情報理論
Fundamental theoretical work on information theory was developed by Harry Nyquist and Ralph Hartley in the 1920s. Information theory, as enunciated by Claude Shannon, in the 1940s, provided a firm theoretical underpinning to understand the trade-offs between signal-to-noise ratio, bandwidth, and error-free transmission in the presence of noise, in telecommunications technology. This was one of the three key developments, along with advances in transistor technology (specifically MOS transistors) and laser technology, that made possible the rapid growth of telecommunication bandwidth over the next half-century.