1. Quantum Mechanics for Beginners
— an introduction —
How the Princess began to Feel the Pea
Science is exciting because it is always in trouble. No matter how excellent a theory is, it always misses some point or other. Even our most precious ideas about the universe are not able to explain everything; there's always a blind spot. And when the hopeful folks zoom in on that blind spot it pretty much always turns out to be a lot larger than anybody thought, and all of us a mere bunch of naive beginners.
At the end of the eighteenth century the blind spot of regular mechanics (=the library of dogmas that teach the ins and outs of objects moving and colliding) covered the behavior of very small objects, such as electrons, and the behavior that light caused when it hit small things like electrons.
Light had been a mystery for centuries. Some experiments proved beyond the shadow of a doubt that light was waves. Some other experiments proved beyond the shadow of a doubt that light was particles. The truth about light was obviously hidden and it wasn't until 1900 that people began to understand that there was something very weird about the world of the small. Something that required a complete revision of understanding.
It was decided that the world of the very small was governed by rules that were different from the rules that governed the world we can see, and regular (or classical) mechanics begat Quantum Mechanics. And that unanticipated breach in mechanics spawned this very important rule:
Hold that thought (1)
Individual quantum particles are subjected to a completely different law than the law to which large objects made from quantum particles are subjected.
The introduction of the quantum
The Quantum Mechanical era commenced in 1900 when Max Planck postulated that everything is made up of little bits he called quanta (one quantum; two quanta). Matter had its quanta but also the forces that kept material objects together. Forces could only come in little steps at the time; there was no more such a thing as infinitely small.
Albert Einstein took matters further when he successfully described how light interacts with electrons but it wasn't until the 1920's that things began to fall together and some fundamental rules about the world of the small where wrought almost by pure thought. The men who mined these rules were the arch beginners of Quantum Mechanics, the Breakfast Club of the modern era.
Names like Pauli, Heisenberg, Schrödinger, Born, Rutherford and Bohr still put butterflies in the bellies of those of us who know what incredible work these boys — as most of them where in their twenties; they were rebels, most of them not even taken serious — achieved. They were Europeans, struck by the depression, huddled together on tiny attics peeking into a strange new world as once the twelve spies checked out the Promised Land. Let all due kudos abound.
Believing the unbelievable
One of the toughest obstacles the early Quantum Mechanics explorers had to overcome was their own beliefs in determinism. Because the world of the small is so different, people had to virtually reformat the system of logic that had brought them thus far. In order to understand nature they had to let go of their intuition and embrace a completely new way of thinking. The things they discovered where fundamental rules that just were and couldn't really be explained in terms of the large scale world. Just like water is wet and fire is hot, quantum particles display behavior that are inherent to them alone and can't be compared with any material object we can observe with the naked eye.
One of those fundamental rules is that everything is made up from little bits. Material objects are made up of particles, but also the forces that keep those objects together. Light, for instance, is besides that bright stuff which makes things visible, also a force (the so-called electromagnetic force) that keeps electrons tied to the nuclei of atoms, and atoms tied together to make molecules and finally objects. In Scriptures Jesus is often referred to as light, and most exegetes focus on the metaphorical value of these statements, but as we realize that all forms of matter are in fact 'solidified' light (energy, as in E=mc2) and the electromagnetic force holds all atoms together, the literal value of Paul's statement "and He is before all things, and in Him all things hold together" (Colossians 1:17) becomes quite compelling.
Particles are either so-called real particles, also known as fermions, or they are force particles, also known as bosons.
Quarks, which are fermions, are bound together by gluons, which are bosons. Quarks and gluons form nucleons, and nucleons bound together by gluons form the nuclei of atoms.
The electron, which is a fermion, is bound to the nucleus by photons, which are bosons. The whole shebang together forms atoms. Atoms form molecules. Molecules form objects.
Everything that we can see, from the most distant stars to the girl next door, or this computer you are staring at and yourself as well are made up from a mere 3 fermions and 9 bosons. The 3 fermions are Up-quark, Down-quark and the electron. The 9 bosons are 8 gluons and 1 photon. Like so:
|Quanta, which form →||Atoms, which form →||Molecules, which form →||Objects|
But the 3 fermions that make up our entire universe are not all there is. These 3 are the survivors of a large family of elementary particles and this family is now known as the Standard Model. What happened to the rest? Will they ever be revived?
We will learn more about the Standard Model a little further up. First we will take a look at what quantum particles are and in which weird world they live.
(If you plan to research these matters more we have written out the most common quantum phrases in a table for your convenience. Have a quick look at it so that you know where to find it in case you decide you need it).
Go to the next chapter:
Big Rules for Small Particles →
Summary 1: Quantum Mechanics for Beginners; an Introduction
- Everything is made up from little chunks called quanta.
- Small particles are completely different animals than large objects.
- The visible universe is made up of 3 fermions and 9 bosons (not counting gravity).
- The matter that makes up the visible universe is part of a larger family of particles called the Standard Model.