1900 in science

• 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.

• Moses Gomberg identifies the first organic radical (according to the modern definition), triphenylmethyl radical.
• Johannes Rydberg refines the expression for observed hydrogen line wavelengths.

• 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.{{cite news|title=Magnetism of the Earth|newspaper=The New York Times|date=January 6, 1900|page=1}}
• Richard Dixon Oldham distinguishes between primary, secondary and tertiary waveforms as recorded by seismometers.{{cite web|first=Andrew|last=Grout|title=Oldham, Richard Dixon (1858–1936)|work=Oxford Dictionary of National Biography|publisher=Oxford University Press|year=2004|url=http://www.oxforddnb.com/view/article/37820|doi=10.1093/ref:odnb/37820|accessdate=2011-10-20}} {{ODNBsub}}

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

• Hugo de Vries publishes the results of his experiments in Mendelian inheritance.{{Cite journal |last=De Vries |first=H. |year=1900 |title=Sur la loi de disjonction des hybrides |trans-title=On the law of hybrid disjunction |url=https://www.biodiversitylibrary.org/page/3581872 |journal=Comptes rendus de l'Académie des sciences |language=fr |location=Paris |volume=130 |pages=845–847}}

• 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.{{cite web|url=http://academic.scranton.edu/faculty/doughertys1/euler.htm |title=36 Officer Problem |url-status=dead |archiveurl=https://web.archive.org/web/20080828085817/http://academic.scranton.edu/faculty/doughertys1/euler.htm |archivedate=2008-08-28 }}
• Alfred Young introduces the Young tableau.

• English surgeon and ophthalmologist Edward Treacher Collins describes the essential traits of Treacher Collins syndrome.{{cite journal|last=Treacher Collins|first=E.|year=1900|title=Cases with symmetrical congenital notches in the outer part of each lid and defective development of the malar bones|journal=Transactions of the Ophthalmological Societies of the United Kingdom|volume=20|pages=190–192}}
• 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.

• 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.

• Kodak introduce their first Brownie (camera).

• April 26 – Guglielmo Marconi patents the tuned circuit.
• 6-10 August The first International Congress of Physics is held in Paris{{Cite book |last=Poskett |first=James |url=https://www.google.fr/books/edition/Horizons/6m8XEAAAQBAJ?hl=en&gbpv=1&dq=%22International+Congress+of+Physics%22+lebedev&pg=PT160&printsec=frontcover |title=Horizons: A Global History of Science |date=2022-03-24 |publisher=Penguin Books Limited |isbn=978-0-241-39411-3 |language=en}}
• 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.{{cite book|first=Edward G.|last=Steward|title=Quantum Mechanics: Its Early Development and the Road to Entanglement|publisher=Imperial College Press|location=London|year=2008|pages=36–42}}
• 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.{{cite journal|last1=Planck|first1=M.|year=1900|title=Über eine Verbesserung der Wien'schen Spectralgleichung|url=https://archive.org/stream/verhandlungende01goog#page/n212/mode/2up|journal=Verhandlungen der Deutschen Physikalischen Gesellschaft|volume=2|pages=202–204}} Translated in {{cite book|last1=ter Haar|first1=D.|author-link=Dirk ter Haar|year=1967|chapter=On an Improvement of Wien's Equation for the Spectrum|url=http://www.ffn.ub.es/luisnavarro/nuevo_maletin/Planck%20%281900%29,%20Improvement%20of%20Wien%27s.pdf|title=The Old Quantum Theory|publisher=Pergamon Press|pages=79–81|lccn=66029628}}
• December 14 – Max Planck restates his law, utilising the Planck postulate, at a meeting of the German Physical Society.{{cite journal|last1=Planck|first1=M.|year=1900|url=https://archive.org/stream/verhandlungende01goog#page/n247/mode/2up|title=Zur Theorie des Gesetzes der Energieverteilung im Normalspectrum|journal=Verhandlungen der Deutschen Physikalischen Gesellschaft|volume=2|pages=237–245}} Translated in {{cite book|last1=ter Haar|first1=D.|year=1967|url=http://www.ffn.ub.es/luisnavarro/nuevo_maletin/Planck%20%281900%29,%20Distribution%20Law.pdf|title=The Old Quantum Theory|publisher=Pergamon Press|page=82|lccn=66029628}}
• December 23 – Reginald Fessenden, experimenting with a high-frequency spark transmitter, successfully transmits speech over a distance of about 1.6 kilometers (one mile), from Cobb Island, Maryland, which appears to have been the first audio radio transmission.
• Gamma rays discovered by Paul Villard while studying uranium decay.

• Karl Landsteiner makes the first discovery of blood types, identifying the ABO blood group system.{{cite journal|last=Landsteiner|first=K.|title=Zur Kenntnis der antifermentativen, lytischen und agglutinierenden Wirkungen des Blutserums und der Lymphe|journal=Zentralblatt für Bakteriologie|year=1900|volume=27|pages=357–62}}
• Carl Rasch coins the term 'polymorphous light eruption'.
• Jōkichi Takamine and Keizo Uenaka discover adrenaline.{{cite journal|last=Yamashima|first=T.|title=Jokichi Takamine (1854–1922), the samurai chemist, and his work on adrenalin|journal=Journal of Medical Biography|volume=11|issue=2|pages=95–102|year=2003|pmid=12717538|doi=10.1177/096777200301100211}}

• Richard J. Ussher and Robert Warren publish The Birds of Ireland.{{Cite book |last=Ussher |first=Richard John |url=http://www.biodiversitylibrary.org/bibliography/49473 |title=The birds of Ireland; an account of the distribution, migrations and habits of birds as observed in Ireland, with all additions to the Irish list |last2=Warren |first2=Robert |date=1900 |publisher=Gurney and Jackson (successors to Mr. Van Voorst) |location=London |doi=10.5962/bhl.title.49473}}

• Copley Medal: Marcellin Berthelot{{cite web |title=Copley Medal {{!}} British scientific award |url=https://www.britannica.com/science/Copley-Medal |website=Encyclopædia Britannica |accessdate=23 July 2020 }}

• January 2 – Una Ledingham (died 1965), English physician specialising in diabetes mellitus and pregnancy.{{cite book|title=The Biographical Dictionary of Women in Science: pioneering lives from ancient times to the mid-20th century|url=https://archive.org/details/biographicaldict00ogil_0|url-access=registration|year=2000|publisher=Routledge|location=New York}}
• March 4 – Heinrich Willi (died 1971), Swiss pediatrician.
• March 8 – Howard H. Aiken (died 1973), American computing pioneer.
• March 19 – Frédéric Joliot (died 1958), French physicist.{{cite web |title=The Nobel Prize in Chemistry 1935 |url=https://www.nobelprize.org/prizes/chemistry/1935/joliot-fred/facts/ |website=NobelPrize.org |access-date=2 January 2022}}
• March 20 – Amelia Chopitea Villa (died 1942), Bolivia's first female physician.
• April 3 – Albert Ingham (died 1967), English mathematician.
• April 25 – Wolfgang Pauli (died 1958), Austrian-born physicist.
• April 26 – Charles Richter (died 1985), American geophysicist and inventor.
• April 28 – Jan Oort (died 1992), Dutch astronomer.
• May 5 – Helen Redfield (died 1988), American geneticist.
• May 6 – Zheng Ji (died 2010), Chinese biochemist and nutritionist.
• May 10 – Cecilia Payne-Gaposchkin (died 1979), English-born American astronomer and astrophysicist.{{cite book|title=The Biographical Encyclopedia of Astronomers|date=2007|publisher=Springer|isbn=9780387304007|location=New York}}
• May 22 – Honor Fell (died 1986), English biologist.
• June 3 – Leo Picard (died 1997), German-born Israeli geologist.
• June 24 – Wilhelm Cauer (killed 1945), German mathematician and electronic engineer.
• June 25
• Zinaida Aksentyeva (died 1969), Ukrainian/Soviet astronomer.
• Philip D'Arcy Hart (died 2006), English medical researcher, pioneer in tuberculosis treatment.
• June 30 – James Stagg (died 1975) Scottish meteorologist.
• July 9 – Frances McConnell-Mills, born Frances Mary McConnell (died 1975), American toxicologist.
• August 25 – Hans Adolf Krebs (died 1981), German-born medical doctor and biochemist.
• August 26 – Hellmuth Walter (died 1980), German-born engineer and inventor.
• October 2 – Isabella Forshall (died 1989), English pediatric surgeon.
• November 5 – Ethelwynn Trewavas (died 1993), English ichthyologist.{{cite news|url=https://www.independent.co.uk/news/people/obituary-ethelwynn-trewavas-1462529.html |archive-url=https://ghostarchive.org/archive/20220501/https://www.independent.co.uk/news/people/obituary-ethelwynn-trewavas-1462529.html |archive-date=2022-05-01 |url-access=subscription |url-status=live|title=Obituary: Ethelwynn Trewavas|date=1993-08-21|work=The Independent|location=London|accessdate=2017-10-22}}{{cbignore}}
• November 21 – Bettina Warburg (died 1990), German-born American psychiatrist.
• November 26 – Anna Maurizio (died 1993), Swiss biologist.{{Cite web|url=http://www.encyclopedia.com/women/encyclopedias-almanacs-transcripts-and-maps/maurizio-anna-1900-1993|title=Maurizio, Anna (1900–1993) {{!}} Encyclopedia.com: FREE online dictionary|website=encyclopedia.com|language=en|access-date=2017-10-22|archive-date=October 23, 2017|archive-url=https://web.archive.org/web/20171023011417/http://www.encyclopedia.com/women/encyclopedias-almanacs-transcripts-and-maps/maurizio-anna-1900-1993|url-status=live}}
• December 9 – Joseph Needham (died 1995), English biochemist and writer on the history of science and technology in China.
• December 12 – Mária Telkes (died 1995), Hungarian-American scientist and inventor.
• December 17 – Mary Cartwright (died 1998), English mathematician, one of the first people to analyze a dynamical system with chaos.{{cite web|url=http://www-groups.dcs.st-and.ac.uk/~history/Obits/Cartwright.html|title=Mary Cartwright Times obituary|website=www-groups.dcs.st-and.ac.uk|accessdate=2017-10-20}}
• Robina Addis (died 1986), English psychiatric social worker.{{cite web|url=http://wellcomelibrary.org/collections/digital-collections/mental-healthcare/robina-addis/|title=Robina Addis|publisher=Wellcome Library|accessdate=2019-03-16}}
• Margaret Altmann (died 1984), German-American biologist.{{Cite book|title=American women of science since 1900|last=Wayne|first=Tiffany K.|date=2011|publisher=ABC-CLIO|isbn=9781598841589|location=Santa Barbara, Calif.|pages=189|oclc=702118874}}
• Ernest Gibbins (killed 1942), English entomologist.

• January 13 – Peter Waage (born 1833), Norwegian chemist.
• January 22 – David E. Hughes (born 1831), British-American inventor.
• March 6 – Gottlieb Daimler (born 1834), German engineer, automotive pioneer.
• March 10 – George James Symons (born 1838), English meteorologist.
• April 1 – George Jackson Mivart (born 1827), English biologist.
• August 4 – Étienne Lenoir (born 1822), Belgian mechanical engineer.
• August 31 – John Bennet Lawes (born 1814), English agricultural scientist.
• September 4 – Charles Harrison Blackley (born 1820), English allergist.
• October 16 – Henry Acland (born 1815), English physician.
• October 29 – Bruno Abakanowicz (born 1852), Polish mathematician, inventor and electrical engineer.

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Category:19th century in science

Category:1900s in science