Dr. Peter Higgs was one of six physicists, working in three independent groups, who in 1964 invented the notion of the cosmic molasses, or Higgs field. The others were Tom Kibble of Imperial College, London ; Carl Hagen of the University of Rochester ; Gerald Guralnik of Brown University ; and François Englert and Robert Brout, both of Université Libre de Bruxelles. One implication of their theory was that this Higgs field, normally invisible and, of course, odorless, would produce its own quantum particle if hit hard enough, by the right amount of energy. The particle would be fragile and fall apart within a millionth of a second in a dozen different ways depending upon its own mass. Unfortunately, the theory did not say how much this particle should weigh, which is what made it so difficult to find. The particle eluded researchers at a succession of particle accelerators, including the Large Electron–Positron Collider at CERN, which closed down in 2000, and the Tevatron at the Fermi National Accelerator Laboratory, or Fermilab, in Batavia, Ill., which shut down in 2011.