The year 1904 in science and technology included many events, some of which are listed below.

Astronomy

• Edward Walter Maunder plots the first sunspot "butterfly diagram"
• Himalia, a moon of Jupiter, discovered at Lick Observatory

Medicine

• Epinephrine first artificially synthesized by Friedrich Stolz.

Physics

• Vacuum tube invented by John Ambrose Fleming

Awards

• Nobel Prizes
  • Physics - John William Strutt, 3rd Baron Rayleigh
  • Chemistry - Sir William Ramsay
  • Medicine - Ivan Pavlov

Births

• January 26 - Ancel Keys, nutritionist.
• March 20 - B. F. Skinner (d. 1990), behavioral psychologist.
• April 22 - Robert Oppenheimer (d. 1967), physicist.
• August 28 - Secondo Campini (d. 1980), Italian jet pioneer.
• November 11 - J. H. C. Whitehead (d. 1960), British mathematician.

Deaths

• January 20 - Dmitri Mendeleev (b. 1834), Russian chemist and inventor of the Periodic table.
• May 10 - Henry Morton Stanley (b. 1841), explorer, journalist.