Born on April 29, 1926, he developed the concept of packet-switched networks with Donald Davies and Leonard Kleinrock.
Is also credited with inventing the metal detector used in airports.
In interviews Baran mentioned how his idea of non-dedicated physical circuits for voice communications were scoffed at by AT&T engineers who at times claimed that Baran simply did not understand how voice telecommunication worked.
http://en.wikipedia.org/wiki/Paul_Baran