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B Energy equivalence issue

  1. Jun 2, 2017 #1
    View attachment 198775

    The expansion of the universe stretches the wavelength of EM-waves. Though the energy equivalence says energy can't be destroyed... so where did the energy go?
     
  2. jcsd
  3. Jun 2, 2017 #2

    Drakkith

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    Staff: Mentor

    That's not energy equivalence, it's the conservation of energy law. Conservation of energy doesn't apply to the universe as a whole, it only applies locally.
     
  4. Jun 2, 2017 #3
    1.)Lol that's what I meant sorry
    2.)What exactly do you mean by saying locally?
     
  5. Jun 2, 2017 #4

    Drakkith

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    Staff: Mentor

    I'm not sure about the technical definition of local, but I believe the idea is that it's a small region of space where things like the curvature of spacetime is negligible and the laws of special relativity can be used.

    For more info on this topic, see this link: http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html
     
  6. Jun 2, 2017 #5
    Thanks that helped
     
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