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The role of mathematics in physics (and science)

  1. Jun 25, 2008 #1
    Hi guys,

    In my blog www.letstalkphysics.com I present an argument (pretty simple)
    that mathematics must be the foundation of any possible universe (as
    it certainly seems to be in ours). I wrote it because it seems that so many
    people, both mathematicians and physicists, not to mention laypeople,
    seem to think that it is a curious
    accident that our universe runs on math. I doubt it, but I am curious what
    some of the math aficionados here think!
  2. jcsd
  3. Jun 25, 2008 #2


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    I think a fallacy in your argument is that the universe must have some set of rules. Why must this be so ? Why can't the universe just be a big set of rather arbitrary happenings (events), say, determined by the fancy will of some or other deity ? What excludes "magic" a priori ? Why can't the universe just be a dream ?
  4. Jun 25, 2008 #3
    Note that you say "rather arbitrary", instead of "arbitrary". There is a big difference between "rather" arbitrary, which implies rules, and completely arbitrary, which is the case with no rules.
    If you put yourself in the position of the creator of a universe, and attempt to further specify a set of "rather arbitrary" constraints, you will quickly find that it is impossible except by being completely precise (or at least, precisely probabilistic, as in quantum mechanics).

    And as for a "supernatural deity", it is the same thing. If such a being exists, it just means that our universe contains things we haven't seen yet. It doesn't change the need for rules, since without some constraints the deity could not even influence its own actions. How could it, since with no rules there can be no connection between the past and the present?

    Indeed, this may be a better way to make my argument (and it is also David Hume's argument). The present has to be constrained by the past, otherwise there can be no coherent sequence of events and no real universe. However, there is no middle ground between complete, mathematical constraints, and no constraints at all. It is simply impossible to write down any kind of "partial" constraints like the "rather arbitrary" rules you suggest above. The closest you can come is exact probabilities, as in quantum mech.
  5. Jun 25, 2008 #4


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    I think you can argue that even though completely chaotic universes might exist, with no physical laws ordering events within them, these would be inconsistent with the existence of life within them.

    The reason that "our universe runs on math" would therefore seem to be anthropic in nature.

    Of course this begs the question about whether mathematics exists as some Platonic ideal, discovered by mathematicians, or whether it is a human construct.

  6. Jun 25, 2008 #5


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    It does not run on math; it runs on a few behaviours (such as electrons like to orbit protons and atoms like to absorb and emit photons) which, when repeated countless times, result in larger, emergent behaviours. Because the small behaviours and the large behaviours are so consistent across untold light years, we can use numbers to represent them.

    i.e. the universe is entirely dervied from simple processes, and these processes are predictable ( = math ).
  7. Jun 25, 2008 #6
    It's difficult for me at least to picture the concept of "no physical laws". For example, is there a space with fixed dimension in which things happen? That is a law...
    Can truly any event happen, e.g. universe turns into a potato, then Bart Simpson, then
    War and Peace wrapped on a torus? If not, then something is constraining the events,
    and those constraints are law of physics. What I claim is that by the time you are
    done specifying what events can occur and which cannot, you will have to define
    them in terms of mathematical constructs, for the simple reason
    that nothing else really can be defined.

  8. Jun 25, 2008 #7
    The source of these regular behaviors is their underlying mathematical basis.
    Indeed, it is not even possible to define an atom or a proton on its own
    (consider all the intermediate
    states of partially-destroyed atoms and protons).
    Only the underlying constituents, electrons and quarks and photons, have a
    definition, because they are fundamental mathematical objects
    within quantum field theory.

  9. Jun 25, 2008 #8


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    No. You've got it backwards.

    The behaviours are due to the underlying physics of the objects. They operated just fine before humans came along and quantified them with mathematics.
  10. Jun 25, 2008 #9
    In my view, mathematics is just a way of describing quantities and relationships. OP should not confuse the map with the territory.
  11. Jun 25, 2008 #10

    Can you express this "underlying physics" in some form other than mathematical? I would be interested to see it...and so would the Nobel Prize committee :-)
  12. Jun 25, 2008 #11
    This sentence repeated over and over again... Georges Perec, one of my favorite author, wrote a lot among other things on this subject. One can argue how the territory is not real until you have a map. One can argue about a 1 to 1 scale map. One can argue about a map, the knowledge of part of it allowing you necessarilly to be able to extend it, by pure thought, without end, and being able to check that it always matches with the territory... which one is the most real ? Please don't over-simplify.

    Platonists vs (?) constructivists : as far as I'm concerned, I was disappointed to face the impossibility of a discussion. Most people are convinced either way, and do not care about pure arguments in favor of one or the other way. I myself do not claim to be convinced either way, at least I am much more interested in hearing other people's arguments than trying to prove them wrong.
  13. Jun 25, 2008 #12


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    Certainly*. But even if I couldn't, so what? The math is just the description. The description is merely for the benefit of humans.

    As before, the universe got along just fine before math came along.

    * let's see:
    1] For thousands of years, describing the underlying physics as the actions of gods or demons worked quite well. Granted, it is no longer sufficient for some of us (though not all of us), but you can't deny that gods and demons did explain why the sun chased the moon across the sky.
    2] Aliens could easily describe our universe using a completely different structure. Granted, they wil have their own form of mathematics, but the point is, the language is just the tool for describing the underlying physics, and it doesn't much matter the details of the tool so long as it's complex enough.

    Hear hear!
  14. Jun 25, 2008 #13
    By "description" I mean of course a description in terms that you can define.
    One can define an electron, using mathematics, but good luck defining a god or
    As for "explanation", that is not the role of science. That is the role of fairy tales.

  15. Jun 25, 2008 #14
    There is a big assumption here: you're assuming that the Universe behaves rationally. There is no guarantee that the Universe follows the laws that govern the reason of men. The Universe is only describable mathematically if is indeed a model of a logical system; it may not be - we don't know.
  16. Jun 26, 2008 #15


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    Astrophysics provides plenty of evidence that the laws of physics discovered on Earth apply equally well across the observable universe, take as an example the precise pattern of spectral lines that identify specific elements in the spectra of distant stars.

    These patterns are described mathematically, there is a numerical relationship between the wavelengths of separate lines in the absorption spectrum.

    These examples provide conclusive evidence that the observable universe behaves rationally.

    If it didn't it would not be possible to 'do' science at all.

  17. Jun 26, 2008 #16
    The issue here is that....nobody yet fully understands the universe. And then you say 'it certainly seems to be in OURS'......which means that you're taking just a single example and then you're assuming this single example applies to everything else.

    Also, it doesn't make sense to say mathematics must be the foundation of any possible universe.....and this is because we don't know what is the origin of the universe.....and therefore we don't know what the foundation of the universe is. And....does maths tell where energy and matter actually came from? It doesn't.
  18. Jun 26, 2008 #17
    Now, I'm not necessarily a constructivist in regards to mathematics, but have more of a naturalistic / physicalistic view. I think that the quantities and relations mathematics describe is very much real and that mathematics is superior to other 'languages' in its unambiguity and component simplicity, but that the specifics symbols and their semantics is mostly a social construct. Similarily, the term "chair" is a social construct, but chairs are not. I'm not sure my elaboration helped, or if I just repeated what I stated earlier.
  19. Jun 26, 2008 #18
    In objectivist metaphysics, the uniformity of nature can be seen as the principle of identity (A is A) applied to action over time. Furthermore, if the uniformity of nature does not obtain, there is no reason for you to think that a rational discussion on the uniformity of nature is possible, since valid perception presupposes the uniformity of nature.
  20. Jun 26, 2008 #19


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    You're still confusing the descriptor with the described.

    By that logic I could claim that all Earthly existence has, at its fundamental, language, since it requires language to describe it.

    I'm still waiting to hear you address the issue as to how the universe managed for 13.69999999 billion years before mathematics came along.
  21. Jun 26, 2008 #20


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    The language of mathematics describes the mathematical landscape of logical relationships between mathematical objects.

    These 'objects': geometrical shapes, real numbers, complex numbers, vectors, tensors, scalars etc. are defined by their properties, i.e. what they do, not what they are.

    The language was invented by humans, the mathematical relationships were there all along.

    2 + 2 = 4 was true even when there were no humans to think so.

    The language of that expression can be translated into other languages such as binary:
    10 + 10 = 100

    or Roman:
    II + II = IV

    but in each case it means the same, a numerical property that first was attached to objects such as:
    :smile::smile: + :smile::smile: = :smile::smile::smile::smile:

    but which exists as an abstract concept that can be logicaly and consistently constructed without any reference to objects at all.

    The mathematics was there all along, it was the language of mathematics that humans have invented.

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