In 1985 during a talk at a symposium on Information Theory in Brighton,
England, a 69 year-old man quietly entered the hall and sat at the back.
After a while, a buzz started to circulate among the audience that
became louder and louder. The speaker looked up from the lectern,
stopped speaking and began to applaud the unassuming elderly man
who had tried to remain incognito. The entire audience of hundreds
of people then turned around, spontaneously stood up and also began to
applaud him. And the story goes they applauded and applauded and applauded
for minutes on end.
Within electrical engineering circles, the name Claude Shannon stands as
a legendary figure. The IEEE Claude E. Shannon Award is one of the most
prestigious awards that can bestowed on an individual for contributions
to the field of electrical communications.
Though he didn't invent the digital computer, the digital mobile phone,
the DVD, CD and MP3 players, disk storage, GPS, WiFi, fiber optic
communication or deep space communication, Claude Shannon's work in the
1930's and 1940's made all of them possible.
If we live in the Digital Information Age, then Claude Shannon could
clearly be said to be its father.
Yet outside of professional engineering circles, like so many important
figures that have helped shape our modern world, he is scarcely known.
Claude Shannon was born in Michigan on April 30th 1916 and died in
February 2001. If he were still alive, today would have been his 95th
birthday. So to mark the occasion, I wanted to bring to the attention
of interested readers some of the achievements of this remarkable man.
Two achievements, each of them revolutionary, stand out in particular.
Shannon was interested in both electrical engineering and mathematics
and not knowing which to pursue, studied both at the University of
Michigan.
In 1936, at age 20, Claude Shannon wrote a Master's Thesis which was
submitted to MIT, entitled "A Symbolic Analysis of Relay And Switching
Circuits". It can be found here -
http://dspace.mit.edu/bitstream/hand...3/34541425.pdf
It is widely regarded as one of the most important master's thesis ever
written. Shannon took the work of a 19th Century English mathematician
and philosopher named George Boole and applied it to the design of
circuits. What we know now as Boolean logic, which is at the heart of
every modern digital device. Shannon's paper makes the connection with
Boolean logic on page 8 and he describes a "calculus of propositions in
which variables are limited to the values of 0 and 1". On page 11, he
makes the connection that relay circuits can be described and designed
in such a way. This paper brought with it a totally new way by which
circuits could be designed - essentially through the use of mathematics
- and it paved the way for the digital revolution including the
digital computer.
His second revolutionary paper was written whilst he was working as a
researcher at Bell Telephone Laboratories in New Jersey in 1948 and is
entitled "A Mathematical Theory of Communication".
It can be found here -
http://cm.bell-labs.com/cm/ms/what/s...hannon1948.pdf
It is the most important paper ever written in the field of
communication and it is the founding paper for the area we know as
"Information Theory". For many, it was like the 20th Century equivalent
of the secret of how to make fire. And it spawned a revolution that
helped shape the modern technological world we live in today. This is the
first time the word "bit", as an abbreviation for "binary digit",
appears in printed form and it is introduced on page 1.
Consider the problem of transmitting information from a source, across
some medium, to a destination. The medium might be wires, wireless or
even the air that carries sound waves. The information might be speech,
television, text ... it matters not. This paper defines for the very
first time what information, in an communications and computer
engineering sense, really is, and it defines it mathematically. Whenever
a message is transmitted through a communications system, the message
can be altered by noise. Before the 1948 paper, engineers would attempt
to overcome noise in ad hoc ways, such as increasing the signal strength
or repeating the message. However Shannon showed that mathematics can be
used to find an optimal way to transmit a message, including optimal
ways to encode it.
What's more, the paper provided the communications equivalent of E=mc^2
with a formula that showed what the maximum rate of information one can
transmit in bits per second is over a medium of a given bandwidth, with
a signal of a given strength and noise of a given strength. For example,
given a medium such as a copper cable, a piece of wireless spectrum or
an optical fiber, there is a maximum rate one can transmit information
over them and which the mathematics tells us we can never transmit any
faster. When this was first introduced in 1948, many engineers scarcely
believed it could be true. However, the engineering endeavors in
communications in the past 60 or so years since then have been largely
about squeezing every bit of channel capacity out of a given medium, to
get as close as possible to the so-called Shannon Limit. For example,
the information that comes over your copper wire ADSL connection is
within a few percent of the theoretical limit and for this reason,
copper cable communications systems are near the end of their
technological life.
One of the many applications of the 1948 paper is that it made reliable
communications with deep space probes possible. An Italian-American MIT
trained engineer and businessman, Andrew Viterbi, came to JPL in the
months before Sputnik was launched and worked on the digital
communications for Explorer 1. This then lead to a PhD in error
correcting codes based on Shannon's work and eventually to an encoding
scheme known as Viterbi encoding. Viterbi encoding and its descendants
found its way into every digital mobile phone, WiFi device and space
communications system in use today. Viterbi went on to co-found
Qualcomm, a multi-billion dollar communications chip company.
To learn more about the extraordinary Claude Shannon, I wholeheartedly
recommend this 30 minute YouTube Video entitled, "Claude Shannon -
Father of the Information Age", that pays tribute to him -
http://www.youtube.com/watch?v=z2Whj_nL-x8
Why the name Claude Shannon deserves to be known by everyone
