Walther Hermann Nernst, ForMemRS (25 June 1864 – 18 November 1941) was a German physicist who is known for his theories behind the calculation of chemical affinity as embodied in the third law of thermodynamics, for which he won the 1920 Nobel Prize in chemistry. Nernst helped establish the modern field of physical chemistry and contributed to electrochemistry, thermodynamics and solid state physics. He is also known for developing the Nernst equation.