Coarse-Tuning vs. Fine-Tuning

I attended an interesting debate last Saturday night between Justin Schieber and Blake Giunta. Blake used the fine-tuning evidence as one argument for God’s existence and Justin countered by pointing to the Coarse-Tuning argument.

What is the Coarse-Tuning Argument?

Assuming that the various finely-tuned constants can take on any value up to infinity, then any finite life-permitting range (even a large one) would become an infinitesimal subset. Thus, even coarsely-tuned parameters could be considered improbable. This is often seen then as a reductio ad absurdum against fine-tuning – for then we should be equally surprised no matter how wide the range of life-permitting values is for a given constant (so long as it was finite).

Blake followed Robin Collins in arguing that coarse-tuning could still represent an improbable situation if indeed we knew that the possible values for the various constants could go to infinity. However, I don’t think many physicists would be persuaded of anything improbable if the universe only required coarse-tuning rather than fine-tuning to support life. In fact this was the expectation prior to the pioneering work of Hoyle, Barrow, Tipler, Carter, and others. No one that I’m aware of argued that physical constants being life-permitting pointed to design until the life-permitting range of constants was discovered to be exceedingly narrow.

Why coarse-tuning would not be accepted as improbable?

Most physicists did not accept a Coarse-Tuning Argument not because it might not be improbable if the possible range was infinite, but rather due to skepticism that the possible range of constants could be infinite. If David Hilbert was right, actual infinities are nowhere to be found in reality and it would be impossible for the constants to be infinite. See my previous blog for a discussion of some of the issues associated with actually infinite quantities. Even if Hilbert is incorrect, one could still argue that one can estimate probabilities by taking limits and that Hilbert’s Hotel shows simply the counter-intuitive nature of dealing with infinities. Even if the actually infinite is possible, physicists generally reject candidate theories that entail the actually infinite – at least if the equations cannot be renormalized to avoid the infinities.

Is the range of possible values for the constants infinite?

The key assumption in the Coarse-Tuning Argument is that the possible range of constants could be infinite. However as Luke Barnes has pointed out the concept of mass becomes incoherent if fundamental particles could exceed the Planck mass. Particles over a certain mass would form a black hole and therefore be impossible to create. Does it really seem physically possible that an electron could have a mass of a billion tons? Might it be prohibitively difficult to create particles with such a huge mass due to the energy or energy density requirements in making it? Would such a massive particle be stable? We could treat the case that the electron’s mass was greater than some huge value as corresponding to there being too few electrons after some small amount of time in which the universe expanded and cooled. This special case would obviously be life-prohibiting as electrons are necessary for chemistry, stellar fusion, and other processes critical for life.

What about force strengths?

Another class of parameters that have to be finely-tuned is force strengths. Most physicists think that at least 3 out of the 4 fundamental forces are unified at certain energy levels – and probably all 4. Thus, there is an underlying relationship between the forces that would constrain their relative strengths. Ratios of the force strengths would not be infinite. If a constant governing a force strength had a value of 0, that special case could also be evaluated with respect to its ability to support life. All 4 fundamental forces are thought to be necessary for life although there are ways to have life without the weak force – but only by compensating with additional fine-tuning in other aspects.

Robin Collins argues that once force strengths become too large we lose our ability to predict whether or not such a scenario would be life-permitting – there could be new physics at such large energy scales. This is not a problem for the fine-tuning argument as defined by leading advocates though because the argument only addresses the parameter ranges for which we can reliably evaluate suitability for life – we consider only the epistemically-illumined region. Here is how John Leslie explains it in his Universes book (which I highly recommend):

If a tiny group of flies is surrounded by a largish fly-free wall area then whether a bullet hits a fly in the group will be very sensitive to the direction in which the firer’s rifle points, even if other very different areas of the wall are thick with flies. So it is sufficient to consider a local area of possible universes, e.g., those produced by slight changes in gravity’s strength, . . . . It certainly needn’t be claimed that Life and Intelligence could exist only if certain force strengths, particle masses, etc. fell within certain narrow ranges . . . . All that need be claimed is that a lifeless universe would have resulted from fairly minor changes in the forces etc. with which we are familiar. (pages 138-9)

In other words, it still looks like the rifle was aimed if it hits a tiny group of flies surrounded by a vast wall without any flies – even though there might be other flies on parts of the wall we cannot see. A design inference can be justified even though we lack complete knowledge about the life-permitting status of all of the possible parameter space. We’re only evaluating the local, finite region for which a determination can be made.

A finite number of physically possible constants?

If one takes the fine-tuning argument based on physically possible parameter space rather than metaphysically possible parameter space, then it’s expected that the range of values for constants is finite. I’ve previously linked to this important article by John Barrow outlining different ways in which physics itself can drive constants to different values. For example, spontaneous symmetry breaking in the early universe affected various parameters related to electromagnetism and the weak force. The Weinberg angle could have taken on other values that would have resulted in alternate derived parameters. However, nothing in those equations allow any of the parameters to go to infinity.

Barrow also notes that unifying gravity and quantum mechanics is only possible if “the true constants of nature are defined in higher dimensions and the three-dimensional shadows we observe are no longer fundamental and do not need to be constant.” Because of quantization, the number of ways of compactifying these extra spatial dimensions would be finite. We can treat the case that quantization is not in effect as a special case that would not plausibly support life. Without quantization, atoms are not stable and would not have consistent properties permitting information to be stored. Even String Theory entails a finite number of possible sets of fundamental constants. Many theorists think it’s quite large, perhaps 10500, but all we need is for it to be finite to avoid the infinities required by the coarse-tuning argument. Refer to my previous blog for other reasons to expect a finite range for constants of nature.

Initial conditions

Cosmologist Luke Barnes also points to the fine-tuning associated with the initial conditions of our universe as an example immune from the problems of infinities. Unless one thinks that probabilistic statements cannot be made despite the reputation of statistical mechanics as a well-established physics discipline, one is able to conclude that our universe started out in an incredibly special, highly-ordered state. The number of life-permitting states is extraordinarily tiny compared to possibilities as Roger Penrose has computed – see my blog for details. Since the number of particles was finite and the volume of space in the early universe was quite small, there is no problem of infinities that prohibits a rough probability estimate.

Summary

More work should be done in assessing the possibilities of infinities and the potential impact on the fine-tuning argument. However, I see no reason that Coarse-Tuning would be a reductio ad absurdum against fine-tuning because if we knew for sure that the constants had an infinite range the finiteness of the life-permitting range should suffice for demonstrating that life-permitting universes are a tiny subset among possibilities. However, physicists are rightly skeptical that these constants could be infinite. I’ve listed several reasons for thinking that the constants couldn’t have an infinite range – which is why physicists were not astounded until they discovered that life-permitting ranges are tiny among possibilities that can be evaluated. We can compute that the universe would be lifeless if gravity were 40 orders of magnitude stronger even though we might have some slight uncertainty about what happens if it were 4000 orders of magnitude stronger and do not know a precise upper bound of what is physically possible.

But We Can’t Even Define Life

In my previous blog I addressed some important issues in making the case that fine-tuning supports theism over atheism. Today I want to look at the objection against fine-tuning that says we can’t assess fine-tuning claims because we can’t even define ‘life’ – or put another way: “fine-tuning claims don’t properly account for other possible life forms.” It has proven surprisingly hard for scientists to agree upon a definition for life. This uncertainty, however, hasn’t prevented biologists from making inferences about life nor has it kept physicists from writing numerous articles claiming that certain changes to physical constants would have resulted in a lifeless universe. In most cases, the inference to a lifeless universe is based upon severe catastrophes such as:

  • A very short-lived universe
  • No stable atoms
  • No chemistry
  • No long-lived sources of energy (such as stars)

It seems plausible that in these situations no life could arise of the kind that could evolve into intelligent, rational creatures. Many fine-tuning constraints involve multiple life-permitting criteria so that even if one of them was incorrect, there would still be other constraints on the life-permitting range of values based on different life-permitting criteria. John Leslie affirms that “many of the fundamental constants have to take the values they do for several independent reasons.” Moreover, even if half of the fine-tuning claims were mistaken there would still be a sufficient number of finely-tuned parameters to conclude that life-permitting universes are rare among possibilities. My fine-tuning claim is therefore robust since it doesn’t rely on all physicists’ claims being true – here it is again:

In the set of possible physical laws, parameters and initial conditions, the subset that permits rational conscious life is very small.

If some peer-reviewed articles are in error, there might be other articles defining other constraints or at least there would be enough remaining evidence to conclude that the life-permitting universes are rare among possibilities. But let’s look in detail at what is necessary for life according to scientists.

What are some essential attributes of any plausible life form?

Self-replicating

Any life form that could evolve to possess intelligence would have to include a self-replicating system. John von Neumann showed that any self-replicator requires certain features such as information storage and processing. Any information storage system would need to be comprised of reasonably stable entities. A star, for example, is a hot plasma of charged particles in rapidly changing configurations and thus is deemed implausible to store information needed to originate and sustain life. Also, in the near vacuum of space there are so few particles interacting that there is no plausible way to replicate enough information for complex life.

Non-trivial information content

As origin of life researcher Stuart Kauffman has noted: “all living things seem to have a minimal complexity below which it is impossible to go.” One theoretical estimate for the amount of information for the simplest possible life form is 113,000 base pairs.[1] Any life form is likely to require polymers of some type to serve as building blocks that can be replicated. There are multiple ways in which a lack of finely-tuned parameters could have prevented the formation of any atoms beyond hydrogen. In this scenario, there would be no polymers and indeed no chemical compounds except for H2. It is implausible to think that if only hydrogen ever existed in the universe that we would have intelligent life or so many physicists have argued.

Preservation of information content during replication

We also have some indications from our own planet of the importance of high fidelity information replication. The canonical genetic code that provides the mapping from RNA codons to amino acids used on our planet is highly optimized and arose early in life’s history[2] (else it wouldn’t be as universal.) Biologists interpret this as evidence of the importance of minimizing errors during translation and replication. The ability to preserve information is therefore recognized as being highly important for life.

Ability to harness energy from environment

Life must be able to harness energy from the environment or else the Second Law of Thermodynamics would pose an insurmountable hurdle. A long-lived stable energy source such as a star would therefore be required.

These same constraints and additional ones are described as prerequisites for life in an important article[3] in the Proceedings of the National Academy of Sciences (PNAS) that explains the attributes of alternate life forms that might eventually be found elsewhere in the universe. This article serves to confirm that the physics literature is making generous assumptions about what could be life-permitting. Here are some key points of the article with my comments provided after the quotations:

  1. “It is predictable that life, wherever we encounter it, will be composed of macromolecules.” I agree – information and storage would most likely require polymers of some type.
  2. “Only two of the natural atoms, carbon and silicon, are known to serve as the backbones of molecules sufficiently large to carry biological information.” I think that most physicists writing about fine-tuning are open to more alternatives than this article but the article raises some important points about the unique suitability of carbon:
    1. Carbon “unlike silicon … can readily engage in the formation of chemical bonds with many other atoms, thereby allowing for the chemical versatility required to conduct the reactions of biological metabolism and propagation. … Silicon, in contrast, interacts with only a few other atoms, and the large silicon molecules are monotonous compared with the combinatorial universe of organic macromolecules”
    2. “Life also must capture energy and transform that energy into the chemistry of replication. The electronic properties of carbon, unlike silicon, readily allow the formation of double or even triple bonds with other atoms.”
    3. “It is critical that organic reactions, in contrast to silicon-based reactions, are broadly amenable to aqueous conditions. Several of its properties indicate that water is likely to be the milieu for life anywhere in the universe.”
  3. “Life that depends only on chemical energy inevitably will fail as resources diminish and cannot be renewed.” This agrees with my point about needing a stable, long-term energy source to overcome the Second Law of Thermodynamics.
  4. “Temperature is a critical factor for life. Temperatures must be sufficiently high that reactions can occur, but not so high that that complex and relatively fragile biomolecules are destroyed. Moreover, because life probably depends universally on water, the temperature must be in a range for water to have the properties necessary for solute transfer.” Again I think that the physics literature is more open-minded in this aspect but certainly at some point it becomes too hot or too cold to either reliably store information or to have enough energy to replicate it.

But Does Life Have to be Carbon-Based Life?

My fine-tuning claim and that by prominent advocates such as Luke Barnes don’t presuppose that any life form would have to be carbon-based – it’s much more general than that. However, this PNAS article is one of many to claim that silicon is the best alternative to carbon as a basis for life. Silicon bears some similarities to carbon as expected from its position just below carbon on the periodic table. If we can understand why silicon-based life doesn’t appreciably increase the possibilities for life, then we can gain confidence in the generality of the fine-tuning claim.

As the PNAS article indicates, carbon is much more suitable for life than is silicon. Consider the specialness of carbon with regard to the number of types of molecules that can be formed with H (hydrogen) and the following elements[4]:

H – 1

He – 0

Li – 1

Be -1

B – 7

N- 7

O -2

Ne-0

C (carbon) – over 2300 known types of molecules just involving C and H

Revisiting our dartboard analogy, consider how a life-permitting region is tiny among possibilities. As a reminder, just one finely-tuned parameter, the cosmological constant, has to be set in a narrow life-permitting region among possibilities that is comparable to hitting a bull’s-eye on a huge wall that is 376 million light-years per side. If the life-permitting region for carbon-based life is small, the region for silicon-based life should be smaller since silicon is less suitable for life than is carbon. Although there is one fine-tuning constraint that specifically references carbon, it turns out to also be applicable to silicon. Unless there was a nuclear resonance at just the right energy level, fusion in stars might have never produced carbon. However, without this resonance level there would be a bottleneck that would also inhibit silicon or elements heavier than carbon from being synthesized. Stars make carbon on the way to making silicon. (Most elements past beryllium were synthesized in stellar fusion from smaller atoms.) Thus, universes that produce silicon are no more likely than those that produce carbon – so the bull’s-eye for silicon-based life is smaller and basically just overlaps the carbon bull’s-eye.

Lessons Learned from Origin of Life Research

Consider how some origin of life researchers admit that the origin of the first life form from non-life is exceedingly improbable even with carbon and a diversity of other elements, long-lived stars, and other helpful attributes in our finely-tuned universe. For example, Christian Schwabe writes: “the formation of the first life is viewed as a chance process that occurred in spite of minuscule odds such as 1:10300 and which is accepted only because we are here.[5]“ Eugene Koonin appeals to the multiverse to overcome a horrendous improbability that he estimates at 10-1018 for a plausible first evolvable cell. Not all researchers are this pessimistic but the slow progress in the field should caution those who think that non-carbon life forms a large region in the space of possible parameters. If carbon is so clearly the best choice for life as most biologists believe and if the origin of life is somewhat of an unlikely event even utilizing organic (carbon-based) molecules such as RNA, how much more unlikely is a naturalistic origin of life without carbon.[6]

Fine-Tuning for Intelligent Life

Recall that my fine-tuning claim refers not to just any life form but to intelligent life. Since theism predicts that God would want some advanced life forms, this raises the bar for constraints on life-permitting universes. If merely primitive replicating cells could originate in somewhat less finely-tuned universe, this still would not count against my fine-tuning claim unless this life could also evolve to achieve intelligence and self-awareness. Clearly more fine-tuning is required for the universe to support rational conscious life than would be required for very primitive life forms.

Closing Thoughts

Most physicists writing about fine-tuning think that there are some very clear-cut cases of fine-tuning such as that for the cosmological constant. Consider, for example, how Nobel prize-winning physicist Steven Weinberg has argued for a multiverse explanation to the fine-tuning of the cosmological constant. He posits vast numbers of universes each with different values for the cosmological constant, the energy density of empty space. Weinberg’s argument for the value being consistent with multiverse predictions relies on a hard limit[7] for the life-permitting range so that our universe can be considered typical among life-permitting universes[8]. Smolin and others have critiqued his prediction as not being that close to what a multiverse would predict but that is irrelevant to my current point which is simply that Weinberg clearly believes that varying this constant by a tiny amount among the possibilities would result in no life of any kind living anywhere in that universe. Refer to my multiverse blog for why our universe would need to be typical among life-permitting universes for a plausible multiverse explanation.

Few physicists specializing in fine-tuning point to other possible forms of life as a supposed refutation to the fine-tuning argument but those who do should write rebuttals to the many peer-reviewed articles claiming life would not exist in certain scenarios involving different physical constants or initial conditions. Skeptics need to show why these authors were mistaken. Perhaps this is a good point of emphasis in urging physicists to be careful in their claims. If some of these fine-tuning claims are over-stated though this would actually provide evidence against a multiverse explanation to the fine-tuning because it would represent ways in which our universe is overly fine-tuned for life. A naturalistic multiverse predicts that our universe should not be more fine-tuned than is minimally necessary to support life.

 


[1] Forster A. C., et alNature Mol. Syst. Biol., 2 . doi:10.1038/msb4100090 (2006).

[2] Early Fixation of an Optimal Genetic Code. Molecular Biology and Evolution. Oxford Journals. Stephen J. Freeland2, et al.

[3] Pace, Norman. “The universal nature of biochemistry”. Proceedings of the National Academy of Sciences 98 (3) (2001): p. 805–8.

[4] This was presented by Luke Barnes at the Philosophy of Cosmology conference in 2013 in Santa Cruz, CA.

[5] Schwabe. Comparative Biochemistry and Physiology Part B: February 1994: (Volume 107, Issue 2) p. 167.

[6] In this blog, I have no intention of getting into discussions about whether or not we have evidence for divine intervention in the origin of life – that is a separate topic. Note that the origin of life and fine-tuning are separate issues. Fine-tuning deals with setting up an environment conducive to life – sort of like that biosphere they setup in Arizona. Conversely, origin of life relates to whether or not life forms were put into that biosphere or originated from non-living matter within it.

[7] By ‘hard limit’ I mean that no other life forms could exist anywhere in universes with cosmological constants whose absolute value exceeded a threshold that is about 120 orders of magnitude less than the natural values predicted by the Standard Model of Particle Physics. BTW, Weinberg first coined the term “Standard Model.”

Important Objections in the Fine-Tuning Debate

In my previous blog I dealt with objections to fine-tuning based on misunderstandings of the nature of the argument or of probability theory. In this blog, however, I attempt to deal with important issues in the debate. If either objection succeeds it would undermine the design inference based upon the fine-tuning evidence.

Could the Laws of Physics Have Been Different?

If there is only one possible set of physics, then there is no sense in which the set of life-permitting physics could be said to be improbable. There are two aspects to considering with regard to whether or not the laws of physics might have been different.

1)      Are there other metaphysically possible alternatives?

Metaphysics is a branch of philosophy so this aspect is really a question that goes beyond science. However even among scientists, few think that there is only one logically possible set of laws of Nature. For example, in one of the classic fine-tuning papers Bernard Carr and Martin Rees note that “even if all apparently anthropic coincidences could be explained [in terms of some deeper theory], it would still be remarkable that the relationships dictated by physical theory happened also to be those propitious for life.[1]” Even if there was only one physically possible set of physics there is still something surprising about the fine-tuning evidence because there is no reason to think that their couldn’t have been different laws, constants, or initial conditions. If there really were no alternatives that were even metaphysically possible, one should be able to derive the laws and parameters of physics without even having to do observations and experiments but as physicist John Barrow notes in regard to the fundamental constants discussed in fine-tuning, “we have never successfully predicted the value of any dimensionless constant in advance of its measurement.”

If one looks at mathematical proofs, the premises are never based on empirical results whereas in science we’ve learned that we need to do experiments to choose among candidate theories. Metaphysicians, therefore, generally recognize that mathematical truths are true in all possible worlds (in the modal logic sense of the word) but that scientific truths are not.

Physicist Paul Davies responds to those few who have tried to argue that “the nature of the physical world would be entirely a consequence of logical and mathematical necessity. There would be no choice about it. I think this is demonstrably wrong. There is not a shred of evidence that the universe is logically necessary. Indeed, as a theoretical physicist I find it rather easy to imagine alternative universes that are logically consistent, and therefore equal contenders for reality.[2]”

2) Are there other physically possible alternatives?

Many leading physicists think that physics itself provides various potential means for varying the fundamental constants. Virtually every physics department is involved in research in theories such as String Theory that entail that the constants of physics actually could be different. As Lee Smolin explains, “string theory makes all the properties of the elementary particles contingent – determined not by fundamental law but by … solutions to the fundamental theory.[3]” String theory was once thought to be the best hope for a Theory of Everything which might explain why the constants of physics take on the values they do. Indeed it might greatly reduce the number of fundamental parameters. However, there seem to be a vast number of solutions to the equations of String Theory although they’re still not well-defined. Some scientists have complained that what was hoped to be a “Theory of Everything” has turned out to look more like a “Theory of Anything.”

In this article, physicist John Barrow lists 5 reasons to expect that the constants of physics can vary.

1)      “We know that the best candidates for unification of the forces of nature in a quantum gravitational environment only seem to exist in finite form if there are many more dimensions of space than the three that we are familiar with. This means that the true constants of nature are defined in higher dimensions and the three-dimensional shadows we observe are no longer fundamental and do not need to be constant. Any slow change in the scale of the extra dimensions would be revealed by measurable changes in our three-dimensional ‘constants’.”

2)      “Some apparent constant might be determined partially or completely by spontaneous symmetry-breakingprocesses in the very early universe. This introduces an irreducibly random element into the values of those constants.”

3)      “Any outcome of a theory of quantum gravity will be intrinsically probabilistic… [thus some constants are] predicted to be spatial random variables”

4)      “A non-uniqueness of the vacuum state for the universe would allow other numerical combinations of the constants to have occurred in different places.”

5)      There are some observations that the fine-structure constant may have varied very slightly over time and/or space. [Newer studies are still not conclusive on this point – the data is somewhat ambiguous.]

Even if the constants and laws of physics couldn’t vary, there is even more reason to think that there were many physically possible sets of initial conditions. Paul Davies states this emphatically:

“Even if the laws of physics were unique, it doesn’t follow that the physical universe itself is unique…the laws of physics must be augmented by cosmic initial conditions…there is nothing in present ideas about ‘laws of initial conditions’ remotely to suggest that their consistency with the laws of physics would imply uniqueness. Far from it…it seems, then, that the physical universe does not have to be the way it is: it could have been otherwise.[4]”

John A. Wheeler agrees: “Never has physics come up with a way to tell with what initial conditions the universe was started off. On nothing is physics clearer than what is not physics.”

What about the laws themselves varying?

Fine-tuning proponents don’t generally seek to quantify the rarity of life-permitting physics among all possible laws but rather at the level of initial conditions and constants as not enough is known to evaluate that case in any detail. As Robin Collins puts it, fine-tuning only considers the epistemically illumined region. As we evaluate the space of possibilities that we have sufficient “light” to evaluate, we discover the remarkable fact that life is only possible in a very small subset. Going back to our dartboard analogy from a previous blog, we have some uncertainty about the size of the wall – maybe it’s not 300+ million light years per dimension or maybe it’s actually larger. The argument is still quite powerful even if we’re over estimating the range of available parameters by a factor of a million million million – and remember this analogy dealt with only one of the many finely-tuned parameters.

In a future blog, I will examine how life depends upon certain laws and principles but will not attempt to make a numerical probabilistic case in that arena. In many candidate physical theories, the laws themselves wouldn’t change in different universes, merely the constants in the equations for those laws.

But We Can’t Assess Exact Probabilities

Another objection is that we can’t assess an exact improbability for life. We can tell something is highly improbable even if we cannot compute an exact value or conduct a series of trial experiments. What are the odds that I would beat Lebron James in a one-on-one basketball game? My only chance would be if he got hurt or something and it would be hard to estimate that very precisely.

I agree that it is premature to put an exact number to the rarity of life-permitting universes among possibilities but I believe that we have a dozen or more independent reasons for thinking it highly improbable. I did toss out the improbability of 1 in 10^100 in a previous blog – as a counterfactual saying in effect that if it could be shown that intelligent life was this rare among possibilities, wouldn’t you count it as some evidence for cosmic design? I indicated that when I present the evidence in detail that I would attempt to justify this number and that many non-theistic physicists accept this magnitude of a number for just a single parameter in some cases.

If we accept the plausible assumptions found in the peer-reviewed physics literature, we do end up with an incredible improbability for a life-permitting universe if physics is set randomly. These articles often cite a natural range for constants based on magnitudes derived from Quantum Field Theory or particle masses as predicted by the standard model of particle physics. For my fine-tuning claim to be defeated virtually all of these physics articles would need to be mistaken.

Computing an exact value involves knowing the exact range of possibilities and the distribution function neither of which is generally known precisely. Many scientists take the principle of indifference to imply a uniform (and thus linear) distribution of possible values for constants, Citing Aguirre’s work, Luke Barnes indicates that it’s unreasonable to expect that new information about underlying physics will invalidate fine-tuning: “In short, to significantly change the probability of a life-permitting universe, we would need a prior that centres close to the observed value, and has a narrow peak. But this simply exchanges one fine-tuning for two – the centre and peak of the distribution.” Barnes/Aguirre discussed this at last summer’s philosophy of cosmology conference amidst many prominent physicists and philosophers who have written about the fine-tuning and no one challenged it. Barnes lists some other key attendees as: Craig Callender (UCSD), Sean Carroll (Cal Tech), Shelly Goldstein (Rutgers), Anna Ijjas (Harvard/Rutgers), Tim Maudlin (NYU), Priya Natarajan (Yale), Ward Struyve (Rutgers), Tiziana Vistarini, (Rutgers), David Wallace (Oxford), Alex Pruss, Chris Smeenk, Fred Adams, Leonard Susskind, Matt Johnson.

In summary, I think it would be a mistake to ignore fine-tuning simply because we don’t know exact ranges that values can take on – if anything we may be underestimating them. As I’m presenting the evidence I’ll try to highlight what physicists are saying with regard to expectations for the range of parameter space and the reader can evaluate whether or not these physicists are mistaken in claiming that life-permitting universes are rare among possibilities.


[1] Bernard Carr and Martin Rees, “The Anthropic Principle and the Structure of the Physical World,” Nature 278, (1979): 612.

[2] Paul Davies in Templeton address in August 1995. http://www.firstthings.com/article/1995/08/003-physics-and-the-mind-of-god-the-templeton-prize-address-24

[3] Smolin. The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next. (New York: Houghton Mifflin Co., 2006), p. 127.

[4] Paul Davies, The Mind of God (New York: Simon & Schuster, 1992), p 169.

 

Image: Courtesy of Kevin Hainline

 

Mistaken Objections that Seek to Trivialize Fine-Tuning

This is my third blog in a series on fine-tuning as evidence for God. Here are the first and second blogs, which deal with the philosophical background. Before I share the evidence I want to refute or at least rebut a few objections seen at the popular level but rarely in scholarly circles – otherwise, readers might just ignore the argument no matter what fine-tuning evidence is presented. Generally one should be wary of dismissive claims that attempt to trivialize what many intelligent physicists and philosophers think is worthy of discussion and evaluation. Even hardened skeptics admit that the fine-tuning evidence is worth evaluating. The late Christopher Hitchens answered a question concerning what is the best argument from the other side: “I think everyone of us picks the fine-tuning one as the most intriguing… you have to spend time thinking about it, working on it. It’s not a trivial [argument].” But let’s consider some popular level responses that seek to trivialize fine-tuning.

The Universe is not Adapted to Us, We’re Adapted to the Universe

This was the primary response given by atheist philosopher Peter Boghossian when I discussed fine-tuning in his recent Q&A session at UT Dallas. This response is based on a fundamental misunderstanding of the articles in the physics literature as addressed in my previous blog. The fine-tuning deals with how the physics has to be setup before life gets started so without fine-tuning there is no evolutionary way for adapting life to the universe.

Aren’t Any Set of Physical Constants Just As Likely As Any Other?

About 5 years ago I had the opportunity to engage in sort of a friendly debate with the head of the science department at the high school where my daughter and son attended. She was taking a “Theory of Knowledge” class as part of the International Baccalaureate curriculum and the instructor needed to provide an example to students of presentations of opposing viewpoints. He had heard that I was an advocate of Intelligent Design and wanted each of us to make presentations supporting our viewpoints. He is an excellent teacher and heads the science department and I was somewhat nervous to be engaging in my first public debate of this type – this was before I had read a dozen or so books on fine-tuning and taken a graduate course on Cosmology. However, the instructor gave a surprisingly weak response to the fine-tuning evidence that I had presented. He set up an analogy for the students of dealing out a set of 5 cards from a set of 10 packs of cards with different backings. The odds of dealing out any particular hand were extraordinarily low but he argued that since any set of cards was just as likely as any other set, no inference could be made that the cards were not dealt at random. This was supposed to refute a design inference because any set of constants of physics is just as likely as any other.

However, the assumption that any set of constants is just as likely as any other is the very thing that we want to know. Starting off with that as an assumption begs the question against design. As Luke Barnes articulates in this excellent podcastdealing with responses to the fine-tuning claim, suppose we’re playing poker and every time I deal I get a royal flush. If this continues to happen, you become increasingly convinced that I’m likely to be cheating. If I responded to an accusation of cheating by just saying “well any set of 5 cards is just as likely as any other so you can’t accuse me of cheating” you would be rational to reject this explanation. The question is not “how likely is any set of 5 cards?” but rather “how likely is it I’m cheating if I just dealt myself 10 straight royal flushes?” This question accounts for the possibility that I’m cheating which would almost certainly be true in this scenario. So the right question is “given the fine-tuning evidence, how likely is it that the constants were set at random?” The values for physical constants conform to a very particular pattern – that which supports life. The fact that we have so many finely-tuned constants makes it unlikely that they were all set at random (at least in the single universe scenario and I’ve already shown some of the problems/challenges in multiverse explanations.)

Puddle Thinking

Another failed objection to Fine-Tuning is based on something written by Douglas Adams, the well known author of Hitchhiker’s Guide to the Galaxy (although this quote is not from that book):

“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, must have been made to have me in it!’”

Richard Dawkins applied this to the fine-tuning at Adams’ eulogy. There is a meaningful lesson perhaps in this analogy but it’s not applicable to the fine-tuning. In the analogy, “gradually, the puddle gets smaller and smaller” but the water still conforms the hole perfectly up to a certain height. If we discovered that any set of constants and initial conditions would permit life, then the puddle analogy would be applicable but since the universe has to be fine-tuned to support life, it’s quite disanalogous! Any configuration of dirt supports water whereas very, very few configurations of physics can support life. Some skeptical scientists who have studied the fine-tuning explicitly state this analogy “doesn’t hold water” – such as David Deutsch.

Improbable Events Happen All the Time

Yeah, but when a series of unlikely events have something in common that is predicted by a hypothesis one generally treats that as evidence for the hypothesis. There are many cases in science where inferences are made based on probabilities. Certain organisms, for example, are considered to be evolutionary descendants because it would be extremely unlikely for unrelated organisms to randomly arrive at the same DNA sequences (from a naturalistic perspective anyway). Unlikely events or states conform to a pattern predicted by the hypothesis of common descent.

In the fine-tuning case, a series of fundamental constant of physics such as various particle masses and force strengths all happen to take on values in a narrow range that permits life. These facts conform to a long-standing hypothesis that God would want to create a life-permitting universe and leave evidence that He created it and thus fine-tuning should be treated as evidence for design.

Just one Universe so Probability of Life Must be 1 out of 1

This response implies a frequentist view of probability whereas my fine-tuning argument deals with a Bayesian approach to probability which deals with epistemic probability (as a degree in belief). Refer to this article in the Stanford Encyclopedia for some issues in the finite frequentism version of probability theory – it might be useful in some contexts but there are many cases in science where we would be unable to make reasonable inferences without a more generalized approach to probability theory. For example, if scientists are reasoning about what caused the disappearance of the dinosaurs, finite frequentism is not a useful tool for analyzing this one-time event. There are also many cases in theoretical physics in which we can compute probabilities for certain events and don’t need to rely solely on past statistics. Suppose we have just created the first ever 20-sided die (an icosahedron with numbered sides). Under the finite frequentist approach, suppose we roll the die one time and obtain a 7, should we assume the probability of rolling 7’s is 1 out of 1? We can do better using theoretical physics and recognize that we have a 1/20th chance of rolling each number if the die is perfectly constructed. In engineering, we frequently assess theoretical probabilities before deciding what to build.

Consider an example from theoretical physics – we can know that universes in which the electromagnetic force is stronger than the strong nuclear force will likely be lifeless without having to find such a universe and test it for the presence of life. In such a universe there would be no stable atoms and thus no way of plausibly storing enough information to support a self-replicating system. As Luke Barnes says, analyzing fine-tuning is “not just like theoretical physics, it is theoretical physics.” He also has an excellent blog dealing with the limitations of finite frequentism.

Irrelevant Objections

A common objection is that the universe is not jam packed with life, therefore the universe is not-fine-tuned for life” or that “we can’t live in most parts of the universe so it’s not fine-tuned for life.” Note that these objections are very human-centric whereas in Christian theology God not humans is the most important thing in the universe. In my introductory blog, these kinds of overly narrow expectations of what God would or wouldn’t do are what I caution against. The logical approach for a skeptic would be to assess whether or not God exists in an open-minded way and then seek out more information about His attributes. A God that is not merely a human creation should differ at least slightly from human expectations. In terms of these particular objections, God may simply want to humble humans and show us how small and powerless we are compared to Him. More importantly though, these objections are irrelevant to the fine-tuning claim that I made:

“In the set of possible physical laws, parameters and initial conditions, the subset that permits rational conscious life is very small.”

Moreover, as Barnes points out – if you can understand why humans can’t live in these other parts of the universe such as the vacuum of space or near a black hole you can understand why the universe needs to be finely-tuned because without such fine-tuning the entire universe would be a near vacuum or too full of black holes for life. So in some sense these objections implicitly affirm the fine-tuning claim.

 

Image: Courtesy of Rachel Hainline

Fine-tuning of the force strengths to permit life

“As we look out into the Universe and identify the many accidents of physics and astronomy that have worked together to our benefit, it almost seems as if the Universe must in some sense have known that we were coming.[1]” Physicist Freeman Dyson

In my previous blog, I discussed how numerous changes to the laws of physics would have resulted in a lifeless universe. I admitted that this was relatively modest evidence for my fine-tuning claim:

“In the set of possible physical laws, parameters and initial conditions, the subset that permits rational conscious life is very small.”

I say relatively modest because the evidence I cite in my blog about the fine-tuning of initial conditions is so powerful and the same I argue applies to the evidence I present in this blog. This blog examines how the constants governing the four fundamental forces of physics must be finely-tuned to support life. Refer to my previous blog for the qualitative aspects of these forces and how they have to be just right to permit life. I now focus on the quantitative constraints on the strengths of these forces if intelligent life is to plausibly exist anywhere the universe. First some background – physicists typically refer to coupling constants for those dimensionless constants[2] which represent the strength of each force. The strength of these forces ranges over about 40 orders of magnitude – that is to say that the strongest force is 1040 times stronger than the weakest force. Thus, it would be surprising if the strengths of these forces must lie in narrow ranges to permit life – at least if the values were set at random such as would be the case in a universe without God. Let’s look at how sensitive these parameters are with respect to permitting life:

1)      Strong nuclear force

This force is important for the existence of stable atoms beyond hydrogen. If the strong force were 50% weaker, no elements used by life would exist because protons couldn’t be held together in the nucleus. The strong nuclear force must exceed the strength of the electromagnetic force sufficiently to overcome the electromagnetic repulsion of positively charged protons. While learning chemistry would be much easier if only the first few elements existed in the periodic table, there would be no physical creatures around to learn it! If the strong force were about 50% stronger no hydrogen would be left over from nuclear fusion processes occurring in the early universe. Hydrogen plays a critical life-supporting role not only as a constituent of water but hydrogen-burning stars last 30 times longer than alternatives. This particular constraint may not make intelligent life impossible but life would certainly be much harder to originate if the available time were so limited and if neither water nor hydrocarbons existed.

Also, hydrogen-bonding is very important in biology for many reasons: information storage in DNA, antibody-antigen interaction, and for the secondary structure of proteins. Remember that parameters that seem beneficial for life but are more fine-tuned than is strictly necessary counts against a multiverse explanation of the fine-tuning because multiverse scenarios predict only what is minimally necessary for life.[3] An even tighter constraint is that if the strong force were more than about 2% stronger protons wouldn’t form from quarks – in which case no chemical elements would exist![4] If the strong force were 9% weaker, stars would be unable to synthesize any elements heavier than deuterium (which is heavy hydrogen).

2)      Electromagnetic force

This force is responsible for chemistry and plays a critical role in stellar fusion which powers life. The electromagnetic force needs to be much weaker than the strong nuclear force for atoms to be stable – so that the radius of the electron orbit is much larger than the radius of the nucleus.[5] Unless the electromagnetic coupling constant (which represents its strength) is less than about 0.2, there would be no stable atoms because electrons orbiting the nucleus would have enough kinetic energetic to create electron-positron pairs which would then annihilate each other and produce photons. Additional examples of fine-tuning for this force strength will be described later in this blog.

3)      Weak nuclear force

The weak force controls proton-proton fusion, a reaction 1,000,000,000,000,000,000 times slower than the nuclear reaction based on the strong nuclear force. Without this, “essentially all the matter in the universe would have been burned to helium before the first galaxies” were formed. Because the weak nuclear force is so much weaker than the strong nuclear force, a star can “burn its hydrogen gently for billions of years instead of blowing up like a bomb.[6]” I’ve previously described the negative ramifications for life if there were no hydrogen in the universe.

John Leslie points out several other ways in which the weak nuclear force is finely-tuned. “Had the weak force been appreciably stronger then the Big Bang’s nuclear burning would have proceeded past helium and all the way to iron. Fusion-powered stars would then be impossible.[7]”

Neutrinos interact only via the weak force and are just powerful enough to blast off outer layers of exploding stars but and just weak enough to pass through parts of the star to get there. The weak force also plays a role in fusing electrons and protons into neutrons during the core collapse of stars to keep the collapse proceeding until it becomes an exploding star (supernova). UK Astronomer Royal Sir Martin Rees estimated that a change in the strength of the weak nuclear force by about 1 part in at least 10,000 relative to the strength of the strong force would have prevented supernova explosions which allow heavier elements to find their way to planets.[8] Without these supernova explosions key heavy elements would be unavailable for life.

4)      Gravitational force

Many physicists think that we’ll eventually discover a Grand Unified Theory, uniting gravity with the other 3 fundamental forces. For this reason Stanford physicist Leonard Susskind remarks that “the properties of gravity, especially its strength, could easily have been different. In fact, it is an unexplained miracle that gravity is as weak as it is.[9]” This probable underlying relationship leads to a natural expectation that gravity could be as strong as the strongest force. The strength of gravity is about 40 orders of magnitude weaker than the strong nuclear force. Based on this expectation that gravity can vary up to strong nuclear force strength, the level of fine-tuning required for life is pretty remarkable:

  • If gravity is weaker by 1 in 1036, stars are unstable to degeneracy pressure (for small stars) or unstable to radiative pressure just expelling huge chunks of the star (for larger stars).
  • If gravity is stronger by 1 in 1040, the universe is dominated by black holes not stars.
  • If gravity is weaker by 1 in 1030, the largest planet that would avoid crushing effects of gravity on any large-brained creatures would have a radius of about 50 meters – which is not a good candidate for an ecosystem and the development/sustenance of intelligent life.

These are huge numbers that may be hard for most readers to visualize.  Thus, consider the following analogy to help understand the improbability of 1 part in 1036. Suppose one could make a sand pile encompassing all of Europe and Asia and up to 5 times the height of the moon.[10] Suppose one grain of sand is painted red and randomly placed somewhere within this pile. A blind-folded person then randomly selects one grain of sand from the pile. The odds that she would select that one red grain of sand are slightly better than the 1 in 1036 odds of a life-permitting strength of the gravitational force based on just one of the above criteria.

Let’s explore a few more fine-tuning cases constraining multiple constants concurrently.

Long-Lived Stars

As I’ve discussed previously, stars play at least two key roles in making the universe life-permitting:

1) As a long-lived power source that helps life overcome the effects of the Second Law of Thermodynamics that would otherwise lead to an eventual state of disarray and equilibrium.

2) For synthesizing elements not created by the Big Bang (which is basically everything past beryllium).

We take the sun for granted as a long-lived stable source of power but note the lack of any comparable long-lived power source on earth as an indication that is not always the case. A star is basically a controlled nuclear explosion held together by gravity – that it can last so long requires a delicate balance of various physical parameters. Consider that the Sun outputs less energy per kilogram of its mass than a person does – without fine-tuning, stars would die out much sooner. Obviously the sun is still able to output enormous quantities of energy because it’s so huge! Another surprising aspect of the sun is that photons generally take at least several thousand years to travel from the sun‘s core to its surface through the ionized plasma.[11] There are significant constraints on the strength of gravity and electromagnetism if there are to be long-lived stars. Luke Barnes summarizes some of the key physics research in this arena:

“There is a window of opportunity for stars – too small and they won’t be able to ignite and sustain nuclear fusion at their cores, being supported against gravity by degeneracy rather than thermal pressure; too large and radiation pressure will dominate over thermal pressure, allowing unstable pulsations.[12]”

Barnes does some calculations based on the possibility that gravity could vary in strength up to the strength of the strong nuclear force and uses a uniform prior distribution of possible values for the gravitational coupling constant and the electromagnetic coupling constant. Using this approach, he computes that “the stable-star-permitting region occupies 1038 of parameter space.” This is even less probable than my previous sand analogy!

Production of Both Carbon and Oxygen in Stars

One of the earliest examples of fine-tuning was discovered by astronomer Fred Hoyle with regard to the fine-tuning required to make both carbon and oxygen in stars. Three distinct coincidences are required to abundantly make both types of elements in stars. These restrictions impose a constraint of about 1 part in 250 on the relative strength of the strong force and the electromagnetic force in both directions. Actually a more recent study by Ekström[13] in 2010 indicated that a change of just 1 part in 10,000 in the electromagnetic coupling constant would have resulted in the inability of stars to synthesize both carbon and oxygen. Despite being an atheist Hoyle conceded:

“Some super-calculating intellect must have designed the properties of the carbon atom, otherwise the chance of my finding such an atom through the blind forces of nature would be utterly minuscule. A common sense interpretation of the facts suggests that a superintellect 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.[14]”

Other Constraints among Force Strengths

For a more comprehensive examination of fine-tuning constraints, refer to Luke Barnes excellent review article that I’ve previously referenced. This review article is an excellent summary of a hundred or so physics articles, and in many cases references multiple articles per fine-tuning constraint. Barnes lists several additional constraints I haven’t mentioned and provides additional details. Just among constraints involving powers of these coupling constants, Barnes lists a half dozen or more cases. Usually the power involves just a squared term but it’s important to note that there are linear, quadratic and inverse relationships among the coupling constants. For example, the electromagnetic force strength is constrained in one way based on a linear constraint and in another way based on a quadratic constraint and in another way based on the inverse of the force strength relative to some other constant. It is remarkable that there is a life-permitting region that simultaneously satisfied these multifaceted constraints.

Also, since each coupling constant can be expressed in terms of more fundamental parameters such as Planck’s constant and the speed of light there are very tight constraints on those parameters as well – especially because of the constraints across different powers of the coupling constant. Thus, Planck’s constant is constrained in one way and the square of this constant is constrained based on a different life-permitting criterion – and likewise for the speed of light.

Moreover, there is a finely-tuned cosmological parameter, known as Q, which can be expressed in terms of various other parameters including coupling constants. In an equation derived by Max Tegmark and Martin Rees[15], there are the following powers on various coupling constants: -1, 16/7, 4/7. Also, there is a natural log of the electromagnetic coupling constant to the -2 power that is taken to the -16/9 power. Without the various contributions of coupling constants taken to the various powers, the value for this parameter Q would not have been life-permitting. Q represents the magnitude of variations in energy density in the early universe. If Q was larger than 10-5 the universe would have consisted of too many black holes to be life-permitting. If Q were smaller than 10-6 there would be gravitationally bound structures in the universe – no stars, no planets and therefore no life. See Barnes’s article on page 32 for more details on the fine-tuning of Q and its relationship to coupling constants.

Finely-Tuned Output of Stellar Radiation

Brandon Carter first discovered a remarkable relationship among the gravitational and electromagnetic coupling constants. If the 12th power of the electromagnetic strength were not proportional to the gravitational coupling constant then the photons produced by stars would not be of the right energy level to interact with chemistry and thus to support photosynthesis. Note how sensitive a proportion has to be when it involves the 12th power – a doubling of the electromagnetic force strength would have required an increase in the gravitational strength by a factor of 4096 in order to maintain the right proportion. Harnessing light energy through chemical means seems to be possible only in universes where this condition holds. If this is not strictly necessary for life, it might enter into the evidence against the multiverse in that it points to our universe being more finely-tuned than is strictly necessary.

Closing Thoughts

It’s important to note how the values of these constants must lie within narrow ranges to be life-permitting based on multiple, independent criteria! My next blog will provide additional examples of this “coincidence.” This multiplicity makes my fine-tuning claim more robust because even if most of these peer-reviewed articles were wrong about fine-tuning claims, there would still be enough cases left to show that life-permitting physics is rare among possibilities.

Also, the question arises as to the likelihood there would exist any value for a constant that could satisfy multiple finely-tuned life-permitting criteria? Why would the life-permitting regions necessarily overlap at a single value that could then permit life relative to all of the constraints? UT Austin philosopher Robert C. Koons argues that this points to a higher-order fine-tuning and thus to design:

“When the value of a single constant is constrained in more than one way, it would be very likely that these independent constraints put contradictory demands on the value of the constraint. By way of analogy, if I consider several algebraic equations, each with a single unknown, it would be very surprising if a single value satisfied all of the equations. Thus, it is surprising that a single range of values satisfies the various anthropic constraints simultaneously. Leslie argues that this higher-order coincidence suggests that the basic form of the laws of nature has itself been designed to make anthropic fine-tuning possible. In other words, Leslie argues that there is evidence of a higher-order fine-tuning.[16]”

This coincidence grows even more surprising when one goes beyond the sheer multiplicity of constraints and also analyzes how differing powers on the constants appear in equations expressing independent and unrelated life-permitting constraints. Why is it that a given strength of electromagnetism turns out to be just right for long-lived stars, atomic stability, proton stability, electron stability, the synthesis of carbon and oxygen, the energy of photons output by stars, and the magnitude of density fluctuations in the early universe? Even speculative multiverse theories do not explain this type of coincidence.


[1] John Barrow and Frank Tipler. The Anthropic Cosmological Principle, p. 318

[2] Actually, these are constants at current densities but in the early universe the 3 non-gravitational forces are thought to have been unified in the sense that at those energy levels all of the forces behaved in the same manner. Once we get beyond the first 1/100th of a nanosecond of the universe though we can speak of these as being constants.

[3] For an explanation of this widely accepted principle, refer to my previous blog: http://crossexamined.org/god-or-multiverse.

[4] Walter Bradley. (He happened to be the head of an engineering department when I was at Texas A&M). http://www.leaderu.com/offices/bradley/docs/universe.html

[5] Luke Barnes. The Fine-Tuning of the Universe for Intelligent Life. Publications of the Astronomical Society of Australia, p. 42. (http://arxiv.org/abs/1112.4647)

[6] Freeman Dyson, Scientific American 225 (1971), p. 56.

[7] John Leslie. The Prerequisites of Life in Our Universe. http://www.leaderu.com/truth/3truth12.html

[8] Martin Rees, Phil. Trans. Roy. Soc. London A 310 (1983), p. 317.

[9] Leonard Susskind, Cosmic Landscape, p. 9.

[10] I know that this is physically unrealistic but this hypothetical analogy aids in visualizing the magnitude of the fine-tuning.

[11] NASA web site. http://image.gsfc.nasa.gov/poetry/ask/a11354.html

[12] Barnes, p. 30.

[13] Ekström S., et al., Astronomy and Astrophysics, p. 514.

[14] Fred Hoyle. Engineering and Science, 11/81, p8-12.

[15] Max Tegmark and Martin Rees The Astrophysical Journal (1998), p. 499, 526

[16] Robert C. Koons. Theism vs. the Many-Worlds Hypothesis. http://www.reasons.org/articles/theism-vs.-the-many-worlds-hypothesis

 

Image: Courtesy of Kevin Hainline

Many changes to the Laws of Physics would be life-prohibiting

In my previous blog, I discussed how the initial conditions of our universe had to be extremely finely-tuned to support life of any kind anywhere in the universe. As part of my ongoing series on how fine-tuning provides evidence for the existence of God, I now turn to the laws of physics themselves. It turns out that life seems to require all 4 fundamental forces of physics. Let’s do a quick survey of some of the many ways that alternate physics could have been life-prohibiting:

1)      Gravity is essential in the formation of stars and planets. As I discussed in a previous blog, life needs something like stars as a long-lived stable energy source. Also, as cosmologist Luke Barnes has pointed out: “if gravity were repulsive rather than attractive, then matter wouldn’t clump into complex structures. Remember: your density, thank gravity, is 1030 times greater than the average density of the universe.”

2)      The strong nuclear force is necessary to hold together the protons and neutrons in the nucleus. Without this fundamental force, no atoms would exist beyond hydrogen and thus there would be no meaningful chemistry and thus no possibility for intelligent life. The positively charged protons in the nucleus repel each other but thankfully the strong nuclear force is sufficiently stronger than electromagnetic repulsion. If the strong force acted at long ranges like gravity or electromagnetism, then no atoms would exist because it would dominate over the other forces. Barnes notes that “any structures that formed would be uniform, spherical, undifferentiated lumps, of arbitrary size and incapable of complexity.[1]”

3)      The electromagnetic force accounts for chemical bonding and for why electrons orbit the nucleus of atoms. Without chemistry, there is no plausible way to store and replicate information such as would be necessary for life. Light supplied by stars is also of critical importance to life in overcoming the tendency towards disorder, as dictated by the Second Law of Thermodynamics. Barnes points out that without electromagnetism, “all matter would be like dark matter, which can only form large, diffuse, roughly spherical haloes.[2]” Suppose like charges attracted and opposites repelled (in contrast with the behavior in our universe), there would be no atoms.

4)      The weak nuclear force plays a key role during core-collapse supernova[3] in the expulsion of key heavier elements, making them available for life rather than just entombed forever in dying stars. Also, the weak force enables the key proton-proton reaction which powers stars in our universe. There is a clever paper by Harnik[4] that attempts to find a life-permitting universe without the weak force but only at the expense of a “judicious parameter adjustment.” See this discussion of the additional finely-tuned constants that were necessary to compensate for the lack of a weak force.[5] Also, some physicists think that the weak force is necessary for there to be matter in our universe.[6]

The existence of matter in our universe relies on some asymmetries in physics that are not yet precisely understood. Most physical reactions produce matter and antimatter in equal proportions and these products would simply annihilate each other upon contact, resulting in a matter-less (and therefore lifeless) universe consisting solely of radiation. We’re fortunate that the laws are such that this asymmetry produces a slight excess of matter over antimatter (about 1 part in ten billion)[7]! It would be premature to try to make a numerical claim that a constant has to be finely-tuned to permit this phenomenon but this unusual asymmetry provides yet another example of how different physics could have been catastrophic for life.

Another key physics principle that is critical for life is quantization. Values are defined as being ‘quantized’ if they can only take on discrete rather than continuous possibilities. Without quantized orbits electrons would be sucked into the nucleus and no chemistry would be possible. This quantization also leads to stable orbitals and consistent chemical properties. If electrons could orbit the nucleus anywhere such as is permissible for planets orbiting a star, then a given chemical element would have properties which are too variable for information storage of the type needed for intelligent life. Consider how the DNA in your genome would become cancerous within a day if its properties/information content were constantly varying. Also, consider how a breath of oxygen could conceivably become poisonous if its properties had no consistency.

Some other aspects of quantum mechanics are also very important to life. We need the Pauli Exclusion Principle so that all electrons don’t just reside in the lowest energy-level orbital. The multiple levels of orbitals contribute greatly to the richness and diversity of chemistry. Not all types of particles follow the Pauli Exclusion Principle – if electrons were bosons rather than fermions they wouldn’t be restricted by this principle. The Pauli Exclusion Principle coupled with the quantization of electron orbitals is responsible for giving matter its rigidity, which is important for the existence of stable structures. Moreover, without quantum mechanics, atoms would decay in about 10-13 seconds as Earnshaw’s theorem demonstrates based on classical mechanics.

Physicist Leonard Susskind points out yet another way that physics could have been life-prohibiting:

‘The photon is very exceptional. It is the only elementary particle, other than the graviton, that has no mass… Were the photon mass even a tiny fraction of the electron mass, instead of being a long-range force, electric interactions would become short-range “flypaper forces,” totally incapable of holding on to the distant valence electrons. Atoms, molecules and life are entirely dependent on the curious fact that the photon has no mass.[8]’

The trend in physics is that the number of cases of fine-tuning is growing over time. For example, physicist Joel Primack recently discovered an important link between the existence of dark matter and galaxy formation. Primack showed that “galaxies form only at high peaks of the dark matter density.“ Galaxies are generally thought to be necessary for life because they are critical for star formation. Thus, even aspects of physics which might seem pointless, such as dark matter, turn out to play an important role in making the universe more bio-friendly. I’ve also referenced an article in a previous blog that discusses how black holes “may actually account for Earth’s existence and habitability.[9]”

Any one of these facts by itself might just be seen as fortunate coincidences but there are enough of them to provide at least modest support for my fine-tuning claim:

“In the set of possible physical laws, parameters and initial conditions, the subset that permits rational conscious life is very small.”

The support is not as strong as what I documented based on our universe’s initial conditions nor as strong as what I will document concerning the fine-tuning of the constants of nature but it adds to the overall case. Moreover, this evidence has some bearing in the consideration of the multiverse[10] as an explanation of fine-tuning because it deals with physics at the level that most multiverse proposals cannot explain. In most multiverse scenarios the laws of physics are the same – what changes are the constants in the equations representing those laws. If you want to explore more about various multiverse alternatives, here is one useful perspective that was referenced in comments of a previous blog. Max Tegmark has proposed what he calls a level 4 multiverse in which all mathematical possibilities are realized somewhere in the multiverse. If we lived in such a multiverse, Occam’s Razor would not be a fruitful heuristic and we wouldn’t have Nobel laureates[11] talking about how simple, elegant theories led them to discoveries. There would be infinitely more equations with lots of complicated terms and expressions than there would be simple equations with minimal terms. Colombia professor Peter Woit provides a powerful critique of Tegmark’s highly speculative metaphysical proposal. These multiverse scenarios in which fundamental laws are different are not widely accepted among physicists.

In summary, life needs all of the 4 fundamental forces of nature and several principles from quantum mechanics. These facts about the laws support my fine-tuning claim that life-permitting physics is rare among possibilities. Standford physicist Leonard Susskind summarizes the physics well:

“It is gradually becoming accepted, by many theoretical physicists, that the Laws of Physics may not only be variable but 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.[12]”

 


[1] Barnes, Luke. The Fine-Tuning of the Universe for Intelligent Life. Publications of the Astronomical Society of Australia, p. 18. http://arxiv.org/abs/1112.4647

[2] Ibid., p, 18.

[3] A supernova is an exploding star and is the key way heavy elements are distributed throughout the universe.

[4]Harnik R., Kribs G., Perez G., 2006, Physical Review D, 74, 035006

[5]Barnes, p. 46-7.

[6] Fermilab website. DOE. http://lbne.fnal.gov/why-neutrinos.shtml

[7] Here is a website if you want to explore this further: http://abyss.uoregon.edu/~js/cosmo/lectures/lec22.html

[8] Susskind, Leonard. The Cosmic Landscape, p. 174-5.

[9] http://www.scientificamerican.com/article/how-black-holes-shape-galaxies-stars-planets-around-them/

[10] If you missed my other blogs and are wondering what a ‘multiverse’ is, a multiverse is simply a collection of universes. If there is a vast ensemble of other universes with widely varying laws this might be a candidate explanation of the fine-tuning. Here was my blog on that topic: http://crossexamined.org/god-or-multiverse/

[11] For example, Eugene Wigner’s famous essay on The Unreasonable Effectiveness of Mathematics in the Natural Sciences. https://www.dartmouth.edu/~matc/MathDrama/reading/Wigner.html. Also, see how Weinberg regards beauty as a guide to finding the correct physical theories: http://www.pbs.org/wgbh/nova/elegant/view-weinberg.html. Or refer to this essay for a historical review: http://www.huffingtonpost.com/david-h-bailey/why-mathematics-matters_b_4794617.html

[12] Susskind, p. 90.

Image: A region of star formation in a small nearby dwarf galaxy (N90) as captured by the Hubble telescope

Fine-tuning of initial conditions to support life

This is the sixth blog in my series on fine-tuning. Here are the previous blogs if you missed them:

Intro/Philosophical Background

If You Don’t Want God, You Better Have a Multiverse!

How Does Fine-Tuning Provide Evidence for God?

Objections

Mistaken Objections that Seek to Trivialize Fine-Tuning

Important Objections in the Fine-Tuning Debate

But We Can’t Even Define Life

We’re finally ready to start exploring the fine-tuning data itself. A logical starting point is the initial conditions of our universe – are those which permit life rare among possibilities?

1)      Energy-Density is Finely-Tuned

The amount of matter (or more precisely energy density) in our universe at the Big Bang turns out to be finely-tuned to about 1 part in 1055. In other words, to get a life-permitting universe the amount of mass would have to be set to a precision of 55 decimal places. This fine-tuning arises because of the sensitivity to the initial conditions of the universe – the life-permitting density now is certainly much more flexible! If the initial energy density would have been slightly larger, gravity would have quickly slowed the expansion and then caused the universe to collapse too quickly for life to form. Conversely if the density were a tad smaller, the universe would have expanded too quickly for galaxies, stars, or planets to form. I argued in my previous blog that it’s implausible to expect life to originate without a long-lived, stable energy source such as a star. Thus, life would not be possible unless the density were just right – if you added or subtracted even just your own mass[1] to that of the universe this would have been catastrophic!

There is, however, a potential dynamical solution to this problem based on a rapid early expansion of the universe known as cosmic inflation. In this blog, I’ll be relying primarily on the most comprehensive review article on fine-tuning in the peer-reviewed literature – this one by Luke Barnes. I’ve referenced it previously and I’m hoping if I reference it enough I’ll get tech-savvy readers to check it out! It may be too technical for some readers and my blog can be viewed as just an attempt at explaining some highlights to non-physicists and tying it into my metaphysical hypothesis that God is the best explanation of the fine-tuning. So let’s look at what Luke Barnes has to say about inflation as a solution to the energy density problem. He points out 6 aspects of inflation that would have to be properly setup, some of which turn out to require fine-tuning. One significant aspect is that the inflation must last for the proper amount of time – inflation is posited to have been an extremely brief but hyper-fast expansion of the early universe. If inflation had lasted a fraction of a nanosecond longer, the entire universe would have been merely a thin hydrogen soup, unsuitable for life. Barnes cites an article by Max Tegmark of MIT that indicates that in a best case scenario about 1 in 1000 inflationary universes would avoid lasting too long. The biggest issue though seems to be that for inflation to start, it needs a very special/rare state of an extremely smooth energy density. Several articles make this point – consider Sean Carroll’s article:

“It is therefore a necessary (although not sufficient) condition for inflation to occur that perturbations be small at early times. . . . the fraction of realistic cosmologies that are eligible for inflation is therefore … 10-66,000,000.”

Barnes also explains why, even if inflation solves this fine-tuning problem, one should not expect new physics discoveries to do away with other cases of fine-tuning: “Inflation thus represents a very special case… This is not true of the vast majority of fine-tuning cases. There is no known physical scale waiting in the life-permitting range of the quark masses, fundamental force strengths or the dimensionality of spacetime. There can be no inflation-like dynamical solution to these fine-tuning problems because dynamical processes are blind to the requirements of intelligent life. What if, unbeknownst to us, there was such a fundamental parameter? It would need to fall into the life-permitting range. As such, we would be solving a fine-tuning problem by creating at least one more. And we would also need to posit a physical process able to dynamically drive the value of the quantity in our universe toward the new physical parameter.”

2)      Initial Conditions in a Very Low Entropy State

Even if inflation somehow could solve the energy density problem and scientists are mistaken that inflation requires its own fine-tuning, inflation doesn’t solve the problem with this next type of fine-tuning which relates to the universe’s initial entropy. What is entropy? Entropy represents the amount of disorder in a system. Thus, a high entropy state is highly disordered – think of a messy teenager’s room. Our universe began in an incredibly low entropy state. A more precision definition of entropy is that it represents the number of microscopic states that are macroscopically indistinguishable. An egg has higher entropy once broken because you’re “opening” up many more ways to arrange the molecules. There are more ways of arranging molecules that would still be deemed an omelet than there are ways to arrange the particles in an unbroken egg in where certain molecules are confined to subsets of the space in the egg – such as a membrane or the yolk. Entropy is thus closely associated with probability. If one is randomly arranging molecules, it’s much more likely to choose a high entropy state than a low entropy state. Randomly arranged molecules in an egg would much more likely look like an omelet that an unbroken egg.

Entropy can also be thought of as the amount of usable energy. Over time the usable energy decreases. This principle is known as the Second Law of Thermodynamics, which says that in a closed system the entropy on average increases until a state of equilibrium is reached. Thus, the Second Law predicts that our universe will eventually reach such a state of equilibrium or “heat death” in which nothing interesting happens. All life will die off long before such a state is reached. Life relies on usable energy from the environment.

It turns out that nearly all arrangements of particles in the early universe would have resulted in a lifeless universe of black holes. Tiny inconsistences in the particle arrangements would be acted on by gravity to grow in size. A positive feedback results since the clumps of particles have an even greater gravitational force on nearby particles. Penrose’s analysis shows that in the incredibly dense early universe, most arrangements of particles would have resulted basically in nothing but black holes. Life certainly can’t exist in such a universe because there would be no way to have self-replicating information systems. Possibly the brightest objects in the universe are quasars, which release radiation as bright as some galaxies due to matter falling into a supermassive black hole. The rotation rates near black holes and the extremely high-energy photons would disrupt information storage, a prerequisite for life[2].

 

Oxford physicist Roger Penrose is the first scientist to quantify the fine-tuning necessary to have a low entropy universe to avoid such catastrophes. “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 1/1010123 [3].” This number is incomprehensibly small – it represents 1 chance in 10 to the power of (10 to the power of 123). Writing this number in ordinal notational would require more zeroes than the number of subatomic particles in the observable universe, 10123zeroes vs. about 1092 particles. Under the assumption of atheism, the particles in our universe would have been arranged randomly or at least not with respect to future implications for intelligent life. Nearly all such arrangements would not have been life-permitting so this fine-tuning evidence favors theism over atheism. We have a large but finite number of possible original states and rely on well-established statistical mechanics to assess the relevant probability.[4]

In a comment on one of in my earlier blogs, someone suggested that perhaps the universe is fine-tuned for black holes rather than life. The incredibly low entropy state of the initial conditions shows, however, that the exact opposite is true – fine-tuning was required to avoid excessive black holes! This fact about the initial conditions also calls into question Smolin’s proposed scenario that universes with differing physical constants might be birthed out of black holes. Smolin suggests the possibility of an almost Darwinian concept in which universes that produce more black holes therefore more baby universes than those which don’t. But if our universe requires statistically miraculous initial conditions to be life-permitting by avoiding excessive black holes, universes evolving to maximize black hole production would be unlikely to lead to life! (Even if the evolution of universes were possible)

Furthermore, the skeptic who thinks that black holes suggest a purposeless universe should consider that black holes can, in moderation and kept at distance, be helpful for life. While a universe comprised of mostly black holes would be life-prohibiting, having a large black hole at the center of a galaxy is actually quite helpful for life. Here is a Scientific American article that documents the benefits of Black Holes for life – it summarizes: “the matter-eating beast at the center of the Milky Way may actually account for Earth’s existence and habitability.”

Does inflation explain the low entropy of the early universe?

Here is how Sean Carroll answers this question: “Not by itself, no. To get inflation to start requires even lower-entropy initial conditions than those implied by the conventional Big Bang model. Inflation just makes the problem harder[5].” Penrose also has harsh words for inflation as an explanation of the low entropy state of the initial universe[6].

Barnes calls inflation a “cane toad solution” for the entropy fine-tuning. Cane toads were brought into Australia from Hawaii starting in 1935 to eat beetles threatening the sugarcane fields. With no natural predators in Australia this strategy was disastrous as these poisonous toads multiplied greatly and wreaked havoc on native species and the ecosystem in general. Thus, Barnes is saying that inflation makes this fine-tuning problem worse. None of this is to say that some version of inflationary theory isn’t true just that it doesn’t help this fine-tuning issue.

How well could a multiverse explain this evidence?

This is a key question to consider as we explore the fine-tuning evidence. If some features seem overly fine-tuned, this would be unexpected if our universe was simply a life-permitting universe randomly selected from a vast ensemble of other universes with other constants or initial conditions. A multiverse explanation for the fine-tuning of the low entropy fails miserably because this universe does seem to be finely-tuned much more than would be minimally necessary. As Penrose says: “We can get the solar system and all inhabitants for much less odds: 1 in 101060 .. These world ensemble hypotheses are worse than useless in explaining the anthropic fine-tuning of the universe.” In other words, Penrose argues that it would be more likely to just have the particles arranged in initial conditions such that you already have pre-formed intelligent life in a single solar system than to have such a large universe as ours in a low-entropy state that could eventually lead to intelligent life.

Even atheist Sean Carroll admits[7] that a multiverse explanation fails for this fine-tuning. First, he agrees with the widely-accepted principle I referenced above: “anthropically-selected parameters should be of the same order of magnitude as the largest value compatible with the existence of life.” He then explicitly agrees that the multiverse cannot by itself explain this particular fine-tuning and quotes Penrose’s numbers. “An example of fine‐tuning well beyond anthropic constraints is the initial state of the universe, often characterized in terms of its extremely low entropy… The entropy didn’t need to be nearly that low in order for life to come into existence. One way of thinking about this is to note that we certainly don’t need a hundred billion other galaxies in the universe in order for life to arise here on Earth; our single galaxy would have been fine, or for that matter a single solar system.” As an atheist he doesn’t view this as an insuperable problem, holding out hope that new physics could somehow explain this low entropy. Carroll indicates that he can’t think of any reason why God would fine-tune the universe more than is necessary, apparently not giving thought to the possibility that God might want to leave evidence that He setup the physics of the universe – evidence of the type that even an infinite multiverse cannot plausibly explain!

Is this evidence for God?

Even if this evidence points to design, why think that God is necessarily the designer?

If this is your perspective, please help remove the stigma on intelligent design so this type of evidence can be fairly evaluated. Also, note that this perspective affirms the claim of leading Intelligent Design advocates that design by itself does not necessarily prove God.

For this particular design evidence, however, I argue that we have reasons for thinking that only a supernatural being could setup these initial conditions in this way. Is it in principle physically possible for a being limited by the laws of physics to setup the initial conditions of our Big Bang? The Heisenberg Uncertainty principle limits our ability to even have knowledge of both position and momentum of particles beyond a certain scale – and it’s even more challenging to think about how so many particles might have their locations and velocities adjusted. The early universe would have been so small that the limits imposed by this physical principle would seem to prevent any physically-limited agent from making the necessary adjustments to the particles or even having knowledge to determine necessary adjustments. Moreover, even those who advocate a naturalistic cause to the Big Bang often admit that the Big Bang represents a spacetime boundary. Many theorists consider our universe to be a causally disconnected region of spacetime – which would make it impossible for a physically limited being residing in a different physical region from affecting anything in this new region of spacetime.
Thus, a supernatural designer seems more plausible than a natural designer. Also, if fine-tuning is required to bring about intelligent life, how did the first natural designers arise?

Does God Have to be Fine-tuned?

To me this seems like asking: “does an uncreated being depend on rare events or rare settings of physical parameters for His existence?” By definition God doesn’t rely on anything for his existence – this is the concept of a necessary being. If the concept of a necessary being seems implausible, I warn you that you might already believe premises that by the rules of logic would entail the existence of a necessary being. I invite you to explore that possibility in this online quiz.


[1] The universe is estimated to contain at least 10^80 atoms – here is one estimate of 10^53 kg: http://en.wikipedia.org/wiki/Observable_universe Anyone old enough to read this blog must weigh at least say 10 kg so this seems to be a safe estimate even after accounting for other forms of matter energy not included in the above mass.

[2] Refer to my previous blog for further justification: http://crossexamined.org/cant-even-define-life/

[3] Penrose, The Emperor’s New Mind, p. 343. He also makes the same argument in Road to Reality on p. 730.

[4] In addition, the entropy equation for a black hole, first developed by Bekenstein and Hawking, is involved in these computations. This equation is widely accepted by the physics community and I’ve read articles by those who believe in string theory and those who believe in loop quantum gravity arguing for their theories by pointing to how they can derive this same equation in their flavor of quantum gravity.

[5] Sean Carroll, http://preposterousuniverse.com/eternitytohere/faq.html

[6] Penrose says in Road to Reality, p. 755: “Indeed, it is fundamentally misconceived to explain why the universe is special in any particular respect by appealing to a thermalization process [such as inflation]. For, if the thermalization is actually doing anything (such as making temperatures in different regions more equal than they were before), then it represents a definite increasing of entropy. Thus, the universe would have had to be more special before the thermalization than after. This only serves to increase whatever difficulty we might have had previously in trying to come to terms with the initial extraordinarily special nature of the universe. . . . invoking arguments from thermalization, to address this particular problem [of the specialness of the universe], is worse than useless!” A couple of pages later Penrose also writes that “the point is that whether or not we actually have inflation, the physical possibility of an inflationary period is of no use whatever in attempts to ensure that evolution from a generic singularity will lead to a uniform (or spatially flat) universe.”

[7] Carroll, Does the Universe Need God? The Blackwell Companion to Science and Christianity. A copy is available online at http://preposterousuniverse.com/writings/dtung/.

Image: Artist’s conception of a black hole.

Credit: European Space Agency, NASA, and Felix Mirabel (the French Atomic Energy Commission & the Institute for Astronomy and Space Physics/Conicet of Argentina)