Otto Stern was a German born American physicist who won the Nobel Prize in Physics in 1943. He was born in a prosperous Jewish family towards the end of the nineteenth century in the Kingdom of Prussia. Because of the financial affluence of his family, he did not have to look for jobs immediately after he finished his education. Instead, he worked as Privatdozent in chosen universities for a long time before landing at his first official academic post in the early 1920s. Initially he concentrated more on theoretical problems. It was only after he met great experimentalists like James Franck and Max Volmer that he began to take interest into experimental physics. Within a short period he developed molecular-beam method and discovered spin quantization with Walther Gerlach. It not only brought him fame, but also opportunity for further research work. Measurement of atomic magnetic moments, demonstration of the wave nature of atoms and molecules, and discovery of the proton's magnetic moment are few of his important works. He migrated to the USA and took up American citizenship when Hitler’s Nazi Party came to power. After working at Carnegie Mellon University for more than twelve years he finally retired and settled in California.
Childhood & Early Life
Otto Stern was born on February 17, 1888 in a prosperous Jewish family in Sohrau, now known as Zory. The town is located in the Upper Silesia region of Poland. However, at the time of his birth, it was part of the Kingdom of Prussia under German Empire.
His father, Oskar Stern, was a rich grain merchant and also owned flour mills. His mother’s name was Eugenia née Rosenthal. The couple had five children, among which Otto was the eldest. In 1892, the family moved to Breslau (now Wroclaw, Poland), where Otto was admitted to Johannes Gymnasium.
As Gymnasium emphasized more on the classics than on mathematics and sciences Stern supplemented his education by reading extensively in private. After passing out from school, he visited several universities as was the norm those days and finally in 1906, entered the University of Breslau with physical chemistry as his major.
Otto Stern completed his studies in 1912 earning his doctorate degree from the University of Breslau. In the same year, he joined Charles University at Prague to study under Albert Einstein.
When in 1913, Einstein returned to his alma mater, ETH Zürich, Otto Stern followed him. For one year he functioned as the Privatdozent of Physical Chemistry at ETH.
In 1914, he joined University of Frankfurt am Main as Privatdozent of Theoretical Physics. In 1915, he received his Habilitation, the highest academic qualification to be attained by any scholar, from the University. Very soon, the World War I broke out and he was inducted into the German army.
Towards the end of the war, he was assigned to military research at Nernst’s laboratory at the University of Berlin. There he became friends with James Franck and Max Volmer, two renowned experimentalists.
Until then Stern had mainly concentrated on theoretical studies of statistical thermodynamics and quantum theory. Now, under the influence of Franck and Volmer, he began to show interest in experimental physics.
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Once the war ended in 1918, Otto Stern returned to the University of Frankfurt am Main and remained there till 1921. Initially, he kept working on the theoretical problems and published a paper on the surface energy of solids. Very soon, he began to feel that he should provide experimental proof.
However, before he could complete his experiment, he received his first official academic post. In 1921, he joined the University of Rostock as the Associate Professor of Theoretical Physics.
In 1922, while teaching at Rostock, Stern along with Walther Gerlach performed their historic molecular-beam experiment. Known as Stern–Gerlach experiment, it confirmed the spin quantization theory, which stated that in a magnetic field, atoms can align themselves only in a few directions only.
Next in 1923, Stern joined the University of Hamburg as Professor of Physical Chemistry and Laboratory Director. Here he established an outstanding research group which undertook many pioneering experiments. Because of him University of Hamburg became a well-known center for atomic, molecular and nuclear research.
During this period Stern led further experiments into the quantum nature of matter. These experiments confirmed many other key manifestations such as wave nature of helium and hydrogen atoms by diffracting beams of these atoms, and irregular magnetic moments of proton and deuteron.
As Adolf Hitler and his Nazi Party came to power in Germany in July 1933 Stern had to resign from his position. By then he had become internationally well known. In 1930, he had been awarded an LL.D. by the University of California, Berkeley. Consequently, he decided to shift to the USA.
In 1933, Stern joined Carnegie Mellon University in Pittsburgh, Pennsylvania as Professor of Physics. He remained there until his retirement in 1945 carrying on extensive research in experimental physics.
After retirement, Stern shifted to California and joined University of California, Berkeley as Professor Emeritus. In the same year, he was elected to the National Academy of Sciences. He spent the rest of his life at Berkeley.
The Stern–Gerlach experiment of 1922 is one of the most important works carried on by Otto Stern. He and Walther Gerlach sent a beam of silver atoms through inhomogeneous magnetic field onto a glass plate and observed their diffraction.
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According to classical physics, the beam should have spread out as a continuous band; instead only two beams were observed. It not only confirmed the spin quantization theory, but also paved the way for further development of modern physics.
Measuring the magnetic momentum of proton by using molecular beam is another of his important work. Undertaken in 1933, the experiment proved that the actual measurement is two and half times of its theoretical value.
He also published many papers. Among them, a series of thirty outstanding papers titled ‘Untersuchung zur Molekularstrahl-Methode, UzM’ (Investigations by the molecular-beam method) is most noteworthy.
Awards & Achievements
Otto Stern received the 1943 Nobel Prize in Physics for his discovery of spin quantization theory. Although the work was done in collaboration with Walther Gerlach, he alone received the prize because Gerlach had stayed back in Germany and was active during Nazi period.
In addition, he was also elected as a member of American Association for the Advancement of Science, American Philosophical Society, National Academy of Sciences and Royal Danish Academy of Sciences.
Personal Life & Legacy
Otto Stern did not marry. As a young man, he was fond of good life and liked to dance. He was also a good tennis player and had many friends.
On March 8, 1939, he became a naturalized citizen of the United States of America. He spent the last part of his life at Berkeley, California. There he led a secluded life, but remained interested in the new discoveries in particle physics and astrophysics. He also went to movies regularly.
He died on August 17, 1969 at the age of 81 at Berkeley. He was stricken with heart attack while watching a movie and died soon after. He was buried in Sunset View Cemetery, El Cerrito, CA.
Kinetics of a photophysical intermolecular deactivation process has been named ‘Otto-Volmer Relationship’ after Otto Stern and his lifelong friend Max Volmer. The two scientists had worked closely for a long time since the World War I.
Otto Stern was the second most nominated person for the Nobel Prize. He received 82 nominations between 1925 and 1945. He ultimately won it in 1943.