Hawking radiation and shrinking black holes

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I am grateful for anyone for their time to answer this question.

Some theories predict black holes will evaporate and eventually disappear. From my limited understanding, Hawking's theory predicts that quantum effects near the event horizon of a black hole are responsible for blackbody radiation. I think this explains how things that fall into a black hole will evaporate. What about what's inside of the event horizon? How does anything escape from the event horizon? and what about the singularity?
 

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256bits
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Hi @docnet
That's a big peanut you are carrying. :smile:

One person who does not receive as much recognition as he should regarding black holes is
https://en.wikipedia.org/wiki/Jacob_Bekenstein
Without his leading research, Hawking might not have made the name recognition and impact he credited with.
In 1972, Bekenstein was the first to suggest that black holes should have a well-defined entropy. He wrote that a black hole's entropy was proportional to the area of its (the black hole's) event horizon. Bekenstein also formulated the generalized second law of thermodynamics, black hole thermodynamics, for systems including black holes
Blackbody radiation and black hole radiation are two different concepts.
It may very well be that black holes produce a thermal black body spectrum when evaporating.

As the black hole emits radiation it looses mass, and the event horizon shrinks in size. The objects that fell into the black hole are not recognizable as the objects anymore as they approach the singularity, but are broken into atomic particles due to the large tidal forces the closer they get. At the singularity, which is a broad general statement, since the laws of physics as we know them, are not calculable, hence the term singularity ( a mathematical concept ), a region ( call it a point ) of infinite density occurs where the atomic particles are themselves not even recognizable anymore. It is suspected that something such as a theory of quantum gravity could help explain.

Have you at least read the wiki, or some other resources on black holes, such as:
https://imagine.gsfc.nasa.gov/science/objects/black_holes1.html
https://en.wikipedia.org/wiki/Gravitational_singularity



What's inside the event horizon? Simply put, the same as what is outside - space.
How does anything escape from the event horizon? From inside, or outside? From inside, nothing.
The singularity? What about it? Our current laws produce a point of infinite density, which is the reason they break down at this point, and why it is called a singularity.
 
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PeterDonis
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I think this explains how things that fall into a black hole will evaporate.
No, that's not what Hawking radiation is. It is not things falling into the black hole evaporating. It is the hole itself evaporating.

What about what's inside of the event horizon? How does anything escape from the event horizon?
Nothing has to escape from the event horizon for Hawking radiation to occur. Hawking radiation comes from just outside the event horizon.

The real question is how Hawking radiation can decrease the mass of the hole, and hence the area of the event horizon, in violation of the area theorem, which Hawking proved, and which says that the area of the event horizon of a black hole can never decrease. The answer is that the area theorem depends on certain energy conditions being satisfied, and the quantum fields responsible for Hawking radiation violate those conditions.
 
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thank you for taking the time to reply to my questions. I am grateful for the information
 
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haushofer
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The real question is how Hawking radiation can decrease the mass of the hole, and hence the area of the event horizon, in violation of the area theorem, which Hawking proved, and which says that the area of the event horizon of a black hole can never decrease. The answer is that the area theorem depends on certain energy conditions being satisfied, and the quantum fields responsible for Hawking radiation violate those conditions.
Do you have any references to that? :)
 
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PeterDonis
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Do you have any references to that? :)
It is discussed in Wald's monograph Quantum Field Theory in Curved Spacetime and Black Hole Thermodynamics, which is where I first encountered it. I think there are references to it in Wald's GR textbook as well.
 
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haushofer
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It is discussed in Wald's monograph Quantum Field Theory in Curved Spacetime and Black Hole Thermodynamics, which is where I first encountered it. I think there are references to it in Wald's GR textbook as well.
Thanks! I just gave away Wald's monograph, but still have its textbook :P
 

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