First thank you for your time. Your answers as well as answers of other
participants has helped me to understand better the opposite viewpoint
and better to organize my thoughts.
You are right that the best is to study a good book but first I have
already a stack of books to read and second reading a book alone is
usually boring. I like much more to clear a question in a discussion. It
is more enjoyable.
What I will probably do is read more about the history development with
Maxwell's demon that John has mentioned. Somehow I have missed it.
I believe that it is normal when we have different opinions but I hope
that my emails has helped you to understand the opposite viewpoint better.
As for engineers and physicists, I do not know. Let us take for example
a landfill. There are too many of them in the modern society and
engineers are trying to find a solution to reuse waste. An open
question: Does your statement that all physical processes are not
irreversible will help engineers to find a better solution?
Finally the JANAF Tables assume that the magnetic field is zero. If it
is not, then one has to add a corresponding term.
On 27.02.2012 20:43 meekerdb said the following:
> On 2/27/2012 10:59 AM, Evgenii Rudnyi wrote:
>> On 27.02.2012 00:13 meekerdb said the following:
>>> On 2/26/2012 5:58 AM, Evgenii Rudnyi wrote:
>>>> I have written a summary for the discussion in the subject:
>>>> http://blog.rudnyi.ru/2012/02/entropy-and-information.html >>>>
>>>> No doubt, this is my personal viewpoint. If you see that I have
>>>> missed something, please let me know.
>>> I think you are ignoring the conceptual unification provided by
>>> information theory and statistical mechanics. JANAF tables only
>>> consider the thermodynamic entropy, which is a special case in which
>>> the macroscopic variables are temperature and pressure. You can't
>>> look up the entropy of magnetization in the JANAF tables.
>> I do not get your point. JANAF Tables have been created to solve a
>> particular problem. If you need change in concentration, surface
>> effects, magnetization effects, you have to extend the JANAF Tables.
>> And this has been to solve particular problems. Experimental
>> thermodynamics is not limited to JANAF Tables. For example, the
>> databases in Thermocalc already include dependence on concentration.
> And you don't get my point. Of course all forms of entropy can be
> measured and tabulated, but the information theory viewpoint shows how
> they are unified by the same concept.
>>> magnetization of small domains is how information is stored on hard
>>> disks, c.f. Donald McKay's book "Information Theory, Inference, and
>>> Learning Algorithm" chapter 31.
>> Do you mean that when we consider magnetization, then the entropy
>> become subjective, context-dependent, and it will be finally filled
>> with information?
> It is context dependent in that we consider the magnetization. What does
> the JANAF table assume about the magnetization of the materials it
>>> Did you actually read E. T. Jaynes 1957 paper in which he introduced
>>> the idea of basing entropy in statistical mechanics (which you also
>>> seem to dislike) on information? He wrote "The mere fact that the
>>> same mathematical expression -SUM[p_i log(p_i)] occurs in both
>>> statistical mechanics and in information theory does not in itself
>>> establish a connection between these fields. This can be done only by
>>> finding new viewpoints from which the thermodynamic entropy and
>>> information-theory entropy appear as the same /concept/." Then he
>> I have missed this quote, I have to add it. In general, the first
>> Jaynes's paper is in a way reasonable. I wanted to better understand
>> it, as I like maximum likelihood, I have been using it in my own
>> research a lot. However, when I have read in Jaynes's second paper the
>> following (two quotes below), I gave up.
>> “With such an interpretation the expression “irreversible process”
>> represents a semantic confusion; it is not the physical process that
>> is irreversible, but rather our ability to follow it. The second law
>> of thermodynamics then becomes merely the statement that although our
>> information as to the state of a system may be lost in a variety of
>> ways, the only way in which it can be gained is by carrying out
>> further measurements.”
>> “It is important to realize that the tendency of entropy to increase is
>> not a consequence of the laws of physics as such, … . An entropy
>> increase may occur unavoidably, due to our incomplete knowledge of the
>> forces acting on a system, or it may be entirely voluntary act on our
>> This I do not understand. Do you agree with these two quotes? If yes,
>> could you please explain, what he means?
> Yes. The physical processes are not irreversible. The fundamental
> physical laws are time reversible. The free-expansion of a gas is
> *statistically* irreversible because we cannot follow the individual
> molecules and their correlations, so when we consider only the
> macroscopic variables of pressure, density, temperature,... it seems
> irreversible. In very simple systems we might be able to actually follow
> the microscopic evolution of the state, but we can choose to ignore it
> and calculate the entropy increase as though this information were lost.
> Whether and how the information is lost is the crux of the measurement
> problem in QM. Almost everyone on this list assumes Everett's multiple
> worlds interpretation in which the information is not lost but is
> divided up among different continuations of the observer.
>>> goes on to show how the principle of maximum entropy can be used to
>>> derive statistical mechanics. That it *can* be done in some other
>>> way, and was historically as you assert, is not to the point. As an
>>> example of how the information view of statistical mechanics extends
>>> its application he calculates how much the spins of protons in water
>>> would be polarized by rotating the water at 36,000rpm. It seems you
>>> are merely objecting to "new viewpoints" on the grounds that you can
>>> see all that you /want/ to see from the old viewpoint.
>>> Your quotation of Arnheim, from his book on the theory of entropy in
>>> art, just shows his confusion. The Shannon information, which is
>>> greatest when the system is most disordered in some sense, does not
>>> imply that the most disordered message contains the greatest
>>> information. The Shannon information is that information we receive
>>> when the *potential messages* are most disordered. It's a property of
>>> an ensemble or a channel, not of a particular message.
>> It is not a confusion of Arnheim. His book is quite good.
> Then why doesn't he know that Shannon's information does not refer to
> particular messages?
>> To this end, let me quote your second sentence in your message.
>> > I think you are ignoring the conceptual unification provided by
>> > information theory and statistical mechanics.
>> You see, I would love to understand the conceptual unification.
> I find that doubt this. If you really loved to understand it there is
> lots of material online as well as good books which Russell and I have
>> To this end, I have created many simple problems to understand this
>> better. Unfortunately you do not want to discuss them, you just saying
>> general words but you do not want to apply it to my simple practical
>> problems. Hence it is hard for me to understand you.
>> If to speak about confusion, just one example. You tell that the
>> higher temperature the more information the system has. Yet, engineers
>> seems to be unwilling to employ this knowledge in practice. Why is
>> that? Why engineers seem not to be impressed by the conceptual
> I'm not an expert on this subject and it has been forty years since I
> studied statistical mechanics, which is why I prefer to refer you to
> experts. Engineers are generally not impressed with conceptual
> unification; they are interested in what can be most easily and reliably
> applied. RF engineers generally don't care that EM waves are really
> photons. Structural engineers don't care about interatomic forces, they
> just look yield strength in tables. Engineers are not at all concerned
> with 'in principle' processes which can only be realized in carefully
> contrived laboratory experiments. But finding unifying principles is the
> job of physicists.