Noun
emission theory (uncountable)
English Wikipedia has an article on:emission theoryWikipedia
(physics) A discredited scientific theory, once considered an alternative to special relativity, proposing that light is emitted at speed c relative to its source instead of applying the invariance postulate.
On the emission theory the velocity should be accelerated by an increase of density in the medium; on the wave theory, it should be retarded. Source: Internet
One of the earliest of these was Al-Kindi (c. 801–73) who wrote on the merits of Aristotelian and Euclidean ideas of optics, favouring the emission theory since it could better quantify optical phenomenon. Source: Internet