Book Review: The Road to Reality: A Complete Guide to the Laws of the Universe, Volume 53, Number 6

For the title of his latest epic, The Road to Reality , Roger Penrose has selected a metaphor that appears frequently in popular expositions of physics. It is no wonder that the phrase has become a favorite among physicists, for it suggests a single-minded pursuit of the ultimate destination: an understanding of all the underlying principles that govern the behavior of our universe. Perhaps that may seem to be an ambitious program. After all, it was not so very long ago that Eugene Wigner asserted, " The great success of physics is due to a restriction of its objectives. " Since that sober assessment , however, stunning progress has changed the outlook of physics so greatly that several of its leading proponents have been emboldened to suggest that a complete grasp of the laws of nature lies just ahead of us. As Penrose asserts, the voyage of discovery has lasted more than two and a half millennia and has been profoundly difficult. At the start of the journey , around 500 B.C.E., Heraclitus identified the major stumbling block: Nature is wont to conceal herself. Mathematical advances aside, the first significant steps on the road to reality were achieved in the period between 1543, the year Copernicus published his heliocentric theory of planetary motion, and 1687, the year Newtonian mechanics was introduced. This era, the first Scientific Revolution, culminated in a working awareness of the solar system, a basic framework for studying dynamics, and a mathematical formulation of one of Nature's interactions, gravity. Many of the hallmarks of progress along the road to reality can already be discerned in the first Scientific Revolution. Because Nature so deftly hides her secrets, a crazy theory is often a prerequisite for making any headway. Copernicus, for example, defied not only established authority but also the common sense of every observer who, under the illusion of being at rest, watched the sun move across the sky. Other necessities for progress— mathematics for formulating and developing a theory and a physical apparatus for testing it—were also essential components of the revolution. The improved instruments for measurement devised by Tycho Brahe permitted Kepler to refute the orbits of Copernicus's system. Newton's calculus allowed him to extend Galilean dynamics and explain the laws that Kepler had observed. The road to reality had taken its now familiar course of revolution followed by successive approximation. The nineteenth century witnessed the …