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Laws of Nature

  1. Feb 19, 2012 #1
    Hello,

    1a) Generally, would anyone mind discussing what laws of nature (aka. physical laws, physical principles, scientific laws, etc.) are?
    1b) Are they only to describe phenomena, i.e., interactions, behaviors, etc.?
    1c) Or do any describe why certain entities are similar?

    Note: by 'entities' I mean anything that exists in reality.

    2) Are there any laws of nature that state, for example, that
    (a) all electrons have the same properties (charge, spin, mass, etc.)?
    and/or
    (b) WHY all electrons are similar?

    Same question for other entities in physics.

    Thanks very much
     
  2. jcsd
  3. Feb 20, 2012 #2

    Nabeshin

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    Science Advisor

    Well, I suppose the only laws there are come in two categories: conservation laws and force laws. Conservation laws tell us certain quantities (momentum, energy, angular momentum, charge, etc.) are conserved no matter what happens. These are the most general of principles. If you like, you can couple these conservation laws with symmetry principles, such as homogeneity (that the universe is the same everywhere) and isotropy (that the universe looks the same in every direction). These are more hypotheses than laws, but are extremely powerful. Force laws tell us how everything in the universe interacts. There are four different forces (Gravity, Electromagnetism, Strong, and Weak nuclear forces), each with its own mathematical description which tells us how these forces influence other particles. Note: Neither of these tell us anything about what is IN the universe to begin with.

    I'm not sure I entirely understand your question, but I think yes. Should be clear from the description I gave.

    To some extent, yes, but they don't exactly come out and say it most of the time. For example, gravity tells us why all celestial objects are spherical, and angular momentum conservation tells us why collapsing systems tend to form disks (think galaxies or planetary systems).


    No, not really. It boils down to observation at some point. It could have been the case that instead of one electron, every one was different. We would have developed different laws then, but I don't think there's any fundamental reason why it has to be one way or another (and would argue that any explanation one might offer is inadequate, insofar as any explanation of WHY nature is the way it is is doomed to be inadequate).
     
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