Re: Ludwig Boltzmann, entropy

Paul J Gans <gans@xxxxxxxxx> wrote or quoted:
> Tim Tyler <tim@xxxxxxxxxxx> wrote:
> >rnorman <rnorman@xxxxxxxxx> wrote or quoted:

> >> The fact is, information in the Shannon sense is most definitely a
> >> notion closely related in formulation to the statistical dynamical
> >> notion of entropy as a measure of a subset of states. Tim Tyler is
> >> sort of partially on the right track. Paul Gans is correct, though.
> >> It is NOT true that entropy is an information-theoretic notion. I
> >> don't believe any information theorist really claims this.
>
> >Entropy *is* in information theoretic notion. It is just not
> >*only* an information theoretic notion.
>
> >Where it's important to distinguish between the terms, people use
> >terms like "information entropy" and "thermodynamic entropy".
>
> >The distinction is pretty irrelevant to this thread, though.
>
> >The discussion started with the question of whether the number of
> >microstates in physical systems was known. They are not known for any
> >physical system - unless you adopt a notion of microstates tht bundles
> >similar velocities together, and call them indistinguishable - and if
> >you do that there's no generally agreed-upon framework that dictates
> >what granularity of "bucket" you can use - and different size buckets
> >produce different results for the number of microstates involved.
>
> I'm sorry but this is wrong. And has been known to be wrong
> since about 1910. That was the period in which Sakur and
> Tetrode worked out the size of a microstate. It turned out
> to be Planck's constant to the third power.
>
> With the development of quantum mechanics and the Heisenberg
> uncertainty principle came an understanding of *why* that
> was the size of a microstate.

Microstates don't have a size. They are configurations.
Classically, each microstate of a system is a statement about
the position, momentum and nature of particles in the system.

> This isn't just speculation. That's the number you need
> to use in the appropriate equations to calculate the entropy.
> And that entropy agrees with experiment.
>
> Got it?

No. There may be more states than you claim - or fewer states.

HUP doesn't place a limit on the number of states the universe
can take, it's a limit on what knowledge embedded observers
can obtain about that state - a different concept.

The entropies calculatied using Boltzmann's constant from thermodynamic
parameters are based on hypotheses about the particulate nature of
matter, the lack of other properites apart from positon and velocity,
the assumption that all the relevant particles are known about, and
speculation about the granularity of the universe. The results from
this model may be interesting - but they should not be mistaken for
what's going on in the real world in any volume of spacetime.
--
__________
|im |yler http://timtyler.org/ tim@xxxxxxxxxxx Remove lock to reply.

.

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