What the Heck is the Aether?

Issac Newton

The aether comes up every so often in steampunk. Often, it’s used as a hand-wavy thing to explain all manner of strange technology or effects the same way ‘subspace’ is used in Star Trek. Am I guilty of using the aether to hand-wave things? Oh yeah, big time. However, the aether is actually a real concept, albeit an outdated one.

The word aether comes from Ancient Greece and was used to described the air-like substance present in the realm of the gods. It has been used to describe various concepts as physics developed as a science. Issac Newton solidified the concept of the aether as a substance that filled the universe at the end of the 1600s. As we all know from the story of the falling apple, Issac Newton developed the first equations that described the effects of gravity. However, while he could describe the effects of gravity, he was left with the mystery of how gravity works.

Newton’s laws of motion describe the way forces work on objects and the inertia of mass, but gravity didn’t really fit in. What force was acting on that famous apple to make it fall to the ground? So Newton created the concept of a substance that filled the universe. In this theory an object’s mass caused this substance to flow toward it. Other objects are then caught up like a log in a river. Newton moved away from this idea latter, but the concept of a universe-filling substance persisted and came to be named ‘aether’.

In the 1800s, new discoveries brought back the idea of the aether in a big way. During the last half of the 1800s, the Victorian age, a number of scientists began to develop the equations that described electromagnetism that would formulate into Maxwell’s equations. An outcome of this work was that electromagnetic radiation (light, radio, microwave, x-ray, etc…) propagated at the speed of light as a wave. That brought of the question of what was waving. Sounds waves waved air, ocean waves waved water, so what did light or other forms of electromagnetism wave? The aether provided the answer.

It seemed like a solid theory, but then scientists started running experiments to detect the aether. The best known of these was the Michelson-Morley experiment. In this experiment, they measured the speed of light in perpendicular directions. If the Earth was moving through the aether that filled the universe, the speed of light would have to be a little different in the two different directions. Think of it like measuring sound while moving through the air. In this analogy, consider the Earth as a boat moving at a good clip. On the top of the boat we affix a device to make a sound and two detectors, one 10 feet away toward the front of the boat and one 10 feet away toward the side of the boat. We’ll also assume there is no wind. When the sound gets made it will radiate through the air in all directions at a constant speed. However, the detectors on that moving boat are also moving through the air. The sound is lot faster than the boat so it will still reach both detectors, but not at the same time. So while the sound is moving at a constant speed, the speed we measure at each detector isn’t the same. The point of the experiment is not to measure the actual speed of sound, but to show that the source and the detectors are all moving through the air.

However, the Michelson-Morley experiment showed no difference in the detected speed of light between the two directions. This result really puzzled scientists at the time. It would take Albert Einstein and his laws of relativity to finally explain the results. Between relativity and quantum mechanics we now understand the nature of electromagnetic waves isn’t the same as sound or water waves and the concept of something waving doesn’t apply. We also gained a new understanding of gravity that saw the effect of gravity as warping space rather than making a substance flow toward mass.

With relativity and quantum mechanics changing the way we saw the universe, the idea of an aether faded away to become a relic of the Victorian age. Nonetheless, recent observations of the universe have suggested an unknown energy, called dark energy, filling empty space and accelerating the expansion of the universe. Maybe the aether will rise once again.

Erik Larson was born in Manhattan — the Kansas one — and raised mostly in Topeka Kansas. He went to college in San Antonio at Trinity University where he earned a degree in physics. After the cancellation of the Superconducting Super Collider, he decided to seek his fortune with software engineering instead.

Eventually, he gained an interest in writing his own fantastical tales and has written three fantasy novels. Cog and the Steel Tower is the first one ready for public consumption. He normally goes by the name Erik Larson, but decided on W.E. Larson for a pen name since there is already a well-known author with his name.

Author: Erik Larson

A software engineer and sometimes writer living in Kansas City.

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