The four forces of nature

There are four known forces. There would be five but Maxwell unified electricity and magnetism, (~1850) when he published his four famous equations. The bonus was an explanation for the behavior of light, and a calculated value for the speed of light in a vacuum.

Today some physicists are trying to combine all of the forces into one force with four forms, described with one set of equations. We are not able to do that yet but success would yield a unified field theory.

Gravity holds galaxies and stars together. It is the weakest of the forces, but affects us directly.

Electric and magnetic forces are linked. A moving magnet may give rise to an electric current and a moving electric charge possesses a magnetic field

The strong force acts between hadrons and holds the nucleus together. It has a very short range of about 10^-15 meters.

The weak interaction is the force that controls beta decay. It is about one ten thousandth the strength within the nucleus of the strong force.

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