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Is this a law of physics?

  1. Aug 23, 2010 #1
    Let's go old school thought experiment.

    If you say no, state the real world exception.
    If you say yes, state the consequences of it not being a law.

    All known systems are observed as the ratio of attractive and repelling fields
     
  2. jcsd
  3. Aug 23, 2010 #2
    It is difficult to answer "yes" or "no" to such a poorly defined question. We do not have much of a context. So let us go old school and you illustrate for us how your formalism deals with a simple falling ball in a uniform gravitational field. Where is your "ratio of fields" in this context for instance ?
     
  4. Aug 23, 2010 #3

    atyy

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    Is the electrostatic force between a point charge and a neutral metallic object always attractive? Michael Levin, Steven G. Johnson http://arxiv.org/abs/1007.2175
     
  5. Aug 23, 2010 #4

    marcus

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    No.

    You ask "Is this a law of physics?"
    To be a law of physics, in the traditional sense, a statement must predict some observable phenomena, so that it can be empirically tested.

    This statement of yours does not appear to predict anything that one could observe.

    In which case it has no empirical content, and therefore cannot be a law of physics.

    =================

    I suppose the right venue for your idea might be a branch of philosophy. Metaphysics?
    The Philosophy of Physics?
    The publishing house called North Holland has a book out called Handbook of Philosophy of Physics. I've read one of the chapters, by George Ellis, which was pretty good. You might like this Handbook of PoP.

    Maybe you could get your thread transfered to Philosophy forum, or to General Physics, where people could discuss it.

    They would probably say that on a metaphysical level your idea is naive or simply wrong, because many if not most physical theories/models do not use the ratio of directional fields to explain/predict. I say "directional" because you qualify your fields idea as "attractive or repelling". Ratios are not always well-defined. May require simplifying assumptions. With enough simplifying assumptions you may be able to cram many physical models into some pre-conceived mold, but then by over-simplifying you lose the ability to make accurate predictions.
     
  6. Aug 23, 2010 #5
    I think the OP needs further explanation.

    I think that all physical systems are defined by their possible states and their observables.

    On the other hand if an "observable" is dimensionful then such an observable is only a quantity (i.e. an actual number) when measured in some units. But since units are not a part of the physical system without themselves being observables it is only really true that "real observables"( for which we can assign some quantity) can be ratios of dimensionful observables.

    Further more I think that in general observables must be accelerations or reaction rates both of which care dimensionful i.e. 1/time. So really only ratio's ok these observables are quantities that are observed in the sense above.

    Then it seems to make sense the repulsive/attractive can be understood as acceleration/declaration.
     
  7. Aug 23, 2010 #6
    me too.
    as written, without explanation, NO..

    The set of all real numbers.

    Then again I have no idea,whatsoever, what old school means.
     
  8. Aug 23, 2010 #7

    marcus

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    Is this a law of physics? No. It's a metaphysics conjecture, and a bad/naive one.

    A photon is approaching a galaxy. It does not accelerate (as if experiencing a force.) What happens is its wavelength gets shorter.

    The language of accel/decel, or of attract/repel is too restrictive to cram all physics laws into that particular format.

    Moreover the Newton force picture depends on having a fixed geomtric setup. What about the bending of starlight observed by Eddington in 1919. Does it really work to put it into an attractive force paradigm?

    A prescriptive metaphysics can be a straight-jacket. Doesn't Philosophy of Physics (PoP) and studying the language/formulation of physical law belongs in general phys. or in philosophy?
     
  9. Aug 23, 2010 #8
    To clarify, this is the kind of answer I'm looking for. To keep the discussion going, I would suggest that a falling ball eventually comes to a sudden stop. Implying the electric field represents a repelling force.
     
  10. Aug 23, 2010 #9
    What about two bodies in orbit with each other?
    There is only an attractive field at work there.
     
  11. Aug 24, 2010 #10
    Well to begin with the electric field didn't disappear. And the orbit didn't get created by nothing. I would also like to point out you need to remember what keeps the system from exploding/evaporating or collapsing into a singularity.

    What if gravity was the only force in a system?
     
    Last edited: Aug 24, 2010
  12. Aug 24, 2010 #11
    How would you use your hypothetical law in an application?

    I can also say that a ripe banana is yellow. It is not debatable, but it doesn't really go anywhere either.

    You have a statement that might be debatable, but how is it useful?
     
  13. Aug 24, 2010 #12
    Re: Is this a law of physics? No. It's a metaphysics conjecture, and a bad/naive one.

    I think you miss the point. I think the question is more about what we can measure directly in a scientific manner (so we don't include "seeing the photon is red" or anything like that). When we make a measurement we get data consisting of numbers and angles. My interpretation( which may be wrong) of the OP is that this data corresponds to ratios of attractive and repulsive forces.

    In the case of light bending clearly this can be understood as an attractive force. Clearly gravity is an attractive force.
     
  14. Aug 24, 2010 #13
    Well for me personally I ask what if the universe is a measurable system. Under the standard model gravity is considered an attractive force but has no repelling equivalent.

    If this law is true, then dark energy in my opinion, could be unified with gravity. If of course this is a true law of physics.

    P.S. If I know the banana is yellow. I eat it. It does go somewhere.
     
  15. Aug 24, 2010 #14
    @OP:
    This is a pointless discussion. Using opposite word to describe phenomenon lead to nowhere. This is very similar to the theological explanations:
    -Yesterday was a sunny day because God was happy. Today is raining because He is angry.

    Such simplified models can explain anything - but I don't believe in them.

    You can call it a science - in fact, chemists do.
    Has anyone noticed how lousy are some chemistry textbooks? Everything is on the line of "electrons bond atoms. Except when they don't" or "Octet is the most stable configuration. Except when it isn't". I don't like most chemistry textbooks for this reason. I do like chemistry, though.
     
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