Quantum: Einstein, Bohr, and the Great Debate about the Nature of Reality

The history of the development of quantum physics has been told many times, sometimes for the benefit of future physicists and sometimes more for the general public (as in John Gribben’s books). This book covers the same ground with two differences. One is that Manjit Kumar opts for a middle road in describing in more detail the history of the quantum. As in other histories, the same characters from Max Planck to John Bell are here with biographical sketches of each one in the text. But Kumar also presents more (not a lot) of the basic equations and more of the technical aspects of their work. Kumar does a fine job of digging into the details of the quantum revolution and the non-physicist can always gloss over the material he or she is not interested in. But, while the book is being sold as written for the general public and centered on the Bohr-Einstein debate about reality, it has more details than some readers may expect.The second difference from other histories of the quantum is Kumar’s emphasis (as the title indicates) on the difference between Einstein and Bohr on how to interpret the quantum results. Einstein never denied the reality of the strange results but claimed the theory was “incomplete.” Do cause and effect function at all levels of the universe independent of our observation? Einstein never wavered in the belief that a complete theory of reality could be understood causally (the famous “God does not play dice” quote) and that the weirdness of quantum results would be explained by (or be a subdivision of) that larger more complete picture. Bohr’s claim was that the “quantum world” (he did not like that term) did not function in the same way as our everyday world. Trying to find a theory that encompassed both was pointless because causality as we understand it could not be imposed on the subatomic world. If, as some have claimed, we have to think causally to make sense of our world, then we are in principle incapable of “understanding” the quantum dimensions. What we are left with is the math and the usefulness (and strangeness) of the results of quantum mechanics, from transistors to computers. There is no point trying to subsume electrons or quarks into our classical way of understanding.This is a fascinating debate and Kumar does an excellent job spelling it out when he gets there but he does not actually get there until two-thirds of the way through the book. When the Great Debate finally arrives, it is profoundly interesting. But the book’s title is somewhat misleading since the actual Bohr-Einstein debate is not sharply defined until Part 3, “Titans Clash Over Reality,” on page 251. Kumar covers a great deal of ground and his research is extensive. So, if the reader is looking for a book not just about the main debate itself but also a book with detailed background leading up to the Bohr-Einstein core disagreement, this book is ideal. I would then recommend it.

I have been reading books on the historical development of 20th century physics and especially quantum mechanics for about 40 years. The first I ever read was Banesh Hoffman's, The Strange Story of the Quantum" which woke me up to the debates in physics. Manjit Kumar's book is among the finest I have read during these 40 years. My own particular interest lies in the development and understanding of the periodic table and here Kumar's book has been extremely illuminating.I have previously presented a somewhat opinionated picture of Bohr's explanation of the periodic table as being somewhat ad hoc, to the extent that Bohr did not derive the configurations of atoms but rather cobbled them together after consulting chemical and spectral information. I am not alone in expressing this view and many historical sources stress how physicists like Pauli were also somewhat underwhelmed at the time by Bohr's explanation. However, on seeing Kumar's carefully reconstructed account of the events I realized more than ever that Bohr's work was still a tremendous triumph. For example Kumar notes how even Einstein was impressed by Bohr's theory. This is something that I will need to include in the eventual second edition of my book on the periodic table.Similarly, Kumar's book has given me a clear and simple way to present the discovery of the second and third quantum numbers. But these are all technical matters and may not be of much value to the general educated reader. I mention them just to emphasize that Kumar's book is a popular exposition but not a vulgarization.Kumar's book is a popularization in the best possible sense of the word, much like the work of Brunowski and Sagan. It presents a very much needed antidote to the, frankly shameful, popularizations by the boy-wonder of British science TV who among other things espouses a completely misleading account of the Pauli Exclusion Principle, apparently believing that heating a diamond causes an effect in every other electron across the universe.Returning to Manjit Kumar, I highly recommend his book to all scientifically literate readers. Complete beginners might feel a little lost but I am referring to those who enjoy the kinds of articles in New Scientist and Scientific American. What I especially liked was the combination of factual accuracy, an excellent historical narrative which helps to bring the major characters to life, and the philosophical insight expressed in a fairly non-demanding fashion. In addition I believe that experts in physics, chemistry, history of science and even the philosophical foundations of physics will derive great benefit from seeing the history of the developments laid out from such a clear and penetrating vantage point as this book achieves.

I'm half way through and i can't wait to finally get to the end.... so I can start reading all over again immediately!Possibly 'not enough physics' (as another reviewer about to start their 1st year as a Physics undergrad) may think, but there's plenty to amaze and inspire within these covers - and definitely with wa-hay more insight than a more mathematical treatment would inspire - unless you're wed to the principle of causality like poor old Schrodinger 😁 (and who would have thought Physicist's were such a randy bunch - you wouldn't find those sorts of fascinating vignettes in a more theoretical tome!)Some fantastic pictures of all the greats - Curie, Einstein, Heisenberg, Bohr, Schroedinger, Pauli, Rutherford to name only a few - absolutely the best book I've read since I left Uni many moons ago.If you also overlay the economic/political and jingoistic overtones of the times it is amazing to think this scientific revolution all took place less than 100 years ago, especially as without which there would be no smartphone from which to read insightful reviews and order great books 🤔👍

This book charts the unfolding of quantum physics in the early part of the 20th century, from Planck's solving of the black box problem with the quantisation of energy in 1900 to the great Bohr/Einstein debate at the Fifth Solvay conference of 1927 regarding the interpretation of quantum reality.Written in an as-it-happened manner by a physicist with deep passion for and understanding of the subject, the book supplies a brief curriculum vitae of the major players in the quest – Planck, Rutherford, Thompson, Bohr, de Brogli, Pauli, Heisenberg, Schrȍdinger and of course Einstein himself - and unfolds the problematic experimental data that emerged together with the theoretical means of dealing with these problems.A story of cutting-edge research, academic brilliance, personal rivalry, determination and deeply held convictions, it captures the excitement of the times in a thrilling roller-coaster of a tale, a ripping yarn made all the more enthralling by its historical accuracy. The book does contain a couple of fairly simple equations, but in a way that enhances rather than obfuscates the narrative. As a history of science it's second to none, but the highly engaging style and sequential unfolding of events adds to an understanding of quantum physics from the perspective of the front-line.The book ends with an account of the Einstein-Podolsky-Rosen paradox and the experimental proof of Bell's theorem which provides the casting vote between the two opposing viewpoints of objective reality versus quantum subjectivity. Highly recommended.

I have spent twenty years reading countless books on quantum physics. Unlike most of the rest which introduce the reader to a new concept and then leave them dangling, this introduced each new area gradually, did not baffle me with pointless facts, and left me feeling more informed than with most of the others combined.I highly recommend this books to those interested in a subject that few people (even the scientists) know to its fullest extent.

An excellent book that carefully traces the history of Quantum mechanics from it's beginnings. Manjit Kumar has a talent for being able to explain not just the events of the time but also the physics in a very straightforward way, while giving readers more detail than I expected to find. I found it fascinating and his style is very easy to read, and very difficult to put down. Only snag I have about the book itself (paperback version 2014 by Icon Books) is that the contents page has a list of illustrations for a plate section that isn't actually included in the book. Such a shame because the titles on the list include the classic fifth Solvay Conference 1927 picture, and many other interesting pictures of the main players from that time (and also Niels Bohr's last blackboard diagram...which I am now really curious to see). Still, this apparent discrepancy is not enough to lose any stars in my review because the book itself is so good. Highly recommend, but look around for the hardback version which may have the illustrations?

Quantum mechanics is one of the most successful scientific theories ever made. But it is utterly non-intuitive for both the scientist and non-scientist alike.In our everyday lives, things happen for a reason - you place a fork on a table and unless someone comes along and moves it, you can be certain that it will be still there the next day. Not so in the atomic world of quantum mechanics, an electron might be here... or it might be there ... or over there. In fact it could be anywhere in the universe at any given time. Quantum mechanics predicts this behaviour in the form of a probability wave function. And it works.But is this the true nature of reality?This is the theme of the book. We have two great scientists - Einstein and Niels Bohr who have a fundamental difference of opinion about the nature of reality.From Einstein's' point of view, an electron has a real set of parameters such as location, velocity, spin and so on that is independent of an observer. He admits that quantum mechanics does a good job in predicting atomic behaviour but he is convinced the theory is not complete.On the other hand, there is Niels Bohr's vision that an electron (or any microscopic entity) has no reality until an observer chooses to measure one of its parameters. He considers quantum mechanics to be complete with no further need for revision or modification.This argument goes on for decades. The book takes the reader through the panoply of scientists who helped put quantum theory together from its beginnings around 1900 to today. Scientists such as Max Planck, Heisenberg, Dirac, Pauli, Oppenheimer, Von Neumann and many, many others are included.The appeal of this book is that it brings humanity to the story of quantum mechanics. It shows the egos, the fears, the ambition of these extraordinary people as the story unfolds over decades.If you want a pure explanation of quantum mechanics then you should look to a dry text book. But if you want the human context in which quantum mechanics evolved then I recommend you read this book.