Sheldon Glashow proposes in 1961 at Harvard an initial theoretical framework to unify electromagnetism and the weak nuclear force — responsible for radioactive decay — as two manifestations of a single underlying electroweak force, an effort at unification directly following the precedent of Maxwell's unification of electricity and magnetism a century earlier. Steven Weinberg, in 1967, and Abdus Salam, a Pakistani physicist at Imperial College London, independently complete the theory by incorporating the Higgs mechanism to explain how the particles that mediate the weak force — the W and Z bosons — acquire mass, while the photon, the mediator of electromagnetism, remains massless. The theory precisely predicts the properties of these bosons years before they could be detected experimentally, and further predicts the existence of weak "neutral currents", experimentally confirmed at CERN in 1973. The final and most spectacular confirmation comes in 1983, when Carlo Rubbia and Simon van der Meer directly detect the W and Z bosons at CERN with the exact masses predicted by the theory a decade and a half earlier. Electroweak unification, together with the quantum chromodynamics describing the strong force, constitutes the core of the standard model of particle physics, the most successful and precisely verified theory in all of fundamental physics.