Vacuum electronics - 100 years

"Fooling around with alternating current is just a waste of time. No-one will ever use it, ever." And yet the man who wrote those words made a discovery that helped alternating current become a practical and efficient medium for energy and information transfer. The man was Thomas Edison and his invention was the vacuum diode: with this device, alternating current could be rectified to make direct current. This eliminated the need to send direct current long distances over wires from one place to another. It also provided rectification of modulated radio waves, which allowed practical radio transmission. The addition of a third element brought us the triode and amplification of wireless signals. This, in turn, gave us the information society in which we still live today. Moreover, Edison\´s invention was the beginning of vacuum electronics, a technology we celebrate today. This article discusses the 100 year history of vacuum electronics from vacuum diodes of Thomas Edison.