“ This null result — the fact that there was no luminiferous aether — was actually a huge advance for modern science, as it meant that light must have been inherently different from all other waves that we knew of. The resolution came 18 years later, when Einstein’s theory of special relativity came along. And with it, we gained the recognition that the speed of light was a universal constant in all reference frames, that there was no absolute space or absolute time, and — finally — that light needed nothing more than space and time to travel through. ”
In the 1880s, it was clear that something was wrong with Newton’s formulation of the Universe. Gravitation didn’t explain everything, objects behaved bizarrely close to the speed of light, and light was exhibiting wave-like properties. But surely, even if it were a wave, it required a medium to travel through, just like all other waves? That was the standard thinking, and the genius of Albert A. Michelson was put to work to test it. Because, he reasoned, the Earth was moving around the Sun, the speed of light should get a boost in that forward direction, and then have to fight that boost on the return trip. The perpendicular direction, on the other hand, would be unaffected. This motion of light should be detectable in the form of interferometry, where light was split into two perpendicular components, sent on a journey, reflected, and then recombined.
