Black Hole; Gravity & Speed Within Questions

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Discussion Overview

The discussion revolves around the behavior of photons near black holes, specifically regarding their interaction with gravity at or beyond the event horizon, and the implications for relativity. It also touches on the nature of objects crossing the event horizon and their fate as they approach the singularity.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant questions whether there is a point near the event horizon where a photon could "float" due to a balance between gravitational pull and the photon's energy attempting to escape.
  • Another participant asserts that photons cannot hover and must always be in motion, suggesting that a black hole's dynamics do not allow for such a scenario.
  • There is a query about the velocity of objects crossing the event horizon, specifically whether they increase in velocity at a fixed rate or if they gradually "blend" into the singularity due to the effects of gravity on their frame of time.
  • A participant relates the first question to the concept of the photon sphere, indicating that a photon cannot be in a state of rest as described in the initial query.
  • Another participant mentions that a photon will reach the singularity within a very few wavelengths, although the exact formula is not recalled.

Areas of Agreement / Disagreement

Participants generally agree that photons cannot hover and must always be in motion. However, there remains uncertainty regarding the specifics of how objects behave as they approach the singularity, and the discussion does not reach a consensus on the nature of these interactions.

Contextual Notes

There are limitations in the discussion regarding the assumptions about gravitational effects and the behavior of light near black holes, as well as the lack of detailed mathematical formulations to support claims made by participants.

KevinMWHM
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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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not fish-like

KevinMWHM said:
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.
 
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
 
KevinMWHM said:
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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