Formulation of quantum mechanics

Date

1925 to 1927

Category

Science, technology & invention

Region

Europe (Germany, Austria, Denmark)

Era

Modern

Significance

Between 1925 and 1927 physicists developed a complete and self-consistent quantum mechanics, replacing the ad hoc 'old quantum theory' of Planck and Bohr.

In July 1925 Werner Heisenberg published a reinterpretation of atomic mechanics in terms of observable quantities, which Max Born and Pascual Jordan formalised as matrix mechanics. In 1926 Erwin Schrödinger, building on Louis de Broglie's wave-particle duality, published wave mechanics and the Schrödinger equation, an alternative formulation soon shown to be mathematically equivalent. Born then supplied the probabilistic interpretation of the wave function, and in 1927 Heisenberg articulated the uncertainty principle, with Bohr's complementarity completing what became the Copenhagen interpretation. Quantum mechanics provided the theoretical foundation for understanding atoms, chemical bonding, solid-state physics and particle behaviour. It underpinned later technologies including the transistor, the laser, semiconductors and nuclear energy, making it one of the most consequential scientific frameworks of the century. Its probabilistic, non-deterministic character also provoked enduring philosophical debate, including Einstein's objections.

Empires active in 1925 to 1927

• Empire of Japan
  1868 CE to 1947 CE
• French Colonial Empire (Second)
  1830 CE to 1962 CE
• Soviet Union
  1922 CE to 1991 CE
• British Empire
  1583 CE to 1997 CE
• Spanish Empire
  1492 CE to 1976 CE
• Portuguese Empire
  1415 CE to 1999 CE

Related science, technology & invention events

• Penicillin and the dawn of the antibiotic era
  1928 (developed for clinical use 1940 to 1945)
• Haber-Bosch Process Industrialises Synthetic Nitrogen Fertiliser
  September 1913
• Discovery of nuclear fission
  December 1938 (explained January to February 1939)
• The Wright Brothers' Powered Flight
  17 December 1903
• Discovery of X-rays and radioactivity
  1895 to 1898
• Germ Theory of Disease Established by Pasteur and Koch
  1882 (Koch's tuberculosis bacillus, 24 March)

Further reading

A Little History of Science

The wider story

A Little History of Science

William Bynum

Warm, jargon-free tour of discovery from Babylonian stargazers to the genome.

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