W. Ross Ashby Digital Archive. Ross Ashby was one of the original members of the Ratio Club, a small informal dining club of young psychologists, physiologists, mathematicians and engineers who met to discuss issues in cybernetics. The club was founded in 1949 by the neurologist John Bates and continued to meet until 1958. The title of his book "An Introduction to Cybernetics" popularised the usage of the term 'cybernetics' to refer to self-regulating systems, originally coined by Norbert Wiener in "". The book dealt primarily with homeostatic processes within living organisms, rather than in an engineering or electronic context. Earlier, in 1946, Alan
Wiener–Khinchin theorem Wiener–Khinchin theorem In applied mathematics, the Wiener–Khinchin theorem, also known as the Wiener–Khintchine theorem and sometimes as the Wiener–Khinchin–Einstein theorem or the Khinchin–Kolmogorov theorem, states that the autocorrelation function of a wide-sense-stationary random process has a spectral decomposition given by the power spectrum of that process. Norbert Wiener proved this theorem for the case of a deterministic function in 1930; Aleksandr Khinchin later formulated an analogous result for stationary stochastic processes and published that probabilistic analogue in 1934. Albert Einstein explained, without proofs, the idea in a brief two-page memo in 1914. For continuous time, the Wiener–Khinchin theorem says that