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If photons have no mass,why would black holes attract light?

  1. Jan 9, 2015 #1
    If photons have no mass, why would black holes attract light?
    I was told that photons have no mass. However I thought that black holes are called "black" because no light can go escape the gravity force in their vicinity. I somehow think that, if light is just photons, then it should not be affected by gravity. Hence black holes could catch everything but light.

    Do I miss something? Is light more than a bunch of photons? Or maybe black holes are not exactly what I think.
     
  2. jcsd
  3. Jan 9, 2015 #2
    Mass is not necessary to be attracted. The trajectory is independent from mass (both in classical mechanics and relativity).
     
  4. Jan 9, 2015 #3
    What makes a black hole to attract any body ? Gravitational force and it depends on mass
     
  5. Jan 9, 2015 #4

    ZapperZ

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    What you missed is reading our Relativity FAQ on this entry:

    https://www.physicsforums.com/threads/why-are-massless-photons-affected-by-gravity.511173/

    This question has been asked many times and it is sufficiently addressed at the simplest level in that entry.

    Zz.
     
  6. Jan 9, 2015 #5

    Nugatory

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    What ZapperZ said. This thread is closed.
     
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