Aether

"According to ancient and medieval science, ether, also called quintessence, is the material that fills the region of the universe above the terrestrial sphere."

"The concept of ether is used in several theories to explain several natural phenomena, such as the traveling of light and gravity."

"In late 19th century, physicists postulatеd that ether permеated all throughout space, providing a medium through which light can travel in a vacuum."