The Grand Design. By Stephen Hawking and Leonard Mlodinov. New York: Bantam Books, 2010. 181 pages.
This recent (and long-awaited) book by Stephen Hawking will sell well. Whether it will sell as well as his phenomenally successful A Brief History of Time (1988), which has sold more than 9 million copies, remains to be seen. But it will sell, since Hawking and his coauthor, physicist Leonard Mlodinov, seeks to answer, in 180 glossy pages, some of the most fundamental questions: Why is there something rather than nothing? Why do we exist? Why this particular set of laws [for our universe] and not some other? (10, 171; italics in the original). This is definitely heady stuff, which will find a receptive audience among folks who don’t know anything about physics or cosmology, but who would like answers to these big questions from an authoritative source.
The proposal that Hawking and Mlodinov (H&M) offer is audacious. According to them, current physical theory tells us that ours is not the only universe, that there are a great many universes (perhaps an infinite number), all created out of nothing. This phenomenal creation “does not require the intervention of some supernatural being or god. Rather, these multiple universes arise naturally from physical law. They are a prediction of science.” Of course, only a very few allow creatures like us to exist, but our presence selects out from this vast array only those universes that are compatible our existence. “Although we are puny and insignificant on the scale of the cosmos, this makes us in a sense the lords of creation” (8-9).
Thus the answers to the big questions H&M ask. Are they satisfactory answers? I don’t think so; but in a brief review, I will need to be brief in my replies. Begin with the theory, M-theory, that is supposed to give H&M multiple universes. M-theory (the “M” stands for “master,” “miracle,” “mystery,” “mother,” or “matrix,” depending on an author’s taste) is an alleged unification of the different versions of super (for supersymmetric) string theory. More precisely, it is a translation guide for relating the different versions. This requires that it be formulated in eleven dimensions, ten spatial and one temporal, one spatial dimension more than the various string theories (115-117). All of the spatial dimensions except the three of ordinary experience are allegedly “curled up” on a scale so tiny that we don’t see them. H&M claim that M-theory also allows for different universes with different laws, depending on how the internal spaces are curled. Indeed, they claim that M-theory has “solutions that allow for many different [space shapes], perhaps as many 10500, which means it allows for 10500 different universes, each with its own laws” (118). At the beginning of their book, H&M are tentative: “We will describe how M-theory may offer answers to the question of creation” (8; my italics). By the end, however, they are emphatic: Because M-theory is the most general supersymmetric theory, it is “the only candidate for a complete theory of the universe...M-theory is the unified theory Einstein was hoping to find” (181; italics in the original).
What are we to make of this? There is no doubt that M-theory is the currently hyped candidate for a “theory of everything,” since it relates the different versions of superstring theory and since some form of superstring theory is widely regarded as the way of unifying general relativity and quantum theory. But there is so far not a shred of empirical evidence for the requisite curled up dimensions; and likely there never will be any direct evidence for them, since they are allegedly on the order of the Planck scale (10-33cm)! Moreover, H&M offer no reason for thinking that solutions of the equations of M-theory allow for as many as 10500 shapes for these dimensions, and so for 10500 different universes. Again, there is no empirical evidence for any of these universes (except our own), and very likely never will be. I conclude that M-theory does not do for H&M what they would like it to do.
There is another line of argument for the same conclusion. It goes as follows: Even if M-theory turns out to be the final theory of everything, it would be just a set of equations and equations don’t do anything. Laws, even dynamical ones, describe how things happen; they don’t make things happen. Hawking seems clearly to have understood that in A Brief History when he wrote: “Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?” “Why,” he asks, “does the universe go to all the bother of existing? Is the unified theory so compelling that it brings about its own existence?” (BH, 174) Hawking sensibly answers the last question in the negative in A Brief History, and H&M seem about to do the same in The Grand Design when they write that “The laws of nature tell us how the universe behaves, but they don’t answer the why questions...”(171). But then they do seek to answer the big why questions listed in the first paragraph of this review in terms of the laws of physics alone: “Because there is a law of gravity, the universe can and will create itself from nothing.... Spontaneous creation [from nothing] is the reason there is something rather than nothing, why the universe exists, why we exist. It is not necessary to invoke God to light the blue touch paper and set the universe going” (180).
Part of a proper reply here is to say, simply, that a law of gravity doesn’t cause the universe (or universes) to spontaneously emerge from nothing any more than does M-theory. Another part of a proper reply is to challenge the notion of “spontaneous creation from nothing.” H&M happily talk about design without a designer and creation without a creator. Indeed, as we have seen, they think that the universe does not need a designer or a creator, since it emerged spontaneously from nothing in accordance with the laws of physics. In one place they say that while stars and black holes “cannot appear out of nothing,...whole universes can” (180). This is a sensational claim, which is no doubt intended to shake readers (and promote sales). But if what they have in mind is emergence from a vacuum state via a quantum fluctuation, then they surely know (113, 137) that the quantum vacuum is not nothing, but is the scene of intense activity, and that ordinary, well-confirmed quantum processes (tunneling and pair-creation, e.g.) occur within an already existing space-time, which doesn’t provide any basis for emergence from literally nothing. On the other hand, if by nothing H&M really do mean literal non-being, then this can’t explain the emergence of the universe (or universes), since non-being can’t do anything, spontaneously or otherwise. “Spontaneous emergence” from nothing, construed as literal non-being, is not only physically unfounded; it is metaphysical nonsense.
Hawking ended A Brief History by saying that if physicists succeed in discovering a complete theory, it should in time “be understandable in broad principle by everyone,” not just a few scientists. Then, in a spirit of optimistic egalitarianism, he said that everyone–philosophers, scientists, and “just ordinary people”–would be able to take part in discussing the questions of why we and the universe exist. “If we find the answer to that, it would be the ultimate triumph of human reason–for then we would know the mind of God” (BH, 175). Never mind that this was certainly not intended to be taken seriously, since Hawking was then, and still is, an atheist; but it did help him to sell an extraordinary number of copies of his book.
The Grand Design will also sell well, since it offers simplistic answers to complex questions. If M-theory is validated as the only candidate for a complete theory of the universe, H&M think that we would have answers to the questions of why the universe exists (it creates itself) and why we exist (there is no other consistent model). And if the theory is confirmed by observation–a huge if, as I’ve indicated–“we will have found the grand design” (181), which requires no designer. Thus in their acknowledgments, H&M begin as follows: “The universe has a design, and so does a book. But unlike the universe, a book does not appear spontaneously from nothing. A book requires a creator...” (187). Indeed!