Jennifer Coopersmith tells the history of the law of conservation of energy in this fascinating book. Although it is almost devoid of equations, a full appreciation of it requires at least advanced undergraduate knowledge of physics and mathematics. Nevertheless, there is much in it that is accessible to motivated students who have completed their introductory physics courses. The subtitle refers to an allegory in Feynman’s Lectures on Physics [R. P. Feynman, R. Leighton, and M. Sands, Feynman’s Lectures on Physics (Addison-Wesley, Reading, MA, 1966), Vol. 1] that illustrates the genesis of a conservation law, while also arguing that the reality of the conserved quantity cannot be taken too literally.
David Mermin recently commented on physicists’ bad “…habit of inappropriately reifying our successful abstractions…” [N. David Mermin, “What’s bad about this habit,” Phys. Today 62 (5), 8–9 (2009)]. Mermin discussed the reification of several prominent abstractions in modern physics ranging from...