The experiment that changed everything

In 1887, in Cleveland, Ohio, Albert Michelson and Edward Morley built the most sensitive measuring instrument of their day. They meant to catch the Aether moving.

Their logic was elegant. If the Earth moves through a stationary Aether, light making a round trip along the Earth's motion should take slightly longer than light making the same trip across it, just as a swimmer takes longer to go upstream and back than to cross a river and back. They split a beam of light, sent it along two perpendicular paths, and looked for a difference.

They found none. The speed of light was the same in every direction.

Physics faced a choice: question the experiment, or question the Aether. It chose to abandon the Aether. In 1905 Albert Einstein's Special Theory of Relativity declared a medium unnecessary. Space became geometry, a coordinate system without physical substance.

RSI reads the same null result in another way, one developed by George FitzGerald and Hendrik Lorentz and completed by Henri Poincaré. Every ruler, mirror and clock is built of knots in the Eternal Consonance. Moving through the medium, a ruler shortens slightly along its motion and a clock ticks slightly slower, by exactly the amounts that hide the motion. These are the contraction and time dilation of relativity, and a medium with these properties is now known to match every one of relativity's predictions. The instruments could not see the medium, because they are made of it. The experiment was correct. The conclusion drawn from it, RSI argues, was not.