First of all, for the premise of this question, let's disregard quantum mechanics and relativity (whose existence is another big question ─ why did either of these very complicated sets of physical laws have to exist when intelligence could clearly arise in a universe without them?) and consider the universe from the perspectives of classical mechanics and electrodynamics exclusively.

If we look at the force fields of each of the four fundamental forces, we find that all of them are perfectly smooth ─ that is, the strength of the force follows a smooth curve over distance. Furthermore, every single instance of a kind of fundamental particle in the universe is identical to each other, and shares every physical property with it.

Now, on the one hand, this might appear intuitive; for example, the reason that gravity and the electromagnetic force follow a perfect 1/x^2 curve over distance is simply that energy is distributed evenly in every direction: from an Occam's Razor perspective, why should we expect that to be any different?

However, on the other, for every conceivable universe with "perfect and consistent" laws, we can imagine an infinite number of functionally identical universes that have negligible imperfections or inconsistencies (e.g. the mass of every electron being a random variable with a tiny, but measurable, variance, or the strength of gravity vs distance graph having tiny bumps). Therefore, inferentially speaking, the a priori probability of finding oneself in a universe with perfect and consistent laws should be 0. And yet, that's exactly the type of universe that we happen to find ourselves in, and what's more, that even appears intuitive to us.

Can somebody propose a plausible explanation for this? I've been struggling with this question for years and still haven't managed to find a satisfactory answer.

  • 3
    how do you know the mass of every electron doesn't have tiny variance? After all, any experimental measurement will differ from any other. Do you know that because you're accepting certain physical theories (classical electrodynamics, for example) that pre-suppose it? I think you might be committing a circularity by assuming a bunch of non-imperfection-containing theories apply to the world, then asking why the world has no imperfections. Dec 6, 2022 at 4:37
  • @Bug Catcher Nakata Rather, I mean that the variance could be much higher than the upper bound that our observations have put on it without affecting the universe on a macroscopic scale, and hence without making the emergence of intelligence any less likely. Besides, if you don't like the argument about electrons, consider the argument about smooth vs bumpy force fields. Which argument you choose to address isn't essential ─ the solution, if it exists, is likely to be the same.
    – Max
    Dec 6, 2022 at 5:40
  • post this on the physics stack exchange. Dec 6, 2022 at 5:43
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    Logic (ergo, physics, because physics and metaphysics are interdependent) is tautological, so you are basically asking why such tautology is consistent (all tautologies are). Remember that all those laws exist only in your mind, not out there, they are just your map of the terrain, not the terrain itself.
    – RodolfoAP
    Dec 6, 2022 at 6:24
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    @Max in-other-words-1: The only way things are consistent is if you reduce your observations to a tautological logic and a physics domain consistent with such tautology. In-other-words-2: there are huge inconsistencies between QM and relativity, so universal laws are not "perfect and consistent". You want to exclude QM? Ok, there is no consistency between gravitational data and matter (dark matter), etc. Even in math, things are not "perfect and consistent": see Goedel's 1st incompleteness theorem: no math theory is complete and consistent at the same time (check what completeness means).
    – RodolfoAP
    Dec 6, 2022 at 11:26

6 Answers 6


I know you said to disregard modern physics, but modern physics, the necessity for it, and the incompleteness of it, is the whole answer to your question.

All "why" questions are questions about what's "under the hood" - what more fundamental principles give rise to the principles observed, like the hidden functional parts of an automobile give rise to its external characteristics. Since you're asking on Philosophy SE, you're presumably trying to skip straight to the most fundamental principles known - the rules of logic.

However, to ask a meaningful "why" question, the phenomenon which we are asking "why" about has to be something real.

The basic answer to "Why does the universe follow classical laws with a particular character?" is the unsatisfying "It's a tautology: by making various simplifying assumptions that are known to be false about the real universe, you defined a fictional universe that follows your fictional laws." Or the equally unsatisfying "It doesn't: the universe doesn't follow the laws of classical physics, unless you make some simplifying assumptions that are known to be false about the real universe."

Despite the excellent predictive power and computational utility of classical physics within its domains of relevance, classical physics unavoidably predicts things that are obviously false: atoms that can't form molecules and do chemistry, stars that can't shine, computers that don't work, circuits that won't close because of slightly oxidized terminals, lights that won't light up, and so on.

We can meaningfully ask why the universe approximates classical physics under certain circumstances.

The answer to that question is well understood: the laws of classical physics, and the domains over which they are reliable, and all their elegance and symmetry, can be mathematically derived from the more fundamental models which make more reliable predictions about the universe, given certain limiting assumptions. For example, the expression of gravity predicted by general relativity, after a transformation to an appropriate coordinate system, reduces to Newtonian gravity when distance to the center of mass of a system is large relative to the mass of the system.

This is not accidental. Since classical physics predicts reality very well under certain conditions, no more-fundamental theory which could not be mathematically re-arranged into a restatement of some aspect of classical physics under the same conditions could be true.

The universe is most accurately modeled by some combination of the Standard Model (an extension of quantum mechanics), General Relativity, and Statistical Mechanics - a branch of physics initially derived from classical mechanics that nonetheless makes good predictions in domains where classical mechanics doesn't work. It might be hypothetically possible to reconstruct StatMech from scratch starting from the Standard Model, reducing us to a combination of just two - I don't know.

These are what is "under the hood" of classical physics, its domains of relevance, and all their characteristics, including the ones of interest to you.

These theories (especially the Standard Model, which doesn't have gravity, and General Relativity, which is all about gravity) rely on incompatible axioms. Although they can be mashed together into useful effective theories, they are thus essentially incompatible. (Effective theories are like theories except that they do not purport to have anything to say about the real nature of the universe, only to make good predictions about certain types of real systems).

This suggests that our best theories are each slightly incorrect and slightly incomplete reflections of an unknown deeper set of physical laws. So the universe almost certainly doesn't follow GR, the Standard Model, and StatMech, either, unless you make some simplifying assumptions that are known to be false about much of the real universe - although very nearly all of the universe comes very, very close.

Those deeper laws, if we ever find them, will be the answer to why GR, the Standard Model, and StatMech have such elegance and reflect such symmetries in nature over their own domains of relevance. We find some hints about their character examining GR and the Standard Model (as Boba Fit describes in a previous answer), and some promising work-in-progress candidates (string theory, loop quantum gravity), but no answers yet.

The yet-unknown laws under the hood of modern physics may or may not turn out to represent a single unified theory - that is, their various parts don't rest on incompatible axioms, and its mathematical expressions reproduce the mathematical expressions that we know work under the circumstances in which they work. If they do, we'll be in a position to go looking for reasons of pure logic why the universe should have such character as to have those yet-unknown laws. For now, we don't know enough to begin to speculate.

We can take guesses at the answer. But in the end, the answers don't mean much without knowing the question. "Why does the universe have the laws it really, truly has, everywhere and always?" doesn't mean much without knowing what laws the universe really, truly has, everywhere and always. Like in Douglas Adams' Hitchhiker's Guide to the Galaxy: even if we somehow guessed the right answer, we would still need to know the meaning of the question to really understand it.



One of our most powerful analysis tools we have is symmetry. And many of the physical laws we have are fundamentally related to symmetry.

Noether's Theorem connects symmetry to conservation laws. So, angular momentum is seen to be directly related to rotational symmetry. Linear momentum is related to translation symmetry. Conservation of energy is related to time-translation symmetry.

You mention particles having the same characteristics. We discover that there are other symmetries that are related to these. Electron charge is related to gauge symmetry. Weak charge (a nuclear parameter) is a broken symmetry, and produces the electro-weak theory. Color symmetry produces the strong nuclear interaction. The uniformity of mass is related to unitary symmetry.

Gravity has its own symmetry that produces the general relativity interactions. Many alternative gravity theories have alternative symmetries as their basis, often larger symmetries that contain the general relativity symmetry as a sub-set.

The program of attempting to find a grand unified theory, the so called "theory of everything" includes the goal of finding the largest possible symmetry of reality. Thus far, it is quite interesting but not complete. But the notion is that there is a very large symmetry that, at high enough energy, is completely restored. What we see is hypothesized to be due to breaking of this symmetry. This is where masses come from through some such thing as the Higgs mechanism.

Along with the grand unification program there is a notion that it may be that there is very little choice in physics. That is, with some quite basic observations, we are steadily forced to conclude that physics is very tightly constrained. Once we observe the symmetries, and explore the possible mathematical structures that could support that symmetry, the conclusion is that there may be only one possible physical reality that matches. This program is BY NO MEANS proven. But it is a possible means of understanding why reality is that way.

  • Interesting. I will admit that understanding why these symmetries are essential to avoiding chaos is a little bit above my paygrade, but I guess it's one potential solution (given what you're saying is correct). Perhaps I should indeed ask this question on Physics Stack Exchange for ideas.
    – Max
    Dec 6, 2022 at 15:56

I don't think this question is coherent. How can you disregard quantum physics but bring up "the four fundamental forces" when two of those were discovered in relation to quantum physics? Also, how can we assign probabilities to the universe being a certain way, especially if the universe just isn't that way in the first place?

It would be like if there was a planet with a bunch of 10KM-tall mountains, you said, "Let's ignore all the mountains with other heights," and then asked, "So why does this planet only have 10KM-tall mountains on it? Isn't that improbable?" as if the fact that there were mountains with other heights didn't nullify the rationality of the question.

Or, then, since classical mechanics/electrodynamics are false, then if we don't look at other theories, we find ourselves just wondering, "Why is the universe the way it is? Isn't it improbable for it to be whichever way it is?" And that leads into problems with probabilistic reasoning when applied to such context-independent/higher-order contextual situations. But so then what reason do we have for believing that the universe has perfect and consistent laws, seeing as, again, the examples you cite (classical mechanics/electrodynamics) aren't actually the laws of this universe?

  • I think your objection both is incoherent and appears to be inaccurate. "Two of those were discovered in relation to quantum physics" ─ I'm reading the Wikipedia History sections on "Strong interaction" and "Weak interaction", and neither mentions anything related to quantum mechanics. But even if this were true, implying from this that those two interactions would be impossible without quantum mechanics is a simple non-sequitur.
    – Max
    Dec 7, 2022 at 16:57
  • And to address your other points: I left out quantum mechanics and general relativity for simplicity. Adding them back to the question wouldn't change anything at all: bumpy force fields would still, a priori, be infinitely more likely than smooth force fields. As to "also, how can we assign probabilities to the universe being a certain way", I'm just applying the principle of indifference. If you don't think it's applicable, and there is a fundamental difference between universes with bumpy force fields and those with smooth ones, please enlighten me on them.
    – Max
    Dec 7, 2022 at 17:00
  • @Max, in the "Elementary particle" Wikipedia article, it says, "Via quantum theory, protons and neutrons were found to contain quarks – up quarks and down quarks – now considered elementary particles." And the "Strong interaction" article refers to quantum chromodynamics as the theory of the strong interaction. Dec 7, 2022 at 19:15
  • @Max and bumpy force fields are not a priori more or less probable, in the context of physics. In physics, it is either the Fermi-Dirac statistics or the Bose-Einstein statistics that carry the objective sense of probability (well, there are also anyons and their higher-dimensional counterparts to consider, but IIRC those straddle the fermion/boson dichotomy). Dec 7, 2022 at 19:18
  • And if we were going to try our hand at transworld probability, we'd have to have a stable theory of how many parallel/possible worlds there are. David Lewis, of modal-realistic infamy, thought there were Continuum-many such worlds. So to make your question go through, we'd have to assume there were either finitely or countably many smooth-field worlds, with the ratio of those to bumpy-field worlds being ℵ0/ℶ1, which is hard to decipher (which aleph does ℶ1 equal? or are those who say that the Continuum is the size of V right?). But why would this ratio be a priori? Dec 7, 2022 at 19:36

To begin with, your assertion that intelligence could clearly arise in a universe without quantum mechanics or relativity is probably not correct.

Quantum mechanics is responsible for the stable existence of atoms and molecules. Without discrete electron orbital energies and orbital shapes set by spherical harmonic solutions to the equations of quantum mechanics there would be no periodic table of elements; ergo, no chemistry and therefore no protein molecules to fashion brains out of.

Relativity is responsible for the energy released by stars. No relativity means no heat from the sun.

Using your description of a world in which every electron has a slightly different rest mass, this would make every atom possess unique electron orbital energies, different from those of all other atoms, making chemical bonding impossible.

Same comments apply if we instead consider every electron to have a slightly different charge than all the others.

We can certainly imagine an infinitude of possible universes in which the electron charge is non-unique, gravity goes as the inverse fourth power of distance, and so on. But the consequences for the evolution of intelligent life in those "slightly different" universes can be mathematically modeled, and this effort so far doesn't yield universes hospitable to the evolution of carbon-based life forms.

So while it is possible that such universes exist, 1) we have absolutely no evidence that any of them actually do, and 2) if they did, we wouldn't be there to notice them to begin with.

  • I feel like this answer misses the point of the question in several different ways. A minor way being that there are other, far simpler ways to make electrons (e.g. via an additional special force) stick to an atom without losing its energy than quantum mechanics. A medium way being that these variations can be almost arbitrarily small, to the point of being insignificant on molecular scales (correct me if that's impossible). And a large way being that my entire problem isn't that we should see evidence for "imperfect" universes ─ it's that we should be IN an "imperfect" universe.
    – Max
    Dec 6, 2022 at 7:31
  • Then I cannot help you. Dec 6, 2022 at 8:00
  • Why not? Is it because you find the problem just as puzzling as I do or because you don't even consider it a problem? If it's the latter, can you explain your reasoning? You clearly know what you're talking about ─ it's just that you don't seem to have read my question very carefully.
    – Max
    Dec 6, 2022 at 8:17
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    @Max I think NN's answer is merely a long-winded way of saying "anthropic principle" en.wikipedia.org/wiki/Anthropic_principle, i.e., the laws of nature must be such that the universe which emerges from them can give rise to intelligent life (well, to us, anyway). In other words, the very fact that we're here talking about it means the universe gave rise to us in the first place, which further means the laws of nature governing this universe must make that possible. Like you said in your question, perhaps many other kinds of universes are possible, but we couldn't exist in most of them
    – eigengrau
    Dec 6, 2022 at 11:08
  • @eigengrau Please read my question carefully. "However, on the other, for every conceivable universe with "perfect and consistent" laws, we can imagine an infinite number of functionally identical universes that have negligible imperfections or inconsistencies". I took the anthropic principle into account, and am only talking about imperfections and inconsistencies that have no effect on the macro (human) scale.
    – Max
    Dec 6, 2022 at 11:21

There is no reason this universe had to have consistent and perfect (always followed) rules. Heck, even the concepts of terms in the rules dont have to be common.

But they are. What do that tells you?

Its designed.

There are patterns, many, many patterns. These patterns have to be put in here. The "probability" of them emerging on their own is infinitismally small. And this is the only universe that exists as per our observation.

There has to be an Entity behind the rules that forces the rules. All creation have to follow rules. The Ruler of the universe must be incredibly powerful.

The terms in the rules are common, thats how rules are related to each other. Also, the rules are universally followed. These things tell that the entire universe is made by one Creator.

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    Lots of complex things emerge without anyone designing them.
    – Scott Rowe
    Jan 2, 2023 at 19:50
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    An entity that would have designed patterns would itself have more patterns and be even more complex than the thing it has designed. So if that entity can just "always have existed", so too could the universe or whatever its extension is Jan 2, 2023 at 20:16
  • Complexity is orderness, it never emerge on its own. All evidences tell that disorderness always increase. This is known as law of entropy in physics. Entropy always increase, never decrease, never stay constant. Once a perfume bottle is opened and its contents are spread in a room they never, ever go back fill the bottle back.
    – Atif
    Jan 2, 2023 at 20:45
  • "Universe existed since forever" dont explain why universe has to follow certain rules. Why are rules so perfect and consistent? The only logical conclusion is, it has a Master. Its the Master that make the universe follow the rules and the Master is incredibly powerful.
    – Atif
    Jan 2, 2023 at 20:50

Why do you imagine there is an answer to your question? You are effectively asking why the Universe is what it is. We have no evidence of anything outside the Universe or of anything that existed before the Universe (we don't even know if it is meaningful to talk about a time before the Universe). Given that, we can only speculate about how the Universe came about. As @bobafit says, you can marshal arguments about symmetries, but that simply raises the question of why we live in a symmetrical Universe.

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