|1 Nicolaas Vroom
|Scientific American Black Hole Mysteries Solved
|Friday 14 October 2022
|2 Phillip Helbig
|Re :Scientific American Black Hole Mysteries Solved
|Saturday 15 October 2022
Scientific American Black Hole Mysteries Solved.
In Scientific American Sept 2022 there are 4 articles about Black Holes.
Here I want to discuss the paper "Paradox Resolved" at page 28.
This document starts with the sentence: "A few years ago a team of chemists unboiled an egg." For more detail select this: https://www.washingtonpost.com/news/speaking-of-science/wp/2015/01/28/how-and-why-chemists-figured-out-how-to-unboil-an-egg/
Next we can read: "The technique is of dubious utility in a kitchen, but it neatly demonstrates the reversibility of physics. Anything in the physical world can run both ways -- it's one of the deepest features of the laws of physics, reflecting elemental symmetries of space, time and causality."
I have a problem with this. Not so much from a mathematical point because we can claim that Newton's Law is time reversible.
But from a physical point. A heating process requires heating equipment (or the sun) to heat the water. A cooling process requires cooling equipment to cool the water. That is why a heating process and a cooling process are not time reversible. (Specific if they include certain cyclic patterns, like the human life cycle)
All these processes are physical irreversible.
Next we read: "But there's a troubling exception: black holes." and: "The black hole does not seem to preserve information. This irreversibility, first appreciated by physicist David Finkelstein in 1958, was the earliest inkling of the black hole information paradox -- "paradox" because how could reversible laws have irreversible effects?" The first question is: can we speak of a paradox?
To investigate you must investigate in more detail what is involved.
Consider what happens when you throw a book in an oven.
It starts to burn and slowly the book 'disappears' and what is left over is ash. This is also a irreversible physical proces. It is impossible, assuming that all what happens after you burn is ash, to recreate the object i.e. the book, which was burned. Besides burning a book on earth, you can also place the book in space ship and let the space ship collide with the sun. Also that is an irreversible process. The space ship can also collide with a black hole and you get exactly the same. The book is lost and cann't recreated.
What has this to do with information?
Assume, what you are reading now, is not an e-mail but text in a book. In that case both the book and the written text is something physical. That is what can burn and return to ash. The contents of the text written in the english language was information in the mind of the person who wrote the book and becomes information in your mind when you read the text. This contents is also irreversible lost when you burn the book.
Is there something what you can call "information paradox"?
I don't think so. All what happens, when something disappears in a BH, is lost forever and can't recreated. The same for our Sun, or when you burn something in a fire.
If you agree, than a lot what is written in the article 1: "Paradox
resolved" has to be rewritten because there they try to solve the
paradox (part of) by using entanglement.
In article 2, at page 36/37 you can read that in order to solve the information paradox, Wormholes are required. In article 3, at page 42/43 as a consequence of the information paradox, the holographic principle is introduced.
In a laboratory the evolution of many chemical reactions evolve towards
a type of equilibrium. Suppose you have A+B --> C+D That means if you
start with 50% A and 50% B than reaction will evolve and STOP when you
get 25% A, 25%B and 25%C and 25%D.
Now you can do two things:
1) Remove C and D. Now you get 12,5% A, 12,5%B and 12,5%C and 12,5%D.
2) Remove A and B. Now you get 12,5% A, 12,5%B and 12,5%C and 12,5%D. but the reaction is now: C+D --> A+B This is in the opposite direction.
However to do that, human intervention is required, which is not available in the processes part of the evolution of the Universe. And this has nothing to do with time reversibility part of Newton's Law. And has 'nothing' to do with the behaviour of a BH.
|In Scientific American Sept 2022 there are 4 articles about Black Holes.
|"But there's a troubling exception: black holes." and: "The black hole does not seem to preserve information. This irreversibility, first appreciated by physicist David Finkelstein in 1958, was the earliest inkling of the black hole information paradox
Jonathan might know more about this topic, but I think that the resolution of the "information paradox" is still not completely clear. However...
|Consider what happens when you throw a book in an oven. It starts to burn and slowly the book 'disappears' and what is left over is ash. This is also a irreversible physical proces. It is impossible, assuming that all what happens after you burn is ash, to recreate the object i.e. the book, which was burned.
...I think that your description is irrelevant, because one could IN
PRINCIPLE reconstruct the book from the ashes and smoke. Impractical?
Yes? Will it ever happen? Probably not.
But the claim that information is lost forever in black holes (possibly with the caveat that that only applies to classical black holes, not taking Hawking evaporation into account) is the claim that it is impossible even in principle to recover it.
Something similar might be the probability that the water in a kettle on a fire might freeze instead of boil. According to the laws of physics, it is possible, but EXTREMELY unlikely. Especially with thought experiments, one has to distinguish between things which are REALLY impossible, and things which are just really difficult and/or really improbable.
[[Mod. note -- A few points:
1. Alas, I know very little about the information paradox.
2. Wikipedia has what looks like a nice article on it: https://en.wikipedia.org/wiki/Black_hole_information_paradox
3. I also know very little about the history of the information paradox, but I doubt that it's correct to credit Finkelstein (1958) with being the first person to appreciate that black holes don't preserve information. Finkelstein's 1958 paper discusses the causal nature of what today we would call a black hole's event horizon, but he only refers to "causal influences" (i.e., matter or energy), not "information" in the sense of the information paradox.
4. To clarify, when Phillip says that *in principle* one can reconstruct the book from the ashes and smoke, he is writing in a "Maxwell's demon" since: all the original atoms of the book are still present in the ashes and smoke, so one could in principle (i.e., by using nanotechnology but without violating any laws of physics) move those atoms back into their original "book" positions and give them back their original room-temperature-thermal-energy velocities, thus re-forming the chemical bonds which were broken by the combustion process and recreating the original book. -- jt]]
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