Researched
Information Theory
Claude Shannon defines information as a measurable quantity (the bit) and shows how to send it without error over noisy lines.
Open in the interactive tree →In “A Mathematical Theory of Communication” (1948) Shannon introduced the bit, entropy and channel capacity: over any noisy channel one can send practically error-free with suitable coding, up to a calculable limit. As early as 1937 he had shown that Boolean logic can compute with switches. Data compression, mobile networks, the internet, storage and cryptography are built on this.
Prerequisites
- Logarithms (Napier)1614Shannon measures information with logarithms
- Probability Theory1654
- Boolean Algebra1854Shannon (1937) applied Boole's algebra to switching circuits
- Industrial Research Laboratory1876Shannon worked at Bell Labs, which funded basic research on communication
- Telephone1876
- Measure-Theoretic Probability1902-1933Entropy is defined on probability distributions, later put on measure-theoretic footing
- Turing Machine1936
Unlocks
- Error-Correcting Codes1950
- Cognitive revolution1956
- Packet Switching1965
- The Internet1969
- Public-Key Cryptography1976
- Deep-space probes (Voyager)1977Voyager's data links use error-correcting codes from Shannon's information theory
- Quantum Algorithms (Shor)1994
- Quantum Key Distribution2016
- Quantum Error Correction2024Quantum error correction extends Shannon's classical error-correcting codes