September 20, 2013

Positivity: ‘The Greatest Genius No One Has Heard Of’

Filed under: Marvels,Positivity — Tom @ 6:00 am

Published by Charlie Martin at

September 13, 2013 – 4:00 pm

One man in the 20th century has had more effect on our daily lives than any other. He is directly responsible for everything digital, and for much of modern communication. And hardly anyone knows his name.

In the 1930s, “computer” was a job description: someone, usually a woman of mathematical bent, with an adding machine and a big sheet of columnar paper who performed a rigorous routine of hand calculations, using paper and pencil, slide rules and tables of logarithms. Stone knives and bearskins weren’t involved, but to modern eyes they might as well have been.

Large research organizations and the Department of War had a few special purpose mechanical computers intended to integrate differential equations. Vannevar Bush (who deserves his own article someday) brought a young grad student to MIT to work on the differential analyzer, a relatively advanced version of these.

… This young man, a recent graduate of the University of Michigan, was named Claude Shannon, Jr. Shannon, while working on the differential analyzer, had the insight that these same computations could be done using combinations of a few simple circuits that performed basic logical operations on true and false values. He described how this could be done, and invented the whole concept of digital circuits, which derive from from Shannon’s thesis on what he called switching theory.

His Master’s thesis.

At about the same time, Alan Turing wrote his series of famous papers on computability; those papers included an idea of how a computer with memory might work, but without Shannon’s switching theory, no one knew how to actually build one. (Google did a great Google Doodle for Turning’s 100th birthday.)

Vannevar Bush then sent Shannon to the Cold Spring Harbor laboratory. Shannon worked with biologists and geneticists, and — remember this was before DNA had been discovered — described how genetics could be understood as an algebra using a small collection of symbols. This was enough to get Shannon a Ph.D. but attracted little attention at the time. However, his Ph.D. is now recognized as pre-figuring what we now call bioinformatics.

During the war, Shannon, still working for the War Department, was put to work on cryptography, where he merely invented a general mathematical basis of nearly all cryptography, and in the meantime proved that there is one and exactly one method of making an unbreakable cipher. This is called a one-time pad.

But this wasn’t enough. He went to work for Bell Labs, and began thinking about radio or telephone signaling. (His original switching theory was already the basic for new telephone switches — direct telephone dialing depended on Shannon’s Master’s.) What was common to all these different ways of signaling we already used: telegraph, telephone, radio, and that new-fangled thing television? Shannon had a surprising insight: what made a signal a signal was whether or not you could predict it. …

Go here for the rest of the story.


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