UNITED KINGDOM - DECEMBER 15: In 1948, William Shockley (1910-1989) invented the transistor, and in the 1950s, transistors began to replace thermionic valves in radio receivers, allowing much smaller, more affordable portable radios to be produced. This radio illustrates the trend towards smaller radios and an altogether more casual attitude to sound broadcasting than had existed in earlier decades. (Photo by SSPL/Getty Images)
