Is Dark Matter Supernatural?

No, it’s not. Don’t be alarmed: nobody is claiming that dark matter is supernatural. That’s just the provocative title of a blog post by Chris Schoen, asking whether science can address “supernatural” phenomena. I think it can, all terms properly defined.

This is an old question, which has come up again in a discussion that includes Russell Blackford, Jerry Coyne, John Pieret, and Massimo Pigliucci. (There is some actual discussion in between the name-calling.) Part of the impetus for the discussion is this new paper by Maarten Boudry, Stefaan Blancke, Johan Braeckman for Foundations of Science.

There are two issues standing in the way of a utopian ideal of universal agreement: what we mean by “supernatural,” and how science works. (Are you surprised?)

There is no one perfect definition of “supernatural,” but it’s at least worth trying to define it before passing judgment. Here’s Chris Schoen, commenting on Boudry et. al:

Nowhere do the authors of the paper define just what supernaturalism is supposed to mean. The word is commonly used to indicate that which is not subject to “natural” law, that which is intrinsically concealed from our view, which is not orderly and regular, or otherwise not amenable to observation and quantification.

Very sympathetic to the first sentence. But the second one makes matters worse rather than better. It’s a list of four things: a) not subject to natural law, b) intrinsically concealed from our view, c) not orderly and regular, and d) not amenable to observation and quantification. These are very different things, and it’s far from clear that the best starting point is to group them together. In particular, b) and d) point to the difficulty in observing the supernatural, while a) and c) point to its lawless character. These properties seem quite independent to me.

Rather that declare once and for all what the best definition of “supernatural” is, we can try to distinguish between at least three possibilities:

  1. The silent: things that have absolutely no effect on anything that happens in the world.
  2. The hidden: things that affect the world only indirectly, without being immediately observable themselves.
  3. The lawless: things that affect the world in ways that are observable (directly or otherwise), but not subject to the regularities of natural law.

There may be some difficulty involved in figuring out which category something fits, but once we’ve done so it shouldn’t be so hard to agree on how to deal with it. If something is in the first category, having absolutely no effect on anything that happens in the world, I would suggest that the right strategy is simply to ignore it. Concepts like that are not scientifically meaningful. But they’re not really meaningful on any other level, either. To say that something has absolutely no effect on how the world works is an extremely strong characterization, one that removes the concept from the realm of interestingness. But there aren’t many such concepts. Say you believe in an omnipotent and perfect God, one whose perfection involves being timeless and not intervening in the world. Do you also think that there could be a universe exactly like ours, except that this God does not exist? If so, I can’t see any way in which the idea is meaningful. But if not, then your idea of God does affect the world — it allows it to exist. In that case, it’s really in the next category.

That would be things that affect the world, but only indirectly. This is where the dark matter comparison comes in, which I don’t think is especially helpful. Here’s Schoen again:

We presume that dark matter –if it exists–is lawful and not in the least bit capricious. In other words, it is–if it exists–a “natural” phenomena. But we can presently make absolutely no statements about it whatsoever, except through the effect it (putatively) has on ordinary matter. Whatever it is made of, and however it interacts with the rest of the material world is purely speculative, an untestable hypothesis (given our present knowledge). Our failure to confirm it with science is not unnerving.

I would have thought that this line of reasoning supports the contention that unobservable things do fall unproblematically within the purview of science, but Chris seems to be concluding the opposite, unless I’m misunderstanding. There’s no question that dark matter is part of science. It’s a hypothetical substance that obeys rules, from which we can make predictions that can be tested, and so on. Something doesn’t have to be directly observable to be part of science — it only has to have definite and testable implications for things that are observable. (Quarks are just the most obvious example.) Dark matter is unambiguously amenable to scientific investigation, and if some purportedly supernatural concept has similar implications for observations we do make, it would be subject to science just as well.

It’s the final category, things that don’t obey natural laws, where we really have to think carefully about how science works. Let’s imagine that there really were some sort of miraculous component to existence, some influence that directly affected the world we observe without being subject to rigid laws of behavior. How would science deal with that?

The right way to answer this question is to ask how actual scientists would deal with that, rather than decide ahead of time what is and is not “science” and then apply this definition to some new phenomenon. If life on Earth included regular visits from angels, or miraculous cures as the result of prayer, scientists would certainly try to understand it using the best ideas they could come up with. To be sure, their initial ideas would involve perfectly “natural” explanations of the traditional scientific type. And if the examples of purported supernatural activity were sufficiently rare and poorly documented (as they are in the real world), the scientists would provisionally conclude that there was insufficient reason to abandon the laws of nature. What we think of as lawful, “natural” explanations are certainly simpler — they involve fewer metaphysical categories, and better-behaved ones at that — and correspondingly preferred, all things being equal, to supernatural ones.

But that doesn’t mean that the evidence could never, in principle, be sufficient to overcome this preference. Theory choice in science is typically a matter of competing comprehensive pictures, not dealing with phenomena on a case-by-case basis. There is a presumption in favor of simple explanation; but there is also a presumption in favor of fitting the data. In the real world, there is data favoring the claim that Jesus rose from the dead: it takes the form of the written descriptions in the New Testament. Most scientists judge that this data is simply unreliable or mistaken, because it’s easier to imagine that non-eyewitness-testimony in two-thousand-year-old documents is inaccurate that to imagine that there was a dramatic violation of the laws of physics and biology. But if this kind of thing happened all the time, the situation would be dramatically different; the burden on the “unreliable data” explanation would become harder and harder to bear, until the preference would be in favor of a theory where people really did rise from the dead.

There is a perfectly good question of whether science could ever conclude that the best explanation was one that involved fundamentally lawless behavior. The data in favor of such a conclusion would have to be extremely compelling, for the reasons previously stated, but I don’t see why it couldn’t happen. Science is very pragmatic, as the origin of quantum mechanics vividly demonstrates. Over the course of a couple decades, physicists (as a community) were willing to give up on extremely cherished ideas of the clockwork predictability inherent in the Newtonian universe, and agree on the probabilistic nature of quantum mechanics. That’s what fit the data. Similarly, if the best explanation scientists could come up with for some set of observations necessarily involved a lawless supernatural component, that’s what they would do. There would inevitably be some latter-day curmudgeonly Einstein figure who refused to believe that God ignored the rules of his own game of dice, but the debate would hinge on what provided the best explanation, not a priori claims about what is and is not science.

One might offer the objection that, in this view of science, we might end up getting things wrong. What if there truly are lawless supernatural actions in the world, but they appear only very rarely? In that case science would conclude (as it does) that they’re most likely not supernatural at all, but simply examples of unreliable data. How can we guard against that error?

We can’t, with complete confidence. There are many ways we could be wrong — we could be being taunted by a powerful and mischievous demon, or we and our memories could have randomly fluctuated into existence from thermal equilibrium, etc. Science tries to come up with the best explanations based on things we observe, and that strategy has great empirical success, but it’s not absolutely guaranteed. It’s just the best we can do.

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60 Responses to Is Dark Matter Supernatural?

  1. Baby Bones says:

    Scientists should embrace pseudoscience for the sake of the challenge to explain the unknown. Why? Because it forces you to think way outside the box. My favorite outlandish or overlooked possibilities are as follows.

    Cold fusion, or in my opinion, using pressure or high electric fields to push light ions (or light atoms) through outer valence orbitals of neutral heavy atoms and seeing what happens.

    The seasonal variation in radioactive decay rates, as apparently evidenced by such changes in carbon 14.

    Stochastic resonance; the idea of using noise as a control input or to improve a signal is so counterintuitive that many of its effects in nature must have been overlooked or dismissed as ‘noise’. Humans are complex non-linear receivers. That means almost everything we perceive might be subtly affected by SR. Furthermore, the idea of noise shares many properties with the idea of entropy and more to the point of this discussion: it shares the properties of the unknown or the unknowable. Yet it can be quantified and it has uses.

    Madelaine Ennis’s homeopathy results. I know, I know, WTF? I read the transcript of the BBC retest, which came up negative. However, the amazing Randi and others appeared to test only the most dilute solutions, whereas they should’ve tested a whole range of concentrations. By rigorously adhering to the albeit wacky hypothesis that like cures like, they could’ve overshot the range of actual effect. The idea of one thing encoding the properties of another thing is not so odd. The idea of cross coupling catalysis won a Nobel prize and there is a similar homocoupling process of like molecules. The hypothesis should have been that histamine acts as a homocoupling catalyst of water. Could it be possible to make unusual chains of water molecules that mimic the biological functions of other molecules? Is that idea completely nuts?

  2. Doug Watts says:

    My particle physics textbook quotes Richard Feynman as saying, “Anything that is not prohibited is mandatory.” So based upon this, and the inflation theory as described in a book by some guy named Carroll, a ‘multiverse’ is not prohibited, as far as we know, so …

  3. Marcel Kincaid says:

    ‘However, based on the evidence to date, might we not be justified in concluding, if only as a working assumption, that “the best explanation” for human behavior is “one that involved fundamentally lawless behavior”?’

    You are apparently quite unfamiliar with the evidence to date.

    On the main point, Blake Stacey and Dave H nail it: “lack of regularity” is an amateurish reference to randomness, which has undergone a lot of technical analysis that Sean seems unfamiliar with, and “supernatural” is a mischaracterization of such randomness — as much as it is for the indeterminacy of quantum events.

  4. pheldespat says:

    @Doug Watts

    Dark matter: Pics, or it didn’t happen.

  5. Pingback: Sean Carroll on the “supernatural” « Why Evolution Is True

  6. Dunc says:

    @29:

    Dark matter: Pics, or it didn’t happen.

    Here you go.

  7. Aiya-Oba says:

    Equator of self-contradiction (oneness of pair), is the Absolute Logic of Spacetime.-Aiya-Oba.

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  9. Dan L. says:

    Multiverse could conceivably be in (2). I seem to remember some loose talk about chalking up the weakness of gravity to diffusion through a multiverse. I’m not advocating such a view, but if we had a theory that predicted strong gravity unless we’re part of a multiverse, and if the multiverse hypothesis was consonant with other theories and data, I see no reason why we couldn’t infer the example of a multiverse the same way we have for dark matter.

    @pheldespat:

    You’re probably just a troll, but just in case you’re not:

    There’s a whole bunch of gravity we can’t account for. We don’t know whether it’s the result of ordinary matter we just can’t see (though it seems unlikely at this point) or some weird kind of matter that’s interactive through gravity but not EM. Or maybe it’s extra curvature in space-time caused by some hyperdimensional being tugging at the fabric of the universe. No one knows. But since astronomers and physicists need to talk about all this extra gravity, they gave it a cute little label, “dark matter.” So when someone says “dark matter is real,” they’re really saying “there’s a whole bunch of gravity that we don’t know how to account for.” Any objections to that?

  10. Pingback: On the supernatural « The Heretical Philosopher

  11. ppnl says:

    Er… why isn’t quantum randomness an example of “lawless phenomena (not reducible in terms of patterns) that intervene substantially in the world”?

    The problem with “supernatural” is that it is usually presented as a negative definition. That is it is defined by what it is not rather than what it is. Any attempt to define it positively either returns it to the domain of science or introduces religious dogma that must be accepted on faith.

  12. AJKamper says:

    A thought on quantum randomness as compared to other lawless phenomena:

    The thing about quantum mechanics is that it’s perfectly predictable statistically–that for macroscopic values it’s pretty exact. What this suggests, I think, is that its apparent randomness is not a result of its lawlessness, but rather of how we perceive the way in which quantum-scale objects obey those laws.

    In other words, QM objects are predictably unpredictable. LAwless objects would presumably be _unpredictably_ unpredictable, though some of the posts about probability theory are interesting on that score. At the same time, the ability to figure out tendencies might be far from equivalent to figuring out exact physical laws.

  13. KWK says:

    DamnYankees (@25):

    My point is that multiple universes don’t constitute an “explanation”, rather, the increase of probabilistic resources they entail is simply a post hoc justification for the improbable results that are observed. Or, to continue your poker analogy, it most certainly would be statistically significant if I were to be dealt a royal flush if I played one and only one hand of poker in my entire life. Chalking that result up to other hands of poker dealt by teapots orbiting the sun between Earth and Mars just doesn’t cut it.

    If you’re going to multiply your (unobservable) entities, you’re welcome to do so; just don’t pretend you’re doing science.

  14. DamnYankees says:

    KWK,

    Actually, it would not be significantly significant if you were dealt a royal flush on the only hand of poker you ever played. You’d just be lucky. Statistically speaking, if you play one hand of poker, the chances of you getting a Royal Flush are *exactly the same* as you getting any other random hand.

    You completely missed the point of the difference. The reason the multiverse explanation is better is that it *reduces* the abnormality to a more stable foundation form which to build an expectation. The multiverse actually explains why the universe is the way it is – maybe you don’t like that explanation, but it is there and it simplifies things. The god explanation doesn’t in fact explain anything at all – all it does it retain the uniqueness of the universe and move the answer back one step. It’s an objectively worse answer than the multiverse one because it can’t answer the question of uniqueness, while the multiverse can.

  15. Will says:

    Interesting post, I think its good that scientists address this question openly, as it’s one of the charges leveled most often against them privately. While your categorization of supernatural events was effective, I still think you don’t completely manage to define the term. I personally like Richard Carrier’s definition: Ontologically basic mental entities (http://richardcarrier.blogspot.com/2007/01/defining-supernatural.html). Anything that is irreducably mental is supernatural, anything else is not. You’ll find this interpretation maps extremely well to what we consider supernatural phenomena, eg ghosts, gods, angels, and souls, but not quantum physics, dark matter, or life.

    A naturalist is someone who believes there are no supernatural phenomena, and hence, no ontologically basic mental entities. A few border cases make this distinction clear. The Stoic and Epicurean gods Carrier describes, both of which arise from natural mechanistic processes and interact with the universe in a natural way, are conceivably amenable to scientific study when a sufficiently high technological level is reached. Amusingly, the dark matter described in Phillip Pullman’s Golden Compass books comes the closest to fuzzing this line as anything I’ve encountered, but even that has to fall on one side in the end.

    All you need to do is say that, while you can’t be 100% sure (as with God etc), you believe there are no ontologically basic mental entities, and you have your answer: everything works through the laws of a mechanistic universe, and is thus open to scientific study.

    That said, I’m open to the possibility that there are some metaphysical processes that science cannot easily gather information about. Max Tegmark and Steven Landsburg’s beliefs about the existential nature of mathematical objects seems like an area where science will have trouble gaining traction for example.

  16. Critics argue that to postulate a practically infinite number of unobservable universes just to explain our own seems contrary to Occam’s razor.

    Tegmark answers:
    “A skeptic worries about all the information necessary to specify all those unseen worlds. But an entire ensemble is often much simpler than one of its members. This principle can be stated more formally using the notion of algorithmic information content. The algorithmic information content in a number is, roughly speaking, the length of the shortest computer program that will produce that number as output. For example, consider the set of all integers. Which is simpler, the whole set or just one number? Naively, you might think that a single number is simpler, but the entire set can be generated by quite a trivial computer program, whereas a single number can be hugely long. Therefore, the whole set is actually simpler. Similarly, the set of all solutions to Einstein’s field equations is simpler than a specific solution. The former is described by a few equations, whereas the latter requires the specification of vast amounts of initial data on some hypersurface. The lesson is that complexity increases when we restrict our attention to one particular element in an ensemble, thereby losing the symmetry and simplicity that were inherent in the totality of all the elements taken together. In this sense, the higher-level multiverses are simpler. Going from our universe to the Level I multiverse eliminates the need to specify initial conditions, upgrading to Level II eliminates the need to specify physical constants, and the Level IV multiverse eliminates the need to specify anything at all.”

    He continues

    “A common feature of all four multiverse levels is that the simplest and arguably most elegant theory involves parallel universes by default. To deny the existence of those universes, one needs to complicate the theory by adding experimentally unsupported processes and ad hoc postulates: finite space, wave function collapse and ontological asymmetry. Our judgment therefore comes down to which we find more wasteful and inelegant: many worlds or many words. Perhaps we will gradually get used to the weird ways of our cosmos and find its strangeness to be part of its charm.”

  17. J.J.E. says:

    Weird… I was just watching “The Universe” by the History Channel on Netflix and saw Sean talking about dark matter. Then this. Fun coincidence!

  18. Svlad Cjelli says:

    I’m willing to tentatively accept “true” randomness (though it’s takes an effort to shut down objection – not resolve but shut down), but I am not clear on what this “lawlessness” is supposed to be if it is something other than “true” randomness. I would also note that Coyne tends to bring up examples of this lawless supernatural that actually do exhibit clear patterns, such as prayer being consistently effective for jews but not for christians.

  19. db says:

    My theory?

    It’s sewer material reflecting energy off bathroom mirrors …and eyes.

    Hidden from view, mysteriously ignored, and hardly given its due weight in our Reality!!

    Put that in your pipe a few moments!

  20. Matt Bright says:

    There’s no real reason, is there (unless you buy into Tegmarkish mathiverse metaphysics) that you can develop a mathematical model which will create a complete and perfect description of the observable universe at all levels. I mean, philosophically speaking there’s no particular reason for maths to work at all as far as I know.

    Isn’t it at least possible that there’s a sort of physical equivalent of Godel’s theorem – maths actually doesn’t fit the universe completely, so there will always be some sort of fundamental disjoint that you can only resolve by shifting your paradigm – at which point a different kind of disjoint will pop up, like a bubble under wallpaper?

    Not that I’m claiming Dark Matter is said bubble, of course, or that if it exists it would be the curtain behind which God is hiding (particularly not the creepy-uncle type personal God of contemporary religions, who wants you to make regular public affirmations that It’s your bestest ever friend and seems overly concerned about what you get up to with consenting adults).

    However, it might be as good a definition of the supernatural as any – the remnant that always persists when you’ve measured the ‘natural’ as closely as you can…

  21. DaveH says:

    @45

    I mean, philosophically speaking there’s no particular reason for maths to work at all as far as I know.

    It would be a poor philosophical utterance, ignoring the contingent facts of the existence of evolved beings. So by the same token you could say that philosophically speaking there is no particular reason for language to work at all.

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  23. Dan L. says:

    I mean, philosophically speaking there’s no particular reason for maths to work at all as far as I know.

    I think I’ve found a few. Try thinking about what it would mean for maths not to work. Really think about it. How could you put together a universe where math was completely useless for describing any aspect of it? How would you even start?

    Such a universe would need to have maximal Kolmogorov complexity. Otherwise, there would be patterns somewhere in it that could be described using relatively parsimonious mathematical statements. But if it has maximal Kolmogorov complexity, then it would just be a swirling void of white noise. What’s the white noise made of? If it’s made of anything in particular, then we could describe that something mathematically — the energy or momenta of the individual particles. But by supposition, we can’t describe anything here mathematically, so the swirling mass of white noise isn’t actually made of anything. But if it’s not made of anything, is it the empty set? Well, no, that would be describing it using mathematics, which by supposition we can’t do.

    I can imagine a universe where math is less useful — where the mathematical definition of divergence didn’t coincidentally describe magnetic fields, for example. But I can’t imagine a universe where it’s useless. Granted, this might just be a failure of imagination on my part, but I think it’s more likely that anyone who thinks mathematics could be useless is the one not using his imagination.

  24. Matt Bright says:

    Not sure where I said that maths might be useless. It works, clearly, to umpteen decimal places for most of the things we know. I’m raising the possibility that it might not always work everywhere, and certainly none to think you can create a structure with it that perfectly maps
    to the physical world.

  25. Matt Bright says:

    Can we ignore that last post, which was the result of attempting to write on a phone-thingy whilst travelling.

    Starting again.

    I definitely didn’t intend to say that maths is or may be ‘completely useless’, because it obviously isn’t. But there is no reason you should be able to use it to create a single, self-consistent picture of the physical universe – that seems to me an article of faith. Not a bad one, necessarily, as it drives all sorts of intellectual activity and discovery that I’d consider to be a virtue in itself.

    And another thing – it’s equally possible that even if there is some hyper-accurate way of depicting the universe mathematically, to do so requires a kind of consciousness that humans just can’t have. Why should it? We’re limited organisms, an intermediate consequence in an ongoing, apparently random process that has given us a mentality shaped by the need to track, manipulate and describe the activities of medium sized objects. Maybe a proper theory of everything requires concepts that are literally unthinkable for us – in the same way as, say, imagining what it would be like to be an electric eel is unthinkable.

    My point being that there is no reason for the universe to make sense, and certainly no reason for it to make sense to us – ‘the supernatural’ (from our point of view) may well exist as a genuine kind of thing sitting beyond our consciousness, forever inaccessible except by mean of tools we’ll never posess, its only effect on the universe we perceive being to make any human attempt to describe it end up in awkward inconsistencies in the maths.

    Which, of course, means there’s no point actually contemplating it and certainly no point bothering about what it might mean that it’s there, but its still, I think, a reasonable possibility, isn’t it?