text: First, the earlier theory which originated from the concept of a hypothetical medium referred as aether. Ether supposedly fills all evacuated or non-evacuated spaces.  The transmission of light or of radiant heat are allowed by the propagation of electromagnetic waves in the aether. television and radio broadcasting waves are types of electromagnetic waves with specific wavelengths. All electromagnetic waves travel at the same speed; therefore, shorter wavelengths are associated with high frequencies. Since every body or fluid is submerged in the ether, due to the vibration of the molecules, any body or fluid can potentially initiate an electromagnetic wave.  All bodies generate and receive electromagnetic waves at the expense of its stored energy.
  In 1860, Gustav Kirchhoff published a mathematical description of  thermal equilibrium (i.e. Kirchoffs law of thermal radiation). By 1884 the emissive power of a perfect blackbody was inferred by Josef Stefan using John Tyndalls experimental measurements, and derived by Ludwig Boltzmann from fundamental statistical principles. This relation is known as Stefan–Boltzmann law.