The Universe Was Perfectly Calibrated
Seven fine-tuned constants with their sources, the multiverse response, the three strongest objections from working physicists, and what is left standing.
There are approximately 1080 atoms in the observable universe. Roger Penrose’s calculation of the probability that the universe began in its observed state by chance yields a number so much larger than that — 1 in 1010123 — that writing out the zeros would require more space than the observable universe contains. And that is one feature of the universe among many.
This is what physicists call the fine-tuning problem. Not a problem in the sense of an anomaly — but a problem in the sense of a discovery so startling that it has reshaped the philosophy of science, divided cosmologists, and prompted some of the twentieth century’s most rigorous skeptics to revisit their most fundamental assumptions.
This article walks through the actual numbers, the scientists who produced them, the objections raised by physicists who reject the design conclusion, and what is left standing at the end. Every claim below is referenced.
First: Understanding the Scale
Before examining the constants themselves, it’s worth pausing on what numbers like 10120 actually mean. Our intuitions, evolved for counting animals and tracking seasons, weren’t built for this.
Crucially: 1020 is not half of 1040. It is one part in 1020 of it — one grain of sand compared to all the Earth’s sand. The jump from 1080 to 10120 is a factor of 1040 — a number larger than the total count of atoms in the universe. When we say something is fine-tuned to 1 in 10120, we are speaking of precision that has no analogy in everyday human experience.
With that scale in mind, consider the grain of sand thought experiment. Suppose someone writes their name on a single grain of sand and hides it among the roughly 1019 grains on Earth. A kidnapper holds your closest friend hostage: find the grain, or they die. You logically know this is impossible. A probability of 1 in 1020 is already, in any reasonable sense, zero.
Now multiply that impossibility by 10100. That is the level of precision we are discussing when we speak of the cosmological constant.
The Constants: What Must Be True for Life to Exist
What follows are seven of the most significant fine-tuned parameters identified by physicists. These are not theological claims — they are peer-reviewed findings from mainstream physics.
Dark energy — the force driving the universe’s accelerating expansion — has a value that must be almost exactly zero, but not quite. Quantum field theory predicts a value 10120 times larger than what we actually observe. This discrepancy is the largest unexplained gap in all of physics.
If the cosmological constant were even fractionally larger than observed, the universe would have expanded too rapidly for any matter to clump together — no galaxies, no stars, no planets. Fractionally smaller (into negative territory), and gravity would have overcome expansion, collapsing the cosmos back in on itself within moments of the Big Bang.
Nobel laureate Steven Weinberg derived an anthropic upper bound on this constant in 1987, showing that a value much larger than observed would have prevented galaxies from ever forming.1 Leonard Susskind, a principal architect of string theory, agrees that chance alone will not account for it — which is precisely why he argues for a multiverse rather than for design. He has conceded in print that if the string landscape fails, defenders of intelligent design would be very hard to answer.8
The universe began with a specific density of matter. If that density had been greater by even 1 part in 1060, gravitational collapse would have crushed everything within seconds of the Big Bang. If it had been lower by the same fraction, matter would have dispersed too rapidly — no stars, no chemistry, no life.
Philosopher Robin Collins offers a vivid analogy for the strength of gravity itself: imagine a dial stretching across the width of the observable universe, marked off in one-inch increments. The band of settings that permits life is less than a single inch wide.5
An objection worth meeting head-on. The 1-in-1060 density figure is exactly the problem that cosmic inflation was proposed to solve: a brief burst of exponential expansion drives the density toward the critical value automatically, so no fine dialling is required. That is a real explanation and it should be granted. But inflation does not come free. It has to begin in a small patch already smooth enough and with a potential shaped precisely enough to start and then stop. Roger Penrose has argued that specifying those starting conditions is harder than specifying the smooth universe inflation was meant to explain,2 and Paul Steinhardt — one of inflation’s original architects — has spent two decades pressing the same objection from the inside.10 The tuning relocates. It does not disappear.
Gravity is also fine-tuned relative to electromagnetism. The ratio between the electromagnetic force and gravitational force between two protons is approximately 1036. If gravity were even slightly stronger relative to electromagnetism, stars would burn out too quickly for planets to develop life; if weaker, stars could not ignite at all.
The strong nuclear force holds protons and neutrons together inside atomic nuclei. Increase it by roughly 2% and two protons can bind directly into a “diproton,” opening a fusion channel that does not exist in our universe. The usual claim is that this would have burned all the hydrogen into helium in the first minutes — no long-lived hydrogen stars, no water, no organic chemistry. This particular claim is contested. Later modelling by Bradford and by MacDonald and Mullan found that a bound diproton would not, in fact, consume all the primordial hydrogen.13,14 We flag it because the argument here does not need it.
The firmer result concerns carbon. In 2000, Oberhummer, Csótó and Schlattl modelled the triple-alpha process in red giants and found that outside a window of about 0.5% in the strong force and about 4% in the electromagnetic force, stellar production of carbon or oxygen drops by a factor of 30 to 1,000.12 Every known living thing is built from both. That is a peer-reviewed result in Science, not a theological inference.
The route to that result runs through Fred Hoyle. In 1953 he calculated that carbon-12 must possess an excited state at around 7.68 MeV, because without it the triple-alpha process could not produce anything like the observed abundance of carbon in the universe. He persuaded a Caltech group to look. Dunbar, Pixley, Wenzel and Whaling found a level at 7.68 ± 0.03 MeV that same year;4 later measurements refined it to 7.654 MeV. It is now called the Hoyle state.
One correction to the popular version of this story. Hoyle is often said to have predicted the resonance “because life exists.” The historian Helge Kragh has shown that neither Hoyle nor his contemporaries connected the carbon level to life at all in 1953; his reasoning ran from the observed abundance of carbon in the cosmos, and the anthropic reading was attached retrospectively in the 1980s.15 The prediction is genuine and remarkable. The anthropic framing of it is a later addition, and this article does not rest on it.
The weak nuclear force governs radioactive decay and drives certain nuclear reactions in stars. It plays a critical role in supernovae — the stellar explosions that scatter heavier elements (carbon, oxygen, iron) across galaxies, seeding future planetary systems with the building blocks of life.
If the weak force were appreciably stronger, the Big Bang’s nuclear burning would have proceeded past helium all the way to iron — leaving no hydrogen, and making long-lived stars impossible. If it were much weaker, supernovae could not expel their outer layers, and those heavy elements would remain locked inside stellar cores forever.
The classic treatment is Carr and Rees (1979), which mapped how the observed strengths of the fundamental forces constrain the structure of everything from nuclei to stars.16 We have removed a specific numerical claim that appeared in an earlier version of this article, because we could not source it. The qualitative constraint is well established; the precise margin for the weak force is not as cleanly quantified as the figures for the cosmological constant or the triple-alpha window, and we would rather say so.
When the universe began, it produced matter and antimatter in nearly equal quantities. When matter and antimatter meet, they annihilate each other into pure energy. If the production had been perfectly equal, every particle would have met its antiparticle — and the universe would contain nothing but light.
For every billion particles of antimatter produced, there were a billion and one particles of matter. That surplus of one part in a billion is the reason anything material exists at all — every star, every planet, every atom in your body. Had the imbalance been very much smaller, there would be far too little matter left to build galaxies. It should be said that this one is weaker than the others as a fine-tuning case: the Standard Model simply offers no account of why the number takes the value it does, and physicists generally treat it as an unexplained parameter rather than a knife-edge.
The electromagnetic force determines how atoms bond with each other — it is literally the force that makes chemistry possible. If it were significantly stronger, electrons would be held so tightly to nuclei that no chemical reactions could occur. If significantly weaker, atoms could not hold electrons in stable orbits.
The electromagnetic force must also be precisely calibrated relative to the strong nuclear force. The ratio between them determines how many stable elements the periodic table contains — and which of those elements can support biochemistry. Carbon, with its unique ability to form four bonds simultaneously, is the architectural foundation of all known life. Its existence depends on this ratio being very close to what it is.
The second law of thermodynamics tells us that disorder (entropy) increases over time. This means the universe must have begun in an extraordinarily ordered, low-entropy state — otherwise the thermodynamic arrow of time (the direction from past to future) could not exist.
Physicist Roger Penrose calculated the probability that the universe began in its observed low-entropy state purely by chance. His answer: 1 in 1010123. This number is so incomprehensibly large that no analogy can capture it. Writing out the zeros alone would require more space than the entire observable universe. The number of atoms in the universe, 1080, is not even a rounding error by comparison.
Penrose’s own conclusion is not design. He holds that the low-entropy start cannot be explained by any currently known physical process, and has spent decades proposing candidates for one — the Weyl curvature hypothesis, and later conformal cyclic cosmology.2 He is not arguing for a Creator. What he insists on is that the specialness is real and demands an explanation. That much is not in dispute; what accounts for it is.
Fine-tuning is not the argument that one of these constants happens to be right. It is the observation that every single one of them must be right — simultaneously — and that changing any one would make life impossible. The odds of all of them aligning by chance are not merely improbable. They are, by any rational standard, impossible.
What Scientists Say
The reality of fine-tuning is not a theological claim — it is a scientific observation that virtually no serious physicist disputes. The disagreement is over what it means, not whether it exists.
Amazing fine-tuning occurs in the laws that make this possible. Realizing the complexity of the events that have happened, it is hard not to use the word ‘miracle.’
How surprising it is that the laws of nature and the initial conditions of the universe should allow for the existence of beings who could observe it. Life as we know it would be impossible if any one of several physical quantities had slightly different values.
The really amazing thing is not that life on Earth is balanced on a knife-edge, but that the entire universe is balanced on a knife-edge. Even if you dismiss man as a chance accident, the fact remains that the universe is fit for habitation in a way that is self-evidently not ‘reasonable.’
If anyone claims not to be surprised by the special features that the universe has, he is hiding his head in the sand. These special features are surprising and unlikely.
In order to produce a universe resembling the one in which we live, the Creator would have to aim for an absurdly tiny volume of the phase space of possible universes — about 1 part in 1010123 of the entire volume.
Read Penrose carefully. His “Creator” is a thought-experiment device — a blind marksman placing a pin somewhere in phase space — and he draws no theological conclusion from it whatsoever. He argues that the low-entropy beginning requires a physical explanation we have not yet found. Some earlier versions of this argument, including an earlier version of this article, attached a second sentence to this quotation about chance. Penrose did not write it, and we have removed it. The number is not in dispute. Only what accounts for it is — and that is the actual argument.
Note the spread. Weinberg was an atheist. Davies describes himself as neither theist nor atheist. Deutsch is a secular Jew and an advocate of the multiverse. Penrose holds to no religion. George Ellis, by contrast, is a practising Christian — we say so rather than quietly implying otherwise. Their convictions run in every direction. Their reading of the physics does not: fine-tuning is real, it is extreme, and it is not yet explained.
The Three Interpretations
Given the reality of fine-tuning, the live explanations reduce to three. This trichotomy is not a finding of physics; it is a philosophical framework, argued most prominently by the philosopher John Leslie and by William Lane Craig.17,22 It is a useful map, and each branch has to be evaluated on its merits. Note in advance that the multiverse, examined in its own section below, is a sophisticated form of the first branch rather than a fourth option.
The most common secular response is simply: we got lucky. Among an infinite space of possibilities, we happened to land in the one that permits life.
But consider what “chance” means here. A probability of 1 in 10120 — for the cosmological constant alone — sits far below what the mathematician Émile Borel called the threshold of practical impossibility, and what William Dembski later named the “universal probability bound”: roughly 1 in 1050. In fairness, that term is not standard usage in mainstream statistics and originates in the intelligent design literature, so we attribute it rather than dress it up as consensus. The underlying intuition, however, is uncontroversial: past some point, no working scientist treats a probability as a live option.
Bare chance, then, is not so much a scientific conclusion as a decision to stop asking. Which is why almost nobody defends it in that bare form. Leonard Susskind, one of the architects of string theory, agrees that luck will not do — and responds by proposing a mechanism that makes our universe unsurprising: the string landscape, an enormous ensemble of universes with differing constants. That is the serious version of the chance reply, and it is taken up below.8
Perhaps the constants couldn’t have been otherwise. Perhaps the laws of physics require these specific values, and no alternative universe is even possible.
This would be a satisfying answer — but physicists don’t support it. There is no known physical principle that forces the cosmological constant to take its observed value, or that requires the strong nuclear force to sit within the narrow window that permits carbon. In their 2006 discussion at the Salk Institute, Richard Dawkins put the suggestion to Steven Weinberg that the constants might simply have to be what they are; Weinberg did not accept it.11
Without a mathematical proof that the constants must be what they are, the probability of any given universe being life-prohibiting vastly exceeds the probability of it being life-permitting. Necessity, as currently understood, explains nothing.
No one encounters a sophisticated machine — a spacecraft, a transistor, a piece of software — and concludes it assembled itself by chance. The hallmarks of design are precision, purpose, and complexity organized toward a goal. We recognise these features even when we don’t observe the maker.
The fine-tuned universe exhibits all these features, at a scale that dwarfs any human engineering by factors impossible to express. The constants are not merely complex — they are specifically, precisely configured toward the single outcome of producing a universe that can sustain observers.
This is an inference to the best explanation, not a proof. It holds only if the trichotomy is genuinely exhaustive and the other two branches really do fail — both of which can be argued, and are, in the objections section below. What can be said without overreach is this: design is a live explanation that accounts for the data, and it has not been eliminated. Two of its rivals have serious trouble.
The Multiverse: A Scientific Response?
The most popular contemporary alternative to a Creator is the multiverse hypothesis. The argument runs: if there are infinitely many universes, each with randomly different physical constants, then by chance alone some subset of them will be life-permitting — and we necessarily find ourselves in one of those. Our “winning” universe requires no explanation; it was statistically guaranteed to exist somewhere.
This is, logically, a coherent response. But it faces serious scientific and philosophical objections that have led some of its most capable defenders to express significant doubts.
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It Is Not Science
No known or proposed experiment can observe, test or falsify the other universes. Princeton cosmologist Paul Steinhardt — a co-founder of inflationary theory who now regards the multiverse it generates as a defect rather than a feature — has described the concept as bizarre, untestable, and ultimately damaging to science.10 In fairness, defenders reply that the multiverse is a consequence of theories with independent motivation (eternal inflation, string theory) rather than an ad hoc rescue, and that indirect signatures such as bubble-collision imprints in the microwave background have been searched for. None have been found. The honest position is that it remains, for now, untested.
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The Multiverse Generator Itself Requires Fine-Tuning
For a multiverse to produce an infinite range of universes with varying constants, some mechanism must exist — a meta-universe generator governed by its own laws and constants. Those laws and constants must themselves be precisely configured to produce the right range of outputs. Fine-tuning is not eliminated; it is pushed back one level. As Paul Davies argues: you cannot use the multiverse to explain fine-tuning if the multiverse itself is fine-tuned.
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The Boltzmann Brain Problem
In many multiverse models, probability strongly favours isolated, momentarily self-aware “Boltzmann Brains” — random fluctuations that briefly assemble a conscious observer — over entire ordered cosmoses. On those models we should expect to be floating brains, not inhabitants of a coherent universe with a consistent past. We are not. Cosmologists take this seriously: Sean Carroll and others treat it as a genuine constraint that rules out whole families of models. It is fair to note that it disqualifies particular multiverse scenarios rather than the idea as such — but no scenario has yet been shown to escape it cleanly.
Steven Weinberg — an atheist who would have preferred a purely naturalistic account — accepted in his 2006 discussion with Richard Dawkins that the fine-tuning of the cosmological constant leaves few live options, and opted for a multiverse.11 We will not speculate about his motives; he gave his reasons and they were physical ones. But notice the shape of the choice. An unobservable infinity of universes is invoked in order to avoid a single unobservable Designer. Both lie beyond the reach of any experiment. Whichever a reader finds more plausible, neither side gets to call the other unscientific and keep a straight face.
The Strongest Objections
An argument is only worth as much as the counter-arguments it can survive. What follows are the three most serious objections raised by physicists and philosophers who reject the design conclusion. They are stated here as their proponents state them, not as strawmen.
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1. The Observer Selection Effect — “Of course we see a habitable universe”
The objection, popularised by Douglas Adams’ parable of the puddle that marvels at how perfectly its hole fits it: we could not have observed a universe that did not permit observers, so our observation of a life-permitting universe carries no information. Conditioned on our existing, the probability of what we see is exactly one.
The response. The selection effect explains why we observe a habitable universe. It does not explain why a habitable universe existed to be observed. John Leslie’s firing-squad illustration makes the distinction: fifty trained marksmen fire at you and all miss. You could not be alive to notice had they hit, so your survival is guaranteed given that you are noticing anything — and yet you would still, quite reasonably, conclude that something other than chance was at work. The selection effect blocks surprise at our own existence; it does not block surprise at the arrangement that made existence possible.17
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2. The Normalisation Problem — “You cannot compute these probabilities at all”
This is the most technically serious objection, pressed by Timothy and Lydia McGrew with Eric Vestrup, and separately by Ikeda and Jefferys.18 To say a constant is “fine-tuned to 1 part in 10120” requires a probability distribution over the possible values of that constant. If the range is unbounded, no uniform distribution over it can be normalised — the probabilities do not sum to one — and the number is therefore not a probability at all. On this view the fine-tuning figures are ratios of intervals, dressed up in probabilistic language they have not earned.
The response. Three lines are usually taken. First, physics does supply natural bounds in several cases: the Planck scale gives a principled cut-off, and the cosmological constant discrepancy is expressed relative to the quantum field theory prediction rather than an infinite range. Second, the argument can be reformulated comparatively — asking not for an absolute probability but whether the observed values are more expected on design than on a single brute universe — which sidesteps normalisation entirely. Third, physicists themselves routinely reason with these ratios when deciding which theories are natural and which require explanation; if the reasoning is illegitimate here, a great deal of ordinary theoretical physics goes with it. We consider this objection unresolved rather than defeated, and readers should know that.
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3. Stenger’s Challenge — “Vary the constants together and life still appears”
The physicist Victor Stenger argued in The Fallacy of Fine-Tuning that the standard presentations vary one constant at a time while holding the rest fixed, which is not how the parameter space works.19 His MonkeyGod simulation varied several constants simultaneously and produced, he claimed, a substantial fraction of universes with long-lived stars.
The response. Stenger’s book drew a detailed, peer-reviewed reply from the astrophysicist Luke Barnes in Publications of the Astronomical Society of Australia, which remains the best single technical treatment of the subject.20 Barnes shows that MonkeyGod varied only four parameters over narrow ranges, tested for stellar lifetime alone rather than for the full set of conditions life requires, and left the cosmological constant — the sharpest case of all — untouched. He also documents that multi-parameter studies, where they exist, generally tighten the constraints rather than relaxing them. Readers who want to check this argument against a hostile expert should read Stenger and Barnes side by side; we would rather point there than pretend the challenge was never made.
None of these objections is frivolous, and the second remains genuinely open. What none of them does is dissolve the phenomenon. The constants sit where they sit, the windows are narrow, and no accepted physical principle explains why. The disagreement is about what follows from that — which is the honest place for a disagreement to be.
Scientists Whose Research Changed Them
The most compelling testimony comes not from theologians, but from researchers who began their careers as committed atheists — and found themselves compelled, by their own findings, to reconsider.
“When I began my career as a cosmologist twenty years ago, I was a convinced atheist. I never in my wildest dreams imagined that one day I would be writing a book purporting to show that the central claims of Judeo-Christian theology are in fact true, and that these claims are a straightforward deduction of the laws of physics as we now understand them. I have been forced into these conclusions by the inexorable logic of my own special branch of physics.”
That passage opens The Physics of Immortality (1994), not The Physics of Christianity, as this article previously stated.9 A caveat is owed here too: Tipler’s wider Omega Point theory is regarded by most physicists as highly speculative, and his testimony proves nothing whatever about the constants. It is included for what it is — evidence that the fine-tuning data have moved serious researchers — and for nothing more.
A common sense interpretation of the facts suggests that a super-intellect has monkeyed with physics, as well as with chemistry and biology, and that there are no blind forces worth speaking about in nature. The numbers one calculates from the facts seem to me so overwhelming as to put this conclusion almost beyond question.
Hoyle coined the term “Big Bang” in a 1949 broadcast while defending the rival steady-state model; whether he intended it as a sneer is disputed, and he later said he meant it as a vivid image. He was a committed atheist who found a cosmic beginning philosophically unwelcome. The carbon-12 work and the wider fine-tuning results plainly shifted him.
But it is worth being exact about where he landed. Hoyle never became a theist and explicitly rejected a personal God. What he argued for was a “superintellect” operating within the universe rather than a Creator standing outside it — a position closer to his later panspermia work than to Christian theism. Claiming him as a convert overstates the record. What he did not retreat from is the sentence quoted above: that the numbers put blind chance almost beyond consideration. That claim, and not a conversion story, is what this article rests on.
Arno Penzias, who shared the Nobel Prize for the discovery of the cosmic microwave background, told The New York Times in 1978 that astronomy points to a universe created out of nothing and delicately balanced to provide exactly the conditions life requires — a description he tied to a supernatural plan.21
One name removed. An earlier version of this article cited Michio Kaku in this section. A widely circulated quotation attributing intelligent-design views to him is misattributed, and Kaku has publicly rejected the position. We have taken him out. Naming scientists who did not say what they are alleged to have said is precisely the sort of thing that discredits an argument that does not need it.
The Only Conclusion That Remains
Fine-tuning is not an argument from ignorance. It is not a “God of the gaps” claim. It is the observation that our best physics reveals a universe calibrated to extraordinary precision, by standards that dwarf anything human minds have constructed, in a way that permits observers — life capable of asking why the universe is the way it is at all.
The three explanations — chance, necessity, design — have been examined by some of the most rigorous intellects in scientific history. Bare chance fails the probability test by margins too vast to express, and its sophisticated form, the multiverse, buys its answer with an unobservable infinity. Necessity has no known physical grounding. Design remains unrefuted. That is not the same as proved, and this article has not claimed otherwise: the objections above are real, and one of them is unresolved. What can be said is that design is a live and coherent explanation of the data, and that the people who dismiss it as unscientific have generally not shown their working.
The medieval theologians argued from the beauty of creation to the existence of a Creator. The physicists of the twentieth and twenty-first centuries have arrived at a parallel conclusion — not from beauty, but from mathematics. Not from faith, but from the numbers themselves.
As the Heavens have always declared the glory of God, the constants of physics declare it in a language that only became legible to us in the last century. The universe is not accidentally hospitable. It was made.
“The heavens declare the glory of God; the skies proclaim the work of his hands. Day after day they pour forth speech; night after night they reveal knowledge.”
Psalm 19:1–2 (NIV)
Shorter version
The 6-minute read: four constants and the three replies
If you want the argument without the citation apparatus — the headline numbers, what physicists said about them, and the three ways of explaining them.
Read the short versionReferences & Further Reading
- Weinberg, S. (1987). “Anthropic bound on the cosmological constant.” Physical Review Letters, 59(22), 2607.
- Penrose, R. (1989). The Emperor’s New Mind. Oxford University Press.
- Barrow, J. D. & Tipler, F. J. (1986). The Anthropic Cosmological Principle. Oxford University Press.
- Hoyle, F., Dunbar, D. N. F., Wenzel, W. A., & Whaling, W. (1953). “A state in C12 predicted from astronomical evidence.” Physical Review, 92(4), 1095.
- Collins, R. (2009). “The teleological argument: An exploration of the fine-tuning of the universe.” In The Blackwell Companion to Natural Theology. Wiley-Blackwell.
- Rees, M. (1999). Just Six Numbers: The Deep Forces That Shape the Universe. Basic Books.
- Davies, P. (1982). The Accidental Universe. Cambridge University Press.
- Susskind, L. (2005). The Cosmic Landscape: String Theory and the Illusion of Intelligent Design. Little, Brown.
- Tipler, F. J. (1994). The Physics of Immortality. Doubleday. (Preface.)
- Steinhardt, P. J. (2011). “The inflation debate.” Scientific American, 304(4), 36–43.
- Weinberg, S. & Dawkins, R. (2006). Discussion at the Salk Institute, “Beyond Belief” conference. [Video recording].
- Oberhummer, H., Csótó, A. & Schlattl, H. (2000). “Stellar production rates of carbon and its abundance in the universe.” Science, 289(5476), 88–90.
- Bradford, R. A. W. (2009). “The effect of hypothetical diproton stability on the universe.” Journal of Astrophysics and Astronomy, 30(2), 119–131.
- MacDonald, J. & Mullan, D. J. (2009). “Big Bang nucleosynthesis: The strong nuclear force meets the weak anthropic principle.” Physical Review D, 80(4), 043507.
- Kragh, H. (2010). “An anthropic myth: Fred Hoyle’s carbon-12 resonance level.” Archive for History of Exact Sciences, 64(6), 721–751.
- Carr, B. J. & Rees, M. J. (1979). “The anthropic principle and the structure of the physical world.” Nature, 278, 605–612.
- Leslie, J. (1989). Universes. Routledge.
- McGrew, T., McGrew, L. & Vestrup, E. (2001). “Probabilities and the fine-tuning argument: A sceptical view.” Mind, 110(440), 1027–1038.
- Stenger, V. J. (2011). The Fallacy of Fine-Tuning: Why the Universe Is Not Designed for Us. Prometheus Books.
- Barnes, L. A. (2012). “The fine-tuning of the universe for intelligent life.” Publications of the Astronomical Society of Australia, 29(4), 529–564.
- Penzias, A. (1978). Interview, The New York Times, 12 March 1978.
- Craig, W. L. & Moreland, J. P., eds. (2009). The Blackwell Companion to Natural Theology. Wiley-Blackwell.
Where this article states a number, the source is cited. Where a claim is contested among physicists, that is said in the text rather than left out. Corrections are welcome at co**********@***il.com.
