, born in 1853
, Stefan spent almost his entire life in Vienna
. As with many 19th Century
experimental physicists his interests were very wide-rangin
by modern standards, but his best-known work were his studies into thermal radiation
He discovered an experimental law describing radiant heat from a hot surface (Stefan's law) and used it to make the first serious attempts to estimate the temperature of the surface of the sun. He was never able to provide a provable theoretical basis for his law although he kept trying to do so until his death in 1893.
Many others attempted to follow up his work and discover the theory behind the practice, and in so doing made many major advances in theoretical physics, leading ultimately to Planck's quantum theory in 1900.