The other answers here attempt to "reason" it from the currently accepted formulas, but it's not how the humanity learned that there's no "190% of the speed of

The other answers here attempt to "reason" it from the currently accepted formulas, but it's not how the humanity learned that there's no "190% of the speed of light." The author of the article we all comment here wrote a book which, if I remember, covers that story in more detail (I linked to it in another post and I highly recommend it to anybody who wants to learn a bit more than when reading an article here or there or read some comments). Just to give you some hints, the real story is not "reasoning" something but the experiments -- the experiments practically produced the results that, when analyzed, are still the best explainable by accepting that the speed of light doesn't change. See: https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_experiment https://en.wikipedia.org/wiki/Michelson%E2%80%93Morley_exper... Michelson is such a genius, that even the most currently advanced experiments today use the same ideas that he used then -- LIGO is also an interferometer: https://www.ligo.caltech.edu/page/what-is-interferometer https://www.ligo.caltech.edu/page/what-is-interferometer Learning from these experiments, even before Einstein, some important formulas we know today as related to special relativity were already developed by others: https://en.wikipedia.org/wiki/History_of_Lorentz_transformations https://en.wikipedia.org/wiki/History_of_Lorentz_transformat...