It feels strange to be asked by his publishers to review a book by Paul Davies. Many years ago, it was partially the fascination provoked by his popularisation books (especially Superforce
) which made me wish to study physics. It is somehow for me like coming back full cycle, if you understand what I mean.
The main theme in Cosmic Jackpot
is, as the subtitle aptly puts it, “why our universe is just right for life”. In other words, it is about the apparent “fine tuning” in the basic constants of physics. For many numbers that play a basic role in the laws of Nature, such as the electron’s charge and the magnitude of the strong nuclear force, it happens that if those numbers had been just slightly different, life could not have developed in the universe. The most extreme example is the recently discovered dark energy; it is 120 orders of magnitude smaller than what would be its “natural” value, and if it was just one order of magnitude bigger the universe would have expanded too fast for stars which could support life to have time to form.
Is this just a brute fact of the universe, or something that cries out for an explanation? Davies thinks the latter, though without going through any formal argument to justify the very idea that an explanation is needed. (I’ll argue later that this is a big omission.) He considers several possible explanations, opting at the end for a rather idiosyncratic one, and with little by the way of argument to support it, in my opinion.
Roughly the first half of the book is dedicated to an exposition for the layman of the fundamentals of particle physics and cosmology. Davies is well-habituated to this kind of popularisation, and delivers it with easeful clarity. The expanding universe, the Standard Model of particle physics, the mysteries of dark matter and dark energy, and the basics of string theory are among the topics covered. For those fascinated by the String Wars™, I may mention that the latter exposition is neither hypeful nor negative, giving fair space to the theory’s archievents and to its open problems.
The second half of the book is dedicated to the fine-tuning for life of the constants of phsysics, and its possible explanations. Of course the “anthropic” explanation, and its concrete realization in the string-theoretical landscape and the eternal inflation framework, take a large part of the discussion. For those who have been asleep the past years, the anthropic principle is the speculative idea that if a large or infinite number of parallel universes with different basic constants or laws (a “multiverse”) exists, then the fine-tuning is not surprising, because we couldn’t find ourselves in any universe but in one of the few that support life. Davies is rather critical of the anthropic principle, although not for the reasons usually aduced against it. (Given the wildly speculative metaphysical explorations of the last chapters, it wouldn’t do for Davies to criticize the anthropic principle on non-falsifiability or other methodological grounds!) His main argument is that as universes can almost certainly be simulated computationally at a much “cheaper” cost than creating them in reality, an infinite multiverse will contain many more simulated universes (created by advanced civilizations for amusement, I gather) than real ones, so the anthropic reasoning would imply that we live in a simulated, Matrix-like universe, because that is the most likely situation to find ourselves. But then we have no reason to have a strong belief in the laws of physics that support the multiverse hypothesis in first place, so the whole anthropic argument collapses. I think this reasoning rests on assumptions shaky enough (is it really so easy to simulate an entire universe? do we really have reasons to believe that civilizations will have interest in perfoerming such simulations by large numbers? do we have any reason to suppose that the typical simulated universe will look like ours, any more than the typical real universe will? etc.) that few anthropicists will be troubled by it. (Those who find these whacky discussions fascinating must check Nick Bostrom’s webpage
I suspect that Davies’ rejection of anthropic explanations does not arise really from the contrived simulation arguments, but from a deeper philosophical conviction: that the ultimate explanation for the universe and its characteristics must be meaningful
in some sense. He is not just interested in the limited question “Why are the constants suitable for life?” but in the more ambituous one “What determines what exists and what does not exist?” The existence of a multiverse in eternal inflation described by string/M-theory seems too arbitrary for him to be a suitable final explanation, a good place to find “the turtle over which all others rest”. He also yearns, and says it so explicitly, for an ultimate explanation which involves life and consciousness in an active way, not in an essentially passive way as the anthropic arguments do.
Given these inclinations, some kind of cosmic Intelligent Design seems Davies’ natural resting place. But in fact he also feels uncomfortable with the notion of a God as ultimate explanation. Having the natural sensibilities of a scientist, not a theologian, he can make little sense of the idea of a “necessary being” that can perform the explanatory role of God, and tends to accept the famous Dawkinsian argument that a creative, personal God must be “complex” and stand in need of explanation instead of being a suitable resting point for explanations. (I share those intuitions as well, by the way, while understanding how some may not share them; it is a subject for yet another one of my “science vs. religion” posts.) He ends up saying that he finds a God and a multiverse about equally complex and unsatsifactory as Final Turtles. A unique self-consistent version of M-theory or other Theory of Everything which predicted the values of all constants of physics necessarily would be more simple and satisfactory than both, but he believes it unlikely that such a theory exists, and anyway one could still ask why the theory is realized in actuality. He also considers the view that everything
logically possible exists, so there is no special problem in determining what will exist, and has a bit of fun playing with its implications before dismissing it. For philosophers, not the least sign of philosophical amateurness in Davies’ book will be that he attributes this theory to physicist Max Tegmark, with only one endnote mentioning philosopher David Lewis, who developed the idea earlier and more rigorously.
Chapter 10, in which Davies exposes his own views, is the less clear and most jumbled of the book. (As a rule, Davies is much better at explaining ideas of others clearly and critizicing and assessing them than at developing (philosophical) ideas of his own.) His preferred speculation is that life and consciousness might be a creative force in Nature, not by guise of a designing God but by an inmanent, teleological principle that makes their appeareance a necessary feature of the universe. In support of this view he enlists a couple of ideas that loyal readers of this blog will remember I discussed and criticized: Chalmers on the irreducibility of consciousness
, and the “backwards causation” interpretation of quantum mechanics
. But of course, even if these ideas were true they would fall very short of supporting Davies’ speculation. He also wanders off tangents borrowing from, among others: Deutsch on evolution and quantum information, Tipler on the universe evolving to a “supermind” as final state, Lloyd on the universe as a discrete computer, and Wheeler on self-explanatory causal loops. What I have, honestly, been unable to find in all this “idea-dropping” is any clear and concrete argument
for the teleological speculations, which Davies is well aware are far from the mainstream views of scientists. For argument, Davies replaces rethoric; a rethoric that everywhere betrays his deep-seated conviction –and also desire, and even emotional need- that the universe be meaninglful, that it must include us, or generally life and consciousness, among its fundamental principles and not only as a casual and fortitious outcome as modern cosmology seems to imply. (He calls this mainstream view “The Absurd Universe”, and seems to believe it renders somehow the scientific enterprise unjustified and pointless.)
As readers must have gathered, I have little sympathy for Davies’ philosophical speculation. The “fine tuning for life” problem seems to me rather arbitrary: as Carl Sagan pointed out once, about the same constants and laws necessary for a universe containing observers are necessary for a universe containing rocks, so why not discuss the “fine tuning for rocks” problem? To frame the discussion the way it is done presupposes that life and consciousness are important or significative features –and despite all Davies’ posturing, we have really no reason to believe they are in an objective sense, apart from our obvious (self-) interest in them. Multiverse-anthropic arguments for adressing these questions have in my opinion a very slight, but not zero, chance of becoming some day testable and scientific; while Intelligent Design arguments have an effective chance of zero, and so do teleological or causal loop principles in absence of a much stronger motivation and articulation for them. So for the time being count me by default as a citizen of the Absurd Universe.
However, despite all this the book does
provide a good and clear explanation of many basic areas of modern physics and cosmology, and provides also reasonably clear and fair discussions of the anthropic and the intelligent design controversies. It is only when Davies lets his own views take the forefront that I start to dislike it. Another virtue of the book is that, for all its philosophical amateurness (in fact, because of it) it can be a refreshing reminder of those “big problems” like why does something exist instead of nothing
, that not only physicists but even also philosophers lose sometimes in the pressure of professional specialization. A breezy and engaging exploration of the mysteries of “life, the universe and everything”, no matter its flaws, can be welcome if only for that reason.
You can also read Chad Orzel's review
, which is a bit more dismissive of the whole subject-matter of the book than I am; although I certainly agree that this subject matter can only be clasified as "philosophy" and not as "science", if there is any kind of distinction between them. I will add links to other reviews as they appear.