Physical world and mathematics

Otto L. Muskens

Otto L. Muskens is a Dutch nanophotonics researcher, Professor of Physics at the University of Southampton since 2014, known for light scattering in nanowire mats.

Otto Laporte

Otto Laporte (1902–1971) was a German-born American physicist at the University of Michigan, known for the Laporte rule in atomic spectroscopy and for shock tube research.

Otto Lehmann (physicist)

Otto Lehmann (1855–1922) was a German physicist who succeeded Heinrich Hertz at Karlsruhe, coined the term "liquid crystal," and promoted the field from 1889 onward.

Otto Lummer (1860–1925) was a German experimental physicist whose precision blackbody measurements at the Physikalisch-Technische Reichsanstalt helped lead Max Planck to the quantum hypothesis in 1900.

Otto M. Nikodym

Otto M. Nikodym (Otton Marcin Nikodym, 1887–1974) was a Polish mathematician known for the Radon–Nikodym theorem, the Nikodym set, and the Nikodym–Grothendieck boundedness theorem; he taught at Kenyon College in Ohio from 1948 to 1965.

Oct 15, 2026

Otto Neurath

Otto Neurath (1882–1945) was an Austrian philosopher, economist, and sociologist, a leading member of the Vienna Circle who founded the Isotype pictorial language and led the Unity of Science movement.

Otto Nordenskjöld

Otto Nordenskjöld (Nils Otto Gustaf Nordenskjöld) was a Swedish geographer and explorer who led the Swedish Antarctic Expedition of 1901–1904, during which his ship was crushed by ice.

Otto Richard Lummer

Otto Richard Lummer (1860–1925) was a German experimental physicist who, with Wien and Pringsheim at the Reichsanstalt in Berlin, verified the radiation laws and prompted Planck's 1900 quantum formula.

Otto Robert Frisch

Otto Robert Frisch was an Austrian-born British physicist who, with his aunt Lise Meitner, interpreted and named nuclear fission, proved it experimentally in 1939, and co-authored the 1940 Frisch–Peierls memorandum showing an atomic bomb was feasible.

Otto Ruff

Otto Ruff (1871–1939) was a German inorganic chemist who became the leading authority on fluorine chemistry after Moissan's death, preparing new fluorides including uranium hexafluoride.

Otto S. Wolfbeis

Otto S. Wolfbeis (1947–2023) was an Austrian chemist who held the chair of Analytical and Interface Chemistry at the University of Regensburg and pioneered optical chemical sensors and biosensors.

Otto Schmidt

Otto Yulyevich Schmidt (Отто Юльевич Шмидт; 1891–1956) was a Soviet mathematician, Arctic explorer, and planetary scientist whose 1944 theory of Earth's origin became the core-accretion model.

Otto Schönherr

Otto Schönherr (1861–1926) was a German chemist at BASF in Ludwigshafen am Rhein, twice nominated for the Nobel Prize, known for the electric-arc oxidation of nitrogen to nitric acid.

Otto Schreier

Otto Schreier (1901–1929) was an Austrian mathematician who solved Hölder's group extension problem, proved subgroups of free groups are free, and refined the Jordan–Hölder theorem.

Otto Stern

Otto Stern was a German-born American experimental physicist who founded molecular beam physics, co-created the 1922 Stern–Gerlach experiment, and won the 1943 Nobel Prize in Physics.

Otto Stolz

Otto Stolz (1842–1905) was an Austrian mathematician, professor at the University of Innsbruck from 1872, known for the Stolz–Cesàro theorem and for coining "Archimedes' axiom".

Otto Struve

Otto Struve (Отто Людвигович Струве, 1897–1963) was a Russian-born American astronomer of a famous astronomical family, known for showing that early-type stars rotate rapidly and for directing four observatories.

Otto Szász

Otto Szász (1884–1952) was a Hungarian mathematician who held a chair at Frankfurt until the Nazis expelled him in 1933, then taught at the University of Cincinnati.

Otto Toeplitz

Otto Toeplitz (1881–1940) was a German mathematician, born in Breslau, who introduced Toeplitz matrices in 1911, helped build the German school of functional analysis, and posed the inscribed-square conjecture.

Otto von Guericke

Otto von Guericke, born Otto Gericke, was a German scientist, inventor, and burgomaster of Magdeburg who invented the air pump and showed the Magdeburg hemispheres in 1654.

Otto Wallach

Otto Wallach (1847–1931) was a German organic chemist who held the chemistry chair at Göttingen and won the 1910 Nobel Prize in Chemistry for his pioneer work on alicyclic compounds, founding terpene chemistry.

Otto Wiener (physicist)

Otto Wiener (1862–1927) was a German physicist whose 1890 experiment photographed standing light waves, showing that the electric component of light drives the chemical effect.

Otto Wilhelm von Struve

Otto Wilhelm von Struve, known in Russian as Otto Vasil'evich Struvé, was a Russian astronomer who directed the Pulkovo Observatory from 1862 to 1889 and discovered over 500 double stars.

Oct 15, 2026

Otway Basin

The Otway Basin is an onshore and offshore sedimentary basin along the coasts of Victoria and South Australia, a gas province formed during the separation of Australia and Antarctica.

Ötzi

Ötzi, the Iceman or Similaun Man: a 5,300-year-old Copper Age glacier mummy found in 1991 by Erika and Helmut Simon on the Tisenjoch, South Tyrol, Italy; displayed in Bolzano, with 92% Anatolian farmer ancestry, dark skin, and an arrow-wound death.

Ou Chen

Ou Chen (陈鸥) is a materials chemist and Professor of Chemistry at Brown University, known for building the first single-component quasicrystalline nanocrystal superlattice, reported in Science in 2018.

Ounce

The ounce, abbreviated oz, is a unit of mass equal to 28.349523125 grams, one sixteenth of a pound; gold and silver are priced in the heavier troy ounce.

Our Lady of La Salette

Our Lady of La Salette is a reported apparition of the Virgin Mary to two shepherd children on a mountain near La Salette, France, on September 19, 1846.

Oct 22, 2026

Out-of-time-order correlator

The out-of-time-order correlator, or OTOC, is a four-point quantum correlation function that tracks how a localized perturbation scrambles through a many-body system, serving as a diagnostic of quantum chaos.