Walther Nernst

Walther Hermann Nernst ForMemRS (German pronunciation: [ˈvaltɐ ˈnɛʁnst] ^ⓘ; 25 June 1864 – 18 November 1941) was a German physical chemist known for his work in thermodynamics, physical chemistry, electrochemistry, and solid-state physics. His formulation of the Nernst heat theorem helped pave the way for the third law of thermodynamics, for which he won the 1920 Nobel Prize in Chemistry. He is also known for developing the Nernst equation in 1887.

He studied physics and mathematics at the universities of Zürich, Berlin, Graz and Würzburg, where he received his doctorate 1887. In 1889, he finished his habilitation at University of Leipzig.

Nernst was born in Briesen, Germany (now Wąbrzeźno, Poland) to Gustav Nernst (1827–1888) and Ottilie Nerger (1833–1876). His father was a country judge. Nernst had three older sisters and one younger brother. His third sister died of cholera. Nernst went to elementary school at Graudenz, Germany (now Grudziądz, Poland).

Nernst started undergraduate studies at the University of Zürich in 1883, then after an interlude in Berlin, he returned to Zürich. He wrote his thesis at University of Graz, where Ludwig Boltzmann was professor, though he worked under the direction of Albert von Ettinghausen. They discovered the Ettingshausen and Nernst effects: that a magnetic field applied perpendicular to a metallic conductor in a temperature gradient gives rise to an electrical potential difference, reciprocally, an electric potential difference produces a thermal gradient. Next, he moved to the University of Würzburg under Friedrich Kohlrausch where he submitted and defended his thesis.

Wilhelm Ostwald recruited him to the first department of physical chemistry at Leipzig University. Nernst moved there as an assistant, working on the thermodynamics of electrical currents in solutions. Promoted to lecturer, he taught briefly at the Heidelberg University and then moved to the University of Göttingen. Three years later, he was offered a professorship in Munich. To keep him in Prussia the government created a chair for him at Göttingen. There, he wrote a celebrated textbook Theoretical Chemistry, which was translated into English, French, and Russian. He also derived the Nernst equation for the electrical potential generated by unequal concentrations of an ion separated by a membrane that is permeable to the ion. His equation is widely used in cell physiology and neurobiology.

The carbon electric filament lamp then in use was dim and expensive because it required a vacuum in its bulb. Nernst invented a solid-body radiator with a filament of rare-earth oxides, known as the Nernst glower, it is still important in the field of infrared spectroscopy. Continuous ohmic heating of the filament results in conduction. The glower operates best in wavelengths from 2 to 14 micrometers. It gives a bright light but only after a warm-up period. Nernst sold the patent for one million marks, wisely not opting for royalties because soon the tungsten filament lamp filled with inert gas was introduced. With his riches, Nernst in 1898 bought the first of the eighteen automobiles he owned during his lifetime and a country estate of more than five hundred hectares for hunting. He increased the power of his early automobiles by carrying a cylinder of nitrous oxide that he could inject into the carburetor. After eighteen productive years at Göttingen, investigating osmotic pressure and electrochemistry and presenting a theory of how nerves conduct, he moved to Berlin, and was awarded the title of Geheimrat.

In 1905, he proposed his "New Heat Theorem", later known as the Third law of thermodynamics. He showed that as the temperature approached absolute zero, the entropy approaches zero — while the free energy remains above zero. This is the work for which he is best remembered, as it enabled chemists to determine free energies (and therefore equilibrium points) of chemical reactions from heat measurements. Theodore Richards claimed that Nernst had stolen his idea, but Nernst is almost universally credited with the discovery. Nernst became friendly with Kaiser Wilhelm, whom he persuaded to found the Kaiser Wilhelm Gesellschaft for the Advancement of the Sciences with an initial capital of eleven million marks. Nernst's laboratory discovered that at low temperatures specific heats fell markedly and would probably disappear at absolute zero. This fall was predicted for liquids and solids in a 1909 paper of Albert Einstein's on the quantum mechanics of specific heats at cryogenic temperatures. Nernst was so impressed that he traveled all the way to Zürich to visit Einstein, who was relatively unknown in Zürich in 1909, so people said: "Einstein must be a clever fellow if the great Nernst comes all the way from Berlin to Zürich to talk to him." Nernst and Planck lobbied to establish a special professorship in Berlin and Nernst donated to its endowment. In 1913 they traveled to Switzerland to persuade Einstein to accept it; a dream job: a named professorship at the top university in Germany, without teaching duties, leaving him free for research.

In 1911, Nernst and Max Planck organized the first Solvay Conference in Brussels. In the following year, the impressionist painter Max Liebermann painted his portrait.