# The speed of light: Was Einstein's second postulate not so revolutionary?

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Summary:: If Maxwell and his contemporaries were asked the following question what would have been their answer? Does the speed of the emitter of a beam of light get added to the speed of light in a vacuum?

If the answer is yes then it seems that Einstein's second postulate was not so revolutionary.
First, you mean "no", and second: I really recommend to have a look at the original papers to understand how brilliant Einsteins work was. At least I recommend to read (a translation of, if needed) "Zur Elektrodynamik bewegter Körper" (On the Electrodynamics of Moving Bodies).
Maxwell created a theory which is by default valid for waves at the speed of light. Nobody knows what Maxwell or his contemporaries would have answered but we all know what Einstein was saying: If the speed of light is constant in every inertial frame than we can understand the asymmetry of the Maxwell equations - which then suddenly disappears. If the speed of light is constant in every inertial frame then Newtonian physics can't be correct. The incredible depth is to see that Maxwell equations transform under a more general transformation law then Newtonian laws. Having understood this and taking the physics for real (not something like an "ether" effect), he corrected first the laws for the special case of moving inertial systems with a constant speed component to each other and then .... okay, I will stop now, I don't want to summarize the well known things.

vanhees71