Time and again physicists have been guided by their sense of beauty not only in developing new theories but even in judging the validity of physical theories once they are developed. It seems that we are learning how to anticipate the beauty of nature at its most fundamental level. â€” Dr. Steven Weinberg
The standard big bang theory postulates that the universe began 10 to 15 billion years ago with an explosion of superheated matter which spread out to form the visible universe. It describes what happened after the big bang, but does not explain why any "bang" should have taken place, how so much matter could arise from nothing if matter can be neither created nor destroyed, or why we see only a minute part of the mega-universe.
These and other perplexing questions are addressed by the inflationary theory of cosmology, formulated primarily by particle physicist Alan H. Guth. The Inflationary Universe: The Quest for a New Theory of Cosmic Origins (Perseus Books, Reading, Mass., 1998; 358 pages, glossary, ISBN 0-201-32840-2, softcover, $18.00) is Guth's personal account of the development of this theory, which gives an intimate picture of the way modern physicists work together. He also explains clearly and accurately for the general reader topics needed in order to understand the inflationary theory itself, such as various aspects of the big bang theory, the particle physics revolution in the 1970s, matter and antimatter, grand unified theories, and various ideas from quantum physics.
Inflationary theory explains the origin of matter and the universe in the first "billion-trillion-trillionth of a second" by means of a period of hyper-rapid inflation which leads to the big bang. Here the observable universe originates from a "false vacuum," a peculiar form of matter predicted by many theories in particle physics. In quantum theory a vacuum is not empty, but "on a subatomic level is a perpetual tempest, seething with activity" (p. 272).
Inflation solves several important problems of the standard big bang theory and, unlike many other theories, its predictions do not depend on knowing details about the conditions which preceded the formation of the universe. It is still a work in progress, and Guth himself agrees with Dr. Frank Wilczek that "while the general idea of an inflationary universe is extremely attractive, the specific models so far put forward do not inspire confidence in detail" (p. 235).
Many interesting concepts are implied by the inflationary theory, including "eternal inflation." By the very nature of the inflationary process, Guth believes, "once inflation begins, it never stops!" (p. 246). As time goes on, further big bangs come forth from the underlying "false vacuum" from which our universe emerged. This ongoing cosmic process eventually creates an infinite series of universes like our own, which Guth terms "pocket universes." By the very nature of inflation itself, these pocket universes are produced at an ever-increasing rate according to a fractal pattern â€” that is, a repeating sequence replicated on smaller and smaller scales.
Schematic drawing of eternal inflation. The four bars represent a part of the universe at successive, evenly spaced times. Each bar is actually three times the length of its predecessor, although the expansion is not shown (p. 247).
Guth believes that "our entire observed universe" is "only a minute fraction of one of these pocket universes. The pocket universe, on the other hand, is only a minute fraction of all that exists . . ." (ibid). Although inflationary theory implies that there was a beginning at some point, and that individual pocket universes will come to an end, "The full universe existed long before our pocket universe, and will continue to exist for eternity" (p. 271). From a perspective that takes in all the pocket universes, evolution
will strongly resemble the old steady state model of the universe. As the pocket universes live out their lives and recollapse or dwindle away, new universes are generated to take their place. Although the ultimate fate of our own pocket universe is no more appealing in the inflationary scenario than in a simple big bang theory, the universe as a whole will regenerate eternally, forever producing new pocket universes. While life in our pocket universe will presumably die out, life in the universe as a whole will thrive for eternity. â€” p. 248
Guth points out that today "the dominant view of the origin of the universe, in both Judeo-Christian and scientific contexts, portrays it as a unique event," and that "modern scientists frequently refer to the big bang as the beginning of time" even though they do not know what came before the big bang.
However, if the ideas of eternal inflation are correct, then the big bang was not a singular act of creation, but was more like the biological process of cell division. If a biologist discovered a bacterium that belonged to no known species, she would presumably invent a new species in which to classify it. However, even though only a single specimen of the new species had been found, she would undoubtedly assume that it was the offspring of a bacterial parent cell. Although she believes firmly that life on earth originated from nonliving materials, the possibility that this particular cell is the result of such an improbable occurrence would be too preposterous to even consider. Given the plausibility of eternal inflation, I believe that soon any cosmological theory that does not lead to the eternal reproduction of universes will be considered as unimaginable as a species of bacteria that cannot reproduce. â€” pp. 251-2
In some respects, the notion of an inflationary universe echoes the succession of inflations followed by "deflations" or "drawings inward" found in ancient Sanskrit literature. In the colorful terminology of ancient India, these expansions were called the "outbreathing" of Brahma, followed by the "inbreathing," which rhythm eventually affects all that comprises the part of the cosmos informed by that particular Brahma. These "Days" and "Nights" of Brahma were recorded thousands of years ago in the religious scriptures of the early inhabitants of India, and transmitted orally long before the creation of the later-used devanagari script.
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If the universe is a universe of thought, then its creation must have been an act of thought . . . Time and space, which form the setting for the thought, must have come into being as part of this act. Primitive cosmologies pictured a creator working in space and time, forging sun, moon and stars out of already existent raw material. . . . Indeed, the doctrine dates back as far as Plato.
"Time and heavens came into being at the same instant, in order that, if they were ever to dissolve, they might be dissolved together. Such was the mind and thought of God in the creation of time."
And yet, so little do we understand time that perhaps we ought to compare the whole of time to the act of creation, the materialization of the thought. â€” Sir James Jeans