Entanglement: The Greatest Mystery in Physics

Rating:
Summary: Good But Doesn't Quite Hit The Bulls-Eye
Review: * Although Albert Einstein helped lay the foundations of modern
quantum physics, in the late 1920s he parted ways with the field,
stating that "God does not play dice with the Universe" and working on
"thought experiments" that would reveal what he saw as fundamental
flaws with the theory.

His last major jab was published in 1935 in a paper co-authored by his
assistant, Nathan Rosen, and another physicist, Boris Podolsky. The
paper took as its starting point the basic concept of quantum physics
that until a particle was measured, its state was not merely unknown,
it was undefined -- its state would be established by the measurement.

The paper written by Einstein, Podolsky, and Rosen, known as the "EPR"
paper after its authors, imagined the simultaneous generation of two
photons (light particles) that had interlinked properties -- for
example, polarizations at right angles to each other. The two photons
propagate in opposite directions. Their state is unknown until one is
measured, for example for its polarization -- but then the state of
the other one is known, no matter how far away it is. This "EPR
paradox" seemed to violate Einstein's theory of relativity, which
stated that nothing can travel faster than the speed of light.
Austrian physicist Erwin Schroedinger described the photons as
"entangled".

Amir Aczel's ENTANGLEMENT describes the history of entanglement,
showing how it originated -- and then shows how it was actually
experimentally demonstrated.

Einstein said the EPR paradox showed that the photons were not
actually undefined before they were measured, with their state
specified by "hidden variables". Danish physicist Niels Bohr rejected
Einstein's argument, but since the issue seemed purely theoretical
that was as far as it went for three decades. In the mid-1960s, a
brilliant Irish physicist named John Bell came up with a persuasive if
hideously subtle proof that it was possible to test the EPR paradox
and prove whether there were hidden variables or not.

This led to a sequence of experiments that demonstrated hidden
variables didn't exist. ENTANGLEMENT describes how the evolution of
the idea of entanglement led to "Bell's Theorem" and then discusses
the series of experiments that put the theorem to the test. It takes
a biographical approach, giving the background of the researchers
involved and telling the story of how they came to perform
these experiments.

Although I was expecting great revelations from ENTANGLEMENT, I have
to confess, if cautiously, that I was a bit disappointed in this book.
It is one of these books for which it is a bit hard to figure out who
the target audience is supposed to be. It seems a little too light
for a serious physicist, though no doubt its historical context is
interesting for that audience, but tends to lead the casual science
reader down a twisting path. I have this sense that the author
didn't quite know how to simplify the argument enough so that casual
readers did not have to wade through complications which are
irrelevant to them.

Like I mentioned, I say this cautiously. This is a good book, not
merely worth reading, but worth rereading, probably more than once. I
was just wishing for something that would make everything clear, which
may have been a completely unrealistic expectation -- this is about as
difficult a subject to write about as can be imagined. I will
continue to mine this book for bits of gold for a long time -- but
somehow I suspect that I will never hit the mother lode with it.

Rating:
Summary: a jumbled mess
Review: Aczel is a poor writer who has absolutley nothing new to say about quantum mechanics. His idea of humor is to suggest that scientists who worked together on refuting the Einstein-Podolsky-Rosen paradox got "entangled" with one another. A single use of this cheap metaphor would have been one too many! The author simply has no gift for translating quantum concepts into a digestible topic for non-mathematicians. Instead, he replaces essential physics with inessential and quite tangential biographical details. While it is certainly interesting to know that the participants took circuitous routes to their involvement with quantum physics these details do nothing to advance the story without a good exposition of their experiments. For example, I could not for the life of me figure out what John Bell actually contributed to the debate from Aczel's book, although its quite obvious that Bell's theorem was crucial to the testing of the EPR paradox! I got much more out of the recent "Hydrogen" by John Rigden - even though some of the same criticism can be aimed at it. Rigden is simply a better writer than Aczel. I will not be tempted to go back and look at his other books on the basis of this.

Rating:
Summary: Terrific topic...dismal delivery.
Review: As a physics buff I had high hopes for this book. The subject has always fascinated me. Sadly this book is a mess. The author has no ability to communicate clearly. This book is more of an historical account than anything else. Who cares where a scientist is born and how he grew up. There are numerious un-explained cryptic diagrams. When the author does explain an experiment it's a confused jumble. Don't let the intrigue of this subject trap you into reading this very poorly written book.
You will end up more confused and frustrated then enlightened.

Rating:
Summary: Great idea, horrible execution
Review: Before tackling this book, I had read some of Dr. Aczel's other works, such as The Mystery of the Aleph and Fermat's Last Theorem. I found those books quite enjoyable, so when I heard that he had published a new book on quantum entanglement, I could hardly wait to grab a copy.

After reading it through, I must say I am sorely disappointed to the work. I am still somewhat unclear as to what exactly entanglement is in any depth. His explanations, which are repeated at least a dozen times to no effect, are poor and left me confused. Diagrams are peppered throughout the book with no explanation or captions, leaving one to think that they're there just for eye-candy. Typos abound in the book and some pages are misnumbered (pages 232-4 especially). The book goes on and on about John Bell's famous theorem, but I am still confused as to what this theorem was and why we should care about it. In fact, the practical effects of entanglement aren't even gotten to until practically the last chapter -- the entire rest of the book is simply a biography on those who are or were working on entanglement.

Overall a terribly written book from an author whom I know can do much better. I am left confused as to the very subject matter the book purports to explain. Save your money on this one.

Rating:
Summary: Disappointing
Review: I was really excited about reading this book when I first bought it and really disappointed when I finished. As mentioned by an earlier reviewer, the biographical information is very interesting, but the physics stinks. I found the technical explanations incomplete and difficult to follow.

In addition, the book was written as if the author was in a hurry to meet a deadline. There was a lot of repetition, several editing errors, and the illustrations seemed to be thrown in just to take up space.

For a much better explanation of this mind-blowing topic, I recommend John Gribbin's "Schrodinger's Kittens and the Search for Reality." Gribbin does his usual excellent job of explaining thing simply enough so you understand what he's saying without needing a Ph.D. in physics. The final chapter of this book wraps everything up with Gribbin's preferred explanation of entanglement and quantum reality. After you read it, you'll be saying to yourself, "Hey, cool!"

Rating:
Summary: The Quantum Reality Einstein Could Not Suppose
Review: In 1935 Einstein, Rosen and Podolsky raised a serious criticism of quantum theory in the form of a paradox. The criticism meant that quantum theory brings about a "spooky action at distance" or "entanglement" between quantum subsystems. Two photons generated at a point with a correlation, for example, continue to have the correlation even after they are separated by a great distance, and a change in the state of one of them affects the other instantaneously. In 1964 John Bell proposed a mathematical theorem experimentally to test the existence of entanglement. Alain Aspect carried out such an experiment in 1982 to show that entanglement is a reality.

Even one of the greatest physicists in history, Albert Einstein, could not suppose that entanglement would be a reality. So it must be quite difficult to make ordinary person understand it. Amir Aczel tried to do this difficult task in this book, but he does not seem to have well succeeded. Just half of a total of 20 chapters is spent to describe the history of quantum mechanics, though a short mention about entanglement appears at a few places. Thus the reader who learned quantum mechanics to some extent at least would find the first half of the book rather tedious. From the story of debate between Einstein and Bohr in chapter 11, the book becomes interesting. However, the author explains neither Bell's theorem nor the details of many experiments understandably. On the final page, the author reveals the reason of difficulty in understanding entanglement writing, "... the quantum theory does not tell us why things happen the way they do; why are the particles entangled?" Was our expectation to the author too big?

A good point of the book is that it includes biographical descriptions of a lot of physicists related to quantum theory and entanglement. I have learned for the first time that Thomas Young, famous for the double slit experiment, was a child prodigy. Schrödinger's anecdotal "entanglement" with women are also told. A bad point is that writing and printing are made rather carelessly. For example, von Neumann's proof of the non-existence of hidden variable in quantum mechanics and John Bell's later challenge to Neumann's assumption are repeatedly described on pages 101 and 102. There are many typos, and especially the contents of pages 234 and 235 should be interchanged. This error, combined with sudden appearance of the description of Borromean rings on page 232, makes the reader confused around these pages.

Rating:
Summary: The Quantum Reality Einstein Could Not Suppose
Review: In 1935 Einstein, Rosen and Podolsky raised a serious criticism of quantum theory in the form of a paradox. The criticism meant that quantum theory brings about a "spooky action at distance" or "entanglement" between quantum subsystems. Two photons generated at a point with a correlation, for example, continue to have the correlation even after they are separated by a great distance, and a change in the state of one of them affects the other instantaneously. In 1964 John Bell proposed a mathematical theorem experimentally to test the existence of entanglement. Alain Aspect carried out such an experiment in 1982 to show that entanglement is a reality.

Even one of the greatest physicists in history, Albert Einstein, could not suppose that entanglement would be a reality. So it must be quite difficult to make ordinary person understand it. Amir Aczel tried to do this difficult task in this book, but he does not seem to have well succeeded. Just half of a total of 20 chapters is spent to describe the history of quantum mechanics, though a short mention about entanglement appears at a few places. Thus the reader who learned quantum mechanics to some extent at least would find the first half of the book rather tedious. From the story of debate between Einstein and Bohr in chapter 11, the book becomes interesting. However, the author explains neither Bell's theorem nor the details of many experiments understandably. On the final page, the author reveals the reason of difficulty in understanding entanglement writing, "... the quantum theory does not tell us why things happen the way they do; why are the particles entangled?" Was our expectation to the author too big?

A good point of the book is that it includes biographical descriptions of a lot of physicists related to quantum theory and entanglement. I have learned for the first time that Thomas Young, famous for the double slit experiment, was a child prodigy. Schrödinger's anecdotal "entanglement" with women are also told. A bad point is that writing and printing are made rather carelessly. For example, von Neumann's proof of the non-existence of hidden variable in quantum mechanics and John Bell's later challenge to Neumann's assumption are repeatedly described on pages 101 and 102. There are many typos, and especially the contents of pages 234 and 235 should be interchanged. This error, combined with sudden appearance of the description of Borromean rings on page 232, makes the reader confused around these pages.

Rating:
Summary: So Easy to Understand it should be a Gradeschool text
Review: The majority of the book is a review of the history of physics leading up to the current understanding of entanglement, including much biographical information about the major players in the quantum mechanics arena. I would have liked to see more than just that last short chapter talking about the implications and possibilities of entanglement.

Rating:
Summary: The History of a Counterintuitive Reality
Review: There must be some eggheads who understand quantum physics. For the rest of us who live in a Newtonian world, all sorts of weird things happen at the atomic scale, things that are too weird ever to be explained. A photon, the basic particle of light, when fired at a screen with two holes in it goes through both holes at once. Not only that, the photon particle isn't a particle at all, but a strange amalgam of particle and wave. A quantum entity can not only be two places at once, it can have two opposite characteristics at once (like opposite directions of spin), and it only settles on one of those characteristics when you look at it closely. Einstein had imbued the universe with his own share of weirdness related to speed of light travel, but he could never accept the weirdness of quantum theory. As physicist David Greenberger remarked, "Einstein said that if quantum mechanics was correct then the world would be crazy. Einstein was right - the world is crazy." Crazy or not, quantum theory has turned out to be correct, experimentally demonstrated over and over again in the last decades, and if we aren't going ever to get used to it, we might try to get to know it better nonetheless. At the heart of quantum physics is the mysterious phenomenon of entanglement, and in _Entanglement: The Greatest Mystery in Physics_ (Four Walls Eight Windows), Amir D. Aczel has valiantly attempted to make the phenomenon plain, and has had good success.

Entanglement is one of those quantum happenings that doesn't make any sense. It involves an instantaneous change in a particle once there is a change in a another particle with which it is entangled. The change is instantaneous, and would be even if the particles were on different sides of the solar system, or even of the universe. Somehow one particle "knows" that the other is changing, but this is not information that is transmitted one to the other. If it were information, it could not travel faster than the speed of light, but the change happens at exactly the same time. Einstein mistrusted the idea, calling it "spooky action at a distance." He would have been amazed that such a thing was not just theoretical, but experimentally proven, and much of this book is the history of how such a experiments came to be. The considerable physics in the book is lightened by anecdotes about the scientists involved. Along with the anecdotes are vignettes of model cooperation between scientists helping each other try to understand, even if their views were in opposition. Entanglement has a colorful history, well told here.

_Entanglement_ ends with a description of some practical applications; this is not just empty theorizing. Teleportation, the dream of science fiction, if it ever occurs, will be done by transferring quantum states of one particle to another. More immediately, using entangled photons as a means of sending an encoded message can reveal if anyone has tried to listen to the message. And quantum computing may change our ideas of the limitations of what computers can do. I predict that I, along with most people in my generation, will continue to see the world in Newtonian terms, but as future generations start using the ideas which are shown in this engaging and challenging history, perhaps they will find quantum mechanics a little less weird.

Rating:
Summary: Dissapointing attempt at writing on important topic
Review: This book appears to have been butchered by non-scientific editors who have removed essential explanation of diagrams and shortened any sentence that appeared to have syntax that would trouble anyone over the age of thirteen. I opened it with high hopes since I was looking for a gentle introduction to an important topic that I could recommend as initial reading for students. But I hesitate to let students near it since it has so many mistakes and blunders. (One quote: `Together with Niels Bohr, Wheeler discovered fission'. Has any scientifically educated person looked through the text before publication??)
The fact that diagrams are full of elements that are not referred to in the text is symptomatic of the very unprofessional way that this book has been produced. Aczel actually has some nice persnal anecdotes... what a wasted opportunity!