[Fis] New Book

  Colleagues,

What do we know about this author? Has he ever participated in any of fis
discussions? He seems to support fis-germane concepts.

Dail Doucette
------------------------------

Information: The New Language of Science
by Hans Christian von Baeyer
Weidenfeld & Nicolson: 2003. 258 pp. £16.99

What is the Universe made of? A growing number of scientists suspect that
information plays a fundamental role in answering this question. Some even
go as far as to suggest that information-based concepts may eventually fuse
with or replace traditional notions such as particles, fields and forces.
The Universe may literally be made of information, they say, an idea neatly
encapsulated in physicist John Wheeler's slogan: "It from bit". Others
rather less boldly suggest that taking a point of view based on information
theory may yield insights into existing theories such as statistical
mechanics and quantum mechanics.

These are speculative ideas, still in the early days of development. Their
most encouraging success is perhaps the resolution of the 'Maxwell's demon'
paradox, a century-old riddle in the foundations of statistical mechanics.
In James Clerk Maxwell's paradoxical thought experiment, a demon of
extraordinary dexterity and visual acuity partitions an initially
homogeneous gas into two parts, one part containing slow-moving molecules
and the other part faster-moving ones. In the thought experiment, the gas
is initially spread evenly through a two-chamber container with a
connecting trapdoor that can be opened and closed by the demon. By
carefully observing the velocity of molecules approaching the trapdoor, and
opening or closing it as appropriate, the demon sorts the molecules so that
fast molecules enter one chamber and slow ones end up in the other.

The resulting system is more ordered than the original homogeneous gas, and
so has lower entropy. Furthermore, by making the trapdoor sufficiently
lightweight, the demon can operate it by expending an arbitrarily small
amount of energy. Thus, a naive analysis suggests that Maxwell's demon
reduces the total entropy of the system, violating the second law of
thermodynamics.

This paradox was resolved in 1982, when physicist Charles Bennett, building
on earlier work by others, notably Rolf Landauer, showed that this analysis
fails to take into account an entropy cost associated with the information
acquired by the demon when it observes the velocities of molecules
approaching the trapdoor. The cost is an entropic price paid when the demon
erases its record of these observations. Remarkably, when this cost is
taken into account, the violation of the second law is found to be illusory
and the paradox is resolved.

A more recent example of information taking a surprising central role in
fundamental science is a bold idea known as the holographic principle.
Roughly speaking, this states that the correct way to describe a region of
space-time is not through a description of fields and forces in the bulk of
the volume, as is conventionally done, but through a theory whose elements
are defined on the surface of the region. The motivation for the principle
comes in part from results about the thermodynamics of black holes
suggesting that the information content of a black hole is proportional to
its surface area, not its volume. Some researchers hope that the
holographic principle will help lead to a quantum theory of gravity, much
as Einstein's principle of equivalence helped to motivate the general
theory of relativity.

These and other examples illustrate the intellectual ferment associated
with the role of information in fundamental science. It is against this
backdrop that Hans Christian von Baeyer's elegant popular book is set.

The book's most appealing feature is its focus on big questions. What is
information? What role does information play in fundamental physics? Where
else in science does information play a critical role? And what common
themes link these areas? Von Baeyer approaches these questions from many
angles, giving us a flavour of some of the most interesting answers
currently being offered.

There is a nice balance between accepted science and speculative ideas. For
example, the standard theory of information, proposed by Claude Shannon in
the 1940s, is introduced early in the book. However, von Baeyer admits that
Shannon's theory has some shortcomings, and provides a flavour of several
other approaches to developing information theories, notably quantum
information theory.

Von Baeyer discusses many fascinating topics in a tour that is broad but
not deep, taking in genetics, bioinformatics, quantum computation, the
foundations of quantum mechanics, and black-hole entropy. He faces, and on
the whole overcomes reasonably well, the difficulty faced by popular
science writers of needing to simplify without misleading. However, I did
notice several unfortunate minor errors of fact.

In summary, von Baeyer has provided an accessible and engaging overview of
the emerging role of information as a fundamental building block in
contemporary science.
Received on Mon Mar 15 13:40:07 2004