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A physicist muses on science, politics, space, and more

Third Thoughts

Steven Weinberg
Harvard University Press
240 pp.
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In his book The Problems of Philosophy, mathematician and philosopher Bertrand Russell writes, “Philosophy is to be studied, not for the sake of any definite answers to its questions … but rather for the sake of the questions themselves; because these questions enlarge our conception of what is possible, enrich our intellectual imagination and diminish the dogmatic assurance which closes the mind against speculation.”

These words describe very well how I feel about Steven Weinberg’s Third Thoughts. This book should be read not only for its insightful and illuminating explanations of a wide range of physical phenomena but also for the opportunity it affords to follow the wanderings of a brilliant mind through topics ranging from high-energy physics and the makeup of the cosmos to poetry, and from the history and philosophy of science to the dangers of economic inequality.

Although most of the book’s 25 essays have already been published, in The New York Review of Books and elsewhere, the collection also contains several original pieces. The whole, however, is greater than the sum of its parts. And even the few, inevitable repetitions are helpful because they make the scientifically challenging concepts (such as those related to the foundations of quantum mechanics or the details of the Standard Model of particle physics) more accessible to uninitiated readers.

In the more scientific essays, I liked in particular the ones entitled “What is an elementary particle?” “Varieties of symmetry,” and “The trouble with quantum mechanics.” The first of these describes the tortuous road toward understanding which subatomic particles are truly “elementary.” The second gives an excellent description of the role symmetries play in deciphering nature’s puzzles. (Since Einstein’s theories of special and general relativity, physicists have realized that symmetry requirements essentially dictate the laws nature has to obey.) The third gives a perspicuous account of the apparent conflict between the fact that on one hand, quantum mechanics allows physicists to predict the results of physical processes with an astonishing precision, whereas on the other, its foundations in general, and the nature of experimental measurement in particular, are far from being understood.


Manned spaceflight, while inspirational, has yielded fewer discoveries than unmanned missions, argues Weinberg.

The section entitled “Public matters” is in my opinion the best in the book, and all essays within it—polemical as they may be—are excellent. Here, Weinberg examines weighty subjects such as climate change, big science, and manned space flight. Regarding the debate on climate change, he correctly concludes that “It is generally foolish to bet against the judgment of science, and in this case, when the planet is at stake, it is insane.” I couldn’t agree more.

In his essay “The crisis of big science,” Weinberg addresses the serious problem of the rising costs of conducting research in both high-energy physics and astrophysics while the United States is also facing serious and sustained economic challenges. His proposed solution: “[A]ll the people who care about these things” should “unite in restoring higher and more progressive tax rates, especially on invested income.” He laments, however, the reality that “given the anti-tax mania that seems to be gripping the public, views like this are political poison. This is the real crisis, and not just for science.”

Weinberg has always opposed government spending on manned space flight, arguing convincingly that most of the scientific breakthroughs in astronomy and astrophysics have come from data collected on unmanned missions. Although he concedes that there is excitement in exploration, he notes that unlike in space flight, people who have made heroic efforts to, say, climb mountains have never expected their expeditions to be funded by the government.

The final section of the book, “Personal matters,” includes such topics as science writing, the importance of being (occasionally) wrong, and the similarities and differences between the craft of science and the craft of art. When he discusses the value of being wrong, Weinberg echoes Bertrand Russell: “It is profoundly instructive to learn that one has been wrong about something. It combats arrogance, and opens the mind to new ideas.”

Although one could perhaps quibble about a few very minor points—Weinberg may underestimate the inspirational value of manned space flight, or its potential value in the future—he has not been wrong in this captivating book.

About the author

The reviewer is an astrophysicist and author. His most recent book is Why?: What Makes Us Curious (Simon & Schuster, 2017).