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. 