Black Hole; Gravity & Speed Within Questions

  • Thread starter KevinMWHM
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  • #1
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2 questions;

Is there a point, either at or just beyond the event horizon where a photon would "float" due to an equal amount of gravity vs the energy of the photon trying to "avoid" said gravity? Does this affect any relativity laws if there is a brief moment where a 3rd frame of reference could possibly see a "motionless" particle of light?

For an object that crosses the event horizon, does it's velocity increase at any kind of fixed rate, thus smashing into the singularity? Or does the effect of gravity on the objects frame of time cause it to slowly "blend" into the singularity?

If the 2nd question is hard to answer because of a lack of knowledge within black holes, what are some of the larger theories regarding what is happening at the center, if there are any?
 

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  • #2
tiny-tim
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not fish-like

Is there a point, either at or just beyond the event horizon where a photon would "float" due to an equal amount of gravity vs the energy of the photon trying to "avoid" said gravity? Does this affect any relativity laws if there is a brief moment where a 3rd frame of reference could possibly see a "motionless" particle of light?
Hi KevinMWHM! :smile:

No, a black hole is not like a waterfall: the speed of light cannot "match the speed of space" in the way a fish could match the speed of a waterfall.

Photons always move, they can't float. :wink:
For an object that crosses the event horizon, does it's velocity increase at any kind of fixed rate, thus smashing into the singularity? Or does the effect of gravity on the objects frame of time cause it to slowly "blend" into the singularity?
I can't remember the exact formula, but a photon will hit the singularity within a very few wavelengths.
 
  • #3
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Hi Tim, Thanx for the link,

So in regards to my first question, would I be correct in relating it to the radius of photon sphere in that a photon, always being in motion, could never be in the scenerio I depicted?


thanks also for the answer

-kevin
 
  • #4
tiny-tim
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Hi Tim, Thanx for the link …
ah, that's an autolink … a unique PF feature! :biggrin:
So in regards to my first question, would I be correct in relating it to the radius of photon sphere in that a photon, always being in motion, could never be in the scenerio I depicted?
Yes, a photon can't hover, it can only keep the same "height" by moving "sideways". :smile:
 

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