Pallavi said:the black hole paradox?
Thank u for your response.Scott said:It's called the Black Hole Information Paradox.
Physics isn't like a religion. So "beliefs" are simply working theories. Today you can work with the theory that the information disappears ("Black Holes have no hair.). Tomorrow you can work with the theory that it is preserved.
That said, it seems that most Physicists are more comfortable with the preservation of information than with its loss.
There is also a Black Hole Firewall Paradox. My personal view on that one is that there is no paradox. You would pass through the event horizon without issue and without a firewall. The fact that you would describe the event differently that people other reference frames is not an issue since you will never get to compare notes with those other people.
I was referring to the black hole information paradoxPeterDonis said:What paradox? @.Scott referred to two of them in his post, but he's just guessing that one of those is the one you meant.
A specific reference to what you are asking about would help.
The first resolution basically says that it is not a paradox. It is a paradox only if one insists on unitarity. I personally don't understand why all this is considered a problem. If the conclusion is that unitarity is violated, then so be it. Why call it a problem and try to resolve it (unsuccessfully so far)?Demystifier said:A list of proposed solutions, each with its advantages and disadvantages, is given here: https://en.wikipedia.org/wiki/Black_hole_information_paradox#Postulated_solutions
First, all other quantum theories are unitary, so it is not clear why exactly quantum gravity should be different.martinbn said:If the conclusion is that unitarity is violated, then so be it.
Ok, but gravity is very different from other things, so no need to expect that quantum gravity will be the same as other quantum theories. Also semiclassical gravity suggests that unitarity is not preserved.Demystifier said:First, all other quantum theories are unitary, so it is not clear why exactly quantum gravity should be different.
Ok, but as far as I am aware all these approaches are not finished yet even as a formulation.Demystifier said:Second, various specific approaches to quantum gravity (e.g. AdS/CFT) seem to be saying explicitly that quantum gravity is unitary, so from that perspective one only needs to understand how exactly unitarity is realized in the case of black holes.
How exactly is it different in a way relevant for unitarity?martinbn said:Ok, but gravity is very different from other things,
True, but semiclassical theory is a mixture of classical and quantum theory, so it is not unexpected that it may lead to inconsistencies.martinbn said:Also semiclassical gravity suggests that unitarity is not preserved.
You are right about that. But I am not offering a proof that gravity is unitary. Perhaps it isn't. What I am offering is arguments why the idea that gravity might not be unitary should not be taken easily.martinbn said:Ok, but as far as I am aware all these approaches are not finished yet even as a formulation.
I don't know if it is relevant for unitarity. But it is quite different from the rest, so the argument "everything else is, thus gravity should be" seems weak.Demystifier said:How exactly is it different in a way relevant for unitarity?
True, that is a possibility. But I've never seen people expressing any doubt that black hole may not radiate.Demystifier said:True, but semiclassical theory is a mixture of classical and quantum theory, so it is not unexpected that it may lead to inconsistencies.
I agree with all this. May be I have the wrong impression, but it seems to me that most people think that it has got to be this way.Demystifier said:You are right about that. But I am not offering a proof that gravity is unitary. Perhaps it isn't. What I am offering is arguments why the idea that gravity might not be unitary should not be taken easily.
In string theory, which is the most popular approach to quantum gravity, gravity is certainly not much different from the rest. The same can be said about effective field theory approaches.martinbn said:I don't know if it is relevant for unitarity. But it is quite different from the rest, so the argument "everything else is, thus gravity should be" seems weak.
Yes, physicists are prone to prejudices too.martinbn said:but it seems to me that most people think that it has got to be this way.
The black hole paradox refers to the conflict between two fundamental theories of physics: general relativity and quantum mechanics. General relativity predicts the existence of black holes, which are regions of space where the gravitational pull is so strong that even light cannot escape. However, according to quantum mechanics, information cannot be destroyed. This raises the question of what happens to the information of an object that falls into a black hole.
Currently, there is no definitive explanation for the black hole paradox. Some scientists propose that the information is stored on the surface of the black hole, while others suggest that it is released back into the universe in a process known as Hawking radiation. However, these theories are still being researched and debated.
Understanding the black hole paradox is important because it challenges our understanding of the laws of physics and the nature of the universe. It also has implications for other areas of science, such as information theory and the search for a unified theory of physics.
Scientists study the black hole paradox through a combination of theoretical calculations and observations. They use mathematical models to simulate the behavior of black holes and conduct experiments to test their theories. They also study the effects of black holes on their surrounding environments, such as the distortion of light and the formation of accretion disks.
There are several potential solutions to the black hole paradox that are currently being explored. These include the holographic principle, which suggests that all the information of an object in a black hole is encoded on the surface, and the firewall hypothesis, which proposes that the event horizon of a black hole is not a smooth surface but rather a fiery wall that destroys any information that tries to pass through it. However, more research is needed to determine which, if any, of these solutions is correct.