Unruh & Hawkins Radiation: A Comparative Analysis

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Discussion Overview

The discussion centers on the relationship between Unruh radiation and Hawking radiation, exploring whether they are manifestations of the same phenomenon. It involves theoretical comparisons and implications of observer-dependent features in physics.

Discussion Character

  • Debate/contested

Main Points Raised

  • Some participants suggest that Unruh radiation and Hawking radiation are similar but not identical, with Unruh radiation being observer-dependent while Hawking radiation is visible to all observers.
  • One participant notes that both phenomena are related by the equivalence principle, though they emphasize that acceleration does not equate to a gravitational field.
  • Another participant challenges the assertion that Hawking radiation is visible to all observers, referencing Hawking's original model where a free-falling observer would not see Hawking radiation, and pointing out that recent models still do not guarantee the same observations for different observers.
  • There is mention of the unresolved nature of the question, particularly in relation to the black hole information paradox.

Areas of Agreement / Disagreement

Participants express differing views on the visibility of Hawking radiation to various observers, indicating that the discussion remains unresolved with multiple competing perspectives.

Contextual Notes

The discussion highlights limitations in understanding the implications of observer-dependent phenomena and the complexities surrounding the black hole information paradox, which remain unresolved.

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Are Unruh radiation and Hawkins radiation manifestations of the same basic phenomenon?
 
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backward said:
Are Unruh radiation and Hawkins radiation manifestations of the same basic phenomenon?
They're similar, for sure. But not completely identical.

The phenomenon of Unruh radiation shows that the number of photons is an observer-dependent feature of the universe: accelerated observers see more radiation. The additional photons can be viewed as stemming from the apparent event horizon that arises in the space-time of an accelerated observer, which makes them very similar to Hawking Radiation.

The difference is that Hawking radiation is visible to all observers, not just accelerated ones.
 
They are related by the equivalence principle, but an acceleration does not equal a gravitational field; they only imply the same physical effects locally in spacetime.
 
Chalnoth said:
The difference is that Hawking radiation is visible to all observers, not just accelerated ones.

Actually we don't know whether that is true. In Hawking's original model, it wasn't; an observer free-falling into a black hole would see no Hawking radiation. There are other more recent models in which the free-falling observer does see something, but it still isn't always the same as what the accelerated observer sees. This question probably won't be resolved until the black hole information paradox is resolved.
 

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