Confinement is the physics phenomenon that quarks cannot be isolated. The color-charged quarks are confined with other quarks by the strong interaction to form pairs or triplets so that the net color is neutral. The force between quarks increases as the distance between them increases, so no quarks can be found individually.
... - Cary Grant, actor (+ 1986)
January 22 - George Balanchine, choreographer (+ 1983)
January 26 - Ancel Keys, scientist
February 1 - S. J. Perelman[?], humorist, ...