William Lane Craig
The absolute origin of the universe, of all matter and energy, even of physical space and time themselves, in the Big Bang singularity contradicts the perennial naturalistic assumption that the universe has always existed. One after another, models designed to avert the initial cosmological singularity--the Steady State model, the Oscillating model, Vacuum Fluctuation models--have come and gone. Current quantum gravity models, such as the Hartle-Hawking model and the Vilenkin model, must appeal to the physically unintelligible and metaphysically dubious device of "imaginary time" to avoid the universe's beginning. The contingency implied by an absolute beginning ex nihilo points to a transcendent cause of the universe beyond space and time. Philosophical objections to a cause of the universe fail to carry conviction.
Source: Astrophysics and Space Science 269-270 (1999): 723-740
The Fundamental Question
From time immemorial men have turned their gaze toward the heavens and wondered. Both cosmology and philosophy trace their roots to the wonder felt by the ancient Greeks as they contemplated the cosmos. According to Aristotle,
it is owing to their wonder that men both now begin and at first began to philosophize; they wondered originally at the obvious difficulties, then advanced little by little and stated difficulties about the greater matters, e.g. about the phenomena of the moon and those of the sun and the stars, and about the origin of the universe.1
The question of why the universe exists remains the ultimate mystery. Derek Parfit, a contemporary philosopher, declares that "No question is more sublime than why there is a Universe: why there is anything rather than nothing."2
This question led the great German mathematician and philosopher Gottfried Wilhelm Leibniz to posit the existence of a metaphysically necessary being which carries within itself the sufficient reason for its own existence and which constitutes the sufficient reason for the existence of everything else in the world.3 Leibniz identified this being as God. Leibniz's critics, on the other hand, claimed that the space-time universe may itself be the necessary being demanded by Leibniz's argument. Thus, the Scottish sceptic David Hume queried, "Why may not the material universe be the necessarily existent Being . . . ?" Indeed, "How can anything, that exists from eternity, have a cause, since that relation implies a priority in time and a beginning of existence?"4 There is no warrant for going beyond the universe to posit a supernatural ground of its existence. As Bertrand Russell put it so succinctly in his BBC radio debate with Frederick Copleston, "The universe is just there, and that's all."5
The Origin of the Universe
This stand-off persisted unaltered until 1917, the year in which Albert Einstein made a cosmological application of his newly discovered General Theory of Relativity.6 To his chagrin, he found that GTR would not permit a static model of the universe unless he introduced into his gravitational field equations a certain "fudge factor" L in order to counterbalance the gravitational effect of matter. Einstein's universe was balanced on a razor's edge, however, and the least perturbation would cause the universe either to implode or to expand. By taking this feature of Einstein's model seriously, Alexander Friedman and Georges Lemaitre were able to formulate independently in the 1920s solutions to the field equations which predicted an expanding universe.7
The monumental significance of the Friedman-Lemaitre model lay in its historization of the universe. As one commentator has remarked, up to this time the idea of the expansion of the universe "was absolutely beyond comprehension. Throughout all of human history the universe was regarded as fixed and immutable and the idea that it might actually be changing was inconceivable."8 But if the Friedman-Lemaitre model were correct, the universe could no longer be adequately treated as a static entity existing, in effect, timelessly. Rather the universe has a history, and time will not be matter of indifference for our investigation of the cosmos. In 1929 Edwin Hubble's measurements of the red-shift in the optical spectra of light from distant galaxies,9 which was taken to indicate a universal recessional motion of the light sources in the line of sight, provided a dramatic verification of the Friedman-Lemaitre model. Incredibly, what Hubble had discovered was the isotropic expansion of the universe predicted by Friedman and Lemaitre. It marked a veritable turning point in the history of science. "Of all the great predictions that science has ever made over the centuries," exclaims John Wheeler, "was there ever one greater than this, to predict, and predict correctly, and predict against all expectation a phenomenon so fantastic as the expansion of the universe?"10
The Standard Big Bang Model
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