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

  • #1

Main Question or Discussion Point

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.
 

Answers and Replies

  • #2
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If photons have no mass, why would black holes attract light?
Mass is not necessary to be attracted. The trajectory is independent from mass (both in classical mechanics and relativity).
 
  • #3
What makes a black hole to attract any body ? Gravitational force and it depends on mass
 
  • #4
ZapperZ
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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.
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.
 
  • #5
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What ZapperZ said. This thread is closed.
 

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