Recently, one of the readers sent me the following question:
Hello! One of the postulates on which the theory of relativity is based is the statement that the speed of light is independent of the reference frame. But essentially, this seems like an unfounded guess by Einstein. Where did he even get this from?
Well, let’s figure it out together. Many people, especially those who last studied physics twenty years ago in school, may have the impression that Einstein made up the fundamental postulates of the theory of relativity out of thin air.
The postulate of the equivalence of all inertial reference frames is intuitively acceptable to most people and raises little doubt. However, the postulate of the invariance of the speed of light was less fortunate. Judging by the questions I receive, many consider it a mere whim of Einstein.
In reality, it is not like that at all. The prerequisites for the hypothesis that the speed of light is independent of the reference frame emerged in the mid-19th century, more than 20 years before Einstein’s birth. This happened when the British physicist James Clerk Maxwell published his famous equations describing the electromagnetic field.
