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Special relativity

Einstein's theory of special relativity deals with measurements made in systems that are in motion relative to each other. Such a system is known as a frame of reference. Measurements made in a moving train are relative to the train and the train is therefore one frame of reference, while measurements made at the side of the track are relative to the ground, the other frame of reference.

Assumptions in special relativity
Einstein made two vital assumptions or postulates when he proposed the theory of relativity and these are:
(a) physical laws are obeyed in all frames of reference
(b) the velocity of light in free space is constant in all inertial frames of reference.

Length appears to get smaller, mass increases and time appears to pass more slowly in a moving frame of reference when viewed from a stationary frame. Any such differences are very small unless the relative velocities are very large, that is, approaching that of light.

 
 
 
© Keith Gibbs 2010