PRESENTACIÓN Quantum Electrodynamic

QUANTUM ELECTRODYNAMICS

QED

By Carlos Ramón | Class 3

CONTENTS

about it

background

feynman diagrams

history

background

QUANTUM PHYSICS

Quantum physics was born by 1900's, when they thought everythig was discovered and suddenly some theories of waves at highs frequencies failed at the attemp. Max Planck reliased that light is made of little quantum packs and that's the origin of the name. Time by time, physicists found out new theories inside this big one which explained different parts of mattery as the forces behind the atom nucleus (Quantum Chromodynamics) or another two forces which are Strong Nuclear Force and Weak Nuclear Force. The last force is electromagnetism.

More background

Quantum Field Theory

Quantum Field Theory is probably the most detailed theory ever. It can explain the Standard Model with with just a simple concept. They are the famous quantum fields, each one responsible of creating a new particle, which is a wave on this field. The problem with this theory is that behind this great simple concept, everything follows quantum rules: the uncertaintly principle and quantum overlapping.

The electromagnetic field is the one important for QED. There is where it surfs photons and their interactions happen. So, lets focus on that.

What's Quantum Electrodynamics

Quantum Electrodynamics is the theory that describes the behavior of photons and their interactions on a quantum field called the electromagnetic field.

This theory is so important because it allows us to understand the fundamental nature of light, which is nothing more than a disturb on the electric and magnetic field at the same time, thing that makes a wave.

On this field, there are photons and electrons, which, obviously, can move around it. Electrons and photons act each one to the other, so there are two probable interactions: -Electron absorbs a photon. -Electron spits out a photon. By this way, the interactions of a particle inside a mess with lots of elements more with charge make this theory so difficult. And, adding to that, this fields are not classical but are quantum, so there are lots of different ways that each particle is going on at the same time, and, of course, interacting simultaneously.

HISTORY

Later, it appeared some scientist who tried to develop this thory based on Dirac's pillars. But experimentally, this mathematical concepts failed so they refixed the theory with the Renormalization. With that, it appeared Richard Feynman, who developed this theory in terms of integrals and looked into the theory with another point of vision. But, then, it was demostrated that the two points were the same.

There are two important people in this theory, in brief. Paul Direc made fundamental bases of this theory resolving a problem of radiation in the atom nucleus. This problem was about photons and electrons, so it was clearly a beginning of this theory.

Feynman Diagrams

Feynman diagrams is a thechnique used to describe electromagnetic processes. The electron with a photon comes and spits out a photon. The energy expelled make the electron goes back. In another way, an electron without a photon comes and absorbs the photon, going back by the energy it has already gained. This is the most simple one, there are more complex ones with lots of photons, electrons and, of course, quantum rules.

THANKS FOR LISTENING

By Carlos Ramón | Class 3