1902 in science
- May 15 – Lyman Gilmore claims to have flown his steam-powered fixed-wing aircraft, although his proof is supposedly destroyed in a 1935 fire.
- Hermann Emil Fischer and Joseph von Mering discover that barbitone (barbital or Veronal) is an effective hypnotic agent. It becomes the first commercially marketed barbiturate, being used as a treatment for insomnia from 1903.
- Auguste Verneuil develops the Verneuil process for making synthetic rubies.
- German chemist Wilhelm Ostwald developed the Ostwald process and patented it in 1902.
- April–May – Eruption of Mount Pelée in Martinique.
- Mercalli intensity scale introduced as a seismic scale for earthquakes by Giuseppe Mercalli.
- December 30 – Discovery Expedition: Scott, Shackleton and Wilson reach the furthest southern point reached thus far by man, south of 82°S.
- Walter Sutton (in the United States) and Theodor Boveri (in Germany) independently develop the Boveri–Sutton chromosome theory, explaining the mechanism underlying the laws of Mendelian inheritance by identifying chromosomes as the carriers of genetic material.
History of science
- May 17 – Archaeologist Valerios Stais identifies the Antikythera mechanism, now considered to be the oldest known analog computer.
- June 16 – Bertrand Russell writes to Gottlob Frege informing him of the problem in naive set theory that will become known as Russell's paradox.
- Gyula Farkas publishes the first proof of Farkas' lemma.
- Henri Lebesgue introduces the theory of Lebesgue integration.
- January 1 – Nurses Registration Act 1901 comes into effect in New Zealand, making it the first country in the world to require state registration of nurses. On January 10, Ellen Dougherty becomes the world's first registered nurse.
- Remains of the second Tyrannosaurus rex specimen, the first recognized as such, are excavated by Barnum Brown in the Hell Creek Formation of Montana.
- Oliver Heaviside and Arthur E. Kennelly independently predict the existence of what will become known as the Kennelly-Heaviside Layer of the ionosphere.
- James Jeans finds the length scale required for gravitational perturbations to grow in a static nearly homogeneous medium.
- Philipp Lenard observes that maximum photoelectron energies are independent of illuminating intensity but depend on frequency.
- Gilbert N. Lewis develops the cubical atom atomic model.
- Theodor Svedberg suggests that fluctuations in molecular bombardment cause the Brownian motion.
- Vienna Psychoanalytic Society begins to meet as the Wednesday Psychological Society in Sigmund Freud's apartment.
- July 17 – Willis Carrier devises air conditioning in New York City.
- December 10 – Old Aswan Dam, designed by William Willcocks, completed across the River Nile in Egypt.
- First Vierendeel bridge built, across the Scheldt at Avelgem in Belgium.
- Orville and Wilbur Wright fly for the first time at Kitty Hawk, North Carolina
- October – First Mountain gorillas (Gorilla beringei beringei) discovered by Captain Robert von Beringe in German East Africa.
- Nobel Prizes
- Hughes Medal first awarded by the Royal Society of London to J. J. Thomson
- June 26 – First recipients of the Order of Merit in the United Kingdom include
- February 10 – Walter Houser Brattain (died 1987), American physicist.
- February 16 – Zhang Yuzhe (died 1986), Chinese astronomer.
- May 25 – Calvin Souther Fuller (died 1994), American physical chemist at AT&T Bell Laboratories.
- June 15 – Erik Erikson, né Salomonsen (died 1994), German-born psychologist.
- August 8 – Paul Dirac (died 1984), English physicist.
- August 13 – Felix Wankel (died 1988), German mechanical engineer.
- November 2 – Sergey Lebedev (died 1974), Russian computer scientist.
- March 6 – Moritz Kaposi (born 1837), dermatologist.
- April 12 – Alfred Cornu (born 1841), physicist.
- May 26 – Almon Strowger (born 1839), telecommunications engineer.
- September 5 – Rudolf Virchow (born 1821), pathologist and biologist.
- September 18 - Thorborg Rappe (born 1832), Swedish pioneer in the education of students with Intellectual disability.
- November 12 – William Henry Barlow (born 1812), railway civil engineer.
- December 22 – Richard von Krafft-Ebing (born 1840), sexologist.
- Vasily Dokuchaev (born 1845), geologist.
- Fischer, E. H.; Mering, J. (1903). "Ueber eine neue Classe von Schlafmitteln". Therapie der Gegenwart (in German). 5: 97–101. Retrieved 2010-09-13.
- "Genetics and Genomics Timeline – 1902: Theodor Boveri (1862-1915) and Walter Sutton (1877-1916) propose that chromosomes bear hereditary factors in accordance with Mendelian laws". Genome News Network. J. Craig Venter Institute. 2004. Retrieved 2011-12-21.
- Haughton, Brian (2006). Hidden History: Lost Civilizations, Secret Knowledge, and Ancient Mysteries. Franklin Lakes, NJ: Career Press. pp. 43–44. ISBN 978-1-56414-897-1. Retrieved 2011-05-16.
- Frege, Gottlob (1997). Beaney, Michael, ed. The Frege Reader. Oxford: Blackwell. p. 253. ISBN 978-0-631-19445-3.
- Farkas, Gyula (1894). "A Fourier-féle mechanikai elv alkamazásai". Mathematikai és Természettudományi Értesítő. 12: 457–472.
- Crilly, Tony (2007). 50 Mathematical Ideas you really need to know. London: Quercus. p. 77. ISBN 978-1-84724-147-4.
- "Barnum Brown". Strange Science. 2015-06-14. Retrieved 2017-12-12.
- Schaller, G. B. (1963). The Mountain Gorilla: Ecology and Behavior. University of Chicago Press. ISBN 0-226-73635-0.