|
The Four Interactions
The
universe, which we know and love, exists because the fundamental particles
interact. |
|
Any
force you can think of -- friction, magnetism, gravity, nuclear decay,
What's the difference between a force and an interaction? This is a hard distinction to make. A force is the effect on a particle due to the presence of other particles. The interactions of a particle include all the forces that affect it, but also include decays and annihilations that the particle might go through. The reason this gets confusing is that most people, even most physicists, usually use "force" and "interaction" interchangeably, although "interaction" is more correct. |
|
Quarks are one type of matter particle. Most of the matter we see around us is made from protons and neutrons, which are composed of quarks. There are six quarks, but physicists usually talk about them in terms of three pairs: up/down, charm/strange, top/bottom. For each of these quarks, there is corresponding antiquark.
|
|
|
Quarks have the unusual characteristic of having a fractional electric charge, unlike the proton and electron, which have integer charges of +1 and -1 respectively. Quarks also carry another type of charge called color charge. |
| How
do matter particles interact ? How do two magnets "feel" each other's presence and attract or repel accordingly? How does the sun attract the earth? We know the answers to these questions are "magnetism" and "gravity," What
are these forces? "How
can two objects affect one another without touching?" |
 |
| Force carriers is a particular force carrier particle can only be absorbed or produced by a matter particle which is affected by that particular force. For instance, electrons and protons have electric charge, so they can produce and absorb the electromagnetic force carrier, the photon. Neutrinos, on the other hand, have no electric charge, so they cannot absorb or produce photons. |
 |
 |
|
|
