The pursuit of scientific research over the past century, not least by physicists, has given us unprecedented knowledge of the universe on scales from the submicroscopic to the cosmic. That new knowledge reflects observations and experiments which can only be meaningfully interpreted via the two reigning theories of modern physics, relativity and quantum mechanics. In many of their central features, these arcane mathematical theories describe nature as behaving in ways that flagrantly defy the common sense every human being acquires through his own direct experience of the world. But common sense has been forced to yield before the power of the new science not only to demonstrate that such bizarre behavior goes on but to exploit it in the otherwise incomprehensible devices, from nuclear bombs to computer chips, that characterize the late 20th century.
The new physics would seem to have triumphed, then, in both theory and practice. In the post-World War II period, the promise of new levels of material benefit—and the exigencies of military competition—were enough to guarantee public support of pure scientific research. This involved the construction of ever more ambitious and expensive particle accelerators that could delve deeper and deeper into the core of the nucleus, and space probes able to venture farther and farther into the depths of the galaxy. In recent years, however, much of the power of those motivations has waned, and science has lost the hearts and minds of many non-scientists (if it ever really had them).
Today, therefore, big science is in big trouble. Proposed appropriations for the Superconducting Super Collider (SSC), the largest accelerator ever, already under construction in Texas, and also for the Space Station, the single large-scale project now left in NASA’s once-bulging portfolio, have had to weather an annual perils-of-Pauline ordeal in Congress. Both now face possible extinction. Similar troubles have befallen the high-energy physicists on the frontiers of basic research who long constituted the elite of the scientific world. They have lost their prestige even in the eyes of many within the scientific community, including physicists in more mundane areas, who believe it is time to switch our priorities to other, less ambitious but potentially more practical areas of research.
Three recent books deal with this situation from different perspectives. While all three are directed to lay readers, two are essentially concerned with the current status of elementary-particle physics as a scientific pursuit. Of these, the one by Nobel laureate Steven Weinberg, Dreams of a Final Theory,1 is a deeply-felt apologia for modern physics, in particular the brand concerned with plumbing the innermost secrets of nature. The other, The End of Physics: The Myth of a Unified Theory, is a less optimistic account of the same subject by David Lindley,2 a research-scientist-turned-writer who is a generation younger than Weinberg.
The third book, Understanding the Present: Science and the Soul of Modern Man, is by Bryan Apple-yard,3 a columnist for the London Sunday Times and, by way of contrast, a thoroughgoing skeptic about the value of science as a major human pursuit. Appleyard welcomes the philosophical problems of contemporary physics with which Weinberg and Lindley grapple, and regards as long overdue the growing public disquiet over science.
Steven Weinberg remains firmly anchored in the mainstream tradition of post-Newtonian thinkers convinced that science, based on direct observation of nature, has given mankind its only source of real truth. In Dreams of a Final Theory, Weinberg’s main interest is to demonstrate that today’s physics, although it has become increasingly abstract and remote from direct observation, is still within that mainstream.
Thus, Weinberg vigorously defends his case that physicists are “beginning to catch glimpses of the outlines” of the “final laws of nature.” Driven by an intense awareness of the powerful opposition to building the SSC, Weinberg also argues that only a machine with the capabilities of the new accelerator can perform the experiments necessary to test current insights regarding the shape of this final theory.
Weinberg is a graceful writer; his 1977 book, The First Three Minutes, was widely hailed for its lucid and accessible account of the modern cosmological theory of creation. He won his Nobel Prize some 25 years ago for explaining that two quite distinct phenomena can be regarded as manifestations of one fundamental force of nature. That surprising unification involved the familiar force of electromagnetism and the previously mysterious, much weaker, force displayed in nuclear interactions involving electrons and the ghostly particles called neutrinos.
In his new book, Weinberg explains how the final theory he foresees will unite not only those two forces, but also the far stronger force that binds particles together within atomic nuclei and the far weaker gravitational force that is inconsequential on the atomic level but dominates the behavior of the universe at large. By uniting all these apparently disparate forces, this theory—sometimes immodestly termed the “theory of everything”—will fulfill an ambition long held by Albert Einstein.
Weinberg takes pains, however, to explain that the current approach is radically different from Einstein’s hoped-for “unified-field theory.” Einstein rejected passionately the idea that quantum mechanics, with its fundamental limitations on describing the universe in the clear, precise, and deterministic way demanded by classical physics, represented ultimate reality. Yet the new final theory will be a “quantum-field theory” that fully accepts just those limitations. Weinberg believes they have been demonstrated to be inescapable, both by the continuing success of quantum mechanics as used every day by practicing scientists and by experiments since Einstein’s death which have tested some paradoxical predictions of quantum mechanics and showed that his usually infallible intuition was wrong.
The aspect of quantum mechanics that so exercised Einstein, symbolized in the popular imagination by Heisenberg’s uncertainty principle, is its insistence that we will never be able to describe fully the behavior of nature on the smallest scale. The final theory sketched by Weinberg goes considerably further in limiting our direct knowledge of nature. He describes the multiplicity of already known subatomic particles, as well as others he hopes will be produced in the SSC, in terms of still smaller entities which we can never hope to detect directly and which are only the material manifestations of invisible fields that indicate a fundamental mathematical order to the universe.
That is a disturbing development for modern science, which since its birth a half-millennium ago, in the age of Copernicus and Galileo, has insisted on observing the phenomena its theories describe. The entities postulated by the new theory are—and will always remain—inaccessible to human observers. Indeed, the beautiful symmetry of the final theory so beloved by Weinberg, a symmetry which arises when the fundamental forces reveal their true nature as aspects of one unified structure, has not been evident in the universe, he admits, since about one ten-billionth of a second after the Big Bang, when the temperature of the universe was about a million billion degrees.
Reproducing those conditions is a feat impossible to achieve in any terrestrial laboratory; nor are they to be found anywhere in the universe today. But Weinberg, invoking explicitly Platonic terms, believes in the truth of the theory because of its mathematical beauty. He is confident it will become generally accepted because from it we will be able to calculate, at least in principle, the properties of particles which actually can be observed.
According to David Lindley, however, we are still uncomfortably far from being able to perform those calculations. In The End of Physics, Lindley, who was trained in theoretical physics and astronomy and is now a senior editor of Science magazine, gives a broader and deeper picture than Weinberg of the historical development of modern physics. His account of the ongoing search for a final theory is more detailed, more accessible to the lay reader, and considerably less optimistic.
Lindley explains in relatively simple terms why particles which appear to be the same when they have high energies may behave in different ways at lower energies; this is the phenomenon of “symmetry breaking,” which produces the different forces we observe. He also discusses how theorists hope to be able to include gravitation—a phenomenon that has long eluded quantum mechanics—in their “theory of everything” by making use of fashionable “superstring” concepts. And he shows in much more detail than Weinberg just how unobservable these concepts really are.
A superstring is an incredibly small construct, smaller than an atomic nucleus by about the same ratio as a nucleus to the earth—or as the earth to the whole visible universe. Originally perceived as 26-dimensional entities, super-strings were made more tractable when four physicists (subsequently dubbed the Princeton string quartet) managed to conceal 16 dimensions in the mathematical woodwork, leaving only 10. After six of these were somehow “rolled up” on an even smaller scale, just four remained, corresponding to the three dimensions of space and one of time which mere human beings are able to discern. This development was the culmination of a series of simpler string theories, including one called supergravity that was for a time favored by Stephen Hawking, the reigning genius of cosmology.
Why should the search for a “theory of everything” be of interest not only to particle physicists trying to explain elementary particles but also to cosmologists? One reason is its relevance, as we have seen, to the behavior of the universe close to the Big Bang. But cosmologists also hope that the theory will help them solve a truly cosmic conundrum: according to calculations, the universe is expanding at a rate that implies it must contain ten times as much matter as astronomers have observed.
The currently favored solution to this riddle is that the universe is full of some mysterious and undetectable “dark matter,” possibly consisting of a hitherto unknown type of particle whose existence might be explained by the final theory. Weinberg, for one, holds out the hope that these particles might be discovered as products of high-energy collisions in the SSC. If they are not, the ever-resourceful theorist has a fall-back position: instead of postulating dark matter, we can begin adjusting terms in our cosmological equations.
Lindley is not impressed by this approach. He sees it as the offspring of incestuous mutual speculation between physicists and cosmologists, each searching desperately for theoretical support in a world with little opportunity for actual observation or experiment. He concludes his account:
This theory of everything will be, in precise terms, a myth . . . a story that offers explanations for everything we can see around us, but can be neither tested nor disproved. . . . This myth will indeed spell the end of physics . . . because physics has reached the end of all the things it has the power to explain.
This conclusion would undoubtedly be seconded by Bryan Apple-yard, who in fact describes science in general as “a form of mysticism that proves particularly fertile in setting itself problems which only it can solve . . . by the employment of [a] bizarre repertoire of thought processes.” Appleyard’s critique extends far beyond the content of the latest theories of particle physics to encompass the whole scientific enterprise, which, he argues, is responsible for many of the spiritual ills afflicting modern man.
In a densely-argued polemic that ranges from Aristotle to the theory of everything, Appleyard characterizes the scientific attitude, or mode of thought, as a constant search for an ever more precise description of nature, a description deliberately independent of human perspective. Because of science’s indubitable success in achieving this aim, a success which has greatly magnified our power to manipulate the world about us, scientific inquiry has itself become increasingly accepted as the only legitimate mode of “objective” knowledge.
But that is not all. According to Appleyard, the deliberately limited and highly fragmented nature of the questions science sets itself, together with the avowedly tentative nature of the answers it gives, has served as a model for culture. This is epitomized in the overwhelming, and overwhelmingly corrosive, tolerance that is the hallmark of modern liberal societies. Acceptance of the scientific mode of thought has led to a general delegitimation of questions of ultimate value that are not subject to measurement, and has foreclosed the possibility of final answers. Even those who still believe in such answers, says Appleyard, have been “marginalized” by the ethos of science, and can no longer regard their own moral choices as absolute.
Yet this atmosphere of all-pervading skepticism has in turn led to a sense of crisis that is most obvious in our schools, beset as they are by a “chronic uncertainty about what there is to teach, about whether there is anything to teach.” So Appleyard holds out a glimmer of hope. Disillusionment with science—or at least with its inability to deal with the spiritual side of man’s nature—has led to a growing backlash. The very decadence of liberal society—“its obvious failure to transmit any value other than bland tolerance”—may make change inevitable.
There are signs of such change, but so far they have been specious ones. Take the environmentalist movement, which might be seen as indicative of a search for new sources of meaning in life. As Appleyard notes, however, environmentalism, despite its proclaimed hostility to the destructive aspects of science, has not only embraced the mistaken idea (inspired by science) that humanity is simply part of nature, but perverted it further to make mankind a villain.
Another misguided response to scientific imperialism is the intense cultivation of the self, both physical—in the form of compulsive exercising and food faddism—and psychological, with countless approaches to self-improvement being peddled by hosts of professional therapists, hucksters, and cultists and eagerly accepted by multitudes. Here, too, Appleyard points out, the nostrums are routinely justified in scientific—or at least pseudo-scientific—terms.
Paradoxically, Appleyard believes that some of the impetus for a move away from the prevailing scientific outlook may come from developments in science itself, like those of quantum mechanics which make untenable the classical scientific idea of a disembodied observer separated from the universe but able to describe it objectively. Other such developments are various “anthropic principles” formulated by puzzled physicists to explain the role of intelligent beings in the universe.
The least ambitious of these theories—the Weak Anthropic Principle—says merely that the universe must have properties that are consistent with the existence of life (if it did not, we would not be here). But various stronger versions have also been proposed, of which the most far-reaching, the so-called Final Anthropic Principle, asserts that intelligence must come into existence and will never die out. Although the Weak Anthropic Principle raises little objection anywhere, except for its possibly tautologous nature, the stronger ones are controversial, especially to Weinberg and the other hard-nosed scientists who share his view that “our species has had to learn in growing up that we are not playing a starring role in any sort of grand cosmic drama.”
As Appleyard points out, however, even if some schools of scientific thought seem to be moving in the direction of recognizing a cosmic meaning to human existence, theirs is still a distinctly minority view. And anyway it is vain to look to science to supply answers about the human role in the universe, because the very nature of science is to be skeptical of its own theories. The only truly fixed principle of science is its willingness to regard every hypothesis as tentative, no idea as sacred—except the idea of the continual progress of science itself toward the ultimate understanding of reality. It is that sacred idea, of never-ending progress, to which Appleyard hopes to lay siege.
In its own way, each of these three books offers a response to the perception that the journey of physics as we have known it since Newton is coming to an end. Weinberg believes that the end will be triumphal; his confident expectation of a beautiful mathematical description of the unity of the fundamental physical forces shaping the universe far outweighs any consideration that his longed-for description can never be confirmed directly by observation. Lindley sees in this Platonic approach not an ultimate triumph but rather a frustrating and seemingly inescapable retreat from physics to metaphysics. And to Appleyard, this retreat, the reductio ad absurdum of a methodological madness that foolishly expects meaningful answers to emerge from trivial questions, may represent the beginning of a long overdue admission that science does not represent the only means to the discovery of ultimate truth.
Ironically, of the three authors, Weinberg is the one whose approach seems closest to that of his avowed nemesis, the religious believer. Such a believer, with his faith in a humanly meaningful universe, Weinberg sarcastically likens at one point to “someone who has convinced himself that he is bound to win a lottery because he desperately needs the money.” Yet from another perspective Weinberg’s embrace of Platonism seems itself the result of a no less desperate need, this time for a final theory. And as for that theory itself? Weinberg, who adamantly refuses to accept the idea that evil in the world (as symbolized for him by the Holocaust) may be part of a larger design, remains in thrall to the idea of a design that was manifest for the merest cosmic blink, at the very beginning of time. Why not, then, a design that will reveal itself at the End of Days?
1 Pantheon, 334 pp., $25.00.
2 Basic Books, 275 pp., $25.00.
3 Doubleday, 269 pp., $23.50.