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How are the physical laws enforced?

  1. Sep 6, 2011 #1
    How are the various physical laws enforced in the universe? Even if there was only physical law out of which other laws manifest, how is that one physical law enforced?
     
    Last edited: Sep 6, 2011
  2. jcsd
  3. Sep 6, 2011 #2
    Physical laws are "enforced" through design. Overtime scientists examine phenomena and attempt to model them, the successful models eventually develop into what we call physical laws.
     
  4. Sep 6, 2011 #3
    I meant, How are the laws enforced in this universe?
     
  5. Sep 6, 2011 #4
    This feels like one of those "Why is the world the way it is?" questions. In that respect the question is more suited for philosophy than for physics.
     
  6. Sep 6, 2011 #5
    A theory becomes a law when it is proven to reliably predict what is in a particular model. The laws do not control the universe. The laws are only reliable means of explaining how the universe works.
     
  7. Sep 6, 2011 #6

    Ken G

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    It sounds like the question is related to the question, "how does a cause lead to an effect"? That question has never had any answer within science, and even philosophy has never succeeded in answering it. Indeed, Hume gives a wonderful argument that it is not a question for philosophy either, because he points out that little children and even animals use the cause/effect relationship easily, yet the best philosophers have never figured out what that connection is. Apparently, the use of the connection, as in physics, is something quite different from understanding the connection-- if any such understanding is even possible.
     
  8. Sep 7, 2011 #7

    A.T.

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    Per definition?
    Is cause/effect reasoning even part of physics? Physics describes the relationships between some quantities. Does labeling the quantities as "causes" or "effects" affect the quantitative result?
     
  9. Sep 7, 2011 #8
    One way that cause and effect becomes essential is when you involve time. Effect cannot preceed cause.
     
  10. Sep 7, 2011 #9

    Ken G

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    I didn't ask if a cause leads to an effect, I asked how it does. That's in teh spirit of the "how" in the OP, and no definition tells us that, unless you know one that does.
    I would say that cause/effect reasoning is certainly part of physics, on the grounds that we do it all the time in physics. As for what does cause/effect reasoning require, or what models do we have of the cause/effect connection, I'd say that question is also along the lines of the OP, and requires philosophical reasoning to address. In my opinion, both the OP, and the related questions around how does a cause lead to an effect, fall outside physics and are not even fertile questions for philosophy (in agreement with Hume).
     
  11. Sep 7, 2011 #10

    Ken G

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    True, but fundamental physics does not attribute an arrow to time, so although cause precedes effect given our conventions of that arrow, this does not define a specific physical relationship if we invert time's arrow. For example, we can say that a man died because someone shot him, or we can say that someone must have shot the man because he died of a gunshot wound. The use of a "because" in physics is always highly contextual, and not part of the fundamental laws. The same holds for the OP question-- we assert laws because we view their usefulness, but we do not assert whether reality is constrained to follow laws, or if laws are constrained to follow reality.
     
  12. Sep 7, 2011 #11

    A.T.

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    That is true, but cause/effect is sometimes misapplied to instantaneous physical quantities, taken at the same time point. Here the choice which is which is arbitrary and doesn't affect the quantitative result. For example.

    Physics : acceleration = force / mass
    Philosophy : The force causes acceleration

    It could just as well be: The acceleration causes force. It would not change the quantitative result.
     
  13. Sep 7, 2011 #12

    Ken G

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    Right, the contextual choices to distinguish cause and effect are generally outside the laws themselves, as is the choices we make around interpreting the meaning of said laws. In short, there is no law of physics that asserts nature must follow laws, so there is also no law that explains why, describes how, or asserts if, nature follows laws at all.
     
  14. Sep 7, 2011 #13
    The question cannot be answered.

    If I were to formulate a theory that all the laws of physics are "enforced" by X then X becomes a fundamental law of physics. The question then becomes "What enforces the law X?"
     
  15. Sep 7, 2011 #14
    The physical laws of the universe are enforced pitilessly by the Universe itself, the sentence is often death, anyone who thinks otherwise is invited to go to the top of a high building and defy the law of gravity while stepping off, or tell the laws of thermodynamics to take a hike while walking into a furnace.
     
  16. Sep 7, 2011 #15
    Nature enfoces the physical laws the physical laws are merely interpretations of what nature is. If you have two laws that describe an aspect of nature and both are consistently true then both laws become equally true.
     
  17. Sep 7, 2011 #16

    Ken G

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    It might be possible for X to enforce itself, depending on what X was, but that would require allowing laws of nature to refer to themselves. If we allow that, we get the Godel-esque problem when we contemplate this law of nature:
    "It is a law of nature that nature does not follow this law."
     
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