Re: Question for Bruno Regarding the question of whether information is physical.

```As far as I remember, the entropy of the black hole is measured in absolute
terms. that is, taking the information from the most fundamental level, at
the Planck scale. But the entropy of a jar is relative to the jar broken
state, not absolute.```
```
The example of a gas is more clear than the one of the jar, which is full
of traps: A  hot gas that is cooled suffer a decrease of entropy measurable
by a thermodinamical formula or a change in the partition function using
statistical mechanics, whatever you like, , But this decrease is relative.
There is no aim to measure absolute entropy.in statistical mechanincs, the
zero of entroy is at temperature 0. conisidering the atoms as points. but
this is just a model upon which calculate relative states of entropy.

But this decrease is the same that if it were calculated in absolute terms,
since the extra entropy beelow the ground state cancel out.

delta H=  (H +HF) -(H2-HF)

here HF is the information that is not  considered below the ground state
up to the planch level. H is the termodinamical information.. Since HF does
not vary (the atoms stay as atoms) it cancel out when calculating
differences of entrophy or information)

For the same purpose, we can considerate other ground states to calculate
increases or decreases of entropy or information. For example in a logic
gate we can consider as ground state the gate discharged, with no regard
for temperature changes, or more accurately, the gate at a certain
temperature. Then the gain or loss of information is easily calculable.

2013/12/5 LizR <lizj...@gmail.com>

> On 5 December 2013 21:53, Alberto G. Corona <agocor...@gmail.com> wrote:
>
>> I´m very interested in what you question. One of the wonders of life is
>> how a living being select relevant information from the environment for
>> their needs. I think that the aestetic sense is a heavy part of the
>> activity of the mind at the unconscious level. Form recognition is
>> computation intensive. It is also very puzzling for me how accurately
>> people recognize intuitively  order or disorder in agreement with what
>> would be the real entropy calculated in physical terms.
>>
>>  It seems that the  filtering of information that is not relevant and to
>> deal with what is relevant has been one of the main evolutionary pressures.
>> A recognized pattern (for example, a porcelain jar with all its details,
>> can be assimilated to a macrostate in entropic terms. A broken porcelain
>> jar reduced to dust makes it undistinguisable from other jars and also
>> unusable for doing a work. For example to transport water. That is why life
>> needs to use low entropic things that can be recognized as interesting
>> patterns.
>>
>
> The vase is only distinct from the dust when viewed above a certain level
> of "coarse graining" - so how does one assign it entropy? It seems like
> entropy exists at our level, but not at the bottom level of atoms and so
> on. Yet a black hole can be assigned an entropy, and you can't get much
> more fundamental than that. It seems to me that there is something missing
> between the thermodynamic "coarse-grained" idea of entropy and the
> (presumable fundamental level) black hole entropy. How is that possible,
> that the same thing exists in two different ways on two different levels,
> one of which appears to be emergent? (Am I missing something important
> here?)
>
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--
Alberto.

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