As a graduate student at MIT, Shannon discovered the analogy between Boolean algebra and digital switching circuits. His master's thesis, A Symbolic Analysis of Relay and Switching Circuits, demonstrated the use of Boolean algebra to analyze and optimize relay switching circuits. In 1948, as a research mathematician at AT&T, Shannon published a ground-breaking paper in the Bell System Technical Journal, "A Mathematical Theory of Communication." In it, he proposed a linear schematic model of a communications system in which pictures, words, and sounds could be more easily and quickly transmitted by sending a stream of 1s and 0s rather than electromagnetic waves. Shannon's discovery that the binary digit was the fundamental element of communication became the foundation for information theory and the springboard for the communications revolution.