160. 1972 – Francis Perrin discovers "natural nuclear fission reactors" in uranium
deposits in Oklo, Gabon, where analysis of isotope ratios demonstrate that selfsustaining,
nuclear chain reactions have occurred. The conditions under which a natural
nuclear reactor could exist were predicted in 1956 by P. Kuroda.
161. 1973 – Frank Anthony Wilczek discover the quark asymptotic freedom in the
theory of strong interactions; receives the Lorentz Medal in 2002, and the Nobel Prize in
Physics in 2004 for his discovery and his subsequent contributions to quantum
chromodynamics.
[50]
162. 1973 – Makoto Kobayashi and Toshihide Maskawa note that the experimental
observation of CP violation can be explained if an additional pair of quarks exist. The two
new quarks are eventually named top and bottom.
163. 1973 – Peter Mansfield formulates the physical theory of Nuclear magnetic
resonance imaging (NMRI)[51][52][53][54]
164. 1974 – Pier Giorgio Merli performs Young's double-slit experiment (1909) using a
single electron with similar results, confirming the existence of quantum fields for massive
particles.