Over the Ether

In ancient and medieval times scholars and philosophers believed that there was a medium which filled out the space of the universe. This medium was called aether or ether, or also quintessence.

Ethers are definitely a class of organic compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups.  But "ether" is a word that can mean several things.

Ether can refer to the upper regions of space.

It was once used as the name of a common surgical anesthetic.

Ether, or luminiferous Ether, was the hypothetical substance through which electromagnetic waves travel. It was proposed by the greek philosopher Aristotle and used by several optical theories as a way to allow propagation of light, which was believed to be impossible in "empty" space.

The brilliant and erratic Nikola Tesla believed that electromagnetic waves propagate in aether and that gravitational and magnetic forces are all directly related to the aether.

It took many years and many experiments, but now we know that, based on scientific evidence, electromagnetic waves do not need a medium to travel through. The existence of ether was not found in the Michelson-Morley experiment performed in 1887, and the the then-prevalent aether theory fell away. Heading in another direction, research eventually led to special relativity, which rules out the existence of aether.

But despite that research in the early days of radio, "over the ether" was a phrase used to refer to radio airwaves, as when a signal comes over the ether.

Radio waves are electromagnetic radiation and, unlike sound waves which require material to vibrate and reflect energy to be heard, radio waves are received by being caught by an antenna. They can then be focussed and amplified using a tuner and amplifier system.