How did scientists measure the speed of light ??
The basic concept on how the speed of light was first accurately measured is realy quite simple. What was done was to set up a reflective octagon. This octagon was then turned at a constant rate. From above the octagon there would be a light source that shines light down onto it. This light is then reflected at an angle of 90 degrees and travels away from the octagon. This light is allowed to travel a long distance, initially the distance between two mountains. It is then reflected back at the octagon with a mirror. When it returns to the octagon it gets reflected downwards. If the octagon is in the right orientation it will reflect the light into a photodetector. If it is not oriented properly it will not hit the photo detector. So if you know the rotational speed of the octagon in rotations per second, call this N (rot/s). And you know the distance between the two mountains say D. You know that when the octagon makes one eigth of a turn it will line up properly. Now you increase the
