Physicists of previous generations were often very conservative about accepting new ideas, especially when the idea was introduced by another physicist. Among the ideas of physics that initially received strong criticism were Newton's theory of gravity, James Clerk Maxwell's laws of electromagnetism, Einstein's special theory of relativity, and Paul Dirac's theory of electrons. These ideas now form the basis of much of our understanding of nature. This tendency to reject revolutionary new ideas was aptly summarized by Max Planck in his "Scientific Autobiography," where he wrote, "A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."
The present generation of theoretical physicists seems to be more accepting of new ideas. It is quite common for a new concept to be eagerly pounced on by numerous workers, who quickly explore its implications and extend it in many directions. The reasons for this change are unclear, perhaps having to do with the recent dominance of theory over experiment. But one of its consequences has been that a vast number of novel ideas have been seriously considered by theoretical physicists in recent years. Some of these have been described in popular books, while others, such as the notion that the world is ultimately composed of stringlike objects, rather than of particles, are too new to have become familiar to non-scientists.
Richard Morris, in his book "The Nature of Reality," describes some of these attitudes toward novelty in physics, in addition to the ideas themselves. Morris' aim is not just to explain the latest speculations of physicists, but to use them to reach toward some general philosophical questions about thought and the universe, such as whether there are limits to what human beings can know.
"The Nature of Reality" is organized into three sections, dealing with matter, with space-time, and with general philosophical questions. The first of these is the least successful, as it tries to summarize most of known physics, and much speculative physics in three short chapters. This makes the section something of a Cook's tour, and a reader who enters into it with the notion that much of modern physics is incomprehensible is unlikely to be convinced otherwise. The second section, on astronomy, cosmology and relatively theory is better as it is more slowly paced. Also, there are more detailed explanations, so that the reader is less often required to take the author's word for unfamiliar conclusions.
While the topics treated in these two sections are similar to those in numerous other popular physics books, the final section is more idiosyncratic. It begins with a discussion of the interpretation of quantum mechanics, but soon considers more general questions such as why anything exists at all. Here Morris uses some of the speculations of physicists, such as the possible existence of tachyons, particles that travel faster than light, to illustrate various views on this question, including the concept that all entities exist that are not forbidden by the laws of nature. Most readers are likely to find this the most interesting part of the book. Morris mainly summarizes others' views about truth and reality, without much critical analysis, but concludes with his own statement about one aspect of physical reality. "But if the concept of the quark gives us a way of understanding experimental data, and of predicting the existence of new phenomena, then perhaps quarks have reality enough." This attitude toward reality would find acceptance among most working physicists, including myself.