Fog

Scattering of radiation by an electron

An observer in the Universe would not have been able to see very far. Photons of radiation could not travel very far before they hit an electron. The photon would bounce off the electron and move away in a different direction. This process is called scattering, and it prevented the radiation from travelling very far.

The result was that the young Universe was foggy.

Electric Charge

As the Universe expanded and cooled the particles moved slower. They began to feel an electric force pulling them towards each other. The electrons carried something called a negative electric charge. Protons on the other hand carried a positive electric charge. These opposite charges attracted, pulling the particles towards each other.

Electric Charge

An electric charge has an electric field around it. This field can create a force on another electric charge which enters it. This is how a proton attracts an electron to create an atom.

A changing magnetic field can create an electric field. Likewise, when an electric field changes, it creates a magnetic field. This is how radiation is created.

There are two kinds of electrical charge, called "positive" and "negative". The force produced by an electric field when two charges meet depends on what type of charge they are.

If the two charges are both the same then the force between them is repulsive. We say "like charges repel". But if the two charges are different, one positive and the other negative, then they attract. We say "opposites attract".