Josef Stefan
Joseph Stefan (Slovene Jožef Stefan) was a Slovene physicist and poet, born: 24 March 1835, St. Peter near Klagenfurt (Slovene Celovec), Austro - Hungary (now Austria), died: 7 January 1893, Vienna, Austro - Hungary.
Stefan graduated in mathematics and physics at the University of Vienna. During his student years, he also wrote and published a number poems in Slovene. He taught physics at the University of Vienna, was Director of the Physical Institute, Vice-President of the Vienna Academy of Sciences and member of several scientific institutions in Europe.
He published nearly 80 scientific articles, mostly in the Bulletins of the Vienna Academy of Sciences and he is best known for originating a physical law in 1879 stating that the total radiation from a blackbody j* is proportional to the fourth power of its thermodynamic temperature T:
j* = σ T4
The law was later in 1884 derived theoretically in the frame of the thermodynamic by Ludwig Boltzmann and hence known as the Stefan-Boltzmann law. This law is the only physical law of the nature named after one Slovene physicist. Today we derive the law from the Planck's Law of Radiation. He provided the first measurements of the thermal conductivity of gases and among others studied difusion. For his treatise on optics he received the Richard Lieben award from the University of Vienna.
Very important are also his electromagnetic equations, defined in vector notation. He was among the first physicists in Europe who fully understood Maxwell's electromagnetic theory.
In mathematics a Stefan's task with movable boundary is well known.
His life and work is extensively studied by physicist Janez Strnad.
See also:
Stefan-Boltzmann constant σ -- Stefan's force.
External links:
- Jozef Stefan: http://www.ijs.si/stefan.html
- Jozef Stefan Institute, Ljubljana, Slovenia: http://www.ijs.si/