Wednesday, 18 February 2015
THE FOUR FORCES
There's four different kinds of fundamental forces, but as we will see later some of them have been unified and it's thought that they are all the same force only in different "modes", but for the sake of simplicity we will first talk about them as different forces.
I'm just going tell you the different between: fermions and bosons and about virtual particles
FERMIONS AND BOSONS AND ABOUT REAL AND VIRTUAL PARTICLES
Bosons are the particles which transmits the different forces between the matter particles, they normally have a whole number spin, 0, 1 or 2. And Fermions which are matter particles they often have spin ½. Real particles are the ones you are familiar with, all Fermions are real particles. The Bosons can sometimes be virtual and sometimes real. Virtual particles are the particles which transmits the force between the particles, e.g virtual photon carries the electromagnetic force between e.g electrons. They are called virtual particles because they can't be directly detected, you can't 'see' them so to speak. But their effect can be noticed, by e.g the actual forces between particles.
The four forces are: the electromagnetic force, the weak nuclear force, the strong nuclear force, and gravity.
THE ELECTROMAGNETIC FORCE
The electromagnetic force affects particles that have electric charge such as protons and electrons. this is the force that enables atoms to form by the electromagnetic attraction between the protons and the electrons which binds them together in atoms, kind of like gravity makes the earth and the other planets orbit around the sun. The forces have an infinite range. The particle that transmits the force is the virtual photons.
THE STRONG NUCLEAR FORCE
The strong nuclear force affects the quarks. the quarks have different colours, and different collared quarks attract each so they join together in protons and neutrons and protons and neutrons(or more precisely the quarks in the protons and neutrons, since the strong force only affects quarks) together in a nucleus. The carrier particle is the gluon(from the English word glue since it binds quarks together). This force is very short ranged.
THE WEAK NUCLEAR FORCE
This force is responsible for various kinds of radioactive decay. And it changes the flavour of particles. Its' force carriers are Z and W bosons.
THE GRAVITATIONAL FORCE
The gravitational force is different from the other forces for three main reasons. All the other forces affect only certain particles such as electron of quarks. But Gravity affect all different particles. And it's very weak, the weakest of all forces. But it makes this up by having, as the electromagnetic force, an infinite range and also the force can only be attractive( meaning that it can only pull things towards it). this has the implication that different gravitational sources can only add up to create a bigger source. This is different from the other forces which can be both attractive and repelling, so they can also reinforce each other to create a bigger force, but they can also cancel each other out making a weaker force.
THE UNIFICATION OF FORCES
It has been found that all the forces is really the same force but only in different 'modes'. To understand this you have to know about something called quantum foam, and virtual particles:
Quantum mechanics says that on the atomic level, your knowledge is limited. This means that you want to know more about one thing, you have to loose knowledge about another thing. This weighing also occur with energy and time. If you want to know the energy level of something better, you'll have to measure it under a longer time. This has the effect that energy levels can fluctuate up and down and the shorter time span the higher the fluctuations. So this means that particle(energy) can pop in and out of existence, and the shorter the time they exist, the higher energy they can have. So all around us particles come into existence and disappear. These particles are virtual, so as said above we can't detect them directly, but we can se the consequence of their energy.
This quantum feature affects the different forces. If we start with the electromagnetic and gravitational force.
The strength of those two forces gets weaker, the further away from the source you are. This can be understood, if you think about the carrier particle. The carrier particle is surrounded by all these virtual particles which disturbs and block out the force which the particle is transmitting. And the closer you get the less virtual particles is there in the way to block out the force, so therefore it should get stronger the closer you get.
The strong and weak force on the contrary gets stronger the further away you get from the source. the somehow use the virtual particles to strengthen their force, and the more particles in the way the stronger the forces gets.
So we have one force which grows at smaller distances and two which gets weaker. First we must remember that the electromagnetic and gravitational force is normally very weak forces and the strong and weak forces normally are very strong. Then it has been discovered that there's one levels(as we go to smaller and smaller levels the electromagnetc and gravitational force gets stronger and the weak and strong force get weaker) where the electromagnetic force should have gotten so strong, and the weak and strong forces have gotten so weak, that they all behave as the same force. But these small scales requires allot of energy, before they can make a difference. Therefore it requires very high temperatures before the forces start to act like one. Temperatures high as the temperature in the beginning of the universe. And it seems like all forces where one and the same in the beginning of the universe. But then as everything cooled of, they branched of one by one to create the different forces we see today.
But on second thought it should be said that they become almost as the same force but not quite.
For them to act as exactly the same force requires something called supersymmetry. supersymmetry means, that for every particle from one of the matter or force family, there is a corresponding particle from the other family but with half(½) a spin different. The problem is that for supersymmetry to work we have to have a hell of a lot more particles, since every particle at the moment doesn't have a symmetry partner.