The Fine Tuning of Cosmological Constants

The fine tuning argument is in principle quite simple. Atheism strongly predicts that this universe will forbid life. Theism strongly predicts that this universe will permit life. Clearly, the universe does permit life, so this favours theism over atheism.

Let’s elaborate on what it means for the universe to permit life. I’m not referring to things like the location of Earth relative to the Sun (though others have done so), instead I’m talking about universal constants. Things like the charge on an electron, or the gravitational constant, or the rate of the expansion of the universe at the Big Bang. It’s no secret that these constants are finely tuned to create a universe that can permit life, and if they were changed often by a fraction of a percent, the universe itself could not exist for more than a few seconds. Sometimes not even that.

In support of this, I’ll cite some physicists:

  • Stephen Hawking:

“The remarkable fact is that the values of these numbers seem to have been very finely adjusted to make possible the development of life… It seems clear that there are relatively few ranges of values for the numbers that would allow the development of any form of intelligent life. Most sets of values would give rise to universes that, although they might be very beautiful, would contain no one able to wonder at their beauty”

  • Paul Davies (British astrophysicist):

“There is for me powerful evidence that there is something going on behind it all….It seems as though somebody has fine-tuned nature’s numbers to make the Universe….The impression of design is overwhelming”

  • Arno Penzias (Nobel prize in physics):

“Astronomy leads us to a unique event, a universe which was created out of nothing, one with the very delicate balance needed to provide exactly the conditions required to permit life, and one which has an underlying (one might say ‘supernatural’) plan.”

I’ll allow you to do your own research on the topic, but the fact is that the level of precision in the cosmological constants is overwhelming. This paper gives some more details about the specific constants. 

Many people will counter this argument by appealing to the anthropic principle. That is, the fact that we are observing the only type of universe that could permit us is not surprising, because we are here to observe it. We could not observe it if we did not exist.

It’s clear that this type of reasoning alone is not sufficient. Anthropic reasoning only indicates that the probability that the universe will permit life given that it is observed is high. It doesn’t indicate that the probability that the universe will permit life given atheism is high. If I were about to be executed by a firing squad of 100, I heard them all shoot, and then observed that I was uninjured, I’d rightly be surprised. It’s true that it’s not surprising that I’m observing it, given that I’d have to be alive to observe it. But it is surprising that all 100 missed. That’s the flaw in this reasoning.

Another common counter-argument is that the cosmological constants can’t actually vary. That they must necessarily be the way that they are. That the laws of physics couldn’t have been different, and neither could the starting conditions of the universe. It seems to me that if you’re willing to accept this, then you implicitly accept the Principle of Sufficient Reason, which states “For every true fact, there is a reason or explanation for why that fact is true”. To accept that the physical state of the universe is necessary is to accept the PSR for at least the physical universe.

If you’re happy to do that, then you should stop reading this argument and instead read my page on the cosmological argument, since the PSR is one of the premises of that argument. If you reject the PSR, then you only have one option available to you to reject the teleological argument.

By far, the most common objection to the teleological argument is the argument that there exists some large (perhaps infinite) number of universes. Couple this with the anthropic principle mentioned above, and you do seem to have a strong objection to the argument.

So why should we reject the multiverse? The most obvious argument is that of Occam’s Razor. We shouldn’t multiply entities needlessly. Since we’re talking about something on the order of 10^500 universes (there are 10^80 atoms in the observable universe) that’s a huge multiplication of entities. Entities that we can not observe, and have no evidence for. If our options are either a designer of this universe, or an unimaginably large number of universes, one of these certainly seems to have fewer entities.

Let’s suppose, however, that we don’t accept Occam’s Razor. We might have good reason to reject it here: under a model like Vilenkin’s, it’s not clear that the universes in the multiverse are separate entities, they are just different locations in space. Or perhaps we take a different understanding of Occam’s Razor, perhaps it is not entities that we want to avoid multiplying, but types of entities, or perhaps behaviours. 

Let’s suppose that there is some huge number of universes. Then there must be something which has conditions which allow multiple universes to begin. Vilenkin proposes such a meta-universe, but this structure itself requires some fine-tuned constants in order to exist. Vilenkin requires a particular level of inflation for his model, for example. We have not really defeated the argument, instead, we’ve just moved the problem.

(The existence of a multiverse comprising mostly life-forbidding universes would lower the degree to which theism predicts that this universe will permit life, but multiverse-hypotheses only predict a generally life-forbidding multiverse given atheism, which begs the question in this context.)

I am no physicist, but the interpretation of QM which predicts multiple universes is not popular among physicsts who specialize in foundations of quantum mechanics, instead the most popular interpretation among this group is a pilot wave theory, in which not only is there no multiverse, but the universe is in fact deterministic. So even appealing to physics doesn’t necessarily make the case for a multiverse. 

For a more detailed discussion of more modern inlfation multiverse models, see chapter 5 of this paper. I will in the future attempt to produce a summary of this, but for now the paper will have to do. Helpfully, the author of the paper also wrote this blog post in summary.

Further reading


8 Replies to “The Fine Tuning of Cosmological Constants”

  1. Great post. I was checking constantly this blog and I am impressed! Extremely useful info specially the last part 🙂 I care for such information a lot. I was looking for this particular info for a long time. Thank you and good luck.

  2. I have an objection to this. If God is truly all powerful, then surely he can create life under any conditions correct? He doesn’t have to fine tune things for life to exist.

    1. In what sense is this an objection to my argument? It is true that God could do this (though I may soon present some reasons why He wouldn’t) but how is it a response to my argument? Which premise are you disputing?

  3. Let us address the multiverse objection. For so many universes to be appearing, let us consider the metaverse basic to this multiverse. Either this metaverse is nothing or it is something. If it is truly nothing, then it has no properties and we have the situation of very many multiple somethings from nothing which seems untenable to most people. If it is not nothing, then it has some properties that may be investigated. We may ask what brought this multiverse into existence. To avoid an infinite regression, we may conclude that the metaverse is somehow eternal. A second question that is rarely asked is what sustains this metaverse, what makes it persist or continue its existence? Again to avoid an infinite regression, we may conclude that the metaverse is somehow self-existent. So now we have a metaverse that is both eternal and self-existent. We understand that the multiverse objection was raised to counter the infinitesimally small chance of a life-supporting universe appearing. Our universe does appear to support form (non-trivial physical arrangements), life, intelligence and apparently accountability. This universe, a subset of the metaverse has such properties. How can it ever be then that while we hold to an idea where form, life, intelligence and apparently accountability are inevitable for some subset, that the superset metaverse which is both eternal and self-existent does not have the properties of form, life, intelligence and apparently accountability?

  4. The biggest irony here is that physicists themselves (the professional cosmology community in academia) are virtually all on the side of naturalism. The people who have studied this for years and whose job it is to come up with explanatory frameworks for the world, the geniuses who are paid to develop the formal, self-contained mathematical models describing the entire history of the universe have not declared that a conception like “God” is the answer to the purported fine-tuning issue in physics (and probably won’t, ever).

    I think it to be true, manifestly true, that if these physicists really meant what these quotes hint at, they might hold your position (theism). Except, celebrity scientists tend to give elusive answers muddled with lots of poetry and a language meant to dazzle the population (the masses). If you were to actually look within the formal papers of these people, you would not find such language of a “supernatural plan” and so on.

    In fact, you are misinterpreting the very quotes, themselves already filtered for the masses. The physicists say “seem to have been”, they say “it seems as though” and “impression of design”. If they believed the universe to be fine tuned under some theistic paradigm, they would simply say the universe is designed, not an “impression” of design, or “it seems designed.”

    Is there something special, some marvelous insight or secret about physics that they just haven’t caught, to which, given attention to, would bring physicists to follow theism? I don’t think so…

    In any case, in the study of cosmology every successful model contrived is completely self contained. That is to say, everything that occurs in these models is completely compatible with the laws of physics. A concept like god is completely absent; it just isn’t necessary, and in fact, these models leave no room for god. It’s about the search for mathematical models that match onto the data as much as possible. It isn’t about abstract principles like the PSR. When you open a physics textbook, terms like facts having “reasons why” is nowhere to be found. This is because the way the universe is known to work these days is through laws of nature: all they say is that if this (like a given value into an equation) then this will occur.

    Philosophical concepts like sufficient reasons are derived from an everyday experience of the universe. We associate things with “causes” and “explanations.” To then extract this to the most fundamental nature of the universe is far from absurd. This is also known as composition fallacy. And I wouldn’t even reject something like the “PSR,” I would simply say that it operates under a particular domain of reality, just like any other of our man made principles. Such as the concept of identity. We know that in the most fundamental sense it is an illusion. I was not the same person I was 10 minutes ago: the atoms that comprised my body are constantly changing and not in some state of equilibrium, such that in say 10 years all of the atoms in my body have been replaced. (I would reference the Ship of Theseus for further reference.) In other words, it is merely humans who prescribes labels like names to packages of meat (us humans).

    Likewise, concepts like the PSR don’t necessarily apply to the most fundamental way of talking about reality. It’s just the wrong way to look at how the universe works. The PSR is a several hundred year old principle which is outdated, frankly. I think ultimately the existence of the universe and questions like “why do laws of physics exist at all” come down to a brute fact. We can come up with models as to the mechanisms and how the universe functions, but there will likely never be an answer to satisfy our human hunger for satisfaction. Again, this is because we are using a kind of rationality based on the toolkit for our everyday life here on Earth (which was originally shaped, of course, by natural selection; our prefrontal lobes are overdeveloped).

    Anyhow, I would also like to address your overall approach to dismissing concepts in physics in cosmology which I find to be incredibly reductionistic. For instance, you dismiss MWI (Multiple Worlds Interpretation) based on the simply appliance of Occam’s Razor, whereby the multiverse’s added entities render it less likely to be true. Of course, Occam’s Razor is always a good assumption to make but not necessarily correct. I don’t need to be a physicist in order to tell that your justification is quite shallow. This is not the right way to talk about these concepts; where is your grand model showing your equations and why we ought to reject it (along with your respective Nobel Prize of course)?

    Leave this to the physicists. It isn’t in your purview, or mine, to talk about whether the multiverse is likely to be true or not. It’s just something that is going to be battled out with math and a lot of hard work and thinking.

    As for the infinite regress thing as something to always avoid such that should it be violated we ought to reject the idea/model, I’ll just say that it isn’t binary like that. Eternal cosmology is a thing. Look at Zeno’s arrow as well.

    I know Hitchens’ Razor is a thing, but this isn’t how physicists treat these concepts, again. Sean Carroll published his new book recently, Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime where he talks about MWI and quantum physics; how physicists don’t understand it very well. Or check out this NYT article by Carroll:

    Also, much of these ideas about these philosophical principles not applying to the fundamental nature of the universe I have borrowed from Carroll himself, who if you already don’t know is a physicist at CalTech that works on MWI and quantum mechanics and so forth. (I am essentially repeating everything Carroll says, so not my ideas, they’re his.)

    In short, theism doesn’t offer a solution to the fine tuning issue. It stops you from thinking about the actual issue when you can just say “god.” We don’t know if our form of life is the only way in which life could have emerged. Think of the puddle analogy made by Douglas Adams. Also, not every parameter is tuned for life (for example, entropy is much much lower than it needs to be). Here is a clip from the legendary debate between Carroll and William Lane Craig:

    I would STRONGLY recommend watching the entire debate as it touches upon a lot of what I (Carroll) have just said (about how physicists think about these things). I would also recommend his 2016 book The Big Picture, as well as this brilliant lecture that goes over the physicist’s perspective of the concept of “god”:

    Priority for you to watch / read:
    1. The short debate clip which addresses fine tuning directly (MUST WATCH).
    2. The entire debate (strongly recommended).
    3. The lecture (also strongly recommended).
    4. The books (if you’re interested enough).

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