Summary: In the early 1860s the Scottish physicist James Clerk Maxwell derived four equations which together describe the behaviour of electricity and magnetism. They predicted the existence of a previously unknown phenomenon: electromagnetic waves. These waves were first observed in the early 1880s, and over the next two decades a succession of scientists and engineers built increasingly elaborate devices to produce and detect them. Eventually this gave birth to a new technology: radio. The Italian Guglielmo Marconi is commonly described as the father of radio - but many other figures were involved in its development, and it was not him but a Canadian, Reginald Fessenden, who first succeeded in transmitting speech over the airwaves. Melvyn Bragg is joined by Simon Schaffer, Professor of the History of Science at the University of Cambridge; Elizabeth Bruton, Postdoctoral Researcher at the University of Leeds and John Liffen, Curator of Communications at the Science Museum, London.
