Marian Smoluchowski (28 May 1872 - 5 September 1917) was an ethnic Polish scientist in the Austro-Hungarian Empire. He was a pioneer of statistical physics and an avid mountaineer.

Born into an upper-class family in Vorder-Brühl, near Vienna, Smoluchowski studied physics at the University of Vienna. His teachers included Franz S. Exner and Joseph Stefan. Ludwig Boltzmann held a position at Munich University during Smoluchowski's studies in Vienna and returned in 1894, when Smoluchowski was serving in the Austrian army. They apparently had no direct contact, although Smoluchowski's work follows in the tradition of Boltzmann's ideas. After several years at other universities (Paris, Glasgow, and Berlin), he moved to Lwów in 1899, where he took a position at the University of Lwów. He was a president of Polish Copernicus Society of Naturalists (1906–07).

Smoluchowski moved to Kraków in 1913, to take over the chair in Experimental Physics Department after August Witkowski, who had long envisioned Smoluchowski as his successor. When World War I began the following year, the work conditions became unusually difficult, as the spacious and modern Physics Department building, built by Witkowski a short time before, was turned into a military hospital. The possibility of working in that building had been one of the reasons Smoluchowski decided to move to Kraków. Smoluchowski was now forced to work in the apartment of the late Professor Karol Olszewski. During his experimental physics lectures, using even the simplest demonstration equipment was virtually impossible.

Smoluchowski lectured in experimental physics, and his students included Jozef Patkowski, Stanislaw Loria and Waclaw Dziewulski. His non-professional interests included skiing, mountain climbing in the Alps and Tatra Mountains, watercolour painting, and playing the piano.

Marian Smoluchowski died in Kraków in 1917, the victim of a dysentery epidemic. Professor Wladyslaw Natanson wrote in Smoluchowski's obituary: "With great pleasure I would revive the charm of his life, knightly softness of his heart, combined with exquisite kindness. I wish I could reconstruct the odd appeal of his personality, recall how restrained he was, modest, and beautifully timid, yet always full of pure, almost unintentional joy."

Smoluchowski was a member of the Copernicus Society of Natural Scientists and the Polish Academy of Sciences and Letters. In 1901 he had married Zofia Baraniecka, who survived him. They had two children, Aldona Smoluchowska (1902-1984) and Roman Smoluchowski (1910-1996). Roman himself was a notable physicist working in Poland and after World War II settling in USA (Institute for Advanced Study, Princeton).

Work

Smoluchowski's scientific output included fundamental work on the kinetic theory of matter. In 1904 he was the first who noted the existence of density fluctuations in the gas phase and in 1908 he became the first physicist to ascribe the phenomenon of critical opalescence to large density fluctuations. His investigations also concerned the blue colour of the sky as a consequence of light dispersion on fluctuations in the atmosphere, as well as explanation of Brownian motion of particles. At that time Smoluchowski proposed formulae which presently carry his name.

In 1906, independently of Albert Einstein, he described Brownian motion. Smoluchowski presented an equation which became an important basis of the theory of stochastic processes.

In 1916, he proposed the equation of diffusion in an external potential field. This equation bears his name.