Homonym: Æther (Ether)
Æther, in ancient Greek mythology, is often considered the personification of the upper sky or the pure, fresh air that the gods breathe. It represents the clear, bright atmosphere above the clouds, contrasting with the lower air that humans inhabit. Æther was thought to be a divine substance that filled the universe beyond the terrestrial sphere.
In scientific terms, Æther was once hypothesized as a medium through which light waves traveled. This concept, known as the luminiferous æther, was prevalent in the 19th century but was later disproven by experiments, including the famous Michelson-Morley experiment. The idea of æther has since been replaced by modern physics, particularly the theory of relativity.