One More Recommendation for Your Holiday Reading: Manjit Kumar’s “Quantum”

This year seems to be a bit unusual. I have not one, but two very strong recommendations for your holiday reading list.

The first book, of course, was David Harriman’s “The Logical Leap: Induction in Physics,” which formed the topic of my last blog post [^]. Now I am very pleased to bring another great book to your notice: Manjit Kumar’s “Quantum: Einstein, Bohr and the Great Debate on the Nature of Reality” [^].

I am in a hurry. So, please do not regard this post even as an attempt to provide a proper review. I am just going to jot down a few points that occur to me on the fly, after having finished reading the book a week ago or so.

Here is my overall opinion of Kumar’s book: This book is the most outstanding account of quantum mechanics meant for the layman that I have ever read in print, period.

Now, that is saying a lot, and yes, I do mean it. … I have read a lot of pop-science type of material on this topic. Throw in also those philosophically oriented popular accounts. I am not exaggerating when I say that Kumar’s book is the best. Yes, Kumar’s book easily beats, just for example, both of Gribbin’s books: “In Search of Schrodinger’s Cat” [^] and its sequel “Schrodinger’s Kitten and the Search for Reality” [^], even Feynman’s books (Lectures and QED), not to mention Alastair I. M. Rae’s “Quantum Physics: Illusion or Reality?”[^].

Compared to Gribbin’s books, Kumar’s is a far more balanced, accurate, and a detailed account, with a lot of material concerning the personalities of the early quantum founders (even though Kumar does not cover the later period in much detail). Compared to Feynman’s accounts, Kumar’s book has one outstanding virtue: it is historically well-ordered, which by itself takes care of streamlining so much understanding in such a subtle manner. And, compared to Rae’s book, Kumar’s book does not care to dwell on the subtleties of the philosophical nonsense. It is a book that manages to keep physics at its focus through and through.

Kumar begins right from Planck’s hesitant acceptance of the quantum nature of emission and absorption of the cavity radiation, and then carefully goes through the evolution of ideas at the hands of Einstein (quantization of radiation itself), Rutherford and Bohr (atomic structure), and then all the European men, young and not so young, who discovered one facet after another in a breathtakingly rapid manner: Heisenberg, Pauli, Born, Jordon, Kronig, Uhlenbeck, Goudsmit, Schrodigner, et al. For each physicist, before describing his work, Kumar first provides an essentialized bio of the man: his family, inclinations in the school, academic work, supervisor and his personality, the ideas already “in the air” at that time, the initial faltering steps and false starts, and even the frustrations before the solution was discovered and the personality clashes after it was. And, Kumar also manages to place all these things in a broader cultural and historical contexts—the demands of the industry and governments to solve particular problems, the two world wars, the antisemitism, the reactions of the academic community to the evils surrounding them, etc.

Even before starting reading this book, I knew that these early quantum physicists worked in a very closely networked manner. But I had hardly realized the deep personal respect they gave each other and the deep feelings of friendship they enjoyed. It is easy to over-dramatize the tension between Bohr and Einstein; so many popular accounts have so routinely done so to such an extent that one might imagine as if Bohr and Einstein were at least playing a turf-war of sorts if not reaching for each others’ throats. You have to read this book to realize how far away such recent depictions have gone from the facts of the matter. Kumar possesses just the right sensitivity to the culture of those times to present just those essential facts with which, after finishing this book, one does come out enlightened about the way this extraordinarily brilliant chapter in the entire history of physics had actually unfolded. And, how cultured and intelligent its main actors were—regardless of whatever errors, even blunders—concerning physics or philosophy—that they might have committed.

This book has helped me correct many of the misleading or wrong impressions that I unwittingly had happened to gather, regarding many founders of QM—and even concerning the contents of their ideas.

Kumar covers the material roughly in the same sequence in which the development actually occurred. In following this policy, it is obvious that it is the author who has work harder, thereby lessening the burden of integration on the reader’s part. In this task, Kumar has succeeded brilliantly. To appreciate the sheer volume of reference material the author must have dug through, just take a look at Mehra’s volumes alone! And, yet, for many controversial ideas, Kumar manages both to present all the relevant material to the reader and and yet also to allow the reader the room to let him think about that issue and come to his own conclusions.

One also comes to develop an appreciation for the subtle nuances in the differences of the ideas held by the founders of QM, and the roles they played. Here, a few things stand out: (i) The way Heisenberg evolved matrix mechanics and the roles played by Born, Jordan, and Pauli, in developing it. (ii) How the idea of spin was so simple—and so much required in the order of development—that it could get introduced way before the 1927 Solvay conference. (iii) How close to the eventual formalism were certain nascent ideas held by the less celebrated physicists. (iv) The roles played by extraordinary mentors like Rutherford, Bohr, Sommerfeld, and others. (v) And yes, the special circumstantial reasons why the Copenhagen dogma could get established so easily in the academia.

There can be scope for improvement. However, in a book like this, it is a secondary or an outright minor matter. In any case, I don’t have any specific suggestion right away—I will have to do a more careful second/third reading before coming up with any. Yet, I must add, there is something that I found something missing right on my first reading.

I would have so much appreciated it if the author could have traced the evolution of Dirac’s re-formulation of QM. This development happened early enough, and it is important enough. The author has rendered a great service by carefully isolating and demarcating how the progression of thoughts occurred in Heisenberg’s formulation—starting with all the relevant events and ideas before his visit to that island resort and going on to the subsequent developments. It would have been a great (and easy) learning for the reader if the author could have done the same for Dirac’s development. This topic is conspicuous by its absence. The absence is all the more remarkable given the fact that (i) Dirac was a British gentleman, just the way the author is, and (ii) the author does manage to touch on such later developments like the EPR controversy and Bell’s inequalities. It is my sincere hope that the author would consider adding a chapter in a future edition. Or, make it available at his blog.

Overall, this book indeed makes for both a great read and a valuable reference. It could even be made recommended supplemental reading for university courses.

All in all, very strongly recommended.

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I don’t expect to write another blog post this year, and so, let me say “Happy New Year!” to you right away!

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A Song I Like:

(Hindi) “yeh raat bheegee bheegee…”
Music: Shankar-Jaikishen
Singers: Manna Dey and Lata Mangeshkar
Lyrics: Hasrat Jaipuri