The Quantum Theory.
The elements of the quantum theory are as follows
-energy is not continues as in every day life, but comes in small quntasized amounts.
-the subatomic particles, have both particle and wave characteristics.
-it is not possible to know definitely two items of information about a particle, for example, its position and momentum. This is known as the Heisenberg Uncertainty principle.
Part 1: Particle wave duality.
As stated in the quantum theory, the subatomic particles have both particle and wave characteristics. While in the real world, objects do have a wave function it is much less obvious. It is not only subatomic particles that do display noticeable wave/particle duality, as stated above energy is not continues but comes in small quantisized amounts. Light, for example comes in light quanta or photons. We will study this in more detail later. 
Part 2: The Atom
Above is Bohr’s model of the Hydrogen atom. Here we see two of the general fundamental particles. Secondary Schools worldwide sell the Bohr structure as the protons and the neutrons in the nucleus and the electrons ‘orbiting’ the nucleus. In reality though, it is much more complex. The hydrogen atom is the most basic atom. Most atoms have two kinds of nucleons: the proton and the neutron. The Hydrogen atom on the other hand, has only one proton.
T 6s 4f, 5d 6p n=6 5s 4d 5p n=5 4s 3d 4p n=4 3s 3p n=3 2s 2p n=2 1s n=1
he main problem with the Bohr model is that the electron has a negative charge and the proton, a positive charge. We will now use an analogy with magnets. A magnet has two poles, a north and as south. When you bring a magnet’s South Pole far enough inside the magnetic field on the northof a magnet they attract and come together.
It is the same for electrons and protons. The electron with its negative charge should be pulled into the nucleus, but it is not. Why? To explain this we must investigate the properties of the electron. Because of the Uncertainty principle, electrons never have zero energy. They also have a property, of angular momentum or ‘spin’. If you have a copy of the Periodic table, you will see on the side the notations ‘n=1, n=2…’ ‘n’ numbers are the energy states. The ‘n=1’ energy state being the lowest energy level.
The spin of the electron is permitted by the uncertainty principle, but is subject to rules. No two electrons may have the same spin. To understand this look at the table at the side. Each section has room for two electrons. This explains why hydrogen bonds with oxygen. With its n=1, 1s state, it has room for two electrons.
Part 3: Schrödinger’s Cat and the Double Slit experiment.
We shall now investigate in further detail the uncertainty principle through an experiment: the double slit experiment.
Take a room with a wall with two slits in it,(note to carry out this experiment in reality would be a lot harder than explained here, assume that the scene may differ from experiment to experiment). Behind it, detector, the detector differs from experiment to experiment.
First, we use a machine gun. We spray the wall in the general area of the slits with bullets. Most land in the middle, others around, and the rest go through the slits. The amount that goes through both slits is in round figures the same. Nothing odd here.
Now close one of the slits, the right one, lets say. The amount that goes through is approximately the same, on the left slit. Again nothing new.
Now try it with water waves. With one slit closed the result is the same as with the bullets. With both slits open you get a wavy pattern. The wave in the centre being larger than what was there with one slit open. That does not surprise us. Everyone has scene the effect of two stones thrown in a pool or pond.
Now with electrons. Try the experiment with one slit open and then the other. The results are the same as with the bullets. Now try both slits open. It’s the same as with the waves! Well, we can’t let an electron defeat us! It seems we have an interference pattern.
This means that the electron has split in half. We’ll only let out one electron at a time and go behind the slit to see where it goes. It only seems to go through one slit!
Well Newton said that to calculate where any particle in the universe is going to go, all you need to do is calculate the position and momentum. So we can see which slit the electron will go through, right? Well an electron is a tiny particle, you need light of a long wavelength to measure its position, but you need light of short wavelength to measure it’s speed. Without speed, you cannot have velocity, and without velocity you can’t have wavelength.
So it seems that Electrons are waves and particles, and when we observe them they are particles, yet when we don’t they are waves. We can’t tell what they are doing without viewing them. That is the collapse of the wave function. Nowhere is this seen more than in the Schrödinger’s cat experiment.
Take a cat in a box with a jar of cyanide some radioactive material and a Geiger counter. When the radioactive material decays the Geiger counter senses it crushes the jar and the cat dies. Well the radioactive material is set so that there is a fifty/fifty chance that it will decay, will it or won’t it? If the material decays the cat dies, if it doesn’t the cat lives. Yet unless we open the box we don’t know. That is when we collapse the wave function, and the cat is dead or alive, so until we know the cat is dead and alive.
From this we get questions. Can the cat be an observer? Can it collapse the wave function itself? Well to explain it comes the Many Worlds Theory or Multiverse Theory.
Akin to the parallel universe of sci-fi, it means that when an electron can go in more than one direction it goes in each, but to do that it creates new universes. So in the double slit experiment when we observed the electron only going through one slit, it went through the other but in a different universe.
