In the late 1940s, Bell Laboratories scientists John Bardeen, Walter Brattain, and William Shockley invented the transistor, the first solid-state amplifier or switch, and in doing so laid the foundation for all modern electronics and circuitry. The three shared the Nobel Prize in Physics in 1956 for the achievement. It may be the most important invention of the 20th century.
This 1965 film shows footage of them reunited/recreating their 1940s lab time to show how it was done, but in real life they had parted. Bardeen had left the labs in 1951 for the U. of IL; Shockley in 1956 to run a semiconductor company in California (laying the groundwork for Silicon Valley), and Brattain retired in 1967 to Whitman College.
Footage courtesy of AT&T Archives and History Center, Warren, NJ
To learn more about the invention of the transistor, watch the original Tech Channel series From the Labs: The Transistor.