Second law of thermodynamics and black holes ?

In summary: Therefore, there are no known alternatives to the Hawking hypothesis that contradict the second law of thermodynamics.
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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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  • #4



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.
 

1. What is the second law of thermodynamics and how does it relate to black holes?

The second law of thermodynamics states that in any closed system, the total entropy (or disorder) will always increase or remain constant. In the context of black holes, the second law suggests that the entropy of a black hole can never decrease, meaning that the event horizon (the point of no return for matter and energy) can never shrink in size.

2. Can black holes violate the second law of thermodynamics?

No, black holes do not violate the second law of thermodynamics. While it may seem like the formation of a black hole violates the law, it is actually the increase in entropy of the surrounding matter and energy that balances out the decrease in entropy of the black hole.

3. How does the concept of Hawking radiation relate to the second law of thermodynamics?

Hawking radiation, a process in which black holes emit radiation and eventually evaporate, is consistent with the second law of thermodynamics. This is because the radiation carries away energy and entropy from the black hole, increasing the overall entropy of the system.

4. What is the role of entropy in the formation and behavior of black holes?

Entropy plays a crucial role in the formation and behavior of black holes. The more matter and energy that are contained within a black hole, the greater the entropy of the system. As a black hole evaporates through Hawking radiation, its entropy decreases. The maximum amount of entropy that a black hole can have is proportional to its surface area.

5. Can the second law of thermodynamics help explain the information paradox of black holes?

Yes, the second law of thermodynamics offers a possible explanation for the information paradox of black holes. This paradox arises from the idea that information (such as the characteristics of matter that falls into a black hole) cannot be destroyed, but it seems to disappear in a black hole. However, the second law states that the overall entropy of a system must increase, meaning that the information is not truly lost but rather encoded in the increased entropy of the black hole itself.

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