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On Fine-Tuning and the Functionality of Physics

  1. Sep 12, 2010 #1


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    For purposes of this thread, I’m going to take it as established that the physics of our universe is very “finely-tuned” in many respects. That is, we can easily imagine alternate versions based on physics almost identical to ours, with slight variance in one or two parameters, in which no stable systems like stars or atoms could have come into existence – a universe supporting only a chaotic mess of interacting particles. This means that the quite complicated physics we find in the Standard Model – plus gravity and whatever else may be out there – seems prima facie to be extremely special and highly functional.

    Obviously that doesn’t have to mean the universe has any specific purpose – for example, to support you or me, or our species. We know from biology that very complex and finely-tuned systems like us can evolve entirely by accident, via natural selection. It’s not clear how physics might have evolved, but we have Smolin’s “cosmological natural selection” hypothesis – i.e. that universes are a kind of self-reproducing organism, creating their offspring inside black holes. So it’s at least conceivable that we could explain the very special and complicated physics of our world as resulting from an evolutionary process of some kind.

    Now I find Smolin’s proposal far-fetched and unattractive for a number of reasons, mainly because it tells us almost nothing about physics. Maybe he’s right that the basic function of physics is to make black holes and create more universes. But that’s pure speculation, and it’s not clear what it has to do with all the actual physics we know about.

    If you look at a living organism, its functionality is obvious. It’s easy to relate almost any aspect of its structure to the functions of growing the organism and helping it survive, and ultimately of reproducing its species. But the functionality of physics doesn’t seem to be obvious at all. Physicists have always imagined the world as a formal structure based on mathematical principles, not as a system that has to do anything in order to exist.

    So it’s tempting just to dismiss the fine-tuning of physics as an observer selection effect, per the “anthropic principle”. I.e. – of course the universe is structured to support the existence of complex systems, because it if weren’t, we wouldn’t be here to observe it. That’s true but completely unhelpful, again because it tells us nothing specific about what physics does or how it works.

    Now my take on the situation is this. I think the “fine-tuning” of so many different aspects of physics is strong evidence that the universe is a highly evolved functional system. As to why we don’t see this functionality – actually I think we do see it, everywhere in physics; we just don’t recognize it as such. What the physical world is doing could very well be complicated, like the reproductive process at the basis of biology, and just as in biology, many different sub-functions may have evolved to support it. I think the problem is that all these functions are so basic to the way the physical world works that we tend to take them all for granted.

    I’ll put a few examples of what I have in mind in the following posts. These are all things we more or less take for granted about physics – things that don’t seem to need explaining because “that’s just how the world is.” Briefly:

    • Physical systems “obey” mathematical equations.
    • Atoms function as “building-blocks” for many kinds of material structure.
    • Physical systems store information over time.
    • The properties of systems are measured by and communicated to other systems.
    These are all complex topics in themselves, but I’m hoping to stay focused on this primary question – do they all contribute to some basic functionality that we might understand as a reason for the finely-tuned physics we observe? The point here is not to impose any a priori principle from outside empirical physics, but to see what physics itself has to tell us if we try to look at it from a functional standpoint.
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  3. Sep 12, 2010 #2


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    As an example of something that goes on everywhere in physics, at least in the macroscopic domain – how is it that physical dynamics can be so amazingly “deterministic”? We know that to very high precision, the way systems move and change “obeys” mathematical laws – in fact, quite a variety of different laws. But how exactly do they manage that?

    The thing is, mathematics has no way actually to compute the dynamics even of very simple systems, except by approximation. There is no equation that describes the motion even of three idealized point-particles interacting via Newtonian gravity in Euclidean space-time – let alone the dynamics of any real physical system.

    In other words, physics is far more powerful than mathematics in its ability to define precise regularities of motion in interacting systems. And it operates just as efficiently with systems involving huge numbers of particles, where many different kinds of interaction go on at once. So how does that happen?

    Usually this doesn’t seem like a question physics can or should even try to answer. “That’s just how the world is,” it’s not something to be explained. In fact, since we take this thing of “obeying laws” for granted, we find it strange and almost paradoxical that at the quantum level, the world is not “deterministic”. The Schrödinger equation and other aspects of QM that do seem to “obey” causal principles make sense to us, but the rest seems crazy.

    But if we put this in the context of the question about functionality, this could well be a primary aspect of what physics does, and does extremely well. In that case, everything we’ve learned about QM superposition, measurement, decoherence and so forth would be crucial information about how this business of “determining” actually gets done, in physics. To me that makes more sense than the notion of systems magically “obeying equations” that don’t actually exist in mathematics.

    We don’t know how this quantum mechanism works, but apparently it involves a random selection that happens when systems interact with each other and communicate the results to other systems. In Newtonian mechanics, the “state of a system” at a given point in time contains an infinite amount of information, so even predicting the exact behavior of a two-body system – for which there is an equation – would require an infinite computation. It seems that QM has a much more practical and efficient way to define and process physical information, operating with probabilities and approximate measurement-outcomes instead of trying to determine a mathematically exact reality.
  4. Sep 12, 2010 #3


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    Here’s another example – we take it for granted that atoms are stable, that each type of atom has distinct properties identical to all others of its type, and that they stick together to make molecules. In other words they work very effectively as standardized “building-blocks” for all the distinct forms of matter we see around us. But what exactly does it take to make a functional building-block?

    So far as I know, there isn’t any easy and obvious way to make something work like this, based on simple mathematical principles. Newtonian mechanics certain doesn’t do the job – if atoms were tiny solar systems held together by gravity, then no two would be exactly alike, and they’d fall apart as soon as you tried to put two of them together. As for electromagnetism, you can’t even get two charged particles into a stable orbit without invoking several quantum principles.

    In our universe, it takes a finely-tuned combination of many different physical laws to make an atom – starting with electromagnetism, the exclusion principle based on particle spin, and whatever it is that gives large masses to the nuclear particles. The large nuclear mass gives the atom a fairly well-defined position and momentum, while the much lighter electrons live in highly-structured “shells” with well-defined energy levels, which let atoms hook up with other atoms in several different ways, without disrupting their structure. The central nuclear charge – that binds a specific number of electrons and so maintains the distinct character of each type of atom – is unaffected by these combinations.

    Atoms also function as tiny "clocks and rods" that define intervals in space and time quite precisely. Without atoms in the universe, it seems there would be no physical means of measuring anything. And despite quantum fluctuation, the angles between the atoms in a molecule are very exact, giving each type of molecule its distinctive chemical properties, and also supporting stable, well-defined material structures at a scale billions of times larger than molecules. On top of all that, atoms are sensitive detectors of electromagnetic radiation, that can store data from past interactions in the energy-levels of their electron-shells.

    Prima facie, it seems that the existence of atoms might be as significant for understanding physics as the existence of organisms is for biology. But the question about how to build a functional “building-block” – or a physical clock or a measuring-rod – doesn’t arise so long as we’re thinking of physics essentially as a formal, mathematical structure.
  5. Sep 12, 2010 #4


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  6. Sep 12, 2010 #5


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    "It is worth noting that any system of equations can be derived from a variational principle: Simply multiply each equation by an undetermined multiplier, add them together, and integrate over spacetime (for PDE’s) or time (for ordinary differential equations). Such an action principle does not add any insights, and probably has no practical benefit. What we want in an action principle is an encoding of the equations of motion without the addition of any extra variables."
  7. Sep 12, 2010 #6
    You are practically declaring the answer in your question. How does the universe instantaneously take everything into account and calculate with absolute precision for every particle in nature? It seems obvious that the "mathematics" that the universe uses must be based on taking everything into account at once. And this means that all events must exists in conjunction with each other, reality is a conjunction of all of its parts, nothing in reality contradicts anything else in reality, all facts imply the others. And the math would have to assigns coordinates to every event and accounts for every implication with some kind of function. It would be interesting to see if anyone has come up with any physical equations this way?
  8. Sep 13, 2010 #7


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    Hello Conrad, your long post contains a good question if interpret it right.

    I do not consider smolins CNS anywhere near a satisfactory answer either, even though it may still be part of it in some way.

    Please correct me if I wrong but to rephrase your long post but I think you ask, that IF the universe and the laws of physics we see are a result of some kind of evolution in darwinian style, then there must have some discriminator to understanf why some laws are more fit than others? Ie with is the function/utility of phhysical law that can allow this idea to make sense? Something like "reproduction" etc.

    Sure we have CNS, but I agree with you that it seems unlikely to be the full depth answer.

    I've been thinking about this and to speak for myself I have an idea on this what works for me.

    The evolution of law are not really fundamentally different processes than ordinary dynamical evolution, it's just that what we physicists normally mean by dynamical evolution is pretty deterministic, and darwinian evolution is more like a random walk. Our attempt to understand uncertainty in QM, is to constrain the random walk by deterministic probabilities.

    I think that each observer encodes physical law, and that this law has evolved to become "objective" withing the local population of interaction observers, simply because it's the only way for that observer to stay stable. An observer that doesn't revise it's strategy in compliance with it's context, are doomed. Further as to "replication" - each observer certianly "contributes" to the environment as well, putting selective pressure on all other observers to also revise and align - this is essentially the "reproduction mechanism". This is drastically different than smolins idea I think.

    So one possibility is to simply view the "evolution" of law, as an ongoing process in this universe, and the specific laws we see here, are simply a result of an evolutionary equilibration process.

    So what we interpret as forcing laws, or determinism (á la structural realism) is in My view nothing by an equilibrium.

    OF course, one may ask, what does this solve? If basically the choice of laws, are the choice of equilibrium? Is the equilibrium unique? Here the question becomes harder and it's still open... but it gives a much better understanding, and there is a clear connection between the choice of equilibrium and the population of the universe. Ie. material systems and laws.

    I think of this as an equiblirium, and that there are fluctuations around the laws, but it's often possible to reinterpret them as "statistical laws". This is how we do it. If we noticed a physical system DISobeying the laws; I can bet some money on that no physicists would interpret it as that - the interpretation would be either dismissing it as a bad data point, or discovery of a new interaction. This is why even the process of INFERENCE of hte laws, from the point of view of another observer(experimenter) does enter this view.

    Last edited: Sep 13, 2010
  9. Sep 13, 2010 #8
    This reminds me of a SF story by Stanislav Lem, according to which the order and harmony of the natural laws were a consequence of a clean-up operation by aliens.
  10. Sep 13, 2010 #9


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    I certainly wouldn't argue that our universe operates on the only kind of physics that could support life, or other kinds of complex structure.

    And if there were only one or two physical parameters that seemed to be "finely-tuned", it would be more than reasonable to see it just as a coincidence that tells us nothing about the world. The fact the the world we live in is a very special and "highly improbable" one isn't significant in and of itself.

    But the fact that we run into apparent fine-tuning in so many different aspects of physics and cosmology takes the issue beyond coincidence. It raises the question about why this particular combination of complex principles works to support a remarkable universe like ours. What does it take to do something like this?

    So the point of fine-tuning, for me, is not to prove anything but just to raise the question about functionality -- i.e. what the world is doing, that's apparently not at all easy to do. If we take as a hypothesis that there is a single key functionality here -- by analogy to the functionality of reproduction in biology -- then we can look at some of the basic features of the physical world as clues to what sort of functionality this is.

    Again, I'm not taking fine-tuning as "proof" that the world is a functional system. It just points to that as a possibility that I think is worth considering. It gives us a very different point of view from which to try to interpret the vast body of knowledge we have about the physical world.
  11. Sep 13, 2010 #10


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    Thanks for the reply... but I don't see that your conclusions have a basis in empirical physics... or mathematics. There is no "absolute" precision in nature, for one thing. And in the structure of spacetime, all events don't necessarily exist "in conjunction with each other" -- for every event there is a specific spacetime region ("past light-cone") containing all the information that would be relevant to it. And it's not at all obvious to me that "taking everything into account at once" would make the calculation problem easier.

    The key point is that while mathematics is amazingly powerful in its own ideal world -- look at the Mandelbrot set for an illustration of what I mean -- its power is very limited when it comes to the kinds of situations we run into in physical dynamics. The Newtonian 3-body problem is a simple example -- in case you haven't come across this before, it's been proven there is no "analytic" solution to this. I understand that to mean that no combination of the simple functions that mathematics is built on reproduces the motion of 3 gravitating bodies -- although that motion is "strictly deterministic" (in classical physics) and you can get an arbitrarily close approximation using mathematical methods.

    In other words, even the simple, classical physics of interacting particles has a kind of complexity that's quite different from the kinds that are "native" to mathematics. That's not to say mathematics is irrelevant to physics! Obviously it's exactly the right tool for describing specific aspects of what the physical world does.

    But the point I'm trying to make is that we should be looking to physics itself to understand what the physical world is doing, rather than assuming a priori that the world is a formal system built on logical / mathematical principles.
  12. Sep 13, 2010 #11
    Can we build a theory without logic and mathematics? Are we going to prove that somewhere the universe is not logical? I don't think there is any alternative except that ultimately the universe must be a manifestation of logic, which we describe with math...somehow.
  13. Sep 13, 2010 #12


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    Hi Fredrik -- One major difference between your idea and Smolin's, if I understand correctly, is that the evolutionary process you have in mind operates all the time (at a "sub-quantum" level?) in our universe. So the process by which we get the seemingly permanent laws of physics that we see in the universe today, is related to the physical processes underlying everything we observe.

    Smolin was thinking of physical law as just "given" somehow in the structure of each universe, so that there would be no question of laws evolving during the history of the universe itself. But in his more recent work he has been emphasizing the uniqueness of this universe and attacking the "multiverse" idea, and also the division of physics into "laws" and "initial conditions" -- so I'm not sure where his thoughts about evolution are heading now.

    Another thing I appreciate is that you're trying to describe a basic functionality that could conceivably evolve. The problem is how to relate "the observer encoding physical law" or "putting pressure on other observers to revise their strategy," etc. with actual known physics.

    What I'm trying to do in this thread is to get on the table some of the big, obvious things we know about physics but take for granted -- on the grounds that if there is a basic functionality to the universe, then it should be visible in almost every aspect of physics. So my question for you is how the logic of inference you're working with might fit into "what the physical world is doing," in this big picture we're trying to bring into focus.
  14. Sep 13, 2010 #13


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    Here’s my third example of what we take for granted about physics, that could be an important feature of “what the world is doing” –

    It’s hard even to conceive of reality without assuming that things with definite properties continue to exist through time. Or, in other words, that there’s information stored out there in the physical world. This is certainly something we all take for granted – except that it’s remarkably difficult to verify this assumption anywhere in fundamental physics.

    Macroscopically, of course it holds true. But the closer we look, the more questionable it gets. Take an electron – an “elementary particle” with a certain definite charge and rest-mass that stay constant over time, the same for all electrons. But the underlying theory is nowhere near that simple. The electron charge generates a field, that combines with the fields generated by other particles, and also acts back on the electron itself. Even in the equations of classical electrodynamics this back-action creates problems with infinities, and in the quantum theory all kinds of “virtual” interactions have to be taken into account as well. All of these things affect the measured values of the electron’s mass as well as its charge, so in fact we can’t tell exactly what the “real” mass and charge of an electron is.

    This kind of situation appears everywhere in quantum physics – that is, what looks at first like a fairly simple set of facts turns out to be the net result of an infinite number of random “virtual” events each contributing to the information we observe. Nowhere does the theory show us anything just “sitting there” continuing to be what it is, over time, like a classical particle on an inertial trajectory through space.

    Again, I’m not trying to prove anything. Even in quantum physics it’s meaningful to talk about systems “having” certain properties and states, even though the “properties” are represented mathematically by infinite series that may not converge, and the “states” by superpositions of all possible states.

    But the nature of quantum theory should at least make us question whether this business of “storing information over time” should be taken as a basic, built-in feature of reality, rather than part of what the statistical operations of quantum mechanics somehow accomplish. After all, the basic fact underlying QM is that all interaction takes place in discrete, momentary events – what Planck once called “atoms of happening”. Quantum events don’t last through time... but they can communicate information that lasts, if it keeps on getting communicated again and again.

    So when we talk about an electron, we might really be talking about an observed “appearance” that persists over time, made of information passed on through the web of momentary interactions, rather than a "real thing-in-itself" that automatically continues to exist, carrying its definite properties through time.
  15. Sep 13, 2010 #14


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    I'm not sure the two points you describe are as I understand it not a contradiction to Smolin. It's true that Smolin as far as I know his argument thinks that the laws change only when a new universe are spawned. Also the spawning of new universes in BH are not really like some other multiverses, it's more like one universe somehow producing children.

    Anyway, I have a different view. Just because you don't like Smolins idea, is no reason for rejecting the entire idea of evolving law.

    However the practical difference is minimal relative to what I propose. Even though I argue that in principle the laws keeps evolving ongoingly, this does not mean that the laws of physics as observer from a human observer changes (except for the obvious fact that our knowledge about laws changes). I'm just suggesting that distorting the laws of physics corresponds to an extreme form of non-equilibrium that is so bad that not even the laws are stable. OTOH, such a situation would be so unstable that it would represent only a transient state. Nevertheless do I think that this idea can increase the understanding and suggest certain research directions - in particular the idea that the microstructure of matter, and the different interactions and their unification by energy scaling, can be understood as an evolved emergence of new interactions as we scal the complexity of the observer. And there I mean that complexity scaling, or "growing larger" observes is not just a mathematical transformation, it's a physical process corresponding to the origin of mass and energy, and I think a good pictures is by evolution.

    Yes. I propose that instead of having a universe populated by matter, OBEYING certain laws - that are only mutated when new universes are spawned, I suggest that the population of matter in the universe encodes inferred views of law; which determines its' action, so that instead of forcing laws, there is a democracy of observers, yielding on average only - laws. BUT even these laws when inferred by a REAL observer, are bound to always evolve.

    The analogy of environment telling the observers how to evolve, and the observers telling the environment how to change is similar to GR (Einsteins equation) but the difference is we take away the structural realism implicit in Einsteins equation itself, and replace it with an evolving equation. So that Einsteins equation itself would correspond to an equilibrium - where all observers have no reason to revise their coded best guess. But on top of this it's also measurement theory (unlike GR).

    Howto connect to current physics and make concrete preduictions is in fact SIMILAR to ST; but with some major differences; there is no continuum; and there is no GIGANTIC landscape, since there is a small landscape that SCALES along with evolution. Also the microstructure I picture is completely different than the string, also the action is different than the string action. But other than that, there are still similar traits. So all I can offer is a motivation for a research program. But that's just about as much as what the other approaches promise as well :)

    ST may think that they still generate nice mathematics; I suggest that the program I advocate would indeed generete general inference mathematics; which would be extremely interesting for AI research as well.

  16. Sep 15, 2010 #15


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    Here’s my last example of something very basic we take for granted about the world – that physical interactions between things can communicate information. Or in other words, they can function as “measurements” of something.

    In classical physics this never became an issue. We assumed everything is what it is, all systems have precisely definite properties, the physical world is a body of well-defined fact – regardless of what anything or anyone observes. So the question of what it actually takes to make an observation was a purely practical one, about how to set up the apparatus for any specific type of measurement.

    But in QM, interactions in general are not measurements. Systems are described as being in a superposition of states, and when systems interact, their superpositions get “entangled”. A measurement is something special, that “reduces” the superposition to the specific state that’s actually observed. Now though there are many ways to interpret this situation (some of which deny that any “collapse” occurs), there remains a basic difference between “virtual interaction” between entangled systems and interactions that convey definite information.

    So it becomes a key question in QM – what constitutes a measurement-interaction? The problem is that any type of physical interaction can function as a measurement, but only in the right context. And though physics knows all about how to describe interactions, there is no clear understanding of what constitutes a “measurement context”.

    I’ve raised this question here before – in this thread on “Why is anything measurable?”
    (The discussion got off-topic quickly, but see page 5, posts 67 – 74.)

    Despite the difficulty of the question, the point here is that QM no longer lets us take it for granted that physical interaction automatically communicates information. And QM strongly suggests that there is determinate information in the world only where there’s a context in which that information can be physically determined.

    So one way of describing the basic functionality of our world might be that it “observes” itself – that it provides a physical context of measurement for all its own characteristics. Where the “reality” of classical physics is just a vast body of given fact, in the world we actually observe, the facts are continually being determined. And they get determined only where they are also communicated and become part of the context that determines other new facts.

    If this picture turns out to make sense, then it’s easy to see how the other “functionalities” discussed above contribute to it. It think it’s clear that physical measurements are possible only if we can count on things “obeying laws” and behaving in precisely predictable ways. So a “self-measuring” universe would presumably have to define certain common structural principles that always apply. There would be no possibility of measurement without the existence of stable atoms and molecules, and the ability to storing information over time in the states and properties of systems is also clearly important.
  17. Sep 15, 2010 #16


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    To sum up — Not only does “fine-tuning” give us a strong reason to explore the notion that the universe is a functional entity, but we can find indications of functionality in many very diverse aspects of physics, and see how they might work together to accomplish what we call “reality”.

    The main difficulty with pursuing this line of thought is that we’re so used to thinking about reality as a set of given facts, based on some underlying formal structure. And until the last few decades, physicists had brilliant success in explaining essentially everything in the world in terms of a remarkably compact set of mathematical principles. But this still leaves the question – why this particular set principles? Particularly since they’re not only complicated but in some cases quite bizarre, and not even clearly consistent with one another.

    In case anyone's interested in exploring what a functional approach might involve, here are links to some other possibly relevant threads –

    Evolving causality

    What are the fundamental information-processes in physics?

    On self-defining laws of physics
  18. Sep 16, 2010 #17


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    Without having read everything, I would like to comment on

    Isn't "finetuning" an indication in physics that we're just overlooking something? As examples I think of Einstein's static universe and cosmological constant (the universe is not static), Ptolemaeus' geocentric model (the earth is not the centre) etc. If we have an explanation for it it wouldn't be finetuning anymore, I would say.
  19. Sep 16, 2010 #18


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    Yes, this makes sense. And if it were only one or two aspects of the current model that seemed to be "finely tuned" it might well point to some specific assumption that needs to be revised.

    But since so many very different aspect of the model seem to be "required" for any of the kinds of physical structure we see in the universe, it makes sense to me to try thinking about the world as pervasively "functional", in the way a living organism is pervasively functional. I.e. many different kinds of structure working together to accomplish something (in the case of an organism, reproducing its species).

    In other words, I would look at all the different formal / mathematical principles of the current model as having different functional roles in relation to "what the universe needs to do" in order to exist. Rather than envisioning some single underlying formal principle -- a single field-equation, for example -- that somehow explains all of them.

    It might be worth noting that in biology one sees examples of "unification" everywhere -- e.g. humans and chimpanzees derive from a common ancestor. If we had a complete fossil record, we could go back and find very simple organisms, at the source of all the different life-forms on Earth. But we would be mistaken if we looked for an explanation of life in its formal simplicity! And I'm thinking that we may be making just this kind of mistake in physics -- pursuing mathematical "unification" as an end in itself.
  20. Sep 16, 2010 #19
    You seem to be saying that all things are consistent with some underlying functionality. Even in that case, the functionality becomes the formal principle which determines the rest of physics. So in any case, we are still seeking some underlying principle (functionality perhaps) from which all of physics is derived so that all the fine tuning is inevitable.
  21. Sep 17, 2010 #20
    Yes. I agree.

    Although physics is good at mathematically describing and rationalising what is observed and measured, it is not quite so good at anticipating the often unexpectedly complicated outcome of clever processes that nature has devised. Especially self-promoting ones; those that make it easier for the same process to continue or repeat itself. Think of how gravitational accretion unexpectedly causes stellar jets to form; how self-promoting fluvial erosion causes complexities like the Grand Canyon and how the self-promoting chemical replication of DNA is responsible for the biological complexities we live among.

    Conversely, in an universe filled with complicated stuff, much of which seems to be the ultimate result of various self-promoting tricks-of-nature, I think looking for some 'underlying functionality' is carrying reductionism too far. I can't find 'functionality' in my dictionary, anyway.

    It is as if physicists "seek him here, ... seek him there, ... seek him everywhere. Is he in heaven?—Is he in hell? That demmed, elusive Pimpernel."
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