On 1/27/2012 11:47 PM, Evgenii Rudnyi wrote:

On 27.01.2012 23:03 meekerdb said the following:On 1/27/2012 12:43 PM, Evgenii Rudnyi wrote:On 27.01.2012 21:22 meekerdb said the following:On 1/27/2012 11:21 AM, Evgenii Rudnyi wrote:On 25.01.2012 21:25 meekerdb said the following:On 1/25/2012 11:47 AM, Evgenii Rudnyi wrote:...Let me suggest a very simple case to understand better what you are saying. Let us consider a string "10" for simplicity. Let us consider the next cases. I will cite first the thermodynamic properties of Ag and Al from CODATA tables (we will need them)## Advertising

S ° (298.15 K) J K-1 mol-1 Ag cr 42.55 ą 0.20 Al cr 28.30 ą 0.10 In J K-1 cm-3 it will be Ag cr 42.55/107.87*10.49 = 4.14 Al cr 28.30/26.98*2.7 = 2.83 1) An abstract string "10" as the abstract book above. 2) Let us make now an aluminum plate (a page) with "10" hammered on it (as on a coin) of the total volume 10 cm^3. The thermodynamic entropy is then 28.3 J/K. 3) Let us make now a silver plate (a page) with "10" hammered on it (as on a coin) of the total volume 10 cm^3. The thermodynamic entropy is then 41.4 J/K. 4) We can easily make another aluminum plate (scaling all dimensions from 2) to the total volume of 100 cm^3. Then the thermodynamic entropy is 283 J/K. Now we have four different combinations to represent a string "10" and the thermodynamic entropy is different. If we take the statement literally then the information must be different in all four cases and defined uniquely as the thermodynamic entropy is already there. Yet in my view this makes little sense. Could you please comment on this four cases?The thermodynamic entropy is a measure of the information required to locate the possible states of the plates in the phase space of atomic configurations constituting them. Note that the thermodynamic entropy you quote is really the *change* in entropy per degree at the given temperature. It's a measure of how much more phase space becomes available to the atomic states when the internal energy is increased. More available phase space means more uncertainty of the exact actual state and hence more information entropy. This information is enormous compared to the "01" stamped on the plate, the shape of the plate or any other aspects that we would normally use to convey information. It would only be in case we cooled the plate to near absolute zero and then tried to encode information in its microscopic vibrational states that the thermodynamic and the encoded information entropy would become similar.I would say that from your answer it follows that engineering information has nothing to do with the thermodynamic entropy. Don't you agree?Obviously not since I wrote above that the thermodynamic entropy is a measure of how much information it would take to locate the exact state within the phase space allowed by the thermodynamic parameters.Does this what engineers use when they develop communication devices?It would certainly interesting to consider what happens when we decrease the temperature (in the limit to zero Kelvin). According to the Third Law the entropy will be zero then. What do you think, can we save less information on a copper plate at low temperatures as compared with higher temperatures? Or more?Are you being deliberately obtuse? Information encoded in the shape of the plate is not accounted for in the thermodynamic tables - they are just based on ideal bulk material (ignoring boundaries).I am just trying to understand the meaning of the term information that you use. I would say that there is the thermodynamic entropy and then the Shannon information entropy. The Shannon has developed a theory to help engineers to deal with communication (I believe that you have also recently a similar statement). Yet, in my view when we talk about communication devices and mechatronics, the information that engineers are interested in has nothing to do with the thermodynamic entropy. Do you agree or disagree with that? If you disagree, could you please give an example from engineering where engineers do employ the thermodynamic entropy as the estimate of information.I already said I disagreed. You are confusing two different things. Because structural engineers don't employ the theory of interatomic forces it doesn't follow that interactomic forces have nothing to do with sturctural properties. BrentYou disagree that engineers do not use thermodynamic entropy

`Yes. I disagreed that information "has nothing to do with thermodynamic entropy", as you`

`wrote above. You keep switching formulations. You write X and ask if I agree. I`

`disagree. Then you claim I've disagreed with Y. Please pay attention to your own`

`writing. There's a difference between "X is used in place of Y" and "X has nothing to do`

`with Y".`

but you have not shown yet how information in engineering is related with thethermodynamic entropy. Form the Millipede example>> http://en.wikipedia.org/wiki/Millipede_memory"The earliest generation millipede devices used probes 10 nanometers in diameter and 70nanometers in length, producing pits about 40 nm in diameter on fields 92 µm x 92 µm.Arranged in a 32 x 32 grid, the resulting 3 mm x 3 mm chip stores 500 megabits of dataor 62.5 MB, resulting in an areal density, the number of bits per square inch, on theorder of 200 Gbit/in²."If would be much easier to understand you if you say to what thermodynamic entropycorresponds the value of 62.5 MB in Millipede.

`The Shannon information capacity is 5e8 bits. The thermodynamic entropy depends on the`

`energy used to switch a memory element. I'd guess it must correspond to at least few tens`

`of thousands of electrons at 9v, so`

S ~ [5e8 * 9e4 eV]/[8.6e-5 eV/degK * 300degK]~17e15

`So the total entropy is about 17e15+5e8, and the information portion is numerically (but`

`not functionally) negligible compared to the thermodynamic.`

Brent

The only example on Thermodynamic Entropy == Information so far from you was the work ona black hole. However, as far as I know, there is no theory yet to describe a blackhole, as from one side you need gravitation, from the other side quantum effects. Thetheory that unites them seems not to exist.EvgeniiMy example would be Millipede http://en.wikipedia.org/wiki/Millipede_memory I am pretty sure that when IBM engineers develop it, they do not employ the thermodynamic entropy to estimate its information capabilities. Also, the increase of temperature would be destroy saved information there. Well, I might be deliberately obtuse indeed. Yet with the only goal to reach a clear definition of what the information is. Right now I would say that there is information in engineering and in physics and they are different. The first I roughly understand and the second not. EvgeniiBrent

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