How do black holes destroy information and why is that a problem?
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How do black holes destroy information and why is that a problem?
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Re: How do black holes destroy information and why is that a problem?
#2This was actually a really accessible description for a layperson. Thank you.
Re: How do black holes destroy information and why is that a problem?
#3This was actually a really accessible description for a layperson. Thank you.
> Think of mixing dough. You’ll never be able to unmix it in practice. But if only you could arrange precisely enough the position of each single atom, you could very well unmix the dough. The same goes for burning a piece of paper. Irreversible in practice. But in principle, if you only knew precisely enough the details of the smoke and the ashes, you could reverse it.
This was a nice description of entropy.
Re: How do black holes destroy information and why is that a problem?
#4To save you the read, the summation is in the second-to-last paragraph:
>As you have probably noticed, I didn’t say anything about information. That’s because really the reference to information in “black hole information loss” is entirely unnecessary and just causes confusion. The problem of black hole “information loss” really has nothing to do with just exactly what you mean by information. It’s just a term that loosely speaking says you can’t tell from the final state what was the exact initial state.
Re: How do black holes destroy information and why is that a problem?
#5> The important thing is that all evolution equations that we know of are time-reversible.
I've heard this before, but it's so surprising to me, when one of the simplest mathematical operations - addition - is not reversible. e.g. if a+b=4, you can't infer the values of a and b (beyond their linear relationship). This non-injectivity is a kind of summarising, with less information, where more than one state maps to one.
So "evolution equations" (reality) are not like addition; state changes never summarise.
Re: How do black holes destroy information and why is that a problem?
#6> The important thing is that all evolution equations that we know of are time-reversible. I've heard this before, but it's so surprising to me, when one of the simplest mathematical operations - addition - is not reversible. e.g. if a+b=4 , you can't infer the values of a and b (beyond their linear relationship). This non-injectivity is a kind of summarising, with less information, where more than one state maps to…
It is not reversible because you’re ereasing information. If you want to have a reversible addition you are not allowed to destroy the information.
The same happens if you apply the standard AND operator to two bits because the output is only one bit, therefore it is impossible to figure out the two input bits. To have a reversible AND operator you can define it like this: f(x1, x2, b) = (x1, x2, b XOR (x1 AND x2)). E.g: f(1,1,0) = (1,1,1). From this output you can get back to the input. This way you can implement a NOT gate as well, and all others gates. At the end you can implement addition using bits and your summation becomes reversible :) You can see that with this definition we are not ereasing any information, hence it becomes reversible.
Re: How do black holes destroy information and why is that a problem?
#7Do they destroy information? Last I checked they don't: https://physics.stackexchange.com/questions/29175/why-is-inf...
Maybe there is some recent development I am not aware of an Susskind is wrong though.
More:
- https://physics.stackexchange.com/questions/450326/why-is-th...
Re: How do black holes destroy information and why is that a problem?
#8Do they destroy information? Last I checked they don't: https://physics.stackexchange.com/questions/29175/why-is-inf... Maybe there is some recent development I am not aware of an Susskind is wrong though. More: - https://physics.stackexchange.com/questions/450326/why-is-th...
That’s why it’s a problem — the two best tested laws of physics contradict each other.
Re: How do black holes destroy information and why is that a problem?
#9> The important thing is that all evolution equations that we know of are time-reversible. I've heard this before, but it's so surprising to me, when one of the simplest mathematical operations - addition - is not reversible. e.g. if a+b=4 , you can't infer the values of a and b (beyond their linear relationship). This non-injectivity is a kind of summarising, with less information, where more than one state maps to…
The difference between them is that physical evolution takes one state to another state, whereas addition takes two numbers to another number.
Re: How do black holes destroy information and why is that a problem?
#10Do they destroy information? Last I checked they don't: https://physics.stackexchange.com/questions/29175/why-is-inf... Maybe there is some recent development I am not aware of an Susskind is wrong though. More: - https://physics.stackexchange.com/questions/450326/why-is-th...
That’s why it’s a problem — the two best tested laws of physics contradict each other.
Which law of physics say information must be lost in a black hole?
AFAIK if information is lost in a black hole it will also violate the second law of thermodynamics - so really you have many many laws saying it cannot be lost - and Hawking temporarily claimed it will be lost in black holes before recanting and saying it won't.
So ... I don't quite follow. I mean this title is as concerning to me as something that claims the earth is flat.