Exploring the Mystery of Black Hole Entropy Increase

In summary, the conversation discusses the concept of entropy in relation to black holes. It is stated that starting with a pure state, the entropy of a black hole increases as its area increases due to the particle being sucked in. This raises questions about the violation of unitary time evolution and the possibility of information being lost in irreversible processes. The conversation also mentions a theory that states information cannot be lost or destroyed, but there is a contradiction with the concept of entropy increase.
  • #1
touqra
287
0
Supposing I started off with a particle, which I know exactly the state it is in, hence, it is in a pure state. And hence also, its entropy is zero.
Now, suppose we throw the particle into the black hole and be sucked in, then, then the area of the black hole increases and hence, the entropy of the black hole also increases.
But, how can this be possible? I started off with a zero von Neumann entropy and why should the entropy/area of the black hole increase?
 
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  • #2
In most physical processes entropy increase, so why are you surprised?
 
  • #4
according to the 2nd law of thermodynamic, entropy cannot decrease..decreasing the chance of a white hole possiblility.
 
  • #5
If you started with a pure state, entropy increase is only possible if you allow for a violation of unitary time evolution. This problem is known as black hole information loss and points out an incompatibility between QM and GR.
 
  • #6
but i thought there is a theory that states that information cannot be lost or destoyed?
 
  • #7
white holes said:
but i thought there is a theory that states that information cannot be lost or destoyed?
Information is lost in irreversible macroscopic processes. I think that the statement is that unitary time evolution of pure quantum states is a principle that should not be violated. In case of quantum field theory of black holes, it's violation is an indication that something is wrong in the theory. If you are interested in knowing more about this I would suggest to ask in the subforum "Beyond the Standard Model".
 

1. What is black hole entropy?

Black hole entropy is a measure of the disorder or randomness within a black hole. It is related to the number of microstates or possible configurations of a black hole.

2. How does black hole entropy increase?

According to the second law of thermodynamics, entropy always increases in a closed system. In the case of black holes, as matter and energy fall into the black hole, the number of microstates increases, leading to an increase in entropy.

3. What is the connection between black hole entropy and the holographic principle?

The holographic principle states that the information within a region of space can be described by degrees of freedom on the boundary of that region. This principle has been applied to black holes, where the entropy of a black hole is related to the surface area of its event horizon, providing a way to reconcile the laws of thermodynamics with the theory of gravity.

4. Can black hole entropy ever decrease?

No, black hole entropy can only increase or remain constant. This is in line with the second law of thermodynamics, which states that entropy can never decrease in a closed system.

5. How does studying black hole entropy help us understand the nature of the universe?

Studying black hole entropy allows us to better understand the fundamental laws of thermodynamics and gravity, which are crucial for understanding the behavior of the universe. It also provides insights into the nature of information and its preservation in black holes, which may have implications for our understanding of quantum mechanics.

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