Discoveries 1900 - 1909   Bubonic plague hits San Francisco 1900   Freud's book, "The Interpretation of Dreams" released 1900   Planck discovers the quantum nature of energy 1901   Marconi receives radio signal over Atlantic 1903   Wright brothers fly first motorized plane 1905   Binet pioneers intelligence testing 1905   Einstein publishes the special theory of relativity 1907   Radiometric dating finds Earth is 2.2 billion years old 1909   Ehrlich finds cure for syphilis 1912   Leavitt discovers a correlation between Cepheids' period and luminosity 1912   Wegener proposes idea of continental drift 1913   Ford installs first moving assembly line 1913   Rutherford and Bohr describe atomic structure 1913   Watson launches behaviorist school of psychology 1915   Einstein announces the general theory of relativity 1915   Pellagra shown to be dietary disease 1918 - 1919   Worldwide flu pandemic strikes 1920   Electric consumer appliances proliferate 1920   KDKA begins to broadcast 1922   Banting and Best isolate insulin 1923   Eugenics movement reaches its height 1923 - 1952   Piaget describes stages of cognitive development 1924   Hubble identifies a new galaxy 1926   Television is developed 1927   Big bang theory is introduced 1927   Heisenberg the states uncertainty principle 1928 - 1945   Fleming discovers penicillin 1929   Hubble finds proof that the universe is expanding 1931   Lawrence invents the cyclotron 1932   Chadwick discovers the neutron 1935   Moniz develops lobotomy for mental illness 1935   Nylon is invented 1938   Electroshock therapy introduced 1942   Fermi creates controlled nuclear reaction 1945   ENIAC is built 1945   The first atomic bomb is detonated 1947   Libby introduces radiocarbon dating 1947   Transistor is invented 1950   Drugs developed for leukemia 1952   Drug for treating schizophrenia identified 1952   Salk produces polio vaccine 1953   Amino acids are created in laboratory 1953   Great Global Rift is discovered 1953   Piltdown Man is revealed as fake 1953   Watson and Crick describe structure of DNA 1954   First successful kidney transplant performed 1959   Leakey family discovers human ancestors 1960   Hess proposes sea-floor spreading 1962   "Silent Spring" is published 1963   Magnetic bands provide evidence of sea-floor spreading 1965   Penzias and Wilson discover cosmic microwave radiation 1967   Bell and Hewish discover pulsars 1969   Apollo astronauts land on the Moon 1971   First commercial microprocessor is introduced 1972 - 1985   CT scan and MRI introduced 1974   Johanson finds 3.2 million-year-old Lucy 1975   Personal computer industry is launched 1975   Role of endorphins discovered 1976   Cosmic string theory introduced 1977   Life is found near deep ocean vents 1980   World Health Organization declares smallpox eradicated 1980   Alvarez finds evidence of dinosaur-killing asteroid 1981   AIDS is officially recognized 1987   Antidepressant Prozac introduced 1992   The Internet gives rise to the World Wide Web 1993   Search for behavioral genes 1994   4.4 million-year-old human ancestor is found 1996   Meteorite from Mars points to possibility of life on other planets

---

Home | Help

WGBH | PBS Online | Search | Feedback | Shop
© 1998 WGBH