Einstein’s Special Theory of Relativity

Einstein special theory of relativity is based on two assumptions:

• The principle of relativity: All the laws of physics have the same form in all inertial reference frames.
• The constancy of the speed of light: The speed of light in vacuum has the same value, c = 3.00 x 10⁸ m/s, in all inertial frames, regardless of the velocity of the observer or the velocity of the source emitting the light.

The first proposition asserts that all the laws of physics, those dealing with electricity and magnetism, optics, mechanics, thermodynamics, etc. will have the same mathematical form or be covariant in all coordinate frames moving with constant velocity relative to one another. This postulate is a far-reaching generalization of Newton’s principle of relativity, which refers only to the laws of mechanics.

Note that proposition 2, the principle of the constancy of speed of light, is consistent with proposition 1. If the speed of light was not the same in all inertial frames but was 3.00 x 10⁸ m/s in only one, it would be possible to distinguish between inertial frames, and one could identify a preferred, absolute frame in contradiction to postulate 1.

Also Read: Einstein Contribution to Planck Formula on the Quantum Nature of Radiation

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