Editing Luminiferous aether (section)

===Wave-theory triumphs===
A century later, [[Thomas Young (scientist)|Thomas Young]]{{efn|Young ascribed aether to [[caloric theory]], pairing light and heat, and cited passages from Newton such as: "A luminiferous ether pervades the Universe, rare and elastic in a high degree," and:<blockquote>Is not the heat conveyed through the vacuum by the vibration of a much subtiler medium than air? And is not this medium the same with that medium by which light is refracted and reflected, and by whose vibration light communicates heat to bodies, and is put into fits of easy reflection, and easy transmission?<ref>{{cite book |last=Gillispie |first=Charles Coulston |author-link=Charles Coulston Gillispie |title=The Edge of Objectivity: An Essay in the History of Scientific Ideas |year=1960 |publisher=Princeton University Press |isbn=0-691-02350-6 |page=[https://archive.org/details/edgeofobjectivit00char/page/408 408] |url=https://archive.org/details/edgeofobjectivit00char/page/408 }}</ref></blockquote>}} and [[Augustin-Jean Fresnel]] revived the wave theory of light when they pointed out that light could be a transverse wave rather than a longitudinal wave; the polarization of a transverse wave (like Newton's "sides" of light) could explain birefringence, and in the wake of a series of experiments on diffraction the particle model of Newton was finally abandoned. [[Physicist]]s assumed, moreover, that, like mechanical waves, light waves required a medium for [[Wave propagation|propagation]], and thus required Huygens's idea of an aether "gas" permeating all space.

However, a transverse wave apparently required the propagating medium to behave as a solid, as opposed to a fluid. The idea of a solid that did not interact with other matter seemed a bit odd, and [[Augustin-Louis Cauchy]] suggested that perhaps there was some sort of "dragging", or "entrainment", but this made the aberration measurements difficult to understand. He also suggested that the ''absence'' of longitudinal waves suggested that the aether had negative compressibility. [[George Green (mathematician)|George Green]] pointed out that such a fluid would be unstable. [[George Gabriel Stokes]] became a champion of the entrainment interpretation, developing a model in which the aether might, like pine pitch, be [[dilatant]] (fluid at slow speeds and rigid at fast speeds). Thus the Earth could move through it fairly freely, but it would be rigid enough to support light.