Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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


    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor

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


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

  6. Jan 9, 2015 #5


    User Avatar

    Staff: Mentor

    What ZapperZ said. This thread is closed.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - photons mass black Date
B Photons, mass, and black holes Feb 8, 2018
B Mass of photon and FTL travel Jan 8, 2018
I Could it be that the photon has a non-zero mass? Mar 14, 2017
I Passive and Active Gravitational Mass of Photons May 31, 2016
B Mass of a photon Apr 17, 2016