From: "R. A. Hettinga" <rah@shipwright.com>
http://www.nytimes.com/2001/02/27/nyregion/27SHAN.html?printpage=yes
February 27, 2001
Claude Shannon, Mathematician, Dies at 84
By GEORGE JOHNSON
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.
<...snippage...>
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 noise.
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 "bit."
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 interacts.
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 touched."
-- ----------------- R. A. Hettinga <mailto: rah@ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'
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