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Re: Claude Shannon

On Fri, 9 Mar 2001, Neil Todd wrote:

> It may have come to the attention of some list readers that Claude Shannon
> has recently died. Perhaps some of our colleagues from MIT/Bell Labs may
> like to say a few words in the way of an obituary? The "Mathematical Theory
> of Communication" has surely had considerable influence in the broad area
> of auditory science, and the concept of information entropy will surely
> continue to be an important theoretical and practical tool in future
> developments.

Here is an informative memorial that appeared in the NY Times recently:

Claude Shannon, Mathematician, Dies at 84

February 27, 2001


Dr. Claude Elwood Shannon, the American mathematician and computer
scientist whose theories laid the groundwork for the electronic
communications networks that now lace the earth, died on Saturday
in Medford, Mass., after a long fight with Alzheimer's disease. He
was 84.

 Understanding, before almost anyone, the power that springs from
encoding information in a simple language of 1's and 0's, Dr.
Shannon as a young man wrote two papers that remain monuments in
the fields of computer science and information theory.

 "Shannon was the person who saw that the binary digit was the
fundamental element in all of communication," said Dr. Robert G.
Gallager, a professor of electrical engineering who worked with Dr.
Shannon at the Massachusetts Institute of Technology. "That was
really his discovery, and from it the whole communications
revolution has sprung."

 Dr. Shannon's later work on chess- playing machines and an
electronic mouse that could run a maze helped create the field of
artificial intelligence, the effort to make machines that think.
And his ability to combine abstract thinking with a practical
approach he had a penchant for building machines inspired a
generation of computer scientists.

 Dr. Marvin Minsky of M.I.T., who as a young theorist worked
closely with Dr. Shannon, was struck by his enthusiasm and
enterprise. "Whatever came up, he engaged it with joy, and he
attacked it with some surprising resource which might be some new
kind of technical concept or a hammer and saw with some scraps of
wood," Dr. Minsky said. "For him, the harder a problem might seem,
the better the chance to find something new."

 Born in Petoskey, Mich., on April 30, 1916, Claude Elwood Shannon
got a bachelor's degree in mathematics and electrical engineering
from the University of Michigan in 1936. He got both a master's
degree in electrical engineering and his Ph.D. in mathematics from
M.I.T. in 1940.

 While at M.I.T., he worked with Dr. Vannevar Bush on one of the
early calculating machines, the "differential analyzer," which used
a precisely honed system of shafts, gears, wheels and disks to
solve equations in calculus.

 Though analog computers like this turned out to be little more
than footnotes in the history of the computer, Dr. Shannon quickly
made his mark with digital electronics, a considerably more
influential idea.

 In what has been described as one of the most important master's
theses ever written, he showed how Boolean logic, in which problems
can be solved by manipulating just two symbols, 1 and 0, could be
carried out automatically with electrical switching circuits. The
symbol 1 could be represented by a switch that was turned on; 0
would be a switch that was turned off.

 The thesis, "A Symbolic Analysis of Relay and Switching Circuits,"
was largely motivated by the telephone industry's need to find a
mathematical language to describe the behavior of the increasingly
complex switching circuits that were replacing human operators. But
the implications of the paper were far more broad, laying out a
basic idea on which all modern computers are built.

 George Boole, the 19th-century British mathematician who invented
the two-symbol logic, grandiosely called his system "The Laws of
Thought." The idea was not lost on Dr. Shannon, who realized early
on that, as he once put it, a computer is "a lot more than an
adding machine." The binary digits could be used to represent
words, sounds, images perhaps even ideas.

 The year after graduating from M.I.T., Dr. Shannon took a job at
AT&T Bell Laboratories in New Jersey, where he became known for
keeping to himself by day and riding his unicycle down the halls at

 "Many of us brought our lunches to work and played mathematical
blackboard games," said a former colleague, Dr. David Slepian.
"Claude rarely came. He worked with his door closed, mostly. But if
you went in, he would be very patient and help you along. He could
grasp a problem in zero time. He really was quite a genius. He's
the only person I know whom I'd apply that word to."

 In 1948, Dr. Shannon published his masterpiece, "A Mathematical
Theory of Communication," giving birth to the science called
information theory. The motivation again was practical: how to
transmit messages while keeping them from becoming garbled by

 To analyze this problem properly, he realized, he had to come up
with a precise definition of information, a dauntingly slippery
concept. The information content of a message, he proposed, has
nothing to do with its content but simply with the number of 1's
and 0's that it takes to transmit it.

 This was a jarring notion to a generation of engineers who were
accustomed to thinking of communication in terms of sending
electromagnetic waveforms down a wire. "Nobody had come close to
this idea before," Dr. Gallager said. "This was not something
somebody else would have done for a very long time."

 The overarching lesson was that the nature of the message did not
matter it could be numbers, words, music, video. Ultimately it
was all just 1's and 0's.

 Today, when gigabytes of movie trailers, Napster files and e-mail
messages course through the same wires as telephone calls, the idea
seems almost elemental. But it has its roots in Dr. Shannon's
paper, which may contain the first published occurrence of the word

 Dr. Shannon also showed that if enough extra bits were added to a
message, to help correct for errors, it could tunnel through the
noisiest channel, arriving unscathed at the end. This insight has
been developed over the decades into sophisticated error-correction
codes that ensure the integrity of the data on which society

 In later years, his ideas spread beyond the fields of
communications engineering and computer science, taking root in
cryptography, the mathematics of probability and even investment
theory. In biology, it has become second nature to think of DNA
replication and hormonal signaling in terms of information.

 And more than one English graduate student has written papers
trying to apply information theory to literature the kind of
phenomenon that later caused Dr. Shannon to complain of what he
called a "bandwagon effect."

 "Information theory has perhaps ballooned to an importance beyond
its actual accomplishments," he lamented.

 After he moved to M.I.T. in 1958, and beyond his retirement two
decades later, he pursued a diversity of interests a mathematical
theory of juggling, an analog computer programmed to beat roulette,
a system for playing the stock market using probability theory.

 He is survived by his wife, Mary Elizabeth Moore Shannon; a son,
Andrew Moore Shannon; a daughter, Margarita Shannon; a sister,
Catherine S. Kay; and two granddaughters.

 In the last years of his life, Alzheimer's disease began to set
in. "Something inside him was getting lost," Dr. Minsky said. "Yet
none of us miss him the way you'd expect for the image of that
great stream of ideas still persists in everyone his mind ever