Walther Nernst

• 1. Introduction

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  Walther Nernst drove a car with a cylinder of nitrous oxide bolted to it, injected directly into the carburetor for extra power. This was not a stunt. It was the natural behavior of a man who sold a lightbulb patent for one million marks and used the money to buy a country estate of more than five hundred hectares and the first of eighteen automobiles he would own over his lifetime. Nernst, born on the 25th of June 1864 in Briesen in the Prussian Province of West Prussia, was one of the most consequential physical chemists of his era. He would formulate the theorem that became the third law of thermodynamics, earn the Nobel Prize in Chemistry, help reshape scientific institutions across Germany, and drive to within sight of the lights of Paris during one of the most catastrophic wars in history. How did a country judge's son from a small Prussian town become the man who changed how chemists understand the limits of matter at the coldest possible temperatures? And what does it mean that, along the way, he also invented an electric piano?

• 2. A New Field Takes Shape

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  Nernst started undergraduate studies at the University of Zürich in 1883, beginning a peripatetic education that would take him through Berlin, back to Zürich, and then to Graz. At Graz, he wrote his thesis under Albert von Ettinghausen rather than under the more famous Ludwig Boltzmann, who held a professorship there at the time. Together, Nernst and Ettinghausen discovered what became known as the Ettingshausen and Nernst effects: apply a magnetic field perpendicular to a metallic conductor sitting in a temperature gradient, and an electrical potential difference appears. Run the relationship the other way and an electric potential difference produces a thermal gradient. After defending his thesis at the University of Würzburg under Friedrich Kohlrausch, Nernst was recruited by Wilhelm Ostwald to the first department of physical chemistry at Leipzig University, arriving as an assistant. Alongside his Leipzig colleagues Jacobus Henricus van 't Hoff and Svante Arrhenius, he was helping lay the foundations of an entirely new theoretical and experimental branch of chemistry. His habilitation at Leipzig was complete by 1889. From there he moved through Heidelberg, then to Göttingen, where the government created a special chair to keep him from accepting a professorship in Munich. At Göttingen, he wrote his celebrated textbook Theoretical Chemistry, which was translated into English, French, and Russian.

• 3. The Nernst Glower and Its Fortune

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  Carbon electric filament lamps of the late nineteenth century were costly and dim, requiring a vacuum inside the bulb to function. Nernst's answer was a solid-body radiator with a filament made of rare-earth oxides, which he called the Nernst glower. It works through continuous ohmic heating: the filament heats until it conducts. The glower operates best in wavelengths from 2 to 14 micrometers, and it gives a bright light after a warm-up period. Nernst sold the patent for one million marks, a decision that proved shrewder than it might appear. He chose not to take royalties, and his instinct was correct: the tungsten filament lamp filled with inert gas arrived shortly afterward and made his device commercially obsolete in the lighting market. The glower, however, never stopped being useful. It remains important in infrared spectroscopy to this day. The fortune from that sale funded more than cars and hunting land. Nernst at Göttingen also derived the Nernst equation for the electrical potential generated when unequal concentrations of an ion are separated by a membrane permeable to that ion. That equation found a permanent home in cell physiology and neurobiology, where it is still widely used.

• 4. The Third Law

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  In 1905, Nernst proposed what he called his New Heat Theorem. The claim was precise: as temperature approaches absolute zero, entropy approaches zero while the free energy remains above zero. This allowed chemists, for the first time, to calculate the free energies and therefore the equilibrium points of chemical reactions directly from heat measurements. The practical implications spread through chemistry and physics. Nernst's own laboratory then found that at low temperatures the specific heats of materials fell sharply and would probably disappear entirely at absolute zero. Albert Einstein had predicted exactly this behavior for liquids and solids in a 1909 paper on the quantum mechanics of specific heats at cryogenic temperatures. Nernst was so struck by the convergence that he traveled from Berlin to Zürich to visit Einstein in person. At that time Einstein was relatively unknown in Zürich, and the visit produced a piece of local commentary: people said that Einstein must be a clever fellow if the great Nernst had come all the way from Berlin to talk to him. Nernst and Max Planck then lobbied together to create a special professorship in Berlin for Einstein, with Nernst contributing to its endowment. In 1913, the two men traveled to Switzerland to persuade Einstein to accept a named professorship at the top university in Germany, with no teaching duties and complete freedom for research. A rival claim to the New Heat Theorem was lodged by Theodore Richards, who argued that Nernst had stolen his idea. The scientific community nonetheless almost universally credited Nernst with the discovery, and in 1920 the Nobel Prize in Chemistry came to him in recognition of his thermochemistry work.

• 5. War, Gas, and Consequences

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  On the day war was declared in 1914, Nernst was on his country estate with colleagues and students he had transported there in a private railway car. His two older sons entered the army. Nernst himself enlisted in the voluntary driver's corps and signed the Manifesto of the Ninety-Three, which supported the German army against charges of barbarism. On the 21st of August 1914, he drove documents from Berlin to the commander of the German right wing in France and advanced with the German forces for two weeks, close enough to see the glow of the Paris lights at night. The battle of the Marne reversed the German advance. When the trench stalemate set in, Nernst brought an idea to Colonel Max Bauer, the staff officer responsible for munitions: use shells to release tear gas and force defenders out of their positions. The idea was tested and observed by Fritz Haber, who argued against it. Haber's counter-proposal was to release a cloud of heavier-than-air poisonous gas instead. The first chlorine cloud attack came on the 22nd of April 1915 but was not backed by a sufficient infantry push, and the chance that chemical weapons would break the stalemate was lost. As a Staff Scientific Advisor in the Imperial German Army, Nernst directed explosives research, including work in his own laboratory that developed guanidine perchlorate, and later moved to trench mortar development. He was awarded both the Iron Cross second class and then the Iron Cross first class, and later the Pour le Mérite. When senior commanders considered unrestricted submarine warfare, Nernst asked for an audience with the Kaiser to warn about the military potential of the United States as an adversary. General Erich Ludendorff shouted him down, calling his warning incompetent nonsense.

• 6. After the War

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  In 1918, Nernst published The Foundations of the New Heat Theorem and, after studying photochemistry, proposed his atomic chain reaction theory: a reaction that produces free atoms capable of decomposing target molecules into more free atoms would sustain itself in a chain. His theory carried a direct conceptual relationship to the natural process of nuclear fission. In 1920, he and his family briefly left Germany because his name appeared on the Allied list of war criminals. That same year he received the Nobel Prize. He was elected Rector of Berlin University for 1921-1922, and in 1924 he became director of the Institute of Physical Chemistry in Berlin. He set up an agency to channel government and private funds to young scientists and declined an offer to become Ambassador to the United States. Two years as president of the Physikalisch-Technische Reichsanstalt, Germany's national physical laboratory, left him miserable. He described the institution as a mixture of mediocrity and red tape and could not cope with running it. In 1927, his work on the decrease in specific heat at low temperatures was extended to gases. He also turned his attention to theories of cosmic rays and cosmology. Then, in 1930, Nernst developed the Neo-Bechstein-Flügel in association with the Bechstein and Siemens companies. The instrument replaced the piano's sounding board with vacuum tube amplifiers and used electromagnetic pickups to produce electronically modified sound, in the same way an electric guitar works. A press release from the time described him as completely unmusical. In fact, he was a pianist who sometimes accompanied Einstein on violin.

• 7. Defiance and Final Years

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  In 1933, Nernst discovered that a colleague he had hoped to work with had been dismissed from his department because he was Jewish. Nernst immediately took a taxi to see Fritz Haber and ask for a position in Haber's institute, which was not under government control. He arrived to find that Haber was already preparing to leave for England. Nernst then declined to fill out a government form requiring him to state his racial origins. The consequences came quickly: he was forced out of his professorship and removed from the board of the Kaiser Wilhelm Institute. Two of his three daughters had married Jewish men; after Hitler came to power, they emigrated, one to England and the other to Brazil. Nernst had been a vocal critic of Hitler and of Nazism throughout. He retired to live quietly in the countryside. In 1937, he traveled to the University of Oxford to receive an honorary degree, using the visit also to see his eldest daughter, her husband, and his three grandchildren. He suffered a severe heart attack in 1939. He died on the 18th of November 1941 at Zibelle, Germany, a place now called Niwica in Poland. His burial was unusual: he was interred three times in total. First near the place of his death, then moved to Berlin, and finally moved again to Göttingen, where he lies near the graves of Max Planck, Otto Hahn, and Max von Laue.