0
$\begingroup$

Are the laws of physics something that exists separately from the universe or is it a description of the physical properties of the universe and objects in it?

$\endgroup$
4
  • 4
    $\begingroup$ It's closer to the truth to say that the "laws of physics" are the preferred mental model of physics held by scientists at any particular time. The "laws" have been expressly falsified a number of times over just a few hundred years, and that's before considering the finer details of working mental models that quietly recede into the dark when discredited. The laws are certainly always intended to be the best possible description of the universe available to science, but that only means the law often has to be changed as understandings change. $\endgroup$ – Steve Dec 27 '20 at 8:49
  • 1
    $\begingroup$ @Steve, your comment illustrates a common misunderstanding for non-scientists. "The science" of any particular field is never completely settled, as hypotheses and theories can always be modified as more information and experimental results become available. BTW, your comment was so good that I think it should have been an answer. $\endgroup$ – David White Dec 27 '20 at 21:52
  • 1
    $\begingroup$ I’m voting to close this question because it is about philosophy of physics (also: philosophy of knowledge, epistemology, ontology), not physics itself. $\endgroup$ – ACuriousMind Dec 27 '20 at 23:42
  • 1
    $\begingroup$ @DavidWhite, I think many non-scientists are led to a misunderstanding by scientists. Theories are often modified not as "more information becomes available", but as scientists seek out more information, or even positively cease rejecting information that is already available. If you were talking to a child, they might think you are describing a science that is always acting on the best information, rather than a science that is often struggling with malign characters who have somehow assumed high authority and yet are exerting a dead hand upon science (as Galileo struggled with, for example). $\endgroup$ – Steve Dec 28 '20 at 11:03
4
$\begingroup$

This is more a philosophy question than a physics one, but I'll answer it here anyway. Laws of physics are a subset of mathematical statements. Mathematical statements are, in turn, a subset of abstract objects.

The ontological status of abstract objects (i.e. whether they exist, and in what way) is a contested question in philosophy. There are prominent philosophers who take opposing views on this.

The position that laws of physics are simply descriptions of what the universe does is a reasonable one and satisfies Occam’s razor. However, that still leaves an interesting philosophical question: what is it that "makes" the universe continue to obey those specific descriptions?

$\endgroup$
8
  • 1
    $\begingroup$ Physical laws, embedded into some mathematical equations, have always a limited regions of "validity" - as far as the precision looks acceptable for humns. Generally, apart from mathematical equations, there are inequalities accompanying the physical laws. $\endgroup$ – Vladimir Kalitvianski Dec 27 '20 at 9:48
  • $\begingroup$ How can an abstract object exist outside of physical reality? Maybe the laws of physics are just how we describe the properties of the universe? $\endgroup$ – Arman Armenpress Dec 27 '20 at 9:58
  • $\begingroup$ @ArmanArmenpress this is definitely a metaphysical question well suited for philosophy.stackexchange.com. This is also a question that's been asked many times there - have you taken a look at the answers? $\endgroup$ – Eletie Dec 27 '20 at 10:37
  • 1
    $\begingroup$ @armanarmenpress importantly, my claim is not that there is something that does not exist in physical reality $\endgroup$ – ReasonMeThis Dec 29 '20 at 9:59
  • 1
    $\begingroup$ @armanarmenpress I think grammatically, the way I phrased my previous comment is a little confusing. A better way of phrasing it would be: my claim is not that there definitely is an entity that actually exists without being in physical reality. My claim is that there could conceivably be such an entity, that there is no incoherence in the possibility of such an entity. So I can certainly give you an example of such an entity: god, ghosts, souls. Maybe they don't actually exist, but there is no incoherence in the possibility of them existing. $\endgroup$ – ReasonMeThis Dec 30 '20 at 2:05
2
$\begingroup$

The laws of Science are an attempt to describe the physical universe in the most economical way possible. An extreme reductionist would say that the laws of Physics suffice to do this. The economy comes about through a few 'powerful' laws having very many consequences that can be deduced from them. The laws, though, don't exist in isolation from each other, but are embedded in a web of concepts.

Are the laws themselves, and the human reasoning associated with the laws, included in the universe that they are describing? I think that most scientists would say "no", but this is a philosophical, specifically a metaphysical, question rather than a scientific one.

$\endgroup$
5
  • $\begingroup$ <Are the laws themselves, and the human reasoning associated with the laws, included in the universe that they are describing? I think that most scientists would say "no", but this is a philosophical, specifically a metaphysical, question rather than a scientific one>. I don't understand, to be honest. $\endgroup$ – Arman Armenpress Dec 27 '20 at 10:03
  • $\begingroup$ I meant that a law, such as Newton's law of gravitation, as something that can be written down and thought about and have consequences deduced from it, is (arguably) not itself part of the physical world it is describing. [I am using 'law' to mean a sort of synoptic description rather than some supposed agency acting in the world.] $\endgroup$ – Philip Wood Dec 27 '20 at 10:17
  • $\begingroup$ That is, you mean that, for example, the law of gravitation is just a description of our observations? $\endgroup$ – Arman Armenpress Dec 27 '20 at 10:26
  • 1
    $\begingroup$ Yes, though 'description' doesn't do it full justice, because of its generality, and the need to use it in conjunction with other laws and concepts in order to predict or explain observations. $\endgroup$ – Philip Wood Dec 27 '20 at 12:16
  • $\begingroup$ Then, a rough description. Or a description in some approximation. $\endgroup$ – Arman Armenpress Dec 27 '20 at 12:18
0
$\begingroup$

The laws that actually govern the universe are of course a part of the universe. What you are getting confused about is that most people who use the phrase "laws of physics" are referring only to their hypothesized laws that they believe or have empirically verified to be accurate approximations of the actual laws. Nobody knows what the actual laws are, but we can be very sure that some models of certain physical phenomena that we consider as a part of solid mainstream science are extremely accurate in the domain of experiments that we have performed so far, such as Einstein's theory of general relativity. It may be that the universe deviates slightly from what Einstein's theory predicts (such as at the quantum level). Even if we later come to a general consensus on a more accurate theory of gravity, it can never be provably correct.

So it is true that physicists' hypotheses about the laws of physics are more or less descriptive in nature, but that has nothing to do with the real laws (which we will never have access to).

I also want to emphasize that (contrary to another answer) we definitely cannot claim that the real laws governing the universe can be expressed as statements in modern mathematics. If you know just a little about foundations of mathematics, you will know that modern mathematics is based on ZFC but there is no physically meaningful ontological justification for ZFC, so it is unclear whether every statement over ZFC has physical meaning or not, or whether real-world phenomena can be meaningfully expressed over ZFC or not. Mathematics, after all, is a sociohistorical product of the human race, not something intrinsic to the universe.

In short, not only do we not know what the real laws of reality are, but we also do not know what foundational system may be compatible with them. In fact, it appears that there is no real-world embedding of the standard mathematical conception of natural numbers even though PA yields accurate real-world predictions. I shall leave you to draw your own (philosophical) conclusions.

$\endgroup$
11
  • $\begingroup$ And what do the laws governing the universe mean? Some independent set of rules that are "written" somewhere and which the universe obeys, or the properties of the universe and its "behavior", which directly depends on its structure? $\endgroup$ – Arman Armenpress Dec 27 '20 at 19:09
  • 1
    $\begingroup$ @ArmanArmenpress: The latter. Let me give you a mathematical analogy to make it clearer, so I hope that you have enough mathematical background to grasp it. A group obeys the group axioms, not because we wrote down the axioms but because a group is by definition a structure that obeys the group axioms! In some sense, the fact that a group obeys the group axioms is just an inherent property of the group (with its structure). However, this is a separate issue from existence. Nothing inherent in a group can explain its existence; we need to construct a group from outside. [cont] $\endgroup$ – user21820 Dec 28 '20 at 7:24
  • 1
    $\begingroup$ So the fact that there exists a given group obeying the group axioms is not an inherent property of the group! Similarly, the laws governing the universe are an inherent part of the universe, but the fact that such a universe exists obeying such laws (even though we have no access to them) is another matter altogether, and we cannot justifiably claim that this fact is inherent to the universe. $\endgroup$ – user21820 Dec 28 '20 at 7:26
  • 1
    $\begingroup$ @ArmanArmenpress: Well I talked about that because in your question you asked about "existence" and were confused with "descriptions". The laws are certainly not mere descriptions, just as the fact that your boat floats on water is not at all merely the sentence "your boat floats on water". Semantic truth is not syntactic statements. The universe satisfies some laws, and this is a truth inherent to the nature of the universe, not a description of the universe. There still must be a source of that truth. Humans are the source of human theories, never truth. $\endgroup$ – user21820 Dec 28 '20 at 17:19
  • 1
    $\begingroup$ @ArmanArmenpress: Correct. $\endgroup$ – user21820 Dec 28 '20 at 17:25

Not the answer you're looking for? Browse other questions tagged or ask your own question.