In 1937 Claude Shannon, then a graduate student at MIT, wrote a master’s thesis titled “A Symbolic Analysis of Relay and Switching Circuits.” Working from the differential analyzer’s complex relay controls and a summer at Bell Labs, Shannon noticed that the behavior of networks of switches and relays - each either open or closed, on or off - exactly mirrored the two-valued algebra George Boole had devised in the 1840s to formalize logic.
The thesis showed that Boolean algebra could be used as a practical engineering tool: a circuit of switches could be written as a logical expression, that expression could be simplified by algebraic rules, and the simplified expression could be turned back into a smaller, cheaper circuit that did the same job. Conditions like “this circuit conducts if A and B are closed, or if C is closed” became equations one could manipulate. An abstracted version was published in 1938 in the Transactions of the American Institute of Electrical Engineers.
This insight - that logic and arithmetic could be carried out by arrangements of simple on-off switches - is the conceptual bridge from Boole’s algebra to the digital computer. Every logic gate, every processor, rests on the equivalence Shannon made explicit. It has been called one of the most important master’s theses of the 20th century, and it came more than a decade before Shannon’s better-known 1948 work founding information theory.