Claude E. Shannon: toys, life and the secret history of his theory of information. (Q2904648)

Illustrated with many drawings, pictures of gadgets and facsimiles of documents (many of them previously unpublished), the author describes how Claude E. Shannon ``converted from a mathematical genius into a technical military scientist'', how his work on air flight control and guided missiles led him to new methods, away from classical analysis to binary coding of control systems and trajectories, thus initializing a revolution in signal transmission and communication theory.NEWLINENEWLINE\smallskip The first chapter is devoted to the description of a variety of machines, instruments and artefacts which Shannon had collected or built by himself such as unicycles (on which he used to juggle), toy-trucks, chess computers (``Cassiac''), other special-purpose computers (named, e.g.,\ ``Throbac'', ``\(7\times 8\) Hoax'', ``Theseus'', ``Nimwit'', ``3-Relay Kit''), mind-reading machines, switching game devices with self-dual graphs, a Rubik-Cube solving machine and the ``Ultimate Machine'' (also called Hand-In-the-Box or On/Off-Machine), which switches itself off immediately.NEWLINENEWLINEIn Chapter 2, it is pointed out how \textit{C. E. Shannon}, in his [A symbolic analysis of relay and switching circuits. Cambridge, MA: MIT (Master Thesis) (1937)], used Boolean algebra, in his [An algebra for theoretical genetics. Cambridge, MA: MIT (PhD Thesis) (1940)], he then used discrete statistics, and in his work as a researcher combined pure mathematics with new applications, e.g. in electrotechnics, communication and machine constructions.NEWLINENEWLINEThe question of the prediction of trajectories in air flight control during World War II is the topic of Chapter 3, especially the controversy between a group associated with Norbert Wiener that interpreted trajectories as time series and used harmonic analysis, and, on the other side, Hendrik Bode and Claude Shannon of the Bell Laboratories group who used geometric approximation by a chain of straigt segments, arcs, circles and parabolas.NEWLINENEWLINEChapter 4 starts with a description of early privacy and secrecy telephone and electronic cryptographic systems like ``Voder'', ``Sigsaly'', ``003-bombe'' and ``Madam X''; parts of which had been analyzed by Alan Turing and by Claude Shannon, who generalized the Vernam method to continuous channels using puls-code modulation. Shannon integrated communication, secrecy, signaling, switching, control, prediction and computation in a mathematical theory of communication, formulating limits and possibilities of an electronic and technical language: coding. He evaluated not only Vernam ciphers or puls-code-modulated radio telphony but also classical cryptographic systems by defining exactly what perfect security is and by describing diffusion and confusion which can be used to improve non-perfect systems, by formulating redundancy, measuring information and defining uncertainty as entropy. This comparison with physical processes allowed him to quantify messages and cryptograms. Although there were many applications of his theory he was not allowed to mention these classified secrets for years. NEWLINENEWLINENEWLINE NEWLINEIn Chapter 5, it is described how the needs of a controlled and secure transmission of commands to the radar-guided missile of the Nike system led to further development of Shannon's information theory; the questions were: how much entropy and information do messages have (to describe movements of dynamic aircrafts), how can these messages be securely coded against interference or countermeasures, which mathematical methods can be used against `jamming' by the enemy, what is the maximal rate of transmission via a channel with a given capacity, and hence how many Nike projectiles can be guided at the same time. Shannon considered the target courses a stochastic process, suggested to make use of the probability distribution of the noise and so to use maximal entropy to hide the signals, to code only the differences in flight trajectories, to compress by reducing redundancy and correlation and to encode properly. The fundamental theorem determining the limits of transmission by the entropy of the source and the channel capacity was also part of the quantitive communication analysis of the Nike projects.NEWLINENEWLINEThe last chapter starts with Shannon's interest in juggling as anorganizing of movements, as signal processing, with his ``jugglometer'' and again with gadgets such as ``No-Drop-Juggling Diorama'', ``12-Clown Zoetrope'', ``W. C. Fields'', the first juggling robot, ``MIJ-Cown'' and ``Gedanken Juggling''. Like the toys described in Chapter 1, these gadgets illustrate aspects of Shannon's theoretical thinking. The ``Ultimate Machine'' is a metaphor for the ultimate missile, the unicycle for information-theoretical coding by discrete sampling of a curve, and the fundamental theorem can be related to juggling with a maximal number of objects and to the control of a maximum number of projectiles.NEWLINENEWLINEThe book ends with 51 pages of end-notes and a bibliography of 9 pages.