pieces,
At which point the cutting ceases?
Atoms are that smallest part,
Beyond which point the cutter's art
No longer functions. So taught us
That ancient Greek: Democritus.
II. But there are things inside Atoms
But I have always found it risible
To call the Atom indivisible,
When deep inside all Atoms lie
Their very tiny Nuclei,
Containing almost all the mass,
Surrounded by a foggy gas:
Electrons! We should all be proud
How much we know about that cloud,
Whose properties were once a mystery
But now belong to science history:
An explanation full and blemish-free
That underlies the whole of chemistry.
III. And things inside the Nucleus
And yet the story's even richer.
Within the Nucleus we picture
Nucleons: still smaller particles,
About which I could write whole articles.
But let it here suffice to say
The two varieties that they
Possess. (1) Protons with a charge
Of electricity just large
Enough to hold Electrons in
Those clouds in which they whirl and spin.
(2) Neutrons: uncharged partners of
The Protons, held to them as love
Binds lovers in their warm embrace,
But bound by Mesons in this case.
What could be to God's greater glory?
And yet there's much more to the story!
IV. And things inside the Nucleons!
The Nucleons themselves have pieces
Described in many a doctor's thesis.
The Standard Model is the name
Of this subnucleonic game.
It underlies the interplay
Of everything. And so, I say:
Enough of idle talk and twaddle:
Let's celebrate the Standard Model!
THE STANDARD MODEL
The Up and Down Quarks are the units
That make both Nucleons behave
In just the manner that they do. It's
Extremely simple. Note that they've
Both got inside them smaller pieces.
For Nucleons are like valises,
Each stuffed with Quarks. We now agree
A Nucleon is made of three
Internal Quarks. Quite elementary:
The Protons are two Ups, one Down
All bound together like a crown;
In Nature’s book another entry:
Neutrons are two
Together, in a single cup.
The Protons all have just one unit
Of charge, electrical. Although
The Neutrons lack charge -- yes they do! (It
Permits them easily to flow
Through crystals.) But this neat arrangement
Requires some genuine estrangement
From common notions. Thus, the charge
Of Up Quarks isn't very large:
Only two-thirds the normal portion
That one expects a charge to be.
What's more, the Down Quark, cunningly,
Has just one-third. And here's a caution:
Up and Down charges, that combine,
Are furnished with a different sign.
So Up-Down-Down has full charge zero
While Up-Up-Down has full charge one.
It doesn't take a super hero
To realize the job's now done.
The tripling has been quite delightful:
The Proton’s charge is just its rightful
Amount. The other way Quarks fall
The Neutron gets no charge at all.
Next you may ask what is the tether
That holds these trios in one place?
Instead of wandering through space
What makes three Quarks remain together?
The Gluons! Gluons do the job
Of making Quarks a single blob.
The way in which the Gluons tie in
A group of Quarks to just one place
Deserves a mention very high in
Examples of a strong embrace.
For if you try to tear asunder
Three Quarks you make a real blunder:
You'll find the harder that you try,
The stronger bond the Gluons tie.
For Gluons bear the strict assignment
Not to let single Quarks appear.
I have to make that very clear.
This property is called Confinement.
However much you try to free
A single Quark, it cannot be.
Each Nucleon's a three-Quark triple
But there's another little stipul-
Ation that has acquired renown:
For you should know that Quarks have color,
Although to make the story duller,
It's not the kind that you can see
But just a form of poetry.
The colors don’t come in profusion.
One Quark is Red, one Green, one Blue.
That's all there is. I'm telling you
To ward off possible confusion.
And here's a final piece of news:
The anti-Quarks have anti-hues.
The anti-Red-Quark, for example,
Has to be colored anti-Red.
Likewise, I'm sure it wouldn't trample
The preconceptions in your head
To learn the hue of anti-Blue-Quarks
Is anti-Blue. And like all true Quarks
The anti-Green-Quark has to mean
A Quark that's colored anti-Green.
Now here's a rule that's quite delicious:
The Red and Green and Blue make White.
The color's disappeared, alright.
And though it may not sound propitious
When color, anti-color play
All of the color goes away.
All particles are colored purely
Neutral if they're directly seen.
In Nucleons the three Quarks surely
Must then be Red, and Blue, and Green.
Another way that's somewhat duller
To make up something lacking color
Directly puts together two
Paired Quarks of hue and anti-hue.
In just this way one makes a Meson,
Like Pion, Eta, Kaon,
And others ones you might not know
Unless you have a special reason.
Only the parts have color. Yes,
The things we see are colorless.
Now Up and Down are not the only
Varieties that Quarks possess.
In case you worried they'd be lonely,
You needn't fear. For I confess
There are two other generations
That furnish Quarkish explanations
Of why there is so big a zoo.
Each generation comes with two
Fine Quarkish partners. One pair's Charméd
And Strange. The other's Bottom, Top.
This makes you wonder, will it stop?
No problem. Do not be alarméd!
There's nothing else we have to fix.
The Quarkish flavors stop at six.
You may remember that I've spoken
About Electrons, tiny things.
They too have partners (I'm not jokin'!)
That fly about as though on wings.
Neutrinos have the smallest masses
Of all the fundamental classes
Of particles. As I recall.
They've hardly any mass at all.
Through endless ranks of rocks and boulder
At speeds approaching that of light
They pass unhindered in their flight.
There's almost nothing that can shoulder
Those swift Neutrinos off their path.
We live in a Neutrino bath!
Here too things come in generations.
A heavy 'lectron called the Mu
Is one of God's more strange creations.
And has its own Neutrino, too.
A third Neutrino fills the picture.
Following a familiar stricture,
Which surely isn't broken now,
Its partner's the still heavier Tau.
Electron, Mu, and Tau along with
All their Neutrinos, commonly
Are known as Leptons. These make three
New generations that belong with
The three Quark pairs. The same format!
Well might one ask “Who ordered that?"
A flavor changing transmutation
Is called a weak decay. And there's
Accompanying it the swift creation
Of Lepton-Antilepton pairs.
The Down- to Up-Quark weak transition
-- Beta decay (from old tradition) --
Creates Electrons, moving fast,
And Antineutrinos in the blast.
This is the way that Neutrons trouble you,
Turning to Protons with the aid
Of two assistants, that are made
Of new gauge fields. Called Z and W
They're massive cousins to a sprite:
The massless Photon, speck of light.
Behold the Higgs! The most elusive
Of particles, I do insist.
Not yet observed, we lack conclusive
Data to show that they exist.
Without the Higgs there'd be no masses
Creating some grotesque impasses.
This means within our Standard tale
The Higgs's the crucial Holy Grail.
Please do not doubt the Higgs' reality.
We're hoping very soon to learn
From evidence produced at CERN
That it exists, with clear finality.
So don't forget: the Higgs's the thing
That makes the Standard Model King.
EPILOGUE: THE HYDROGEN ATOM
Democritus had not a notion
Hydrogen in ancient
Much less an inkling of the motion
Within its Atom, without cease.
But we, today, know that there's really
A swift Electron, moving freely
Around three Quarks, of different hue
All bound by Gluons' cosmic glue.
If you were ever once afraid of
Not understanding Nature's ways,
Here it unfolds, beneath your gaze.
These are such stuff as dreams are made of.
See how the Quarks and Gluons prance!
Behold their magic as they dance!