Can everything that happens in the universe be explained in terms of just three forces?  Particle Physicist Brian Cox talks us through the history of our scientific understanding, revealing why scientists have come to believe this.

Brian explores the unification of electricity and magnetism, and the discovery of the strong and weak nuclear forces.  He also explains more about the Large Hadron Collider experiment at CERN, which may help scientists come up with a single "theory of everything".

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Produced for the Science and Technology Facilities Council by Brook Lapping Productions in association with Teachers TV (see links below).