Not to be confused with a volatile liquid whose gases render people unconscious, the ether that many 18th and 19th century scientists and philosophers refer to is an invisible “sea” that was believed to permeate all of space, through which light waves were thought to travel in the way sound waves travel through air.
The idea was first proposed by the ancient Greeks. Aristotle called it the plenum, a fullness which contained the essence of everything in space. James Clerk Maxwell proposed the term “ether” to explain how radio waves worked. His idea, however, was disproved a few years later by Michelson and Morley, who demonstrated that light doesn’t travel through a substance in space. The idea, however, is beginning to make a comeback, in a somewhat modified form.
The new form of the idea is variously called “the quantum field,” the “unified field,” the “zero-point field,” and the “quantum substrate.” This is not a medium through which measurable waves travel, but a unified holon at the subatomic level, out of which particles emerge and within which they are eternally connected, no matter how far apart they may seem to be.
So, when I interpret a 19th-century metaphysician’s use of the word “ether” I always translate it as “quantum field” or “substrate” because they’re not concerned about how waves travel but rather are describing an always-and-everywhere-present ground or “substance” out of which all form emerges, depending on the thought, or consciousness, present.
P.S. The term “ether net,” as used with computers, is a misnomer, based on the colloquialism that grew out of the idea that we are surrounded by such an energy-information “sea” in which light and radio and therefore information, travel—the information is “somewhere out there in the ether.”