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

```Yes there is no loss of information* at the lowest level,* that is at the
quantum level . But at the lowest level, there is NO notion of HEAT. only
speeds and momentums of elementary particles.  HEAT and temperature and
entropy are statistical parameters, words used in the macroscopical laws to
define sum of energies and mean energies or disorder of particles because
the energy of each particle is not know at the human scale but each
particle carry all the information intact.```
```

THe post is talking about the loss of information contained in a macrostate
consisting of a phisical bit of information stored in a macroscopical
object.  For example a gate. The conservation of information on the laws of
physics refers to the information of the microstates.  not macrostates,
whose information can be lost. and loss of information in a macrostate
generate increase of entropy by the following reason:

in terms of state, an increase of entropy is produced when we pass from a
macrostate with less possible microstates to other with more possible
microstates.  At the beginning we have one macrostate , for example 1
formed by all the possible configurations of electrons in a gate when it
stores a 1.   when erased, we have a macrostate that may be one of the
possible configurations of electrons that may be in a gate with a 1 OR a 0
or a neutral state. So the entropy has increased because the new
macrostate (erased) has more microstates than the original. the disorder
has increased. How that entropy increase is produced in the erase depend on
the process. It may be by means of a short circuit in the gate. The
electrons circulate and hit the atoms producing  heat. the potential
electric energy of attraction produces cynetic energy in the atoms and heat.

The microstate-macrostate transition is the same case that happens when we
have a gas of different types confined in a room and other room empty. When
we communicate the rooms, the gas expand and fill both rooms, the entropy
increased because the final macrostate admits more possible configurations
speeds and positions of particles in the  two rooms . Something similar,
not equal, happens with gas of electrons in a gate.  Measured in
termodinamical terms, the temperature decreased and the entropy measured in
termodinamical terms  delta Q/T has increased. Q is the  thermal energy or
heat.

However the process is different. in the first case, potential energy is
dissipated and there is increase of Q, in the other the potential energy is
dissipated against the vacuum and produces reduction of T. Q/T seems to be
proportional to the number of microstates in a macrostate.

The availability of information in the form of macrostates when entropy is
low is what permits living beings to compute in order to anticipate the
future and survive. That can only happen in the direction of entropy
increase.  I wrote something all of this here:

http://www.slideshare.net/agcorona1/arrow-of-time-determined-by-lthe-easier-direction-of-computation-for-life
I

2013/12/4 meekerdb <meeke...@verizon.net>

>  On 12/3/2013 6:17 PM, freqflyer07281972 wrote:
>
>  Hey everyone,
>
> Here is a question for Bruno (and anyone else who wants to chime in) --
>
> I came across this
> post<http://www.preposterousuniverse.com/blog/2013/11/28/thanksgiving-8/>over
> at Sean Carroll's Preposterous Universe blog, wherein he seems to be
> claiming that the
> relationship between information, entropy, and physical processes is
> pretty well in the bag, i.e. it is well understood by physicists
> and it seems that the concept of information can be cashed out entirely in
> terms of physical processes.
>
>
> But if the processes are reversible (and they can be) then there is no
> entropy increase and no heat.  Feynman already outlined how this would have
> to be done in quantum computers.
>
> I think the problems are far from solved.  Black holes, in the
> semi-classical approximation seem to destroy information and there are
> various proposals for preserving the unitary evolution of quantum
> mechanics, but none that are completely satisfactory.
>
> Brent
>
>
>
> What does this do to your thought experiment and your Platonic orientation
> towards questions of information theory?
>
> How would you go about explaining the deep relationship between entropy,
> information, and the physical evolution of the universe?
>
> Cheers,
>
> Dan
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--
Alberto.

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