There are perhaps only
three
types of universally crucial quantities in this world. The first is energy
E, or equivalently mass
m according to Einstein's energy-mass transition formula:
E=M c2. The second is momentum or angular momentum
(or spin)
J. And the last, yet
perhaps the most mysterious and fascinating, is entropy
S.
With this well claimed, you start to question me: "Jackie, are you
teaching a course in physics or mathematics?"
It doesn't matter, as long as you do bear a great mission in your mind and
heart, and an extraordinary goal to accomplish. If still you are
attempting to comfort your inner psychology, then please let us call it
mathematical physics, but in this splendid era of
information
and digitial technology.
In classical mechanics, unlike energy (or Hamiltonian) and momentum,
entropy does not belong to a
single particular state in the phase
space. Instead,
it is immersed within an ensemble (or often a large collection) of all
possible states (or quantized (eigen) states
as in quantum mechanics), and
characterizes the overall degree of freedom of such a system, or
pessimistically speaking, chaos. Thus entropy is a powerful tool for
studying many-body systems, such as
a balloon of gas molecules, a lattice of crystals, a beam of light
full of photons, and, even in the much larger scale, the earth as a system,
and a black hole in the universe.
Now, your nerves just cannot stop jumping and fluttering - "So Jackie, at
the end of the day, what you are saying is that you are indeed planning to
teach
physics !!!" Hold on, please. In 1910, how many even greatest minds on this
planet once trusted Einstein's equation: "Are you insane, Einstein?!
how can touchable and visible mass be turned into abstract and intangible
energy?" That is also my point --- why cannot mechanical or tangible physics
be useful for abstract and sometimes seemingly psychological theory of information
and patterns? So, please, calm down, and let me finish. [This as well natually reminds
you the celebrated duality between tangible "particles" and abstract "waves" in quantum
mechanics.]
It is certainly not I who have proposed this approach for the first time
in this world. In fact, the real credit should go to the great applied mathematician
Claude Shannon, the founder of modern
information and communication theory. In this semester, we plan to read his
original and seminal paper that was written in the wake of World War II (also
an intense war of coding and code breaking), in which the originally very "mechanical"
notion of Entropy was ingeniously introduced as a fundamental tool or variable for
rigorously studying the mathematical theory behind telegraph, telephony, human
languages, etc., or simply, the theory for information and communication.
On the other hand, according to one of the most influential figures of modern Pattern
Theory,
Ulf Grenander, a pattern is often formed from
an ensemble of basic elements (or
"atoms") which are "assembled" together under certain local (or short-range)
interaction/communication (regularity) "energies." Therefore
it seems very natural that an
abstract Pattern Theory has to be a many-body
theory, which, just like the duality between particles and waves in physics, is
necessarily connected to the
more tangible theory of Thermodynamics and
Statistical Mechanics. This, of course, is only the benign speculation (or faith) of a young
applied mathematician.
"
What is information, and what is pattern?
" is a serious question to be investigated by everyone of us in this
information era, not only computer scientists or mathematicians, just
as Neo asked Murpheus in the Hollyhood hit "The Matrix" - "What is the Matrix?"
The Matrix is a world with patterns and information all designed and created
by human or machine intelligence for being felt "real", while we are living
in a complex "real" world, and constantly, and often subconsciously,
searching for the meaning, information, and patterns of this world. Are they
really different? Perhaps not, just as what Einstein's equation is saying.
Or perhaps you will feel as much shocked someday as Neo did - there indeed
exists no solid boundary between physics/the physical world and abstract
information and patterns !
Yes,
physics is about information, and information
is a new interpretation or novel view of physics. Recent advancements
in string theory and black holes are indeed indicating that perhaps this
entire universe is simply a hologram, or The Matrix !
Such story-telling style is certainly attractive and amusing for this friendly
mission statement. But what is more exciting and impressive is
that today we do
not have to become as vague
as story-telling. Numerous tools such as the Entropy are allowing
us to explore all the fascinating facets of the information and pattern theory
quantitatively, robustly, reproducibly, and accurately. It is the perfect
time for young applied mathematicians to devote part of their movie time
to this new course. Yes, we do not have to
WATCH Neo in an IMAX theatre. We
ARE
Neo's, in this real life.
And, that is THE mission of this course. Many theories and applications
in Mathematical Image and Vision Analysis (Miva) will be further explored
in this course, including Gibbs image model by
Geman and Geman (brothers)(1984),
visual pattern learning based on the Maximum Entropy
Principle by
Zhu and Mumford (1997),
the entropy based searching of best
wavelet bases by
Coifman and Wickerhauser (1992), and the mathematical
theory of perception by
Mumford (ICM 2002).
And, not mentioning all the great topics in Statistical Mechanics that are
prevailing in modern applied mathematics: Monte-Carlo similuation, Gibbs/Markov
random fields, simulated annealing, renormalization group method, mean-field
and large deviation theory, and phase transitions...
First created on September 3, 2003. Last
modified on September 5, 2003.