The word 'interstellar' (between the stars) was coined by Francis Bacon in the context of the ancient theory of a literal sphere of fixed stars. Later in the 17th century, when the idea that stars were scattered through infinite space became popular, it was debated whether that space was a true vacuum or filled with a hypothetical fluid, sometimes called aether, as in René Descartes ' vortex theory of planetary motions. While vortex theory did not survive the success of Newtonian physics, an invisible luminiferous aether was re-introduced in the early 19th century as the medium to carry light waves; e.g., in 1862 a journalist wrote: "this efflux occasions a thrill, or vibratory motion, in the ether which fills the interstellar spaces."