Born: 13 Jan 1864 in Gaffken, East Prussia (now Poland)
Died: 30 Aug 1928 in Munich, Germany

It was [Wien's] idea to use as a good approximation for the ideal blackbody an oven with a small hole. Any radiation that enters the small hole is scattered and reflected from the inner walls of the oven so often that nearly all incoming radiation is absorbed and the chance of some of it finding its way out of the hole again can be made exceedingly small. The radiation coming out of this hole is then very close to the equilibrium blackbody electromagnetic radiation corresponding to the oven temperature.

In 1896 Wien derived a distribution law of radiation. Planck, who was a colleague of Wien's when he was carrying out this work, later, in 1900, based quantum theory on the fact that Wien's law, while valid at high frequencies, broke down completely at low frequencies.

While studying streams of ionized gas Wien, in 1898, identified a positive particle equal in mass to the hydrogen atom. Wien, with this work, laid the foundation of mass spectroscopy. J J Thomson refined Wien's apparatus and conducted further experiments in 1913 then, after work by E Rutherford in 1919, Wien's particle was accepted and named the proton.

Wien received the 1911 Nobel Prize for his work on heat radiation.

In [4] a letter from Einstein to Wien is described in which he asks Wien to conduct an experimental proof of the principle of equivalence which Einstein had proposed from purely theoretical considerations in 1907:-

In 1912 [Einstein] turned by letter to W Wien with the request to measure the difference between the periods of oscillation of pendulums made of uranium and lead, as well as the proportionality of inertial and gravitational masses of a uranium and a lead weight, respectively, namely with a torsion balance. The letter testifies that Einstein was not aware of the Eötvös experiment when he formulated the principle of equivalence ...

Wien also made important contributions to the study of cathode rays, X-rays and canal rays