Quote - Are you familiar with the Michelson-Morley experiment and the Lorentz transformations? That's where the speed limit of the Theory of Relativity comes.

Yes, I know. The purpose of the Michelson-Morley experiment was to measure the absolute speed of Earth. The idea was as the Earth is moving, measuring the speed of light in the direction of the movement and the speed of light in the opposite direct with the difference of speeds we can know the absolute speed of Earth. Michelson-Morley planed carefuly the experiment and did it in 1887. The result was a failure, they were unable to see any difference in any direction of the measured speeds of light. The experiment was revisted, repeated many times and always failed.

This was the fundamental stone of Einstein's Theory of Relativity. As the Michelson-Morley experiment failed to give any differences in light speeds, Eistein postulate that the speed of light is always the same in any direction and independent of any movement. From this postulate Einstein created his theory.

This story is very well known, everybody knows and is repeated thousands of times, but there is more story that nobody knows and nobody tells you:

 

Do you think that Michelson-Morley were comformed with the failure of their experiment and were happy with Einstein's explanation and then dedicated to the garden of their houses ?  Of course not ! They continued their work, revised their failled experiment, created new experiments and in 1926 they had success and were able to measure the absolute speed of Earth. Everybody knows about their failed experiment, but nobody knows about their successful experiment.

Michelson-Morley were not only the ones, other scientists created other experiments and among them was a guy named Georges Sagnac that in 1913 had also success in measuring the absolute speed of Earth.

As the successful experiments shows that the speed of light is not the same in any direction and this contradicts Einstein's basic postulate on which all his theory was built. In consequence the successful experiments were burried, ignored and send to dusty cold files where almost nobody knew that ever existed.

These experiments remained forgoten and nobody knew about their existence until the 70's. Sagnac experiment was resurrected by other reasons nothing to do with Relativity. Replacing the light sources of the Sagnac experiment by lasers it was posible to create a small, very cheap solid state without moving parts device that was able to measure the absolute speed of something with excellent precission. Something very useful for planes and missiles. It contradicst Eintein's theory ?, who cares, it works, is useful and so, everybody use it today.

Stupidity also evolves!