Now my personal credences are 55% String Theory with broken Supersymmetry, about 1-5% to Loop Quantum Gravity, and about 40-44% credence in other theories.
That means String Theory still is the most likely theory that applies to reality, but definitely not overwhelmingly confidently likely.
One other problem for String Theory is the black hole information paradox has been solved solely by normal physics, that is there is no need to posit strings to solve the paradox. Conjunctions are never likelier than their conjuncts, so solely solving the black hole information paradox using normal physics is strictly more likely than positing String Theory and the AdS/CFT correspondence.
the black hole information paradox has been solved solely by normal physics, that is there is no need to posit strings to solve the paradox
Well: this “solution” to the paradox was discovered by working within string theory. Then they found a way to carry out the argument at a level of approximation that doesn’t need to know what the fundamental theory is. That is the only sense in which they were able to dispense with string theory. They don’t actually have an alternative fundamental theory in which the argument can also be carried out.
Meanwhile, I put “solution” in quotes because it is far from clear what’s going on here, and how it relates to other “solutions” that have been proposed, like Mathur’s fuzzballs, Hawking et al’s soft quantum hair, and Papadodimas and Raju’s state-dependent observables. For example, is the island of quantum information in the black hole interior, a baby universe that becomes genuinely disconnected from the original space-time, or is it just a brane that buds off while remaining immersed in a common higher-dimensional space? This is related to a larger debate within string theory, about how to interpret the lower-dimensional models that are being used here.
To explain to everyone, the reason the black hole information paradox has been solved is that 2 things happened:
First, the Page Curve was resolved as, yes black holes do preserve and shed information, thus we’ve resolved whether information is destroyed as Hawking and Preskill thought, or does unitarity prevail in black holes, preserving information. Now we know that information must be preserved. Incredibly they even got it to work in our own flat universe.
Second, they got rid of both string theory and the AdS-CFT Correspondence/Holographic universe assumption, removing 2 burdensome details from the solution. It’s inspired by string theory and the AdS/CFT Correspondence/Holographic universe theories, but they don’t rely on these assumptions to solve the paradox. We’ve finally managed to get the answer without relying on burdensome details.
Now how it happens is unfortunately unsolved, and here the best theories like wormholes are pretty speculative. But we don’t need the how in order to appreciate the answer to the original Black Hole Information Paradox.
I have just done some further research, and found a rather serious criticism of the idea that “quantum extremal surfaces reproduce the Page curve, and that explains everything”. The claim is that entanglement islands only show up in theories with a massive graviton—which is very unlike our world. This claim is being emphasized by the string theorist Suvrat Raju, most recently in section 4.2 of this paper from last year. He actually mentions the article from Quanta Magazine, as an example of a “misleading” “popular description”.
His own position is that everything about real-world quantum black holes is explained by an extra nonlocality of information in quantum gravity (what he calls “holography of information”); that the Page curve is a property of any ordinary quantum system in which entanglement is leaking across a boundary; and it’s because massive gravity doesn’t possess the property of holography of information, that the Page curve shows up in that case.
Now my personal credences are 55% String Theory with broken Supersymmetry, about 1-5% to Loop Quantum Gravity, and about 40-44% credence in other theories.
That means String Theory still is the most likely theory that applies to reality, but definitely not overwhelmingly confidently likely.
One other problem for String Theory is the black hole information paradox has been solved solely by normal physics, that is there is no need to posit strings to solve the paradox. Conjunctions are never likelier than their conjuncts, so solely solving the black hole information paradox using normal physics is strictly more likely than positing String Theory and the AdS/CFT correspondence.
Here’s a link:
https://www.quantamagazine.org/the-most-famous-paradox-in-physics-nears-its-end-20201029/
Well: this “solution” to the paradox was discovered by working within string theory. Then they found a way to carry out the argument at a level of approximation that doesn’t need to know what the fundamental theory is. That is the only sense in which they were able to dispense with string theory. They don’t actually have an alternative fundamental theory in which the argument can also be carried out.
Meanwhile, I put “solution” in quotes because it is far from clear what’s going on here, and how it relates to other “solutions” that have been proposed, like Mathur’s fuzzballs, Hawking et al’s soft quantum hair, and Papadodimas and Raju’s state-dependent observables. For example, is the island of quantum information in the black hole interior, a baby universe that becomes genuinely disconnected from the original space-time, or is it just a brane that buds off while remaining immersed in a common higher-dimensional space? This is related to a larger debate within string theory, about how to interpret the lower-dimensional models that are being used here.
To explain to everyone, the reason the black hole information paradox has been solved is that 2 things happened:
First, the Page Curve was resolved as, yes black holes do preserve and shed information, thus we’ve resolved whether information is destroyed as Hawking and Preskill thought, or does unitarity prevail in black holes, preserving information. Now we know that information must be preserved. Incredibly they even got it to work in our own flat universe.
Second, they got rid of both string theory and the AdS-CFT Correspondence/Holographic universe assumption, removing 2 burdensome details from the solution. It’s inspired by string theory and the AdS/CFT Correspondence/Holographic universe theories, but they don’t rely on these assumptions to solve the paradox. We’ve finally managed to get the answer without relying on burdensome details.
Now how it happens is unfortunately unsolved, and here the best theories like wormholes are pretty speculative. But we don’t need the how in order to appreciate the answer to the original Black Hole Information Paradox.
I have just done some further research, and found a rather serious criticism of the idea that “quantum extremal surfaces reproduce the Page curve, and that explains everything”. The claim is that entanglement islands only show up in theories with a massive graviton—which is very unlike our world. This claim is being emphasized by the string theorist Suvrat Raju, most recently in section 4.2 of this paper from last year. He actually mentions the article from Quanta Magazine, as an example of a “misleading” “popular description”.
His own position is that everything about real-world quantum black holes is explained by an extra nonlocality of information in quantum gravity (what he calls “holography of information”); that the Page curve is a property of any ordinary quantum system in which entanglement is leaking across a boundary; and it’s because massive gravity doesn’t possess the property of holography of information, that the Page curve shows up in that case.