I am distressed by the way that atheism, at least for some people, has managed to metamorphose into just another religion. As far as I am concerned, a blind, dogmatic faith that there is no god is no different from any other kind of blind, dogmatic faith. I respect it, the way I respect all faiths (note that lower-cased 'g' on 'god'), but I had always thought of atheism as being somehow better, and linked to the valuable notion of skepticism. No more, apparently; The Fallacy of Fine-Tuning
is an excellent example. I had seen a brief summary of the argument in chapter 5 of Stenger's earlier book God: The Failed Hypothesis
, and didn't like it much. Now, he has expanded it to book length. I like it even less in its new form.
Stenger's presentation is deceptive at several different levels. First, the purpose of the book, as the title suggests, is to dispute the validity of the "fine-tuning argument", the claim that many of the universe's parameters appear to be carefully adjusted to a narrow range which makes life possible. There are, unsurprisingly, a number of people in the Christian apologist/Intelligent Design camp who like the idea, and Stenger goes to some lengths to make it look as though he is primarily arguing against them when he says that a wide range of settings for the universe's parameters would still have made it potentially hospitable to life. He rarely mentions that there are many extremely respectable scientists who are not in any way affiliated to ID, but still think fine-tuning makes good sense. More about that soon.
Second, Stenger includes numerous pages of complicated-looking formulas and graphs. It is evident from glancing at the other reviews here that non-expert readers often have a hard time understanding his math, and are inclined to take it on trust; they naturally assume that Stenger, who has had a distinguished career as a particle physicist, is presenting scientific support for his views in an honest and straightforward way. This is, unfortunately, far from clear.
So, third, and the crux of the matter: just how valid are Stenger's arguments? I am no expert, but I have read a reasonable amount in this area, and I immediately felt very suspicious about some of the points he makes. After just a few minutes of looking around, I found Luke Barnes
, a young scientist who's currently working as a postdoctoral researcher at the Sydney Institute for Astronomy. Barnes, who is
an expert, posted a long paper on arXiv comprehensively criticizing Stenger's book. A short version
was accepted by the Publications of the Astronomical Society of Australia, a reputable peer-reviewed journal.
I am not competent to judge many of Barnes's points just based on my own reading (as noted, he's an expert, I'm not), but some of things he mentions are so flagrant that I am quite sure he is correct. To name two important examples, Stenger says that the enormous difference in strength between the gravitational and electroweak forces is not in need of explanation. As Barnes points out, the "hierarchy problem"
is one of the central mysteries of modern physics; it is ridiculous to say that there is nothing to discuss. Even more importantly, Stenger several times dismisses claims from the fine-tuning community on the grounds that they are explained by the mechanism of inflation in the early universe. It is well-known that inflation needs to be very finely tuned (probably to ten or eleven decimal places) in order to explain the observed data. Stenger nowhere mentions this critical point, which he is surely aware of.
In his blog, Barnes is articulate and funny when explaining what's wrong with Stenger. I particularly recommend his post from May 2 2012, "In Defence of The Fine-Tuning of the Universe for Intelligent Life"
, where he rebuts Stenger's response to his critical paper. Here is the concluding passage:
Large red letters on Stenger's homepage inform us that "No reputable physicist or cosmologist has disputed this book". I guess that makes me a disreputable cosmologist. In the meantime, a shortened version of my paper has been accepted for publication by Publications of the Astronomical Society of Australia. The fate of Stenger's paper 'A Case Against the Fine-Tuning of the Cosmos', submitted to the "Journal of Cosmology", is unknown.
In any case, if you'd rather decide this issue by a show of hands rather than good arguments, then let's play pick the odd one out of these non-theist scientists.
Wilczek: life appears to depend upon delicate coincidences that we have not been able to explain. The broad outlines of that situation have been apparent for many decades. When less was known, it seemed reasonable to hope that better understanding of symmetry and dynamics would clear things up. Now that hope seems much less reasonable. The happy coincidences between life's requirements and nature's choices of parameter values might be just a series of flukes, but one could be forgiven for beginning to suspect that something deeper is at work.
Hawking: "Most of the fundamental constants in our theories appear fine-tuned in the sense that if they were altered by only modest amounts, the universe would be qualitatively different, and in many cases unsuitable for the development of life. ... The emergence of the complex structures capable of supporting intelligent observers seems to be very fragile. The laws of nature form a system that is extremely fine-tuned, and very little in physical law can be altered without destroying the possibility of the development of life as we know it."
Rees: Any universe hospitable to life -- what we might call a biophilic universe -- has to be 'adjusted' in a particular way. The prerequisites for any life of the kind we know about -- long-lived stable stars, stable atoms such as carbon, oxygen and silicon, able to combine into complex molecules, etc -- are sensitive to the physical laws and to the size, expansion rate and contents of the universe. Indeed, even for the most open-minded science fiction writer, 'life' or 'intelligence' requires the emergence of some generic complex structures: it can't exist in a homogeneous universe, not in a universe containing only a few dozen particles. Many recipes would lead to stillborn universes with no atoms, no chemistry, and no planets; or to universes too short-lived or too empty to allow anything to evolve beyond sterile uniformity.
Linde: the existence of an amazingly strong correlation between our own properties and the values of many parameters of our world, such as the masses and charges of electron and proton, the value of the gravitational constant, the amplitude of spontaneous symmetry breaking in the electroweak theory, the value of the vacuum energy, and the dimensionality of our world, is an experimental fact requiring an explanation.
Susskind: The Laws of Physics ... are almost always deadly. In a sense the laws of nature are like East Coast weather: tremendously variable, almost always awful, but on rare occasions, perfectly lovely. ... [O]ur own universe is an extraordinary place that appears to be fantastically well designed for our own existence. This specialness is not something that we can attribute to lucky accidents, which is far too unlikely. The apparent coincidences cry out for an explanation.
Guth: in the multiverse, life will evolve only in very rare regions where the local laws of physics just happen to have the properties needed for life, giving a simple explanation for why the observed universe appears to have just the right properties for the evolution of life. The incredibly small value of the cosmological constant is a telling example of a feature that seems to be needed for life, but for which an explanation from fundamental physics is painfully lacking.
Smolin: Our universe is much more complex than most universes with the same laws but different values of the parameters of those laws. In particular, it has a complex astrophysics, including galaxies and long lived stars, and a complex chemistry, including carbon chemistry. These necessary conditions for life are present in our universe as a consequence of the complexity which is made possible by the special values of the parameters.
Guess who?: The most commonly cited examples of apparent fine-tuning can be readily explained by the application of a little well-established physics and cosmology. ... [S]ome form of life would have occurred in most universes that could be described by the same physical models as ours, with parameters whose ranges varied over ranges consistent with those models. ... . My case against fine-tuning will not rely on speculations beyond well-established physics nor on the existence of multiple universes.