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Entropy Demystified: The Second Law Reduced to Plain Common Sense

Entropy Demystified: The Second Law Reduced to Plain Common Sense

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Author: Arieh Ben-naim
Publisher: World Scientific Publishing Company
Category: Book

List Price: $29.00
Buy New: $26.92
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Rating: 5.0 out of 5 stars 9 reviews
Sales Rank: 81858

Media: Paperback
Edition: Expanded
Pages: 250
Number Of Items: 1
Shipping Weight (lbs): 0.9
Dimensions (in): 9 x 6 x 0.5

ISBN: 9812832254
Dewey Decimal Number: 541
EAN: 9789812832252

Publication Date: June 18, 2008
Availability: Usually ships in 1-2 business days

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Editorial Reviews:

Product Description
In this unique book, the reader is invited to experience the joy of appreciating something which has eluded understanding for many years -- entropy and the second law of thermodynamics. The book has a two-pronged message: first, that the second law is not infinitely incomprehensible as commonly stated in most textbooks on thermodynamics, but can, in fact, be comprehended through sheer common sense; and second, that entropy is not a mysterious quantity that has resisted understanding but a simple, familiar and easily comprehensible concept.

Written in an accessible style, the book guides the reader through an abundance of dice games and examples from everyday life. The author paves the way for readers to discover for themselves what entropy is, how it changes, and, most importantly, why it always changes in one direction in a spontaneous process.

In this new edition, seven simulated games are included so that the reader can actually experiment with the games described in the book. These simulated games are meant to enhance the readers understanding and sense of joy upon discovering the second law of thermodynamics.

Contents: Programs for Simulating Some of the Games in the Book; Introduction, and a Short History of the Second Law of Thermodynamics; A Brief Introduction to Probability Theory, Information Theory, and All the Rest; First Let Us Play with Real Dice; Let s Play with Simplified Dice and Have a Preliminary Grasp of the Second Law; Experience the Second Law with All Your Five Senses; Finally, Grasp It with Your Common Sense; Translating from the Dice-World to the Real World; Reflections on the Status of the Second Law of Thermodynamics as a Law of Physics.


Customer Reviews:   Read 4 more reviews...

5 out of 5 stars Another way to enjoy fundamental physics!   October 15, 2007
Diego Casadei (NYU and CERN)
18 out of 19 found this review helpful

Arieh Ben-Naim, professor at the Hebrew University of Jerusalem, taught
thermodynamics and statistical mechanics for many years and is well
aware that students learn the second law but do not understand it,
simply because it can not be explained in the framework of classical
thermodynamics, in which it was first formulated by Lord Kelvin (i.e.
William Thomson, 1824-1907) and Rudolf Julius Emanuel Clausius
(1822-1888). Hence, this law and the connected concept of entropy are
usually surrounded by some mysterious halo: there is something (the
entropy), defined as the ratio between heat and temperature, that is
always increasing. The students not only do not understand _why_ it is
always increasing (it is left as a principle in classical
thermodynamics), but also ask themselves what is the _source_ of such
ever increasing quantity.

We feel comfortable with the first law, that is the principle of energy conservation, because our experience always
suggests that if we use some resource (the energy) to perform any work,
then we are left with less available energy for further tasks. The
first law simply tells us that the heat is
another form of energy so that nothing is actually lost, something which
we can accept without pain. In addition, the second law says that,
though the total energy is constant, we can not always recycle 100% of
it because there is a limit on the efficiency of conversion of heat into
work (the highest efficiency being given by the Carnot cycle, named
after Nicolas Leonard Sadi Carnot, 1796-1832). Again, we can accept it
quite easily, because it sounds natural, i.e. in accordance with our
common sense: we do not know any perpetual engine. But our daily
experience is not sufficient to make us understand what entropy is, and
why it must always increase.

The author shows that, if we identify the entropy with the concept of
"missing information" of the system at equilibrium, following the work
done by Claude Elwood Shannon (1916-2001) in 1948, we obtain a well
defined and (at least in principle) measurable quantity. This quantity,
apart from a multiplicative constant, has the same behavior as the
entropy: for every spontaneous process of an isolated system, it must
increase until the equilibrium state is reached. The missing
information, rather than the disorder (not being a well defined
quantity), is the key concept to understand the second law.

I should say here that the identity of entropy and missing
information is not a widespread idea among physicists, so that many
people may not appreciate this point. However, the arguments of this
book are quite convincing, and different opinions are also taken into
account and commented.

In addition, Ben-Naim thinks that the entropy should be taught as an
dimensionless quantity, being defined as the ratio between heat, that is
energy, and temperature, that is a measure of the average kinetic energy
of the atoms and molecules. The only difference with the missing
information, again dimensionless, is the scale: because the missing
information can be defined as the number of binary questions (with
answer "yes" on "no" only) which are necessary to identify the
microscopic state of the system, this number comes out to be incredibly
large for ordinary physical systems, involving a number of constituents
of the order of the Avogadro's number. This numerical difference makes
me think about the difference between mass and energy, connected by the
Einstein's most famous equation E = m c^2: they could be measured using
the same units (as it is actually done in high-energy physics), the sole
difference being that even a very small mass amounts to a huge quantity
of energy.

The mystery of the ever increasing entropy can be explained once (and
only if) we realize that the matter is not continue, but discrete. The
author basically follows the work of Josiah Willard Gibbs (1839-1903),
who developed the statistical mechanical theory of matter based on a
purely probabilistic approach. First, one has to accept the fact that
macroscopic measurements are not sensitive enough to distinguish
microscopic configurations when they differ for thousands or even
millions of atoms, just because the total number of particles is usually
very large (usually of the order of 10^23 at least). Then, under the
hypothesis that each microscopic state is equally probable, i.e. that
the system will spend almost the same time in each micro-state, one can
group indistinguishable micro-states into macro-states. The latter are
the only thing we can monitor with macroscopic measurements. Under the
commonly accepted hypothesis that all microscopic configurations are
equally probable, macro-states composed by larger numbers of
micro-states will be more probable, i.e. the system will spend more time
in such macro-states.

As a naive example, one could start with a system prepared in such a way
that all its constituents are in the same microscopic configuration.
One could think about a sample of N dices, all of them showing the same
face, say the first one. The questions could be: (1) "Are all dices
showing the same face?"--Yes--; (2) "Is the face value larger or equal
than 3?"--No--; (3) "Is the face value larger or equal than 2?"--No--;
at this point we know that the value is 1. In general, the number of
binary questions is proportional to the logarithm in base 2 of the
number C of possible configurations, that is O(log_2 C). Now imagine to
randomly mix the dice by throwing all of them. The answer to the first
question would be "No", so that a completely different series of
questions has to be asked to find the microscopic configurations.
First, one may procede by finding how many dice show the value 1, for
example, asking O(log_2 N) questions. Suppose that the answer is Mthen one should find exactly what dice are showing this face, by asking
O(N) questions. The next step is to find how many dice show the value
2, among the N-M remaining ones, and so on. When N is very large, the
number of questions increases rapidly. So far, we have being speaking
about "microscopic" configurations, describing the exact state of all
dice. Now, we can imagine to be interested only in the "macroscopic"
configuration defined by the sum of all values. It is very easy to
imagine that the "microscopic" configurations corresponding to sum
values around 3N (corresponging to a uniform distribution of values)
will be many more than those with sum near N or 6N (which need all dice
showing 1 or 6, respectively). If we repeatedly shake the box or throw
all dice, most of the time we will obtain a sum near to 3N, and larger
deviations will be rarer. Hence, such a system will soon approach the
"equilibrium" state in which the sum is very near to 3N.

As a matter of fact, when the number of possible microscopic
configurations increases, the probability distribution of macro-states
becomes narrower and narrower, so that for ordinary systems the
probability to have a fluctuation large enough to be measured is
incredibly small. Actually, as Ben-Naim clearly emphasizes, the
probabilistic formulation of the second law of thermodynamics allows us
to quantify its validity, in terms of the time one should wait to be
able to find a fluctuation large enough to be measured. It comes out
that, for ordinary systems, the probability to have any measurable
fluctuation away from the equilibrium state is so low that the universe
age is practically negligible compared to the time we should wait to
observe such fluctuation. From this point of view, the second law is
far more "absolute" than the other laws of physics, for which at best we
could state that they are valid since the beginning of the universe life.

The book is a very good reading for all students who approach the
thermodynamics and also for more advanced people who do or do not feel
comfortable with the fascinating concept of entropy. Ben-Naim is also
the author of a more technical book ("Statistical Thermodynamics Based
on Information. A Farewell to Entropy", World Scientific, A Farewell To Entropy) in
which these guidelines are the base for a more detailed treatment of
statistical mechanics. Because we usually learn things much better when
following a cyclical approach, I encourage the readers to start with the
book "Entropy Demystified" and then seriously consider to go deeper into
the details of statistical mechanics with the more technical book by
Ben-Naim, of which I was delighted to read the draft.



5 out of 5 stars Entropy - no big deal   November 7, 2007
Nico van der Vegt
10 out of 11 found this review helpful

"... Arieh Ben-Naim invites the reader to experience the joy of appreciating something which has eluded understanding for many years -entropy and the second law of thermodynamics". This statement on the back cover for sure will reflect the experience of many who read this book. I highly recommend it to anyone who wants to understand or teach the mysterious concept "entropy". Just sit back, open this delightful book, and experience how your foggy ideas are cleared up within just a couple of enjoyable hours. You need no prior knowledge; if you have learned how to read and how to count numbers between one and ten you possess all qualifications needed to read and appreciate all of its contents. The author not only succeeds to brilliantly explain the meaning of entropy, its statistical interpretation and why common sense leads us to conclude entropy (most likely) is ever-increasing - he moreover provides compelling arguments to do away with the second law altogether: ".. because science will find it unnecessary to formulate a law of physics based on purely logical deduction". This concluding sentence by Ben-Naim will be further substantiated in a forthcoming book by the same author. In addition to the present book, which I highly recommend to everbody who wants to learn about entropy in general, I also want to recommend another recent book by Ben-Naim on molecular theory of solutions to students and scientists interested in the entropy of solvation processes. The scientific literature on this topic is huge and -above all - utterly confusing. Ben-Naim's clearly formulated ideas have helped me a lot in understanding the subject better.



5 out of 5 stars Entropy Defuzzyfied   October 16, 2007
GK
7 out of 7 found this review helpful

Adam Smith's "Invisible Hand" leads many people to think, that markets have the power to repair "themselves". But even in markets as open systems, there are irreversible processes, as the openness of real systems always is limited. Adam Smith, still in a Newtonian world, didn't know anything about the "second 'law' of thermodynamics" and "entropy". But at least today we should know better. Unfortunately entropy still seems to be some mystic thing to many, which to deal with should be avoided. (Knowing about entropy also increases responsibility. Some like to avoid that as well.)

You can't "avoid" entropy. Entropy is something very real: E.g. in broadband transmission the cost (e.g. chip size, power dissipation, heat generation) of managing entropy is almost proportional to the amount of entropy, which is to be managed. And climate change also can be explained by the entropy accounting (entropy generation, import, export) of the biosphere and the clogging of the interfaces of the biosphere, which are required to get rid of the entropy generated within the biosphere.

Therefore we need comprehensible explanations for entropy. My personal interest is not so much in entropy itself, but in how teachers and authors manage to explain entropy. Arieh Ben-Naim manages to get rid of all the fuzz which comes with so many publications related to entropy. He really manages to demystify entropy. I think, there are two paths which one could select to explain entropy. One is within information processing, the other one uses statistical physics. Ben-Naim chose the second one and thus not only managed to demystify entropy, but also demystified statistical physics: From my point of view, you just need a high school degree in order to be able to comprehend his book. Or you even may be lucky to have a teacher, who uses this book in the final high school year.

Economists and social scientists could get some help from the book too in understanding, what entropy really means. Indicators like the inequality measures of Theil and Kolm are entropy measures. And Nicholas Georgescu Roegen will be easier to understand. (The book would have been helpful to him too.)

Besides its content, I also like the making of the little book from Arieh Ben-Naim. It got very nice illustrations. And they are not just nice, they also are helpful. Here scientific thinking comes together with simple love to make things beautiful. It seems, that good science also leads to good aesthetics.

Related to this book, I also recommend the publications of M.V.Volkenstein (like Physics and Biology), although they are mostly out of print.





5 out of 5 stars A highly intuitive approach to understanding the Second Law   August 31, 2007
J. R. Harland (San Diego County)
2 out of 2 found this review helpful

In this book, Arieh Ben-Naim gives a very clear exposition of the Second Law of Thermodynamics--one of the most important principles of modern science. Moreover, the author lays out a compelling argument for why this "law" is not deeply mysterious, as is commonly believed, but natural and intuitive. The argument is based on an analogy with a class of easily understood dice games, which are analyzed in great detail. The essential features of the dice-game model--that is, the features which exhibit the exact behavior predicted by the Second Law--are then extrapolated to various real-world thermodynamic systems in a very lucid way. The book includes nice introductions to probability theory and information theory, although only the bare rudiments of these theories are needed to understand Ben-Naim's arguments. The author concludes the book with a critique of some commonly held views among the scientific community regarding the Second Law. In particular, it is argued that if the atomic theory of matter had preceded the formulation of the Second Law, rather than visa-versa, the Second Law would have been understood in a much more intuitive way from its inception, and thus would never have gained the near mythical status it has commanded over the past 150 years.


5 out of 5 stars Understanding entropy   July 25, 2007
JPF
1 out of 1 found this review helpful

If we ask science and engineering students to list the topics they find harder to grasp, inevitably "entropy" and "The Second Law" will be included. Apart from Physics - majors, which are exposed to Thermal Physics, all other students generally do not get the microscopic or atomistic view of entropy and of the Second Law. I can talk for myself: I did undergraduate and postgraduate degrees in engineering, covering Thermodynamics in both, I did hundreds of calculations with entropy, without getting a clue of what it is!
In this book, Arieh Ben-Naim gives that microscopic interpretation of entropy and of the Second Law in a very simple and clear way. He uses analogies that everyone can follow. At the end of the book, the reader will have understood the Second Law, plus some basic probability calculations. The author likes to interpret this Law under the framework of Information Theory and relates entropy to missing information. This is not the main goal of the book and you can stick to a more direct interpretation of entropy, as given by Ralph Baierlein, for whom it is simply equivalent to multiplicity.
In conclusion, I highly recommend this book to everyone, with or without a technical background, who wants to see the light of the Second Law. You will love the book and you will love Thermodynamics!


 
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