Great Idea 7

Idea 7: Unification of Electricity and Magnetism

    Scottish Physicist James Clerk Maxwell unified electricity and magnetism, predicted the existence of electromagnetic waves and identified light as an electromagnetic wave of oscillating electric and magnetic fields moving with a speed c (in vacuum) (1865)

    In his revolutionary paper titled “A Dynamical Theory of the Electromagnetic Field,” 
Published in June 1865 in the Philosophical Transactions of the Royal Society, Maxwell described how electricity and magnetism are closely connected. The paper shows how their combined action creates electromagnetic waves. Maxwell further demonstrated that these waves can propagate 

through any medium, including perfectly empty space. He proved that if the waves travel through pure vacuum, they must move at the speed of light. Finally, he made the giant leap that light, in all its forms, is electromagnetic waves of different frequencies.

Electromagnetism was the first true unification of forces. Its formulation showed that nature offers deep mathematical connections between varied phenomena. Today physicists are searching for a “theory of everything” that unites all of the natural forces: gravitation and the strong and weak nuclear forces, along with electromagnetism.