Otto Stern

Molecular beams, space quantization and the proton's surprising magnetism (1919-1933)

• Emilio Segrè wrote that until about 1934 all important molecular beam experiments came from Stern's lab, and that later beam labs were founded by his students or their pupils.^[5]
• Isidor Rabi learned the beam method as a visitor to Stern's Hamburg lab from 1927, then added radio waves to create magnetic resonance, the basis of NMR spectroscopy and MRI.^[6],[9]
• MRI reads the magnetism of hydrogen nuclei, the protons whose magnetic moment Stern's team first measured in 1933; more than 95 million MRI scans are now done each year.^{[3],[14],[15]}
• NIST says its first atomic clock (1949) used Rabi's resonance technique; cesium-beam clocks followed from 1955, the second has been defined by cesium since 1967, and GPS satellites carry atomic clocks.^[17],[19]
• A 1933 experiment in Stern's lab by his assistant Otto Frisch showed that atoms recoil when they absorb light, the effect later used, from the 1970s on, to cool atoms with lasers.^[6],[8]
• His biographers count about 20 Nobel Prizes awarded for work based on his molecular beam method, including prizes for the maser, NMR and the atomic clock.^[6]

Stern's main gift was a method and a standard of proof. His molecular beams let physicists test quantum theory on single, isolated atoms, and the Stern-Gerlach experiment became the textbook demonstration of quantization and, later, of spin and quantum measurement. His technologies arrived mostly through others, above all his Hamburg guest Isidor Rabi. We record two small ripple shares of outcomes already counted for Rabi and others: 0.5% of the people who have benefited from MRI scans, and 0.3% of the US economic benefits of GPS, which relies on atomic clocks. Both are low-confidence judgments, because the chains from his laboratory to hospitals and satellites are long. We claim nothing for fundamental physics itself, or for the maser, laser cooling and reaction chemistry his work also seeded, because no honest number exists for them. No harm claim is recorded: our sources document no deaths or injuries tied to his work.

Fundamental scienceHealthTechnology

Each number is the laureate’s credited share of a real-world outcome, cumulative to 2025. The whole outcome, the share of credit, and the reasoning are shown so you can check the arithmetic. Outcomes shared with other laureates are counted once on the impact page.

• Low confidenceRippleModeledHealth

  People who have benefited from MRI examinations worldwide since the early 1980s

  1.5–5.5

  million people benefited, credited share

  That is 0.5% of 300 million–1.1 billion people benefited since 1981.

  How this number was built

  Same whole-outcome range as the Rabi and Bloch profiles. Nobel Assembly: clinical MRI began in the early 1980s; over 60M exams in 2002. GE HealthCare: over 95M scans a year. Low: 0 (1981) rising to 60M (2002) = 0.66B exams; 60M to 95M over 2003-17 = 1.16B; 95M a year for 2018-25 = 0.76B; total 2.6B. High assumes 110M by 2017 and 130M by 2025 (unsourced): 2.9B. An OECD-data study cites estimates that 20-50% of imaging is low-value, so 50-80% count as beneficial; assume 4 (low) or 2 (high) scans per person: 2.6B x 0.5 / 4 = 0.33B, rounded to 0.3B; 2.9B x 0.8 / 2 = 1.17B, rounded down to 1.1B. Share 0.005, a sixth of Rabi's 0.03: Rabi built his resonance method on Stern's beams and magnetic state-sorting, learned in Stern's lab, and Stern first measured the proton magnetism MRI reads. But bulk NMR, imaging, magnets and computing came from others. Credited: about 1.5M-5.5M people.^{[6],[9],[14],[15],[16]}

  Sources: NobelPrize.org (Nobel Assembly at Karolinska Institutet); GE HealthCare; Healthcare (MDPI), via PubMed Central; arXiv (preprint 1109.4864); Springer, via OAPEN Library

• Low confidenceRippleModeledTechnology

  Economic benefits of GPS to US private industry, which depends on atomic clocks

  $9.6–19.2

  billion in economic value, credited share

  That is 0.3% of $3.2–6.4 trillion in economic value since 1984.

  How this number was built

  Same range as the Einstein and Rabi profiles. RTI International's 2019 study for NIST puts US private-sector GPS benefits for 1984-2017 at about $1.4 trillion, range $903 billion-$1.8 trillion (2017 dollars). Its Figure ES-1 shows about $300 billion of benefit in 2017 alone; scaling by the study's own range gives $200B-$400B a year. For 2018-2025 we hold that rate flat, with no further growth: 8 x $200B = $1.6T (low) and 8 x $400B = $3.2T (high). Totals $2.50T-$5.00T in 2017 dollars; BLS CPI-U (313.689 / 245.120 = 1.28) gives about $3.2T-$6.4T in 2024 dollars. Other countries excluded. Share 0.003: NIST's first atomic clock (1949) used Rabi's resonance technique, which grew from Stern's molecular beams; Rabi (0.01), Ramsey, clock builders and relativity were essential. Credited about $9.6B-$19B.^{[9],[17],[18],[19]}

  Sources: National Institute of Standards and Technology (NIST); US Bureau of Labor Statistics; National Institute of Standards and Technology (NIST); Springer, via OAPEN Library

• Minor

  Military service and research in World War I

  Stern entered the German army in 1914 (Segrè says he was drafted; Toennies and colleagues say he volunteered) and served mainly as a weather observer at Lomsha in Russian Poland. Late in the war Walther Nernst had him transferred to a military office in Berlin. Segrè writes that Stern and the other physicists there gave as much time as they could to pure physics.^[5],[6],[10]

• Minor

  Consultant to the US War Department in World War II

  After becoming a US citizen in 1939, Stern served as a consultant to the War Department during World War II; Toennies and colleagues note that citizenship let him join secret military research. Our sources give no details of this work. Segrè notes only that one Pittsburgh paper, on changes in potassium chloride under X-rays, was connected with war work. Our sources document no link to weapons development.^[5],[6],[7]

• Minor

  Dual-use descendants

  Atomic clocks, which grew from the beam resonance methods of Stern's school, are essential to GPS. RTI International's report for NIST notes that GPS was originally launched for US military use and was first used in combat in the 1991 Persian Gulf War.^{[9],[17],[19]}

• 1933

  Persecution

  Under the Nazi civil service law of 7 April 1933, his Jewish assistants Estermann, Frisch and Schnurmann were dismissed. Stern was exempt only as a World War I veteran and expected more antisemitic measures to follow.^[6],[8],[12]

• 1933

  Censorship

  The new authorities ordered the portrait of Einstein removed from his Hamburg office. He took it home, and it later hung in his study in Berkeley.^[5],[9]

• 1933

  Exile

  He resigned his Hamburg chair and emigrated to the United States. His institute soon fell apart. In Pittsburgh, with meagre Depression-era support, he never regained the lead in the field he had built.^{[5],[6],[10],[11]}

• 1933

  Exile

  Warned that she was on a Nazi list of people to be arrested for political reasons, his older sister Berta fled Breslau with her family in April 1933. Austria and Switzerland refused them; they lived in France for three years before reaching the US.^[9],[20]

• —

  Family killed

  His stepmother, Paula Stern, and her two sisters starved to death at Theresienstadt, a Nazi ghetto from which more than three-quarters of the Jewish prisoners did not survive.^[9],[13]

Stern was born in Upper Silesia to Oskar Stern and Eugenie Rosenthal. His longtime colleague Immanuel Estermann wrote that his parents belonged to a prosperous Jewish family of grain merchants and millers. The biographies we consulted say nothing about religious practice or his personal view of Judaism, and Wikipedia describes the household of his sister Berta as a secular Jewish family. Nazi law treated him as Jewish: he escaped the 1933 dismissals of Jewish university staff only because he had served in World War I. His stepmother died in the Holocaust. After the war he avoided official ties to Germany and refused his German pension.^{[5],[6],[8],[9],[10],[11],[20]}

1. February 17, 1888

   Born in Sohrau, Upper Silesia (now Żory, Poland), the eldest of five children of Jewish mill owner Oskar Stern and Eugenie Rosenthal.^[1],[5],[6]

2. 1892

   The family moves to Breslau (now Wrocław), where he later attends the Johannes Gymnasium.^[2],[5]

3. 1912

   Earns his PhD in physical chemistry at Breslau and becomes Albert Einstein's first postdoctoral co-worker, in Prague and then Zurich.^[2],[6]

4. 1914

   Serves in the German army in World War I, mostly as a weather observer at Lomsha in Russian Poland; late in the war he works in Berlin.^[5],[6]

5. 1919

   As Max Born's assistant in Frankfurt, begins his molecular beam experiments and by 1920 uses a beam to measure the speeds of gas atoms directly.^[5],[6],[8]

6. February 1922

   Walther Gerlach, completing their joint experiment in Frankfurt while Stern taught in Rostock, splits a beam of silver atoms in two with a magnetic field, proving space quantization.^{[1],[6],[7],[8]}

7. 1923

   Becomes professor of physical chemistry and director of a new institute at the University of Hamburg, the center of molecular beam research.^[2],[5]

8. 1933

   His team measures the proton's magnetic moment at about 2.5 times the value theory predicted, showing the proton has inner structure.^[3],[6],[8]

9. 1933

   After the Nazis dismiss his Jewish assistants, he resigns his Hamburg post, before he too can be forced out.^[5],[8],[9]

10. 1933

    Emigrates to the United States as research professor of physics at the Carnegie Institute of Technology in Pittsburgh.^[2],[5]

11. November 9, 1944

    Announced as winner of the unshared 1943 Nobel Prize in Physics; he receives it in New York that December, as war prevents a Stockholm ceremony.^{[1],[3],[4],[6]}

12. 1945

    Retires from Carnegie Tech, settles in Berkeley near his sister Berta, and is elected to the US National Academy of Sciences.^[5],[9]

13. December 12, 1946

    Delivers his Nobel lecture, "The Method of Molecular Rays".^[21]

14. August 17, 1969

    Dies in Berkeley, aged 81, after a heart attack suffered at the movies.^[1],[5]

1. 1.Otto Stern - Facts · NobelPrize.org (Nobel Prize Outreach)
2. 2.Otto Stern - Biographical · NobelPrize.org (from Nobel Lectures, Physics 1942-1962, Elsevier, 1964), 1964
3. 3.The Nobel Prize in Physics 1943 - Award ceremony speech (broadcast lecture by E. Hulthén, 10 December 1944) · NobelPrize.org, 1944
4. 4.Otto Stern - Nominations · NobelPrize.org (Nobel Prize nomination archive)
5. 5.Otto Stern 1888-1969: A Biographical Memoir, by Emilio Segrè · National Academy of Sciences, Biographical Memoirs, 1973
6. 6.Otto Stern (1888-1969): The founding father of experimental atomic physics, by J. P. Toennies, H. Schmidt-Böcking, B. Friedrich and J. C. A. Lower (Annalen der Physik 523, 2011) · arXiv (preprint 1109.4864), 2011
7. 7.Stern and Gerlach: How a Bad Cigar Helped Reorient Atomic Physics, by Bretislav Friedrich and Dudley Herschbach · Physics Today (American Institute of Physics), 2003
8. 8.Otto Stern's Molecular Beam Method and Its Impact on Quantum Physics, by Bretislav Friedrich and Horst Schmidt-Böcking (chapter 5 of Molecular Beams in Physics and Chemistry, Springer, open access) · Max Planck Society repository (MPG.PuRe), 2021
9. 9.Molecular Beams in Physics and Chemistry: From Otto Stern's Pioneering Exploits to Present-Day Feats, ed. B. Friedrich and H. Schmidt-Böcking (open-access book; cited: Preface; ch. 3, L. K. Templeton, 'My Uncle Otto Stern'; ch. 4, A. Templeton, 'My Great Uncle'; ch. 7, D. Kleppner, 'Our Enduring Legacy from Otto Stern') · Springer, via OAPEN Library, 2021
10. 10.Stern, Otto (Complete Dictionary of Scientific Biography entry by Immanuel Estermann) · Encyclopedia.com (Charles Scribner's Sons / Gale), 2008
11. 11.Otto Stern (1888-1969) - Short portrait · ETH Library, ETH Zurich
12. 12.Law for the Restoration of the Professional Civil Service · United States Holocaust Memorial Museum, Holocaust Encyclopedia
13. 13.Theresienstadt · United States Holocaust Memorial Museum, Holocaust Encyclopedia
14. 14.Press release: The Nobel Prize in Physiology or Medicine 2003 (magnetic resonance imaging) · NobelPrize.org (Nobel Assembly at Karolinska Institutet), 2003
15. 15.Committing to sustainability in MRI · GE HealthCare
16. 16.Diagnostic Technology: Trends of Use and Availability in a 10-Year Period (2011-2020) among Sixteen OECD Countries · Healthcare (MDPI), via PubMed Central, 2023
17. 17.Economic Benefits of the Global Positioning System (GPS), final report by RTI International · National Institute of Standards and Technology (NIST), 2019
18. 18.Consumer Price Index for All Urban Consumers (CPI-U), series CUUR0000SA0 · US Bureau of Labor Statistics
19. 19.A Brief History of Atomic Clocks at NIST · National Institute of Standards and Technology (NIST)
20. 20.Lieselotte Templeton · Wikipedia
21. 21.Otto Stern - Nobel Lecture: The Method of Molecular Rays (12 December 1946) · NobelPrize.org, 1946