David Cassidy's new survey of twentieth-century physics is indeed short: about 170 pages of text. It aims for a brief introductory synthesis for students and the general public, so much of it will be familiar to scholars. It is primarily a history of American physics, though with occasional nods to developments abroad, such as for quantum mechanics. It has chapters on the fin de siècle emergence of American physics; growth in the First World War and the 1920s; the Depression; the Second World War, radar and the bomb; two chapters on postwar physics; Sputnik and the 1960s; and a long concluding chapter on the last four decades. A useful appendix provides data on numbers, demographics and funding of American physicists.

Cassidy's book will serve well as a synthesis for undergraduate courses in history of physics. It nicely complements recent short surveys of nineteeth-century physics, including Bruce J. Hunt's Pursuing Power and Light (2010) and Iwan Rhys Morus's When Physics was King (2005), both of which tell a mostly European story. Mary Jo Nye's Before Big Science (1996) covers the period from 1800 to 1940 and includes chemistry. Cassidy starts his story at the turn of the twentieth century and focuses on physics in the US. He provides a short alternative to more detailed surveys of twentieth-century physics, such as Helge Kragh's Quantum Generations (1999) and, on the American context, Daniel J. Kevles's The Physicists (1995). One regrets, though, the assumption – certainly grounded in teaching experience – that today's undergraduate can only tackle two hundred pages of text in a term.

Cassidy gives due attention both to ideas and to institutions. For the former, he generally provides clear explanations of physical concepts and theories; the book's brevity, however, at times limits discussion, and topics such as band spectra, isotopes, quantum field theory and quarks may mystify non-physics majors. For institutions, Cassidy pays particular and welcome attention to industry, where many – by the end of the century, most – American physicists worked. He shows how the rise of physics helped underpin the American century, through physicists' familiar role in nuclear weapons and other military technologies, and through their perhaps less recognized contributions to commerce; Cassidy nicely traces developments such as integrated circuits, lasers and supercomputers to their roots in physics research.

Cassidy addresses familiar issues for American physics, including the rise of collaborative Big Science, and especially the twin tensions between pure and applied science, and between political autonomy and the desire to serve national interests and tap federal funds. He shows how the American political system and society had subsumed physics by the 1970s, evident in the disappearance of powerful scientist–administrators. The book implicitly reveals this development: the early chapters include short biographical sketches of exemplary figures: Jewett, Hale, Millikan, Lawrence, Oppenheimer, Karl Compton, Melba Phillips, Vannevar Bush. These capsule biographies disappear from the postwar chapters. Cassidy documents persistent sexism, ethnic and racial discrimination and anti-Semitism in the physics profession. He also touches on historiographical debates, especially Paul Forman's thesis on military influence on postwar science and Forman's later argument about modernity, postmodernity and transcendent values among physicists and their historians.

Although Cassidy describes American physics in a celebratory mood at the end of the twentieth century, his survey suggests a more ambivalent rise-and-fall narrative, which jibes with frequent expressions of a discipline in crisis in recent forums such as Physics Today. Some of this declinism stemmed from funding cuts, highlighted by the cancellation of the Superconducting Super Collider; some from loss of control, not only in the political arena, but also in industrial labs, which increasingly subordinated research to product development and marketing (or outsourced it altogether). Cassidy also chronicles the diffusion of the physics discipline, through fields such as chemical, medical, computational, plasma and condensed-matter physics, and more explicit interdisciplines such as astrophysics, geophysics and biophysics. These fields often have their own specialized societies and journals, and Physical Review, which by 1993 was publishing seventy thousand pages of research a year, has splintered into five separate sections.

Finally, Cassidy notes that internationalization and globalization, evident in the predominance of foreign graduate students in American physics programmes, have diluted the notion of a national physics community. He concludes that a similar history focused on physics in a single nation will be impossible a century from now. That assumes that a coherent discipline of physics, a historical construct of the last few centuries, is itself still around to chronicle.