For 50 years, radio dominated the airwaves as the first mass medium. Ken Burns examines the lives of three men who shared the responsibility for its invention and early success.For 50 years, radio dominated the airwaves as the first mass medium. Ken Burns examines the lives of three men who shared the responsibility for its invention and early success.For 50 years, radio dominated the airwaves as the first mass medium. Ken Burns examines the lives of three men who shared the responsibility for its invention and early success.