Is there an ultimate theory of nature—a “Final Theory”—from whose principles all laws that govern the workings of the physical universe may be deduced? Such a theory would provide the complete underlying rules that control, in finest detail, every action of inanimate or animate matter—including all the (non-random) activities of our very selves. Might such a theory even be within the actual grasp of today’s physicists? Steven Weinberg, in his new book, Dreams of a Final Theory, provides an unqualified “yes” in answer to the first of these questions, and he also gives expression to a belief in the genuine plausibility of the suggestion put forward in the second. Should we be persuaded by these striking claims? Wherever our sympathies initially lie, we must, indeed, pay close attention to what Weinberg says; for, probably among all of today’s theoretical scientists, he most authoritatively represents the viewpoint of established fundamental physics.
Weinberg himself supplied some of the essential theoretical underpinnings to the standard theory of modern particle physics. With Abdus Salam and Sheldon Glashow, he received the Nobel Prize for that important ingredient of particle physics known as “electroweak theory”—which provides a theoretical unification of the weak nuclear force, which causes radioactive decay, with the electro-magnetic force. (I shall have more to say about this theory shortly.) But his expertise lies more broadly than this. He has written two highly authoritative and widely acclaimed books on another extensive area of fundamental physics—that encompassed by general relativity and cosmology. Thus, he is an expert not only on the physics that controls the tiniest ingredients of matter but also on the theory of space-time itself—from Einstein—which governs the structure of the universe on its largest scales.
In his semi-popular 1977 classic The First Three Minutes, Weinberg presented a vivid and well-authenticated account of the first three minutes of our universe’s very existence, and of the specific nature of its (now observed) contents. For the comprehensive picture of what is believed to have gone on at that very early time, detailed theories of both particle physics and cosmology are needed simultaneously. This picture is now referred to as the “standard model of the big bang.” Weinberg’s own most important theoretical contributions (to the electroweak model referred to above) must be combined with another theory of modern particle physics, worked out by others, that describes strong nuclear forces. These two schemes together provide what is known as the “standard model of particle physics.” To round off his powerful command of physics, Weinberg is well read in matters of history and philosophy (though he regards the latter discipline as having little direct positive influence on the progress of science).
These credentials do not, by themselves, compel us to accept Weinberg’s views on the ultimate nature of reality; but if we are interested in such issues in any serious way, we must indeed pay due attention to his arguments. There is also the question of …