Second law of thermodynamics and black holes ?

AI Thread Summary
The discussion centers on the relationship between the second law of thermodynamics and black holes, particularly regarding entropy. It is argued that when mass with entropy enters a black hole, the area of the black hole increases, suggesting that entropy is preserved. However, concerns are raised about black hole evaporation potentially leading to a decrease in entropy, which would violate the second law. The validity of Hawking radiation is highlighted as a crucial factor, as it theoretically supports the preservation of thermodynamic laws, though it has yet to be observationally confirmed. Ultimately, all laws of thermodynamics remain valid, and any contradictions in models would indicate incorrect formulations in relation to thermodynamics and general relativity.
HossamCFD
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second law of thermodynamics and black holes ?!

I am having a hard time thinking about the perservation of the second law of thermodynamics in black holes. If we throw a mass that have some level of disorder (entropy) into a black hole, it will disappear and that will appear to us as violating the second law of thermodynamics (entropy can only increase or at least remains constant in an adiabatic reversible process). yet some said (I think Hawking was one of them) that when B.H absorbs mass its area will increase and that is an indication that entropy is preserved inside a B.H. I have no problem accepting that, however, what if a B.H evaporates ? does that imply that entropy dicreased in our universe? can the second law of thermodynamics cease to be valid in B.Hs ?
 
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Can the second law of thermodynamics cease to be valid in B.Hs?

Negative.

The entropy of an isolated system can only increase.

If such a mathematical model predicts an affirmative result, then the mathematical model probably has been formulated incorrectly with respect to Thermodynamics and General Relativity.

Theoretically with respect to Hawking radiation all the laws of thermodynamics are valid with all masses down to quantum particles and quantum Planck scales, where these scales themselves become quantum limits due to singularities.
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I see, so you're saying that given that Hawking's radiation are true, the second law of thermodynamics is valid, right ?

I understand that Hawking radiation is one of the few theories that combine quantum mechanics with general relativity, but has it been validated yet ? or even can it be validated ?

one more thing, I am curious to know what are the alternatives to the Hawking hypothesis that contradicts with the second law ?
 
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HossamCFD said:
given that Hawking's radiation are true, the second law of thermodynamics is valid, right?

All the laws of thermodynamics are valid and therefore Hawking radiation is a valid theory based upon that consequence.

HossamCFD said:
has it been validated yet?
Hawking radiation has not been observationally verified.

HossamCFD said:
can it be validated?
Affirmative, by observing the radiation emitted by a Black_Hole or quantum Black_Hole particle.
HossamCFD said:
what are the alternatives to the Hawking hypothesis that contradicts with the second law?
If such a mathematical model predicts an affirmative result, then the mathematical model probably has been formulated incorrectly with respect to Thermodynamics and General Relativity.
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