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Quantum

Quantum

Three cheers for 100 triumphant years

05 Nov 1999

Quantum Generations: A History of Physics in the Twentieth Century
Helge Kragh
1999 Princeton University Press 504pp £18.95/$29.95hb

In mid-December 1900 Max Planck presented a series of papers to the Prussian Academy of Sciences in Berlin that were, eventually, to revolutionize not only physics as a discipline, but our entire conceptions of the constitution of matter and energy. It would be fair to say that the century that followed was the century of physics par excellence, just as – if one were to believe recent developments – the coming century will be that of molecular biology and the study of the mind.

Academic physics at the turn of the 20th century was a relatively new profession, one that had evolved from a broad-ranging natural philosophy into a vibrant, growing and increasingly specialized field, producing cohorts of scientists and engineers who would exponentially populate industry, research laboratories, the military and government. By the middle of the century, physics and physicists – in particular theoretical physicists – reached the zenith of popular and professional recognition, mostly as a result of the extraordinary, and frightening, harnessing of nuclear power.

For several decades after Hiroshima, the services of physicists were highly sought, their independence guaranteed by lavish funding and accolades. And even though some high-priced projects such as the Superconducting Super Collider have not succeeded, the profession is flourishing and continuing to expand. Astronomy and astrophysics, materials science, optics and telecommunications are all exploding with discoveries and inventions, and despite dire predictions to the contrary, young people all around the world seem to be eager to enter a career in science and engineering with unabated optimism.

Helge Kragh’s book Quantum Generations is geared to just such inquisitive minds. The book is an ambitious one-volume history, the first comprehensive textbook to address most of the significant aspects in the intellectual history of 20th-century physics. Kragh’s achievement as far as depth and scope are concerned is quite remarkable. Quantum Generations is a slightly old-fashioned (not pejoratively so!) “survey” book written by a very knowledgeable historian of physics. Kragh – a professor of history of science at Århus University in Denmark whose other recent books include a biography of Paul Dirac and a history of cosmological controversies – has covered most of the significant institutional, political and national aspects of physics, and has drawn on all the available scholarship in a deft and inclusive manner.

While the book examines in detail the major, well established and recognized highlights – from the work of Planck, Einstein and Bohr to quarks and string theory, from the philosophical implications of quantum mechanics, the atom bomb and the militarization of science, to “big science” projects such as CERN – some of the most interesting chapters are those that depart from traditional narratives. These include science and politics in the Weimar Republic, and physics in totalitarian regimes. Kragh is fundamentally interested in pursuing broad theoretical themes across many decades, such as the predominant role played by the electromagnetic view of nature and the pursuit of a unified theory, well into the present.

But despite what the publishers say in the book’s press release, Quantum Generations will not be easily accessible to those ignorant of physics. Although there is hardly an equation in sight, Kragh implicitly assumes much physics knowledge. Moreover, it often seems as if he expects his readers to be already committed to what we now know, as if they come with a full-blown understanding of the significance of the questions asked and the success of the answers provided by the physicists in question. Ultimately, Kragh insists on illustrating a triumphant, rational march of science towards clearly articulated progress.

And despite historians’ recent fascination with scientific practice, Kragh’s book only occasionally gives a nod to experiment, instruments and technology, or to education, the popular image of science, and the often disturbing incomprehensibility of modern physics to the general public. Nor do we get a sense that scientists ought to concern themselves with what the rest of the world thinks of them. Implicit in this book is the assumption that the achievements of modern physics justify unlimited resources and unlimited faith. It is perhaps the unproblematic approach to the history of science that is most characteristic of Kragh’s self-confident and eloquent writing style.

For historians of science such as myself, the most intriguing chapter is perhaps “Science Under Attack – Physics in Crisis?” Here Kragh rather linearly and causally links the work of J D Bernal, Herbert Marcuse, Thomas Kuhn, Paul Feyerabend and the more recent sociology of scientific knowledge and social constructivism to the growing anti-scientific climate and the alleged decline in the interest of young people in physics. And while it is true that enrollments in physics PhD programmes in the US have declined by 27% since 1992 – probably due to the end of the Cold War and the reduction in defence-related employment opportunities, rather than a few dozen academic books on the social construction of science – the total number of science and engineering PhDs awarded by US universities rose by 25% to some 26 000 in the ten years to 1995. These statistics indicate shifts in interest, rather than mere disinterest in science and engineering.

Moreover, the comprehensive bibliography in Kragh’s book shows that the history of physics is not, as many believed in the early 1980s, a closed subject. On the contrary, the last 15 years have seen the publication of an impressive number of monographs, biographies, popularized books and specialized articles that have changed and deepened quite dramatically our understanding of the history of modern and contemporary physics.

For physicists who want to “humanize” their courses, or brush up on their professional past, for those who teach the history of modern science, and for anyone fascinated with physics, I can recommend this book as an indispensable resource.

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