1900 in science

The year 1900 in science and technology involved some significant events, listed below.

Aeronautics

July 2 – The first rigid airship flight is made by the LZ1 designed by Ferdinand von Zeppelin.
c. October 3 – The Wright brothers begin their first manned glider experimental flights at Kitty Hawk, North Carolina; their first few attempts fail.

Chemistry

Moses Gomberg identifies the first organic radical, triphenylmethyl radical.
Johannes Rydberg refines the expression for observed hydrogen line wavelengths.

Earth sciences

January 5 – Physicist Dr Henry A. Rowland of Johns Hopkins University in Baltimore announces his theory that the cause of Earth's magnetic field is its own rotation, based on experiments to produce magnetism by the rotation of a motor.
Richard Dixon Oldham distinguishes between primary, secondary and tertiary waveforms as recorded by seismometers.

Exploration

American explorer Robert Peary first sights Kaffeklubben Island, the northernmost point of land on Earth.

Genetics

Hugo de Vries publishes the results of his experiments in Mendelian inheritance.

Mathematics

Max Dehn introduces two examples of Dehn plane and the Dehn invariant.
David Hilbert states his list of 23 problems which show where some further mathematical work is needed.
Russell's paradox is first discovered by Ernst Zermelo but he does not publish it, and it is known only to Hilbert, Husserl and other members of the University of Göttingen.
Gaston Tarry confirms Euler's conjecture that no 6×6 orthogonal Graeco-Latin square is possible.
Alfred Young introduces the Young tableau.

Medicine

English surgeon and ophthalmologist Edward Treacher Collins describes the essential traits of Treacher Collins syndrome.
German gynecologist Hermann Johannes Pfannenstiel publishes his description of the "Pfannenstiel incision", a transverse incision used in genitourinary surgery that continues to be widely used.

Paleontology

Barnum Brown finds the first partial skeleton of Tyrannosaurus rex in eastern Wyoming.
Dr. James K. Hampson identifies the Island 35 Mastodon skeleton in the Mississippi River.

Photography

Kodak introduce their first Brownie (camera).

Physics

April 26 – Guglielmo Marconi patents the tuned circuit.
6-10 August The first International Congress of Physics is held in Paris
* Pyotr Lebedev presents first experimental evidence of radiation pressure during the conference
October 7 – Max Planck hosts fellow physicist Heinrich Rubens for tea and considers news that Rubens' experiments have contradicted Planck's theories. Later this evening, Planck reviews and refines his calculations to what will be announced on October 19 as Planck's law.
October 19 – Max Planck first states Planck's law of black-body radiation to a meeting of the German Physical Society in Berlin, marking the birth of modern quantum mechanics.
December 14 – Max Planck restates his law, utilising the Planck postulate, at a meeting of the German Physical Society.
December 23 – Reginald Fessenden, experimenting with a high-frequency spark transmitter, successfully transmits speech over a distance of about 1.6 kilometers, from Cobb Island, Maryland, which appears to have been the first audio radio transmission.
Gamma rays discovered by Paul Villard while studying uranium decay.

Physiology

Karl Landsteiner makes the first discovery of blood types, identifying the ABO blood group system.
Carl Rasch coins the term 'polymorphous light eruption'.
Jōkichi Takamine and Keizo Uenaka discover adrenaline.

Zoology

Richard J. Ussher and Robert Warren publish The Birds of Ireland.

Awards

Copley Medal: Marcellin Berthelot

Births

January 2 – Una Ledingham, English physician specialising in diabetes mellitus and pregnancy.
March 4 – Heinrich Willi, Swiss pediatrician.
March 8 – Howard H. Aiken, American computing pioneer.
March 19 – Frédéric Joliot, French physicist.
March 20 – Amelia Chopitea Villa, Bolivia's first female physician.
April 3 – Albert Ingham, English mathematician.
April 25 – Wolfgang Pauli, Austrian-born physicist.
April 26 – Charles Richter, American geophysicist and inventor.
April 28 – Jan Oort, Dutch astronomer.
May 5 – Helen Redfield, American geneticist.
May 6 – Zheng Ji, Chinese biochemist and nutritionist.
May 10 – Cecilia Payne-Gaposchkin, English-born American astronomer and astrophysicist.
May 22 – Honor Fell, English biologist.
June 3 – Leo Picard, German-born Israeli geologist.
June 24 – Wilhelm Cauer, German mathematician and electronic engineer.
June 25
* Zinaida Aksentyeva, Ukrainian/Soviet astronomer.
* Philip D'Arcy Hart, English medical researcher, pioneer in tuberculosis treatment.
June 30 – James Stagg Scottish meteorologist.
July 9 – Frances McConnell-Mills, born Frances Mary McConnell, American toxicologist.
August 25 – Hans Adolf Krebs, German-born medical doctor and biochemist.
August 26 – Hellmuth Walter, German-born engineer and inventor.
October 2 – Isabella Forshall, English pediatric surgeon.
November 5 – Ethelwynn Trewavas, English ichthyologist.
November 21 – Bettina Warburg, German-born American psychiatrist.
November 26 – Anna Maurizio, Swiss biologist.
December 9 – Joseph Needham, English biochemist and writer on the history of science and technology in China.
December 12 – Mária Telkes, Hungarian-American scientist and inventor.
December 17 – Mary Cartwright, English mathematician, one of the first people to analyze a dynamical system with chaos.
Robina Addis, English psychiatric social worker.
Margaret Altmann, German-American biologist.
Ernest Gibbins, English entomologist.

Deaths

January 13 – Peter Waage, Norwegian chemist.
January 22 – David E. Hughes, British-American inventor.
March 6 – Gottlieb Daimler, German engineer, automotive pioneer.
March 10 – George James Symons, English meteorologist.
April 1 – George Jackson Mivart, English biologist.
August 4 – Étienne Lenoir, Belgian mechanical engineer.
August 31 – John Bennet Lawes, English agricultural scientist.
September 4 – Charles Harrison Blackley, English allergist.
October 16 – Henry Acland, English physician.
October 29 – Bruno Abakanowicz, Polish mathematician, inventor and electrical engineer.