The weak side of the force
Three physicists, Steven Weinberg, Abdus Salam and Sheldon Glashow, receive the Nobel prize in physics for proposing the electroweak theory. They believe that two of the four fundamental forces – the electromagnetic force and the weak force – are in fact different facets of the same force. Under high-energy conditions such as those in a particle accelerator, the two would merge into the electroweak force. But three hypothetical force-carrier particles described by the theory have yet to be confirmed in experiments: the W+, W- and Z0 bosons. These are heavy particles; so finding them would require an accelerator that could reach an unprecedented level of energy.