Re: Request: computation=thermodynamics paper(s)

[Evgenii Rudnyi]

On 15.04.2011 21:44 meekerdb said the following:

Entropy and information are related. In classical thermodynamics the
 relation is between what constraint you impose on the substance and
 dQ/T. You note that it is calculated assuming constant pressure -
that is a constraint; another is assuming constant energy. In terms
of the phase space in a statistical mechanics model, this is
confining the system to a hypersurface in the the phase space. If you
had more information about the system, e.g. you knew all the
molecules were moving the same direction (as in a rocket exhaust)
that you further reduce the part of phase space and the entropy. If
you knew the proportions of molecular species that would reduce it
further. In rocket exhaust calculations the assumption of fixed
species proportion is often made as an approximation - it's referred
to as a frozen entropy calculation. If the species react that changes
the size of phase space and hence the Boltzmann measure of entropy.

Brent


First how do you define information? According to Shannon?

Then if we consider a thermodynamic system, the Second Law

dS = dQ/T

does not impose constraints as such. It is held for any closed system 
and for any process. The only assumption here is that the system 
possesses a temperature. If one can define temperature than the entropy 
follows according to the Second Law unambiguously and I do not see how 
one additionally will need information, whatever it means.


If you speak about reaction chemistry, let us consider a simple exercise 
from classical thermodynamics.


Problem. Given temperature, pressure, and initial number of moles of
NH3, N2 and H2, compute the equilibrium composition.

To solve the problem one should find thermodynamic properties of NH3, N2 
and H2 for example in the JANAF Tables and then compute the equilibrium 
constant.


From thermodynamics tables (all values are molar values for the 
standard pressure 1 bar, I have omitted the symbol o for simplicity but 
it is very important not to forget it):


Del_f_H_298(NH3), S_298(NH3), Cp(NH3), Del_f_H_298(N2), S_298(N2), 
Cp(N2), Del_f_H_298(H2), S_298(H2), Cp(H2)


2NH3 = N2 + 3H2

Del_H_r_298 = Del_f_H_298(N2) + 3 Del_f_H_298(H2) - 2 Del_f_H_298(NH3)

Del_S_r_298 = S_298(N2) + 3 S_298(H2) - 2 S_298(NH3)

Del_Cp_r = Cp(N2) + 3 Cp(H2) - 2 Cp(NH3)

To make life simple, I will assume below that Del_Cp_r = 0, but it is 
not a big deal to extend the equations to include heat capacities as well.


Del_G_r_T = Del_H_r_298 - T Del_S_r_298

Del_G_r_T = - R T ln Kp

When Kp, total pressure and the initial number of moles are given, it is 
rather straightforward to compute equilibrium composition. So, the 
entropy is there. What do you mean when you state that information is 
also involved? Where is in this example the related information, again 
whatever it is?


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Re: [OT] Love and free will

[Rex Allen]

On Sat, Apr 16, 2011 at 4:41 AM, Evgenii Rudnyi use...@rudnyi.ru wrote:
 On 15.04.2011 21:16 Rex Allen said the following:

 On Fri, Apr 15, 2011 at 3:45 AM, Bruno Marchalmarc...@ulb.ac.be
 wrote:

 I think it is a bit dangerous, especially that there is already a
 social tendency to dissolve responsibility among those taking
 decisions.

 Rewarding bad behavior will get you more bad behavior - but this is
 a consequence of human nature, and has nothing to do with free will.

 Even if we take a purely deterministic, mechanistic view of human
 nature, the question remains:  What works best in promoting a
 well-ordered society?

 Society, in that crime is only an issue when you have more than one
 person involved.

 Is more criminal behavior due to correctable conditions that can be
 alleviated through education programs or by a more optimal
 distribution of the wealth that is generated by society as a whole?
 In other words, can criminal behavior be minimized proactively?

 Or is most criminal behavior an unavoidable consequence of human
 nature, and thus deterrence by threat of punishment is the most
 effective means of minimizing that behavior?  In other words, can
 criminal behavior only be addressed reactively?

 The question is:  As a practical matter, what works best?

 What results in the greatest good for the greatest number?  Whatever
 it is, I vote we do that.

 It seems that your question As a practical matter, what works best?
 implies that there is still some choice. Could you please comment on how
 such a questions corresponds to your position in respect on free will?

That I don’t believe in free will doesn’t imply that I shouldn't act.
It just means that I don’t believe that I am the ultimate author of my
actions.

A welding robot in a car factory has no free will, and yet it goes
about it’s business anyway.  Free will is not required for action.

If the robot reacts to sensor input, it’s reactions don't require free
will in order to explain.

And neither do my actions and reactions require free will to explain.
Determinism, randomness, or some mixture of the two are sufficient for
explanation.

But even without free will, I still have things that I want.  And if I
want to do something and I’m able to do it, then I will do it.  If I
don’t want to do something, then I won’t.  Determinism doesn’t change
this...it just states that I don’t *freely choose* what I want or how
I act on those wants.

What ultimately matters to me is the quality of my experiences.  And I
act accordingly.  When my head hurts, I take aspirin.  But a robot
could be programmed to make that same kind of “choice”:  if damage
detected, then activate repair routines.  It's not indicative of free
will.

Returning to your original question - I want to live in a well ordered
society, and I act accordingly...by voting that we focus on pragmatic
solutions, and by advising against muddying the water with nonsensical
concepts like free will and moral responsibility that come with
compatibilism.

Why do I want to live in a well ordered society, and why do I feel
that the approach mentioned above is the best way to achieve that
goal?  Why does it matter to me?

Well...to the extent that this isn't determined by the causal
structure of reality, it's random.

But it still matters to me, even though I recognize that it doesn't
matter in any other sense.  And this subjective meaning is enough.

The libertarians and compatibilists are focused on the wrong thing.
It’s not the choices that matter...it’s the experience.

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