K1    Early Experiments to Measure the Speed of Light

The speculative-philosophical phase of discussion on the speed of light lasted until 1676. Only Galileo attempted, shortly after 1600, an experimental clarification of the issue, but with his lanterns and helpers stationed on opposing hills, he had no real chance of getting a result. He also correctly interpreted that the speed of light is much larger than the speed of sound. René Descartes on the other hand, put all of his prestige on the line with a (weak) argument for an infinitely large speed of light.


Presentations on the topic ‘speed of light’ might comprise one of the following areas:


Also interesting is the experiment of Fizeau concerning the speed of light in flowing water (1851). He could not understand his results because he assumed the classical addition of velocities. Applying the addition of velocities according to STR yields his results immediately (see e.g., [25-103ff],
[19-80f]  or  [14-120]
).


The definition of the speed of light from 1983 opens the way to the ideas outlined in next section: For c = 1 (by definition) we obtain a new system of units, which takes into account the very core of the STR!