The Four Fundamental Forces

The properties of the four fundamental forces are summarised in the following table.

 

 

 

Mediating Particle

Force

Relative Strength

Range

Name

Mass

Charge

Spin

Strong

1

Short

Gluon

0?

0

1

Electromagnetic

Infinite

Photon

0

0

1

Weak

Short

80.4, 80.4, 91.2 resp

1

Gravity

Infinite

Graviton

0

0

2

There are several things to note:

Both gravity and the electromagnetic force have infinite range. The mediating particle of both these forces are stable and do not decay spantaneously. This means that the flux of the force particles through a sphere drawn around the source of the force is a constant no matter how big the sphere, and this implies the force must obey alaw.

The weak force is mediated by massive particles. We may find the approximate range of the weak force using Heisenberg's Uncertainty Principle for virtual particles

We can estimate the range of the force now by assuming the force particles travel at the speed of light for this time.

This approach is general and can be used to estimate the range of forces from the masses of the mediating particle.

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