Professor Krauss, author of “A Universe from Nothing,” has responded to Eric Metaxas’s Wall Street Journal article, Science Increasingly makes the case for God with a rebuttal titled, No, Astrobiology has not made the case for God (New Yorker, January 24, 2015). Having read Krauss’s rebuttal, I found it to be utterly devoid of quantitative reasoning, scientific predictions or novel arguments. That should tell you something: it’s a polemic masquerading as science.
A question of bias
Let me note for the record that Krauss is not merely an atheist, but a self-described antitheist. On the subject of God, he does not pretend to write as a disinterested scholar: he openly admits that he has an ideological axe to grind. As he declared in an interview with New Atheist Sam Harris, which was aptly titled, “Everything and Nothing” (January 3, 2012):
“I cannot hide my own intellectual bias here. As I state in the first sentence of the book, I have never been sympathetic to the notion that creation requires a creator. And like our late friend, Christopher Hitchens, I find the possibility of living in a universe that was not created for my existence, in which my actions and thoughts need not bend to the whims of a creator, far more enriching and meaningful than the other alternative. In that sense, I view myself as an anti-theist rather than an atheist.”
Not only does Krauss not believe in God: he doesn’t want there to be a God. One could hardly expect such a man to assess the scientific evidence for a Creator in a detached manner, if there were any evidence.
“Don’t know much about biology…”
I should note also that Professor Krauss’s Ph.D. is in physics, and that he has no qualifications whatsoever in the field of biology. Thus when he disparages author Eric Metaxas on the grounds that he is not a scientist, and then proceeds to write 2,000 words on the subject of how he thinks life could have originated even in a universe unlike our own, it’s a classic case of the pot calling the kettle black.
Indeed, Professor Krauss’s astonishing ignorance of biology is the biggest problem with his article. Take this passage, for instance:
…[W]hen we consider the evolution of life on Earth, we have to ask what factors could have been different and still allowed for intelligent life. Consider a wild example, involving the asteroid that hit Earth sixty-five million years ago, wiping out the dinosaurs and a host of other species, and probably allowing an evolutionary niche for mammals to begin to flourish. This was a bad thing for life in general, but a good thing for us. Had that not happened, however, maybe giant intelligent reptiles would be arguing about the existence of God today.
Unfortunately, Krauss’s argument fails on two counts. First, nowhere in Eric Metaxas’s article does the author argue for fine-tuning on the grounds that human beings wouldn’t be here if the parameters of the universe were even slightly different. Rather, Metaxas’s argument is that these parameters are finely-tuned for life – and more specifically, intelligent life. Indeed, Metaxas explicitly acknowledges the possibility of other intelligent life-forms in his discussion of the (so far unsuccessful) Search for Extra-Terrestrial Intelligence (SETI).
Second, Krauss reveals his ignorance of biology when he casually asserts that the dinosaurs were wiped out sixty-five million years ago. Krauss appears to be unaware that evolutionary biologists currently classify birds as dinosaurs, leading paleontologist Simon Conway-Morris of the University of Cambridge to quip: “As far as dinosaurs becoming intelligent is concerned the experiment has been done and we call them crows.” And crows – especially the New Caledonian crow, pictured above – are undeniably pretty smart animals – although strictly speaking, I wouldn’t call them intelligent, since they’re incapable of justifying their choices – a feat which requires language. But I digress.
Problems with the origin of life
Krauss is also appallingly naive regarding the massive problems confronting scientific theories about the origin of life. He blithely asserts that non-random chemical processes make the emergence of life inevitable:
An even more severe problem in Metaxas’s argument is the assumption of randomness, namely that physical processes do not naturally drive a system toward a certain state. This is the most common error among those who argue that, given the complexity of life on Earth, evolution is as implausible as a tornado ravaging a junkyard and producing a 747. The latter event is, indeed, essentially statistically impossible. However, we now understand that the process of natural selection implies that evolution is anything but random… Natural selection drives systems in a specific direction, and the remarkable diversity of species on Earth today, each evolved for evolutionary success in a different environment, is one result.
Non-randomness is now understood to have a likely impact on the first appearance of life. For example, new insights into geophysical and chemical processes in extreme environments suggest that early Earth naturally favored the production of relatively large organic molecules. Moreover, we have continued to find in space the more sophisticated components associated with the evolution of life on Earth. The build-up of these complex precursors of life is, therefore, far from purely random. Furthermore, a recent interesting, if speculative, proposal suggests that, when driven by an external source of energy, matter will rearrange itself to dissipate this energy most efficiently. Living systems allow greater dissipation, which means that the laws of physics might suggest that life is, in some sense, inevitable.
I note in passing that even if living systems allow “greater dissipation of energy,” what the paper’s authors need to show is that these systems allow the most efficient dissipation of energy of any physical system, which is a very tall claim indeed.
Krauss’s smug put-down of Fred Hoyle’s famous “tornado in a junkyard” argument is over thirty years out of date. We’ve all read about Hoyle’s fallacy, thank you very much. However, Professor Krauss appears to be blissfully unaware of the work of Dr. Eugene V. Koonin, who is a Senior Investigator at the National Center for Biotechnology Information, National Library of Medicine, at the National Institutes of Health in Bethesda, Maryland, USA. Dr. Koonin is also a recognized authority in the field of evolutionary and computational biology. Recently, he authored a book, titled, “The Logic of Chance: The Nature and Origin of Biological Evolution” (Upper Saddle River: FT Press, 2011). I think we can fairly assume that when it comes to origin-of-life scenarios, he knows what he’s talking about.
In Appendix B of his book, “The Logic of Chance<", Dr. Koonin argues that the origin of life is such a remarkable event that we need to postulate a multiverse, containing a very large (and perhaps infinite) number of universes, in order to explain the emergence of life on Earth. The reason why Dr. Koonin believes we need to postulate a multiverse in order to solve the riddle of the origin of life on Earth is that all life is dependent on replication and translation systems which are fiendishly complex. As Koonin puts it:
The origin of the translation system is, arguably, the central and the hardest problem in the study of the origin of life, and one of the hardest in all evolutionary biology. The problem has a clear catch-22 aspect: high translation fidelity hardly can be achieved without a complex, highly evolved set of RNAs and proteins but an elaborate protein machinery could not evolve without an accurate translation system.
Dr. Koonin provides what he calls “a rough, toy calculation, of the upper bound of the probability of the emergence of a coupled replication-translation system in an O-region.” (By an “O-region,” Dr. Koonin means an observable universe, such as the one we live in.) The calculations on pages 434-435 in Appendix B of Dr. Koonin’s book, “The Logic of Chance,” are adapted from his peer-reviewed article, The Cosmological Model of Eternal Inflation and the Transition from Chance to Biological Evolution in the History of Life, Biology Direct 2 (2007): 15, doi:10.1186/1745-6150-2-15. The model itself is not intended to be realistic one – that’s why it’s called a toy model – but it makes some very generous assumptions about the availability of RNA on the primordial Earth. After performing what he calls “a back-of-the-envelope calculation” of the odds of the emergence of “a primitive, coupled replication-translation system,” which requires, at a minimum, the formation of “two rRNAs with a total size of at least 1000 nucleotides,” “10 primitive adaptors of about 30 nucleotides each,” and “one RNA encoding a replicase” with “about 500 nucleotides”, Dr. Koonin calculates:
In other words, even in this toy model that assumes a deliberately inflated rate of RNA production, the probability that a coupled translation-replication emerges by chance in a single O-region is P < 10-1018. Obviously, this version of the breakthrough stage can be considered only in the context of a universe with an infinite (or, at the very least, extremely vast) number of O-regions.
Krauss waxes lyrical about the large number of planets in our universe on which life could have originated. The best current estimate for the number of planets in the universe is 1024. Even if we multiply that number by Koonin’s calculated odds of 1 in 101,018, they’re still fantastically long odds. So when Krauss writes that “we have discovered a surprisingly diverse group of new solar systems,” and that “even in our solar system, there are a host of possible sites where life might have evolved,” he is overlooking a very simple mathematical point. The total number of atoms in the universe is just 1080. That number is still dwarfed by the figure of 101,018, calculated by Koonin.
Krauss is fond of quoting Carl Sagan’s dictum that extraordinary events require extraordinary evidence. I have to ask: if this is not extraordinary evidence, then what is?
I should add that Dr. Koonin’s 2007 paper, which contained the calculations listed above, passed a panel of four reviewers, including one from Harvard University, who wrote:
In this work, Eugene Koonin estimates the probability of arriving at a system capable of undergoing Darwinian evolution and comes to a cosmologically small number…
The context of this article is framed by the current lack of a complete and plausible scenario for the origin of life. Koonin specifically addresses the front-runner model, that of the RNA-world, where self-replicating RNA molecules precede a translation system. He notes that in addition to the difficulties involved in achieving such a system is the paradox of attaining a translation system through Darwinian selection. That this is indeed a bona-fide paradox is appreciated by the fact that, without a shortage [of] effort, a plausible scenario for translation evolution has not been proposed to date. There have been other models for the origin of life, including the ground-breaking Lipid-world model advanced by Segrè, Lancet and colleagues (reviewed in EMBO Reports (2000), 1(3), 217–222), but despite much ingenuity and effort, it is fair to say that all origin of life models suffer from astoundingly low probabilities of actually occurring…
…[F]uture work may show that starting from just a simple assembly of molecules, non-anthropic principles can account for each step along the rise to the threshold of Darwinian evolution. Based upon the new perspective afforded to us by Koonin this now appears unlikely. (Emphases mine – VJT.)
Think about that. A leading evolutionary biologist has calculated that the odds of even a very basic life-form – a coupled replication-translation system – emerging in the observable universe are 1 in 1 followed by 1,018 zeroes. To overcome those astronomical odds, he posits a multiverse containing a vast number of universes. But there are several reasons why the multiverse solution won’t work, as we’ll see below.
But for all its ingenuity, Dr. Koonin’s multiverse won’t work. The multiverse hypothesis faces five formidable problems: first, it merely shifts the fine-tuning problem up one level, as a multiverse capable of generating even one life-supporting universe would still need to be fine-tuned; second, the multiverse hypothesis itself implies that a sizable proportion of universes (including perhaps our own) were intelligently designed; third, the multiverse hypothesis predicts that most of the intelligent life-forms that exist should be “Boltzmann brains” that momentarily fluctuate into and out of existence; fourth, the multiverse hypothesis predicts that a universe containing intelligent life should be much smaller than the one we live in; and fifth, the multiverse hypothesis cannot account for the fact that the laws of physics are not only life-permitting, but also mathematically elegant – a fact acknowledged even by physicists with no religious beliefs.
The first problem with the multiverse hypothesis is that the multiverse itself requires fine-tuning – a point which has been demonstrated by Dr. Robin Collins, a Professor of Philosophy and chair of the Department of Philosophy at Messiah College in Grantham, Pennsylvania. Dr. Collins also spent two years in a Ph.D. program in Physics at the University of Texas at Austin before transferring to the University of Notre Dame where he received a Ph.D. in philosophy in 1993. In an influential essay entitled, The Teleological Argument: An Exploration of the Fine-Tuning of the Universe (in The Blackwell Companion to Natural Theology, edited by William Lane Craig and J. P. Moreland, 2009, Blackwell Publishing Ltd.), Dr. Robin Collins offers a scientific explanation of why even a “multiverse-generator” would still fail to eliminate the need for fine-tuning:
In sum, even if an inflationary-superstring multiverse generator exists, it must have just the right combination of laws and fields for the production of life-permitting universes: if one of the components were missing or different, such as Einstein’s equation or the Pauli Exclusion Principle, it is unlikely that any life-permitting universes could be produced. Consequently, at most, this highly speculative scenario would explain the fine-tuning of the constants of physics, but at the cost of postulating additional fine-tuning of the laws of nature.
A second problem with the multiverse hypothesis, which has been pointed out by physicist Paul Davies, is that the multiverse hypothesis is every bit as “theological” as the theistic hypothesis that the universe was made by God, since it, too, implies the existence of intelligently designed universes:
Among the myriad universes similar to ours will be some in which technological civilizations advance to the point of being able to simulate consciousness. Eventually, entire virtual worlds will be created inside computers, their conscious inhabitants unaware that they are the simulated products of somebody else’s technology. For every original world, there will be a stupendous number of available virtual worlds – some of which would even include machines simulating virtual worlds of their own, and so on ad infinitum.
Taking the multiverse theory at face value, therefore, means accepting that virtual worlds are more numerous than “real” ones. There is no reason to expect our world – the one in which you are reading this right now – to be real as opposed to a simulation. And the simulated inhabitants of a virtual world stand in the same relationship to the simulating system as human beings stand in relation to the traditional Creator.
Far from doing away with a transcendent Creator, the multiverse theory actually injects that very concept at almost every level of its logical structure. Gods and worlds, creators and creatures, lie embedded in each other, forming an infinite regress in unbounded space.
— Paul Davies, A Brief History of the Multiverse, New York Times, 12 April 2003.
A third problem with the multiverse hypothesis is that if we live in a multiverse, then we would expect biological life-forms like ourselves to be vastly outnumbered by “Boltzmann brains.” Cosmologist Luke Barnes helpfully explains in his essay, The Fine-Tuning of the Universe for Intelligent Life:
We should be wary of any multiverse which allows for single brains, imprinted with memories, to fluctuate into existence. The worry is that, for every observer who really is a carbon-based life form who evolved on a planet orbiting a star in a galaxy, there are vastly more for whom this is all a passing dream, the few, fleeting fancies of a phantom fluctuation. This could be a problem in our universe – if the current, accelerating phase of the universe persists arbitrarily into the future, then our universe will become vacuum dominated. Observers like us will die out, and eventually Boltzmann brains, dreaming that they are us, will outnumber us. The most serious problem is that, unlike biologically evolved life like ourselves, Boltzmann brains do not require a fine-tuned universe. If we condition on observers, rather than biological evolved life, then the multiverse may fail to predict a universe like ours. The multiverse would not explain why our universe is fine-tuned for biological life (R.Collins, forthcoming). (p. 61)
Fourth, if we live in a multiverse, then we would expect our universe to be much, much smaller than it actually is. To quote Dr. Luke Barnes again:
Another argument against the multiverse is given by Penrose (2004, pg. 763). As with the Boltzmann multiverse, the problem is that this universe seems uncomfortably roomy… In other words, if we live in a multiverse generated by a process like chaotic inflation, then for every observer who observes a universe of our size, there are 1010123 who observe a universe that is just 10 times smaller. This particular multiverse dies the same death as the Boltzmann multiverse. (p. 62)
Fifth and finally, the multiverse hypothesis fails to explain the striking mathematical elegance of the laws of nature, since there’s absolutely no reason, from a purely naturalistic standpoint, why life-permitting laws should have to be mathematically elegant as well. In his 1753 classic, The Analysis of Beauty, the English painter William Hogarth argued that simplicity with variety is the defining feature of beauty or elegance. The elegance of the laws of Nature has been remarked on by many scientists, including physicist Paul Davies, the author of the best-selling book, Superforce: The Search for a Grand Unified Theory of Nature (New York, NY: Simon and Schuster):
A common reaction among physicists to remarkable discoveries of the sort discussed above is a mixture of delight at the subtlety and elegance of nature, and of stupefaction: ‘I would never have thought of doing it that way.’ If nature is so ‘clever’ that it can exploit mechanisms that amaze us with their ingenuity, is that not persuasive evidence for the existence of intelligent design behind the physical universe? (1984, pp. 235-36.)
Fine-tuning expert Dr. Robin Collins argues in his 2009 essay, Universe or Multiverse? A Theistic Perspective (in B. Carr, ed., Universe or Multiverse?, Cambridge University Press) that theism offers the only good explanation for the fact that the laws of physics are not only life-permitting, but also mathematically beautiful:
… [A]lthough the observable phenomena have an incredible variety and much seeming chaos, they can be organized via a relatively few simple laws governing postulated unobservable processes and entities. What is more amazing, however, is that these simple laws can in turn be organized under a few higher-level principles … and form part of a simple and elegant mathematical framework…
Atheism seems to offer no explanation for the apparent fine-tuning of the laws of nature for beauty and elegance (or simplicity with variety). Theism, on the other hand, seems to offer such a natural explanation: for example, given the classical theistic conception of God as the greatest possible being, and hence a being with a perfect aesthetic sensibility, it is not surprising that such a God would create a world of great subtlety and beauty at the fundamental level. Given the rule of inference that, everything else being equal, a natural non-ad hoc explanation of a phenomenon x is always better than no explanation at all, it follows that everything else being equal, we should prefer the theistic explanation to the claim that the elegance and beauty of the laws of nature is just a brute fact.
Putting the cart before the horse
And what is Professor Krauss’s response to the evidence of fine-tuning? Remarkably, he resurrects an old argument put forward by Science fiction writer Douglas Adams in a speech at Cambridge in 1998.
Here’s how Adams wittily phrased it:
Imagine a puddle waking up one morning and thinking, “This is an interesting world I find myself in — an interesting hole I find myself in — fits me rather neatly, doesn’t it? In fact it fits me staggeringly well, may have been made to have me in it!”
Professor Krauss makes a similar observation in his article. After acknowledging that “a small change in the strength of the four known forces (but nowhere near as small as Metaxas argues) would imply that stable protons and neutrons, the basis of atomic nuclei, might not exist,” he goes on to airily dismisses this as “old news” and adds: “while it’s an interesting fact, it certainly does not require a deity.” Krauss then provides his own alternative explanation:
Once again, it likely confuses cause and effect. The constants of the universe indeed allow the existence of life as we know it. However, it is much more likely that life is tuned to the universe rather than the other way around.
The fallacy in this argument should be obvious. The notion that life has adapted to the constants of this universe presupposes the very fact that Krauss needs to explain: namely that life exists in the first place. But as Krauss admits, relatively small changes in the constants of our universe would render the existence of atoms – and hence life – impossible. And if we bear in mind the awkward fact that the emergence of life even within a life-friendly universe like our own is fantastically improbable (as we’ve seen above), it should be apparent to the unbiased reader that Krauss’s solution explains nothing at all.
But Professor Krauss wants to have a little fun at the expense of fine-tuning proponents like Eric Metaxas, so he invents a humorous analogy to drive home his point:
We survive on Earth in part because Earth’s gravity keeps us from floating off. But the strength of gravity selects a planet like Earth, among the variety of planets, to be habitable for life forms like us. Reversing the sense of cause and effect in this statement, as Metaxas does in cosmology, is like saying that it’s a miracle that everyone’s legs are exactly long enough to reach the ground.
Unfortunately, Krauss’s analogy is completely inept. For gravity presupposes the existence of massive objects, such as planets. No mass, no gravity. The physical constants of the universe, on the other hand, do not presuppose the existence of life; rather, the existence of life presupposes the fact that these constants have life-permitting values. Krauss is putting the cart before the horse.
It is a trivial fact that if you live in a planet whose gravity is strong enough to keep you from floating away, then of course your legs will be long enough to reach the ground. But the fact that if the constants of Nature were varied even slightly, life of any sort would be impossible, is a far from trivial fact. It’s a pity that Professor Krauss can’t see the difference.
Bad physics, too: Krauss’s fine-tuning fallacies
It gets worse. Although Professor Krauss is a physicist who has written extensively on fine-tuning, he doesn’t appear to be up-to-date with the scientific literature on the subject. Don’t take my word for it; that’s the verdict of cosmologist Dr. Luke Barnes of the Sydney Institute of Astronomy (University of Sydney), who, in a blog article titled, Comment on “Science Increasingly Makes the Case for God”, excoriates Krauss’s letter to the editor of the Wall Street Journal (December 26, 2014), which was written in reply to Eric Metaxas’ article in the same journal. (Krauss’s more recent article in the New Yorker is a lengthier re-hash of .) Commenting on Krauss’s claim that “We currently DO NOT know the factors that allow the evolution of life in the Universe,” Barnes comments:
[Krauss] [c]onflates “we don’t know everything” with “we don’t know anything”. There are clear fine-tuning cases. With a relatively small tweak to the cosmological constant or the quark masses, we can make universes with no atoms, or one hydrogen atom per observable universe, or that last only a fraction of a second before recollapsing. In these cases, the details of which chemical reactions first formed life on Earth aren’t particularly relevant. We know enough, even if there is a lot more we’d like to know about life.
In his article in the New Yorker, Professor Krauss ridicules Eric Metaxas for his claim that there are more than 200 known parameters necessary for a planet to support life. Krauss also argues that the fine-tuning of the strength of the four forces of Nature is nowhere near as precise as Metaxas claims it is. But when one reads Dr. Barnes’s review, it becomes apparent that Krauss is failing to see the wood for the trees.
In his 2015 blog article, Comment on “Science Increasingly Makes the Case for God”, Dr. Barnes scathingly observes:
… Krauss’s statement that the force strengths could be “vastly different” contradicts most of the literature and is completely indefensible.
In the same article, Dr. Barnes points out some factually incorrect claims made by Eric Metaxas, including his list of 200 fine-tuning parameters – which appears to be derived from the work of astrophysicist Hugh Ross, who listed 154 parameters back in 2004. Dr. Barnes goes on to observe that Hugh Ross makes no attempt to separate the wheat from the chaff in his list, and he suggests that Eric Metaxas could have made a much better case if he had chosen to concentrate on just six parameters for which we do have really good evidence of fine-tuning, as fine-tuning expert Dr. Robin Collins does in his online essay, The Teleological Argument. .
Dr. Barnes also corrects Eric Metaxas’s claim that if the ratio between the nuclear strong force and the electromagnetic force had been off by even one part in 100,000,000,000,000,000, then no stars could have ever formed. But at the same time, Barnes adds that physicist Paul Davies has stated that the weak force is fine-tuned to one part in 1040 – or one followed by forty zeroes – which is even more impressive.
And that’s not all. In an Arxiv paper titled, The Fine-Tuning of the Universe for Intelligent Life (which was later published in abridged form the Publications of the Astronomical Society of Australia), Dr. Barnes skillfully dismantles frequently-heard criticisms of the fine-tuning argument. So how low are the odds of a fine-tuned universe? Barnes helpfully supplies from numbers in an blog article titled, In Defence of The Fine-Tuning of the Universe for Intelligent Life.
…[T]he cosmological constant alone gives 10-120. The Higgs vev is fine-tuned to 10-17. The triple alpha process plausibly puts constraints of order 10-5 on the fine-structure constant. The “famous fine-tuning problem” of inflation is 10^-11 (Turok, 2002). The fine-tuning implied by entropy is 1 in 1010123 according to Penrose.
I have to say that those numbers sounds pretty impressive to me.
Finally, in response to Krauss’s claim that the fine-tuning we observe “is more likely an example of life being fine-tuned for the universe in which it evolved, rather than the other way around,” Dr. Barnes acidly remarks:
Again, a statement without justification in the scientific literature, unless Krauss is referring to a multiverse.
Delivering his verdict on the articles by Metaxas and Krauss on fine-tuning, Barnes comments:
It’s annoying that both “sides” get the science wrong. Someone should set them straight.
Now, it is hardly surprising that Eric Metaxas – who, as Krauss reminds us, is an author, not a scientist – should have made a couple of scientific errors in his article for the Wall Street Journal. But Professor Lawrence Krauss is a scientist – and a physicist, to boot. In fact, he’s the only physicist to have received awards from all three major American physics societies: the American Physical Society, the American Association of Physics Teachers, and the American Institute of Physics. In 2012, he was awarded the National Science Board’s Public Service Medal for his contributions to public education in science and engineering in the United States. For a physicist of Krauss’s stature to be rebuked by a cosmologist for getting his facts wrong is embarrassing, to say the least.
Krauss’s irrelevant objection to the fine-tuning of the cosmological constant
At one point in his article, Krauss acknowledges the existence of fine-tuning in the cosmos, only to discount its significance:
In fact, one of the most severe apparent fine tunings often referred to by creationists like Metaxas is that of the so-called cosmological constant, the energy of empty space that has recently been discovered to be causing the expansion of the universe to accelerate over time. It remains one of the biggest mysteries in physics, as it appears to be over a hundred and twenty orders of magnitude smaller than our theories suggest it could be. And if it were as large as the theories suggest it should be, then galaxies, stars, and planets would never have formed.
Is this a clear example of design? Of course not. If it were zero, which would be “natural” from a theoretical perspective, the universe would in fact be more hospitable to life. If the cosmological constant were different, perhaps vastly different kinds of life might have arisen. Moreover, arguing that God exists because many cosmic mysteries remain is intellectually lazy in the extreme.
Let’s put this in perspective. We’re talking about a physical constant whose value would preclude the existence of galaxies, stars, and planets – let alone life – over a vast range of magnitudes. Indeed, the value of this life-permitting constant is “a hundred and twenty orders of magnitude smaller than our theories suggest it could be.” And what does Krauss do? Complain, because it is not exactly zero. Apparently he thinks a Deity would have made it exactly zero, but it isn’t, so there isn’t a Deity. That’s what I call straining at gnats and swallowing camels. But in any case, Krauss’s objection is based on faulty science.
Krauss claims that if the value of the cosmological constant were exactly zero, the universe would be more hospitable to life. The basis for this claim appears to be the fact that in the absence of dark energy, a flat universe (like our own) would expand forever but at an ever slower rate which approaches but never quite reaches zero. But with dark energy, the expansion rate of the Universe initially slows down, due to the effect of gravity, but eventually increases. What that means is that our universe will fly apart much faster than it would if the cosmological constant were zero, giving life less time to evolve.
Is this an argument against fine-tuning? Not at all. If the sole objective of the Designer were to make a life-friendly cosmos, then the very small positive value of the cosmological constant might be puzzling. But if the Designer additionally wants the intelligent life-forms in the cosmos to be able to infer His existence, then a very long-lived cosmos might actually hinder that inference, because it would weaken the argument – put forward by evolutionary biologist Eugene Koonin above – that the probability of life evolving in our universe within the time available is vanishingly low. Unless there is a multiverse, this argument would imply that the first living thing was created. But in a very old universe, this argument would be much harder for scientists to make.
Additionally, further evidence is becoming available which suggests that the small non-zero value of the cosmological constant might be the maximum value which is compatible with the existence of life. Consider the following facts. Back in the 1980s, physicist Steve Weinberg predicted that the cosmological constant would have a value of less than a hundred times the currently accepted value. In 1992, Weinberg refined this prediction of the cosmological constant to 5 to 10 times the matter density. In 1995, Weinberg’s argument was refined by Alexander Vilenkin to predict a value for the cosmological constant that was only ten times the matter density, which is about three times the current value since determined. Judge for yourself. Which way does the evidence seem to be pointing?
I have examined Professor Krauss’s objections to the fine-tuning argument and found them wanting. I conclude that belief in the existence of an Intelligent Designer Who fine-tuned the universe for life and discoverability remains scientifically reasonable.