Special theory of relativity:

Einstein's special theory of relativity is the physical theory of relativity based on assumption that the speed of light in a vacuum is a constant and the supposing that the laws of physics are invariant in all the inertial systems. Einstein's theory of relativity is the theory that the space and time are relative concepts rather than absolute concepts. The special theory of relativity was based on 2 main postulates: 1st that the speed of light is constant for all the observers; and 2nd is that observers moving at constant speeds should be subject to the same physical laws. By following this logic, it was theorized that time should change according to the speed of a moving object relative to the frame of reference of the observer. The theory states that space and time both are relative, which holds true in the special case where the gravitational field is absent.

Relativity was the concept from where comes the Einstein's mass-energy equation, E=mc², which implied that matter and energy were equivalent and that a single particle of matter could be converted into a huge quantity of energy. As the special theory of relativity held true in the absence of a gravitational field. The theory of special relativity is based on 2 postulates namely: Principle of Relativity: The physics laws of are the same for all the inertial reference frames. Principle of Constancy of the Speed of Light: Light always propagates through the vacuum at a velocity, c, which is independent of the state of motion of the emitting body. Special relativity yields to a number of consequences from applying Lorentz transformations at high velocities. They are: Length contraction, Time dilation, Relativistic velocity addition, Velocity transformation, Relativistic Doppler effect. Simultaneity & clock synchronization, Relativistic kinetic energy, Relativistic momentum, and Relativistic total energy, Relativistic mass.