The work under review is a reprint of the 1995 edition, with a new preface by the author. The book was originally published in French as Mélodie secrète in 1991. It is useful to note these dates since books on science, contrary to those on the humanities, tend to be outdated more quickly as new discoveries are made.
Trinh Xuan Thuan is a Vietnamese astrophysicist and has been a professor of astronomy at the University of Virginia since 1976. Besides authoring scientific articles on galaxy formation and evolution (in 2004 he co-authored a study identifying possibly the youngest galaxy), he has written several popular books on astronomy which have been praised for lucidity, accessibility, and elegance. The Secret Melody amply exemplifies these qualities, the most convincing proof of this being that it is understandable, at least most of it, to this reviewer, a certified science ignoramus.
Professor Thuan (actually his family name is Trinh, though Vietnamese are addressed by their first names, even formally) is well aware of the spectacular new findings in cosmology thanks to new observational techniques and telescopes since the book was first published over a decade ago. In his new preface he mentions two of these. The first concerns the counter-intuitive discovery in 1998 of the acceleration of the universe (with it, the pervasiveness of the repulsive anti-gravity force called “dark energy”). The second is the study by NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) of the afterglow of the Big Bang, in which it is discovered that the first stars were born only 200 million years after the Big Bang (much earlier than previously thought) and that the age of the universe is 13.7 billion years. Thuan assures us that these discoveries have not invalidated the Big Bang theory; on the contrary, they put it on a firmer ground: “The idea that the universe started its existence from an extremely small, hot, and dense state is still the best we have in town for explaining the properties of the bewildering diverse content of the cosmos, the fossil radiation, planets, stars, clusters, and galaxies” (xiii). Furthermore, the idea that the universe went though an early inflationary phase is still valid.
The task of reviewing this book in this venue is of course not to evaluate its scientific contribution, for which the reviewer is dismally unqualified, except to recommend it most enthusiastically for those interested in contemporary cosmology but having little or no scientific background. What warrants a critical examination of this book by a philosopher or a theologian is the two claims it makes. First, according to Thuan, “modern science has demolished all the classic arguments concerning the existence of God.” The second claim is made in the form of a rhetorical question: “The universe has been very precisely fine-tuned to allow our existence: change the physical laws ever so slightly, and we shall no longer be here to talk about them! Is this astonishingly precise fine-tuning the result of chance or the manifestation of the will of a Supreme Being?” (xviii). Is the second point a forerunner of the Intelligent Design argument?
Consider the second claim first. According to the “anthropic principle,” proposed by Brandon Carter (and named by Hubert Reeves the “complexity principle,” to avoid excessive anthropocentrism), the fact that a slightest alteration in the properties and laws of the universe would make the emergence of life and intelligence impossible suggests that humankind did not emerge by chance in an indifferent universe but rather that its existence is linked with the universe in a close symbiosis. The anthropic principle would imply therefore that the universe has a “grand design.” But, Thuan points out, “to talk of a Grand Design is to talk about a supreme creator, about God” (239). Therefore, the questions that cosmologists ask, Thuan suggests, seem to be similar if not identical with those asked by theologians: “How was the universe created? Was there a beginning to space and time? Will the universe come to and end? Where did it come from and where it is going?” (239).
It is precisely here that Thuan’s arguments falter. And this brings to his first claim, namely, that the classic arguments proposed by philosophers and theologians for the existence of God have been demolished by science. Thuan takes these arguments—he mentions Plato, Aristotle, Thomas Aquinas, and Kant as their proponents, which is bizarre, since Kant explicitly rejects the arguments which he takes Thomas to be making—to be variants of “the chain of causes” reasoning: “Everything has a cause. Such a chain cannot be infinite. Sooner or later, we must encounter the first cause, responsible for all the content of the universe. That first cause is God” (240). Had Thomas argued this way in his celebrated quinque viae, making God to be no more than the temporally first or the hierarchically highest cause in a chain of intramundane causes, Thuan would have hit the target. But anyone familiar with Thomas’s arguments can show that this is not at all what Thomas is doing and that Thuan’s arguments amount to shadow-boxing. Hence, Thuan’s statements such that “quantum uncertainty has shattered the argument for a first cause” (241) are philosophically suspect.
On the other hand, Thuan provides no aid and comfort to the Intelligent Design proponents. He explicitly asserts that “apart from its simplicity and elegance, it [the Big Bang theory] has a quality essential in any good theory: It has great powers of prediction. The most important of its predictions ... have been spectacularly confirmed by observations” (261). Furthermore, for him, neither beauty and complexity in the universe nor the emergence of life and consciousness nor even the possibility of extraterrestrials demand the existence of a creator God; these “extremely complex systems may be the result of perfectly natural evolutionary processes that follow well-understood physical or biological laws” (243). Nevertheless, Thuan is willing to make a “wager” in the Paschalian tradition: “For myself, I am prepared to bet on the existence of a supreme being” (249). He would rather err on the side of “sense and hope” than on that of “nonsense and despair,” like Jacques Monod and Steven Weinberg.
Of course, Thuan “final wager” (248) resonates well with perhaps most if not all people: Who would choose “nonsense and despair”? Yet, in the end, there is something quite unsatisfactory with Thuan’s fundamental posture, and this is due to his basic misunderstanding and cavalier dismissal of the metaphysical arguments for God’s existence. There remains an unbridgeable divide between Thuan the scientist and Thuan the believer. As an astrophysicist, he is committed to the possibility of an explanation of the universe through chance, but he says, “Science is no great help when it is a question of faith. Scientists have to weigh the risks and take the plunge” (249). There is however a serious equivocation here: it is not as a scientist qua scientist that Thuan takes his plunge into the ocean of theistic faith, but as human being, seeking “sense and hope.” But because he has prematurely undercut the philosophical underpinnings for an affirmation of God’s existence, he risks drowning in fideism, and the gap between science and faith remains as wide as ever. In spite of this, one cannot be but grateful that an astrophysicist of Thuan’s stature is willing to begin a serious conversation that scientists and theologians have studiously avoided among themselves, at least in polite company.