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Momentum of Light

  1. Apr 7, 2012 #1
    A stationary object is floating on space and then it starts sending a continuous beam of photons. It seems correct to assert that the object accelerates since photons have momentum. In the initial condition the center of mass is at rest and thus it should remain at rest since photons have no mass. But it also accelerates because photons have momentum.
    What happens in this situation?
  2. jcsd
  3. Apr 8, 2012 #2


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    Staff: Mentor

  4. Apr 8, 2012 #3

    the photons have energy so they have momentum. Everything works out. I can't resist attaching a file which gives a simple proof of E=mc2 without using calculus or even having to solve a quadratic equation. I attach it because it uses an argument so close to the one you state.

    Hope this helps



    Attached Files:

    • emc2.pdf
      File size:
      27.8 KB
  5. Apr 8, 2012 #4
    Lorentz transformation is what I think your looking for.
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