1915 in science

Astronomy

• March 19 – Pluto is photographed for the first time but is not classified as a planet.
• Einstein's new theory of general relativity is used to explain Mercury's strange motions that baffled Urbain Le Verrier.
• Robert Innes discovers Proxima Centauri, the closest star to Earth after the Sun.

  Chemistry

• Thomas Lyle Williams produces the mascara Maybelline.

  Earth sciences

• May 22 – Lassen Peak, one of the Cascade Volcanoes in Northern California, erupts, sending an ash plume 30,000 feet in the air and devastating the nearby area with pyroclastic flows and lahars. It is the only volcano to erupt in the contiguous United States between 1900 and 1980.
• Alfred Wegener publishes his theory of Pangea, which he calls Urkontinent.

  Paleontology

• The new theropod dinosaur genus and species Spinosaurus aegyptiacus is assigned by German paleontologist Ernst Stromer.

  Life sciences

• A global pandemic of encephalitis lethargica begins.
• Walter Bradford Cannon coins the term fight or flight to describe an animal's response to threats.
• Thomas Hunt Morgan, demonstrates non-inherited genetic mutation, undermining the conceptual basis of eugenics.
• Reginald Punnett's Mimicry in Butterflies is published in Cambridge
• Clara H. Hasse publishes a paper identifying the cause of citrus canker which leads to the development of methods for controlling the disease, saving the citrus crops in the southern United States from being wiped out.

  Mathematics

• Emmy Noether proves her theorem that any differentiable symmetry of the action of a physical system has a corresponding conservation law.
• Wacław Sierpiński describes the Sierpinski triangle.

  Physics

• August – Ada Hitchins' experimental results indicating that radium is formed by the decay of uranium are published.
• November 25 – Albert Einstein presents to the Prussian Academy of Sciences the Einstein field equations of general relativity. He abandons his hole argument for general relativity.
• Arnold Sommerfeld develops a modified Bohr atomic model with elliptic orbits to explain relativistic fine structure.

  Psychology

• Danish psychologist Edgar Rubin publishes Synsoplevede Figurer introducing the optical illusion which becomes known as the Rubin vase.

  Technology

• January 19 – Georges Claude patents the neon discharge tube for use in advertising.
• February 4 – John G. A. Kitchen patents the reversing rudder.
• March 3 – The National Advisory Committee for Aeronautics, the predecessor of NASA, is established in the United States.
• July 1 – First use of synchronization gear in aerial warfare.
• September 9 – William Foster & Co. of Lincoln in England complete the first prototype military tank "Little Willie".
• Wolfgang Gaede invents the diffusion pump.
• William Mills patents, develops and manufactures the Mills bomb, a hand grenade, at the Mills Munition Factory in Birmingham, England.
• Dagobert Müller von Thomamühl produces a form of hovercraft.

  Awards

• Nobel Prize
• * Physics – Sir William Henry Bragg and Sir William Lawrence Bragg
• * Chemistry – Richard Martin Willstätter

  Births

• January 11 – Lucille Farrier Stickel, American wildlife toxicologist.
• February 26 – Wang Daheng, Chinese optical physicist.
• February 28 – Peter Medawar, Brazilian-born British biologist, co-recipient of the Nobel Prize in Physiology or Medicine for his work in immunology.
• March 15 – Laurent Schwartz, French mathematician.
• March 16 – Kunihiko Kodaira, Japanese mathematician.
• May 30 – Henry Aaron Hill, American fluorocarbon chemist and first African American president of the American Chemical Society.
• June 15 – Thomas Huckle Weller, American virologist and co-recipient of the Nobel Prize in Physiology or Medicine for his work on polio.
• June 19 – Katherine Sanford, American cell biologist.
• June 24 – Fred Hoyle, English astronomer and science fiction writer.
• July 28 – Charles Hard Townes, American physicist and co-recipient of the Nobel Prize in Physics for developing the maser.
• October 1 – Jerome Bruner, American developmental and educational psychologist.
• October 26 – Lu Jiaxi, Chinese physical chemist.
• November 18 – Tang Aoqing, Chinese quantum chemist.
• November 30 – Henry Taube, Canadian-born recipient of the Nobel Prize in Chemistry.
• December 5 – Ren Xinmin, Chinese rocket scientist.
• December 22 – A. E. Wilder-Smith, English-born organic chemist.

  Deaths

• February 17 – Stanislaus von Prowazek, Bohemian-born parasitologist.
• April 19 – Sir Thomas Clouston, Scottish psychiatrist.
• March 21 – Ambrosius Hubrecht, Dutch zoologist.
• March 24 – Margaret Lindsay Huggins, Irish-born astronomer.
• May 2 – Clara Immerwahr, German chemist.
• May 7 – Marie Depage, Belgian nurse.
• May 13 – Morgan Crofton, Irish-born mathematician.
• July 22 – Sir Sandford Fleming, Canadian engineer and surveyor known as the "father of time zones".
• August 10 – Henry Moseley, English physicist.
• September 26 – Tsuruko Haraguchi, Japanese psychologist.
• October 11 – Jean Henri Fabre, French entomologist.
• October 15 – Theodor Boveri, German geneticist.
• December 19 – Alois Alzheimer, German neuroscientist.