A. B.'s Reviews > Quantum: Einstein, Bohr and the Great Debate About the Nature of Reality

Quantum by Manjit Kumar
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it was ok

Modern physics is highly focused in relativity and quantum mechanics (QM). The former theory is the result of Albert Einstein's work, repeatedly confirmed over the last 98 years. The latter theory, whose degree of completeness is still an issue, is the result of concepts developed by Niels Bohr and work of his followers, which have led to two principles: [ i ] complementarity, viz., one can only get the complete picture of, say, an electron by using two concepts that contradict one another but are at the same time together, (e.g., wave vs. particle dichotomy), and [ ii ] indeterminacy (or uncertainty), viz., one cannot exactly determine at the same time some variables like the position *and* the momentum of that electron. This is often known as the Copenhagen interpretation of QM.

Manjit Kumar's book, released in 2007, gives a historical account of the still unresolved "problem of getting the interpretation proved" --to quote Paul Dirac-- of the meaning of QM and the nature of matter and light, as seen from the perspective of the debates between Bohr and Einstein, and their scientific fellows, which reached a climax at the Fifth Solvay International Conference of October 1927. Mr Kumar touches on some philosophical aspects of the competing views underlying these debates, but does not really delve into them.

The book is acceptably well written, despite a strong sophomoric tendency to bring up unnecessary anecdotes. The most flagrant ones are those about Erwin Schrödinger's sexual proclivities -- the nine references to his affairs in the twenty-four pages of chapter nine, including its title, are more suitable for those gossipy magazines in cashier aisles of North-American food markets than for a book on quanta (unless, of course, the author favors that "enjoying a secret tryst" is the best way to conceive wave mechanics). Zeitgeist of the millennium, I suppose.

The last chapter of the book, where the author unveils an overt anti-Bohr perspective, leaves plenty to be desired. Mr Kumar concludes that "Einstein has been vindicated, in part," in reference to what Einstein himself called his *instinctive* distrust of the Copenhagen interpretation (a distrust he did not support with a published interpretation of his own, however), encapsulated in the letter where he accuses Bohr of believing "in the God who plays dice." This conclusion, far from being universally shared, is apparently based on: ( i ) conceptual difficulties of QM not yet resolved; ( ii ) the "many worlds" interpretation of Hugh Everett's formulation, which Mr Kumar appears to take for granted that not only it would satisfy Einstein's demand of a tangible foundation for QM, but that it is a complete formulation as well; and ( iii ) the meager results of a poll of 90 physicists at a quantum conference 18 years ago, of whom less than half indicated an actual preference (Benjamin Disraeli would be amused). Nonetheless, a number of experiments in the 8 years after the book was completed have supported complementarity, and transformed the 'spukhafte Fernwirkung' into a reality. They include an experimental test of the famous Einstein vs. Bohr recoiling double-slit 'gedanken experiment,' in dispute 80 years ago at the Solway conference -- using resonant X-ray photoemission from molecular oxigen, in 2015 Miron and others showed the materialization of that thought experiment "in full agreement with Bohr's complementarity principle" (go.nature.com/2HQoWaI).

For a perspective of the philosophies underlying the debates, the concepts put forward by Arthur Koestler in his book The Act of Creation (1964) are worth mentioning. Arguing that "the glory of science is not in a truth more absolute than the truth of Bach or Tolstoy, but in the act of creation itself" (p. 252), Koestler also concludes that "bisociation" is a consistent element of the process of discovery. Bisociation, defined as the simultaneous association of an idea or object with two fields ordinarily not regarded as related, fits complementarity like a glove.

Finally, this book contains a GROSS MISTAKE, unacceptable in an author claiming "a degree in physics" who should understand basic concepts. It is a mistake the author makes about the effect discovered by Arthur Compton --namely, the increase in the wavelength of most secondary X-rays scattered after firing an X-ray beam on a graphite target--, which was a crucial finding that demonstrated light is quantized. In p.139 [2011 Norton edition, ISBN 978-039307829-9], Mr Kumar says that "Compton understood that the difference in wavelength (and therefore frequency) meant the secondary X-rays were not the same as the ones that had been fired at the target. It was as strange as shinning a beam of red light at a metal surface and finding blue light being reflected." The latter sentence is an erroneous simile of the effect discovered by Compton: as any physics undergraduate knows (and many a high-school student too), red light has a LONGER wavelength and therefore lower frequency and energy than blue light. The correct simile would be finding red light being reflected when shining a blue light beam at the metal surface.

This mistake is not just a mere transposing error made in passing, but a major conceptual one. This is so because Mr Kumar makes it when trying to explain the scattering in his own words, something requiring full attention. And this is more flagrant as that sentence ends with a footnote about the Comptom effect using visible light. I am flabbergasted that none of the reviews of this book that I have seen mentions this awkward mistake, and that, in the absence of a correction, the book could have been shortlisted for a Samuel Johnson Prize. Seriously?
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March 23, 2019 – Shelved as: to-read
March 23, 2019 – Shelved

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