Victor Stenger is a famous “Internet Infidel” atheist, but what makes him different is that he is has a PhD in physics. He wrote a book published by the atheist publisher Prometheus Press where he explains why he thinks that the universe is not fine-tuned for embodied sentient life.
An Australian physicist named Luke Barnes decided to write a response to his book, and the response is summarized (without the math!) on Uncommon Descent. Barnes has a PhD in Astronomy from Cambridge. He did postdoctoral research in Switzerland at the Institute for Astonomy, and now he is doing more postdoctoral research at the University of Sydney . The response that he wrote does not talk about God, or explanations of why the fine-tuning happened. I have no idea where his convictions are on any of that, because his response just talks about the fine-tuning itself from a scientific point of view.
Here’s how Uncommon Descent explains Barnes’ response.
Professor Victor Stenger is an American particle physicist and a noted atheist, who popularized the phrase, “Science flies you to the moon. Religion flies you into buildings”. Professor Stenger is also the author of several books, including his recent best-seller, The Fallacy of Fine-Tuning: How the Universe is Not Designed for Humanity (Prometheus Books, 2011). Stenger’s latest book has been received with great acclaim by atheists: “Stenger has demolished the fine-tuning proponents,” writes one enthusiastic Amazon reviewer, adding that the book tells us “how science is able to demonstrate the non-existence of god.”
Well, it seems that the great Stenger has finally met his match. Dr. Luke A. Barnes, a post-doctoral researcher at the Institute for Astronomy, ETH Zurich, Switzerland, has written a scathing critique of Stenger’s book. I’ve read refutations in my time, but I have to say, this one is devastating.
In his paper, Dr. Barnes takes care to avoid drawing any metaphysical conclusions from the fact of fine-tuning. He has no religious axe to grind. His main concern is simply to establish that the fine-tuning of the universe is real, contrary to the claims of Professor Stenger, who asserts that all of the alleged examples of fine-tuning in our universe can be explained without the need for a multiverse.
Dr. Barnes’ ARXIV paper, The Fine-Tuning of the Universe for Intelligent Life (Version 1, December 21, 2011), is available online, and I shall be quoting from it below. Since the paper is quite technical at times, I’ve omitted mathematical equations and kept the references to physical parameters to a minimum, since I simply wish to give readers an overview of what Dr. Barnes perceives as the key flaws in Professor Stenger’s book.
First, the abstract:
The fine-tuning of the universe for intelligent life has received a great deal of attention in recent years, both in the philosophical and scientific literature. The claim is that in the space of possible physical laws, parameters and initial conditions, the set that permits the evolution of intelligent life is very small. I present here a review of the scientific literature, outlining cases of fine-tuning in the classic works of Carter, Carr and Rees, and Barrow and Tipler, as well as more recent work. To sharpen the discussion, the role of the antagonist will be played by Victor Stenger’s recent book The Fallacy of Fine-Tuning: Why the Universe is Not Designed for Us. Stenger claims that all known fine-tuning cases can be explained without the need for a multiverse. Many of Stenger’s claims will be found to be highly problematic. We will touch on such issues as the logical necessity of the laws of nature; objectivity, invariance and symmetry; theoretical physics and possible universes; entropy in cosmology; cosmic inflation and initial conditions; galaxy formation; the cosmological constant; stars and their formation; the properties of elementary particles and their effect on chemistry and the macroscopic world; the origin of mass; grand unified theories; and the dimensionality of space and time. I also provide an assessment of the multiverse, noting the significant challenges that it must face. I do not attempt to defend any conclusion based on the fine-tuning of the universe for intelligent life. This paper can be viewed as a critique of Stenger’s book, or read independently.
Here’s a quote that I wanted to put out there from the paper about how widely accepted fine-tuning is among scientists:
There are a great many scientists, of varying religious persuasions, who accept that the universe is fine-tuned for life, e.g. Barrow, Carr, Carter, Davies, Dawkins, Deutsch, Ellis, Greene, Guth, Harrison, Hawking, Linde, Page, Penrose, Polkinghorne, Rees, Sandage, Smolin, Susskind, Tegmark, Tipler, Vilenkin, Weinberg, Wheeler, Wilczek. They differ, of course, on what conclusion we should draw from this fact. Stenger, on the other hand, claims that the universe is not fine-tuned.
That is a very diverse list. I know that Sandage, Ellis, Page, Tipler and Polkinghorne are theists. But I also know that Weinberg, Rees, Hawking, Greene, and Dawkins are atheists. So scientists all across the spectrum of worldview admit that the fine-tuning is real.
Now, let’s look at Barnes’ paper and see why Victor Stenger disagrees with the view of those scientists.
1) Stenger doesn’t show why the entropy at the beginning of the universe isn’t a case of fine-tuning:
We turn now to cosmology. The problem of the apparently low entropy of the universe is one of the oldest problems of cosmology. The fact that the entropy of the universe is not at its theoretical maximum, coupled with the fact that entropy cannot decrease, means that the universe must have started in a very special, low entropy state. (p. 23)
Let’s return to Stenger’s proposed solution… Stenger takes it for granted that the universe is homogeneous and isotropic. We can see this also in his use of the Friedmann equation, which assumes that space-time is homogeneous and isotropic. Not surprisingly, once homogeneity and isotropy have been assumed, Stenger finds that the solution to the entropy problem is remarkably easy.
We conclude that Stenger has not only failed to solve the entropy problem; he has failed to comprehend it. He has presented the problem itself as its solution. Homogeneous, isotropic expansion cannot solve the entropy problem – it is the entropy problem. Stenger’s assertion that “the universe starts out with maximum entropy or complete disorder” is false. A homogeneous, isotropic spacetime is an incredibly low entropy state. Penrose (1989) warned of precisely this brand of failed solution two decades ago... (p. 26)
2) Stenger responds to calculations showing the need for fine-tuning by speculating that future calculations will overturn the ones we have now:
The Cosmological Constant, Lambda
The cosmological constant problem is described in the textbook of Burgess & Moore (2006) as “arguably the most severe theoretical problem in high-energy physics today, as measured by both the difference between observations and theoretical predictions, and by the lack of convincing theoretical ideas which address it”. A well-understood and well-tested theory of fundamental physics (Quantum Field Theory – QFT) predicts contributions to the vacuum energy of the universe that are [approx.] 10^120 times greater than the observed total value. Stenger’s reply is guided by the following principle:
Any calculation that disagrees with the data by 50 or 120 orders of magnitude is simply wrong and should not be taken seriously. We just have to await the correct calculation. [FOFT p. 219]
This seems indistinguishable from reasoning that the calculation must be wrong since otherwise the cosmological constant would have to be fine-tuned. One could not hope for a more perfect example of begging the question. More importantly, there is a misunderstanding in Stenger’s account of the cosmological constant problem. The problem is not that physicists have made an incorrect prediction. We can use the term dark energy for any form of energy that causes the expansion of the universe to accelerate, including a “bare” cosmological constant (see Barnes et al., 2005, for an introduction to dark energy). Cosmological observations constrain the total dark energy. QFT [quantum field theory – VJT] allows us to calculate a number of contributions to the total dark energy from matter fields in the universe. Each of these contributions turns out to be 10^120 times larger than the total. There is no direct theory-vs.-observation contradiction as one is calculating and measuring different things. The fine-tuning problem is that these different independent contributions, including perhaps some that we don’t know about, manage to cancel each other to such an alarming, life-permitting degree. This is not a straightforward case of Popperian falsification. (pp. 34-35)
3) Stenger doesn’t consider the full range of values when deciding if something is fine-tuned or not:
Protons, Neutrons, Electrons
We turn now to the relative masses of the three most important particles in our universe: the proton, neutron and electron, from which atoms are made. Consider first the ratio of the electron to the proton mass, … of which Stenger says: “…we can argue that the electron mass is going to be much smaller than the proton mass in any universe even remotely like ours.” [FOFT p. 164] (p. 50)
The fact that Stenger is comparing the electron mass in our universe with the electron mass in universes “like ours” is all the evidence one needs to conclude that Stenger doesn’t understand fine-tuning. The fact that universes like ours turn out to be rather similar to our universe isn’t particularly enlightening. (p. 50)
Finally, and most importantly, note carefully Stenger’s conclusion. He states that no fine-tuning is needed for the neutron-proton mass difference in our universe to be approximately equal to the up quark-down quark mass difference in our universe. Stenger has compared our universe with our universe and found no evidence of fine-tuning. There is no discussion of the life-permitting range, no discussion of the possible range of [mass(neutron) – mass(proton)] (or its relation to the possible range of [mass(down quark) – mass(up quark)], and thus no relevance to fine-tuning whatsoever. (p. 51)
Those are just a few of the examples in the paper, highlighted in the Uncommon Descent article (emphasis theirs).
UPDATE: Commenter Eugene advises me that Barnes’ paper has now been published in a peer-reviewed journal. The journal is published by Cambridge University.