Particle Physics

Introduction

Particle physics is the study of the subatomic, microscopic particles that make up the universe, both at the elementary (unable to be split further) and composite (made up of smaller particles) levels. At this scale, quantum mechanics comes into effect, meaning some very strange things happen. Because the scales involved are so small, huge detectors are needed to give massive amounts of energy to these tiny subatomic particles, which are then collided together. The results of these collisions give hints into the correct theory that describes nature.

The Standard Model

The main problem of particle physics is in combining all of the fundamental forces of nature into a single, unifying theory, which can describe all interactions between particles.

The four fundamental forces are: gravity, electromagnetism, the weak nuclear force and the strong nuclear force.

There are four fundamental forces in nature (as currently understood). Each one has a different relative range and strength. This means that at extremely long ranges such as planets and galaxies, physics is dominated by the long-range force of gravity, despite its relative weakness, whilst at the subatomic scales, it is electromagnetism, the weak and the strong forces that dominate interactions.

It is because gravity is irrelevant for the small scales that particle physics is concerned with that it can safely be ignored, because our instruments just aren't good enough to be able to detect the tiny tiny difference that gravity would make.

Gravity Electromagnetism Weak Nuclear Force Strong Nuclear Force
Strength Extremely weak Strong Weak Extremely strong
Range Long Long Short Short
Theory General Relativity Quantum Electrodynamics Electroweak Theory Quantum Chromodynamics

The Standard Model of particle physics is the combination of three of the four fundamental forces (ignoring gravity): electromagnetism, weak force and strong force. It is one of the most successful theories in the history of physics, and there have been no experiments so far that contradict it.

See Also