・・・１９０５ Theory of electromagnetism that Albert Einstein（1879-1955） announced.
・The universe is the 4-dimensional world of time and space. The "space-time" seen from the watcher is a relative thing which is rectified by Lorentz transformation, and is extended or is shrunk.
・The length of a spacecraft is shrunk by a cross direction at a rate of.
(Ｖ: Motion speed, Ｃ：Light speed)
・At the system which exercises, compared with an external system, only is delayed in time.
・If the mass of the object which exercises reaches the velocity of light, it will become infinite.
・Only the light speed (electromagnetic waves) does not change.
※ Special relativity is the theory which dealt with the inertia system in the state where there is no gravity.
※ In accordance with Special relativity and general theory of relativity, it is called theory of relativity.
※ According to theory of relativity, the phenomenon in which an error becomes large if Newtonian mechanics describes (movement near the speed of light and movement in a big gravitational field) , can be described correctly.