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This is the dude who came up with concepts of "Aliasing", "Signal to Noise

Ratio", and "Sampling Rate"....

Packet loss meant nothing before him....

Moment of silence for a most righteous, outstandingly smart dude.

R

Father of Information Theory died at 84...

This is the THE Shannon of "Shannon's Sampling Theorem" fame.

http://ccrma-www.stanford.edu/~jos/r320/Shannon_s_Sampling_Theorem.html

Shannon, C.E., "Communication in the Presence of Noise," Proc. IRE, Vol. 37,

No. 1, January 1949.

----------

*>From the NY Times
*

Claude Shannon, Mathematician, Dies at 84

February 27, 2001

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.

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

night.

"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

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."

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