https://www.quantamagazine.org/the-black-hole-information-paradox-comes-to-an-end-20201029/
The Quanta article says that a group of researchers first considered black hole evaporation in the context of the conjectured AdS/CFT duality. Then they were able to eliminate the link to AdS/CFT using path integrals.
The Wikipedia page:
https://en.wikipedia.org/wiki/Black_hole_information_paradox
discusses the work of Penington et al.
The claims remind us of the announcement by Stephen Hawking in 2004 that he is able to recover the information which has fallen into a black hole, using Euclidean path integrals:
https://arxiv.org/abs/hep-th/0507171
Does Hawking radiation exist? Vladimir Belinski has claimed that the calculation by Hawking is erroneous. In this blog we have raised questions about conservation of momentum if we assume that the black hole horizon radiates photons. A photon carries away a momentum p. What, and how, could absorb the opposite momentum -p?
As far as we know, no one has refuted the criticism by Belinski, and no one has shown a mechanism which would conserve momentum.
What about the claims that we can use a path integral and show that the information falling toward the black hole horizon is preserved, after all?
Let us assume that a macroscopic black hole forms, and it devours and crushes a large part of the wave function, or, of the path integral.
In quantum mechanics, one cannot simply throw away a part of the wave function or a path integral. It is a strange claim that the remaining part would be equivalent to the entire original wave function.
The horizon of a black hole is classically a one-way surface. Information can fall in, but can never come back.
Let us do a thought experiment: instead of a black hole, we have a horizon which leads to a wormhole, and the wormhole opens into a white hole in some other part of our universe. If we claim that the horizon necessarily returns back the information which has passed by, how do we explain that the same information ends up to another part of our universe? This is against the "no-copying" principle of quantum mechanics.
People who claim that a black hole horizon must necessarily give up the information it has devoured, kind of claim that the universe behind the horizon is "inferior" to our own universe. They think that the entropy should be calculated based on what is on our side of the horizon, and we should ignore what is behind the horizon. That does not sound like a reasonable assumption. Why would the other side be inferior to our side?
The Quanta magazine article points at the large number of assumptions and idealizations which Penington et al. use. That is a weakness in the new work.
No comments:
Post a Comment