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I Symmetries and Conservation Laws

  1. May 14, 2018 #1
    I've been caught by a quite interesting statement of Berkeley physics Course Vol.1 (Chap. 5), that says "In the physical world there exist a number of conservation laws, some exact and some approximate. A conservation law is usually the consequence of some underlying symmetry in the universe.".

    I made a quick search on internet and found that a good thing to understand best this relationship between symmetries in a physical system and conservation laws, is the understanding of the so called "Noether's Theorem". I'd like to know if anyone has a better suggestion. My specific desire is to be able to identify which symmetry causes that particular conservation and why (for ex. I know the homogeneity of space is the cause of the conservation of linear momentum, but I haven't think about why).

    Thank you!
  2. jcsd
  3. May 14, 2018 #2


    Staff: Mentor

  4. May 14, 2018 #3
    That's a quite common "myth": actually the "homogeneity of space" has nothing to do with momentum conservation. This law comes instead from the "translations invariance of the system's Lagrangian" . If you are an high school student, this can be a good reason to study physics at university: probably you cannot completely understand the meaning of this (as others) invariance without a good knowledge of physics and mathematics.

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