Science is replete with hypotheses that we fucked around with a little too much before finding out they were best consigned to the trash heap of history. When luminiferous aether’s death knell tolled, it needed to be disentangled from nearly every major concept in physics.
Today’s Moment of Science… let there be a better explanation for light.
The luminiferous aether hypothesis came to popularity in the 1600s and it was worked into our fundamental understanding of physics for hundreds of years. Light has properties of waves, and waves travel through a medium. So surely light waves from distant stars had to be traveling through some invisible thing.
Some believed the luminiferous aether could be physically obtained by boiling down absurd quantities of piss; this turned out to be phosphorus (and a putrid lab). While earth, air, fire, and water were established as the four elements that made up the world, aether was its own type of stuff, separate from the others. It was referred to as ‘quintessence,’ or the fifth element.
It was a reasonable enough explanation for that one thing. Then we had to try to fit it into the universe as a whole, and shit got complicated. Gravity, heat, electricity, magnetism and light? At some point in physics they all kinda jumble together. Aether was either employed as an explanation or it served as an inconvenient extra puzzle piece.
The concept started breaking down. If something wasn’t a fit for the current model of aether? As it turned out, when working with an invisible stuff that nobody’s ever measured, touched, seen, or even proved existed, it’s super easy to claim the magical stuff God is hiding in plain sight all around us picked up a new skill this week. It somehow consisted of invisible solid particles that needed to be simultaneously completely rigid to transport light but a fluid to allow solids to move through it. Aether was whatever it needed to be depending on the last physicist torturing it.
“The only aether which has survived is that which was invented by (Dutch scientist Christiaan) Huygens to explain the propagation of light,” physicist James Maxwell stated in 1878. “Aethers were invented for the planets to swim in, to constitute electric atmospheres and magnetic effluvia, to convey sensations from one part of our bodies to another, and so on, until all space had been filled three or four times over with aethers.”
The concept already trembled on shaky ground. Then in the 1880s, Albert Michaelson and Edward Morley quite accidentally delivered its fatal blow. They had a rigorous experimental design laid out to measure the aether that they were sure existed.
Michaelson designed a contraption called an interferometer to measure the speed of light as it traveled, presumably, through aether. Aided by the known velocity of the planet itself, taking measurements from multiple directions, they’d find any changes to the speed of light. If it followed classical Newtonian mechanics, it would change speed relative to the medium it was being propagated in, and that’s how they’d measure the aether.
Unfortunately, aether suffered from not existing, and they measured no changes to the speed of light.
It’s still one of the most famous failed experiments in history.
Scientists were shocked at the results. Their peers suspected that the pair must have done something wrong. But nobody was able to get positive results that could be replicated.
Then Einstein proposed the theory of special relativity postulating that the speed of light was a constant. It made a lot of things fall into place in the absence of aether, but left a little bit of a clean up to deal with in Newtonian mechanics.
Michaelson won the Nobel prize in 1907 for his work with optical precision instruments, including the interferometer. Over a hundred years later, interferometers were used in detecting a phenomenon first predicted by Einstein: gravitational waves.
Reportedly, despite his study contributing immensely to the advancement of the field, Michaelson believed in luminiferous aether through his death in 1931. Einstein visited Michaelson on his deathbed. His daughter begged Einstein not to get into it about the fucking aether.
This has been your daily Moment of Science, just reminding you that if you’re tempted to feel bad about being wrong, literally every genius was wrong about this hundreds of years.
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