Introduction to special relativity

The special theory of relativity was first put forward by Einstein in 1905. His aim was to take care of some theoretical concerns about classical electrodynamics, but ultimately he came up with a modification of the laws of mechanics itself. Special relativity explores the structure of space and time and their effect on motion, forces and other dynamical phenomena. His approach was based on two physical postulates and is explained in the main article Special relativity. But in 1908 Hermann Minkowski realised that the theory could be made more statisfactory by basing it on some postulated geometric properties of space and time. In fact, he recognised that special relativity destroyed some of the absolute separation between space and time present in Newton's mechanics. He formulated special relativity on a four-dimensional spacetime, a mathematical construct that unifies space and time into a single object. This insight proved vital in the further development of physics.

Special relativity predicts some strange effects, such as that a rod will become shorter as it moves at higher speeds and that time will behave differently for different observers. All of these effects can be very simply explained and predicted from the geometrical formalism advanced by Minkowski. This article aims to give a gentle, non-technical introduction to the theory based on geomterical intuition and explain some of the terminology and formalism involved. A more advanced, encyclopedic description will be found in the parent article Special relativity. It will be helpful to approach relativisic mechanics by first studying some properties of the classical (Newtonian) picture.