Customer Reviews

Great Ideas in Physics

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A book like this is sort of a double-edged sword. Sure, when dealing with the lay person whose interest in physics (and the like) is sparked more by a temporal curiosity than by a need to know, 'popular' works like this tend to cover as much as necessary in as little space as possible, and in a way that translates easily for the non-specialist. As such, I applaud Dr. Lightman for not only attempting to educate the "simply curious" on very complicated areas of science but actually doing a noble job in the process.

Nevertheless, there are problems by which educators and science enthusiasts alike will simply cringe when reading (as Jesse Engelberg intimated). One example from among the questionable portions of the text will serve to prove this point. In the opening section concerning the Conservation of Energy, the author does a remarkable job in deriving many of the equations leading up to the first law of thermodynamics; however, he makes a much-too-often-committed mistake concerning molecular motion at absolute zero. From page 44 the text reads:

"Zero degrees Kelvin is called absolute zero. It is the coldest that any substance can be. From [Equation (I-14){provided on page 43}], we see that absolute zero means that <v^2>=0, which can be achieved only if every single molecule in the substance is motionless (aside from ordered motions). If even a single molecule is moving, then <v^2> will be larger than zero, and the substance will have a temperature higher than absolute zero."

Aside from the author's unexplored meaning of what an "ordered motion" is (perhaps this is the vibrational motion contended for in the following), anyone amply versed in Physical Chemistry and Thermodynamics is well aware that molecules are motionless at absolute zero only when referring to translational and rotational motion--not vibrational motion. Again, this is where a book like this would lose some of its luster by having to explain the difference to a general reader, but to say that molecules become motionless at absolute zero is utterly wrong and serves only to perpetuate misconceieved and erroneous notions of science among those reading such works for the first time. In fact, one of the fundamental tenets of quantum theory is this idea that all matter continues to execute vibrational motion, EVEN AT ABSOLUTE ZERO. It would be hard to believe that someone as educated as the author actually believes such a common, grievous error to be the case; hence, he should have qualified the statement a little more clearly by pointing out that translational and rotational motion are being referred to in the context (which of course would have demanded a longer and more arduous discussion on each type of motion) or he should have simply taken this portion out of the text.

As such, I am in agreement with the final comment made by Jesse Engelberg, namely: "buy this book if you are already conversant with the physics it discusses (thermodynamics, quantum mechanics, and relativity) and want to read about the history and philosophy of them." While I do not see the need to "only" buy the book if one is already well exposed to physics and has a desire to learn its history, I would warn new readers to pay more attention to the history and development of the ideas delineated in the work rather than some of the final equations (which do not always conform to scientific convention anyway) and quantitative data.

Very simply, get a feel for what is being said as a whole and seek the meat of the details elsewhere.

Alan Lightman, Senior Lecturer in Physics at MIT and author of the recent best-seller _Einstein's Dreams_, serves up four fundamental concepts that form the foundation of modern physics in an easy-to-read, comfortable manner. Not being a physics buff, I was pleasantly surprised at the ease with which Lightman commands and communicates his subject. After developing a beginner's understanding of the conservation of energy, the second law of thermodynamics, the theory of relativity, and quantum mechanics, it is fascinating to watch each of these ideas find traction in the world around you. For those who might view physics as an esoteric field that bears no real relevance to the lives of ordinary people, Lightman encourages them to look at the impact of these ideas, not only the science of the modern world, but on the social, spiritual, and intellectual aspects of the modern era as well. By weaving passages from writers, philosophers, theologians, and social theorists, Lightman explores the wide-ranging impact that physics has had on every academic field imaginable.

While some may find the text to be pedestrian and lack the hard math of more ambitious texts, this book is not geared towards experts and should not be considered anything more than a fun read for the informed. If you're ready to begin exploring the world of physics, this is a nice place to start. Just be prepared to view the world differently after you're done.

Whether the physics in this book is perfect or not, one thing is certain: the physics is readable. This is not a book for the aspiring physicist, I made that mistake. This is a book for a person curious about some of the major developments in the subject but NOT interested in the minutia and the math behind the theory. Physics is not just for nerds with overpowered calculators, anybody can be fascinated by this stuff.

This is a decent book when it comes to discussing the philosophical implications of physics, but its discussions of the concrete physics are lacking. There are many typos and ambiguous problems, and in some cases important concepts are actually explained incorrectly. Only buy this book if you are already conversant with the physics it discusses (thermodynamics, quantum mechanics, and relativity) and want to read about the history and philosophy of them.

I am starting to self-study physics and mathematics as part of a broader interest in astronomy and cosmology.
I am delighted by this book which focuses on 4 fundamental topics and explains them clearly with only algebra.
This is a great intro, very pedagogical, and I don't feel cheated on the science, compared to other popularizations.
I just wish there would be the solutions to ALL the exercises, and hope A.Lightman does a sequel.

This book both impressed and disappointed me. One of the disappointments is the way Lightman advances the notion that some physical theories can be logically deduced, a priori, without performing experiments, and without experiencing the real world. I thought we'd conquered that siren's song centuries ago, but it lives on in Lightman's book.

For example, Alan argues that "Thermodynamics is essentially nothing more than the theory of probability, and that the second law might have been logically deduced on the basis of pure mathematics, with no experience of the world. He repeats his faith in a priori reasoning on pages 27-28 where he claims to provide a derivation of the "law" of conservation of gravitational and kinetic energy "using only logic and algebra." In another example, he argues that, with only a pencil and paper, Maxwell discovered the theoretical possibility of traveling waves of electromagnetic energy. And he promotes the myth that Einstein's theory of relativity is an example of "deductive science, [in which] the scientist begins by postulating certain truths of nature, with only secondary guidance from outside experiments, and deduces the consequences of the postulates.

In so forcefully advancing a central role for a priori reasoning, Lightman fools himself and does a disservice to the student. For example, in deriving the "law" of conservation of gravitational and kinetic energy, his proof makes use of the fact that things fall down. But that's an observation. Without that observation, Alan wouldn't know if things fell down, upwards, sideways, some arbitrary direction, or just *sat there*. His a priori proof also uses the fact that things fall with a constant acceleration. But for hundreds of generations before Galileo, people thought otherwise until corrected by observation. Further, Alan's proof assumes that all masses fall with the same acceleration, regardless of composition, which is yet another bit of information based on observation.

To me, it's incredible that I could pick up a book written in the 21st century, ostensibly on physics, and read a philosopher who argues there are physical theories "deduced" "using only logic and algebra. The problem seems to be that, once the deductive arguments are two or more steps removed from the experimental results, Alan has a tendency to forget the observations all together and then make unwarranted claims about the power of a priori reasoning and deductive logic based on "postulates." The whole idea of a priori reasoning in the total absence of experimental observations should have been, at the very least, discarded when Darwin taught us that our brains are a product of evolution, and thus designed by natural selection to analyze the real world.

The level of difficulty is aimed at high school students or freshman college students who are just being exposed to ideas in science and physics. But I don't recommend this book for beginning students because of the aforementioned philosophical problems. There are also too many technical problems.

For example, Lightman uses two colliding balls to illustrate the conservation of kinetic energy, but his explanation fails to mention (at all) that kinetic energy is conserved only for elastic collisions. He could and should have used conservation of *momentum,* which is always conserved, but he fails to mention that conservation law at all. So, although his explanation is correct as far as it goes, it is inexcusably misleading and incomplete.

I genuinely enjoyed some of Alan's derivations, as they provided peripheral views on scientific concepts that are illuminating. But some derivations are sloppy, and likely to mislead beginning students, especially when Alan takes tenable conclusion and then makes sweeping conclusions, culminating with the declaration of "law." This wouldn't be a problem if he explained along the way that the reasoning is non-rigorous, and that the conclusions are only tenable, and subject to further experimental testing and validation. But he does just the opposite by giving the reader a false sense that the reasoning is far more rigorous than it really is.

I enjoyed the author's explanation of thermodynamics. The examples, starting out with small numbers of ideal molecules, nicely illustrate key principles. And, I like the way he expands these principles. This is one of the best sections in the book. I enjoyed his development of the first and second laws of thermodynamics, with the singular complaint that he provides so much time to bad philosophers who use thermodynamics to misrepresent evolution. He doesn't just let the philosophers and religious fanatics misrepresent evolution, either. He does it himself. For example, on page 110 Alan summarizes a philosopher's argument with the comment:

"Here Adams describes the conflict between Evolutionists, who think human society is forever progressing upward, and the Degradationists, who believe in the second law of thermodynamics."

The idea that evolution says "human society is forever progressing upward" is a flagrant misrepresentation of evolution. This sort false dichotomy misrepresents both evolution and thermodynamics, and is roughly in line with bogus arguments from religionists like Henry Morris, to whom Alan allots over a page of explanation under the bold-typed headline "The Second Law Used to Refute the Theory of Evolution." True, he does offer a paragraph explaining that the earth is a closed system, but to offer so much time to Morris, without a word from great scientists and philosophers like Dawkins, is just unforgivable. Without exception, every reference to evolution was either negative or neutral, which is an unforgivable slight on the greatest theory of the 19th century.

The conservation of energy, the theory of thermodynamics, the theory of relativity, and quantum mechanics are, truly, all great ideas in physics; hats off to Alan Lightman for writing a book about them. But it's a real shame the book had to be cluttered by the other stuff.