The negative result of Michelson-Morley experiment gave rise to postulates of Special Theory of Relativity by Einstein. Which are given below :
First Postulate: The fundamental laws of physics have the same form for all inertial frames. No preferred inertial system exists. This is the principle of relativity.
Second Postulate: The speed of light in free space has the same value in all inertial
frames of reference. This is the principle of constancy of the speed of light.