General Relativity and Hawking Radiation at the Event Horizon

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Discussion Overview

The discussion revolves around the apparent conflict between General Relativity (GR) and Hawking Radiation (HR) at the event horizon of black holes. Participants explore the implications of GR's prediction of infinite time for objects falling into black holes versus HR's prediction of finite time for black hole evaporation.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant notes that GR indicates an outside observer sees a falling object appear to hover at the event horizon for an infinite amount of time, raising questions about the implications of this observation.
  • Another participant agrees that GR's prediction of infinite time applies only if the black hole remains unchanged, suggesting that the evaporation of the black hole alters the conditions being considered.
  • A clarification is made regarding the correct terminology, specifically the name "Hawking Radiation," attributed to Stephen Hawking.
  • A participant acknowledges the conditional nature of the infinite time prediction, indicating a realization of the importance of the assumption that the black hole remains static.
  • One participant expresses skepticism about the current understanding of both GR and Quantum Theory, highlighting the complexities involved in such extreme scenarios.

Areas of Agreement / Disagreement

Participants generally agree that the infinite time prediction of GR is conditional on the black hole remaining unchanged, but the discussion remains unresolved regarding the implications of this condition in light of Hawking Radiation.

Contextual Notes

The discussion highlights the limitations of current theories in reconciling the predictions of GR and HR, particularly in extreme conditions where both theories intersect.

Chris11235
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The question is to resolve a logical conflict.

GR says as we fall into a black hole, an outside observer will see that event come to a stand still as if the falling object is hovering at the horizon. This stand still extends to infinite time. Unfortunately, I've read and hear the term "infinite" time used to describe this through experiment from a number of respectable physicists. Assuming that is the correct term then it conflicts with another effect about black holes; the Hawkin radiation (HR). If HR predicts that the black hole eventually evaporates in finite amount of time, that must predict the falling object at some time disappears. The conflict is GR predicting infinite time while HR predicts finite time.

While I'm not a Physics/Mathematician, I still think that these extreme conditions of the experiements should at least converge to the same logical result. What am I missing?
 
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GR predicts infinite time, IF the BH were to stay as is. Clearly you are right in that when it evaporates, this no longer holds because you are talking about different conditions.
 
phinds said:
GR predicts infinite time, IF the BH were to stay as is. Clearly you are right in that when it evaporates, this no longer holds because you are talking about different conditions.

Aahha, of course. The "If stay as is" is the condition I overlooked. thanks.
 
I think you are expecting a lot from the current understanding of both GR and Quantum Theory. This is an extreme case in both theories where they meet.
 

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