Six Millennia of Truth Seeking
From Clockwork to Crapshoot: A History of Physics. Roger G. Newton. xii + 340 pp. Harvard University Press, 2007. $29.95.
According to historian Roger G. Newton, the thing that has gradually separated physics from the other branches of science over the past 6,000 years is "the ability to predict future events with some confidence of success." Humans demonstrably had this ability (with regard to the movements of heavenly bodies, for example) as far back as 4000 B.C., which is where Newton begins his new history of physics, From Clockwork to Crapshoot. It is a general-interest survey that seeks to cover a trip lasting six millennia in only 312 pages of text.
The first part speeds by quickly. Three millennia pass in the first 10 pages, and a fourth, dominated by ancient Greece, is gone by page 40. The author treats the Greek world as essentially a precursor to the clockwork universe. This is a gross oversimplification. To Aristotle, the cosmos was less a clock than a vast ecosystem. His view was that it has sometimes overlapping domains inhabited by qualitatively different kinds of things exhibiting qualitatively different kinds of behaviors; to understand it all, he believed, it is necessary to look at things in complementary ways. Thus it would have been nice if the author had paused to indicate how Aristotle might have explained, say, the motion of a horse pulling a cart on the road to Athens—an action whose full explanation would necessarily include the desire of the merchant to feed his family, the market system and so forth. Then later that explanation could have been contrasted with Isaac Newton's discussion in the Principia of a horse tethered to a weight, which involves only forces, masses and velocities. The comparison would have helped readers to understand how Aristotle saw the world and to appreciate more completely the truly novel character of the idea of a clockwork universe that appeared a millennium later.
But no matter. The book's title suggests that the author really means to begin with what he calls "The First Revolution," the world of Kepler, Galileo and Newton, when physicists were able to look at the entire universe, in microcosm as well as macrocosm, as a giant machine not just in a metaphorical sense but in the more literal sense that they could imagine themselves actually being able to predict in detail the future course of events, both in the heavens and here on earth.
There is much to cover: astronomy and mathematics; sound, light and electromagnetism; thermodynamics and statistical physics. Roger Newton's approach is to give us only thumbnail portraits of the scientists: the highlights of their careers and some personal detail, such as information about their marriages, children and siblings. The narrative is brisk but often formulaic; pages and pages pass with each paragraph devoted to yet another person. En route the reader finds brief discussions of key terms: Maxwellian distribution, Gaussian distribution, mean free path, entropy, degrees of freedom, the equipartition theorem and so forth.
Sometimes Newton is too perfunctory in his stories, as if he has told this particular one too many times, has forgotten the value of entertaining his audience and so neglects to deliver the punch line. When he notes that the Muslim natural philosopher Ibn al-Haitham (known in the West as Alhazen) gave a correct explanation for the Moon illusion, why not say what it is? Or when he tells us that Ludwig Boltzmann wrote a "hilarious description" of his trip to California, why not offer up a sample of the humor?
Every so often it becomes clear that the author is recycling material from other histories, as when he repeats without question the legend that Scottish botanist Robert Brown observed an irregular motion of pollen grains, later explained by Einstein as due to the impact of water molecules. That legend is false; Brown was actually looking at particles inside pollen grains.
The pace of the story picks up in the 20th century with what the author calls "the second revolution in physics, which replaced determinism by probabilistic predictions." Here he provides brief portraits of Max Planck, Albert Einstein, Ernest Rutherford, Niels Bohr, Werner Heisenberg, Paul Dirac, Wolfgang Pauli and their successors. Again, there's just the right balance of color and information—Lorentz transformation, inertial versus gravitational mass, quantum jumps, transition probabilities and so forth—to ensure that a general reader is both engaged and edified. In the end, Newton makes some interesting points about how the focus of science has shifted not only from determinism to probability, but also from explaining the motion of matter to understanding its structure.
From Clockwork to Crapshoot offers a rather narrow view of physics history. The narrative is blissfully free, for instance, of any sign that social events or technological developments played a significant role. The author shows no interest in the self-understanding of the scientists—in their conceptions of what they thought they were doing and how this might have changed over time. All of them, from Aristotle onward, are treated as though they thought they were up to the same things that modern scientists think of themselves as pursuing.
Many histories today focus on marginalized and forgotten figures or episodes of confusion and failure. This book is not one of them. It uncovers no unheralded people, no overlooked discoveries. Best suited for beginners, it's a fairly competent and concise survey of well-marked territory. It knows where physics ends up and relates events as if they were on a fairly steady progress toward that goal.
Such books can be of great value. They give us a sense of how, in the development of physics as of other branches of science, new sights first appear dimly on the horizon, slowly come into plain view and eventually vanish into the distance. Each landscape yields to another, until the travelers find themselves in an entirely new world. With a broader conception of history, Newton might have been more successful in achieving this effect.