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Topic: Thermodynamic entropy

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  Entropy - Wikipedia, the free encyclopedia
In thermodynamics entropy S is an extensive quantity describing heat flowing between two bodies, where the corresponding intensive quantity is the temperature T.
In Boltzmann's definition, entropy is a measure of the number of possible microscopic states (or microstates) of a system in thermodynamic equilibrium, consistent with its macroscopic thermodynamic properties (or macrostate).
Entropy is the only quantity in the physical sciences that "picks" a particular direction for time, sometimes called an arrow of time.
en.wikipedia.org /wiki/Entropy   (3735 words)

 Information entropy
Entropy is a concept in thermodynamics (see thermodynamic entropy), statistical mechanics and information theory.
The entropy rate of a data source means the average number of bits per symbol needed to encode it.
Entropy effectively bounds the performance of the strongest non-lossy (or nearly non-lossy) compression possible, which can be realized in theory by using the typical set or in practice using Huffman, Lempel-Ziv or Arithmetic coding.
www.guajara.com /wiki/en/wikipedia/i/in/information_entropy.html   (497 words)

 ENTROPY   (Site not responding. Last check: 2007-10-21)
Entropy is at a maximum when the molecules in a gas are at the same energy level.
The similarity between the two types of entropy is merely formal in that both are expressed as the logarithm of a probability.
The thermodynamic entropy S = k log W is a function of the dispersion W of heat, with k being Boltzmann's CONSTANT.
pespmc1.vub.ac.be /ASC/ENTROPY.html   (143 words)

 Everything you always wanted to know about Thermodynamic entropy
The thermodynamic entropy S, often simply called the entropy in the context of chemistry and thermodynamics, is a measure of the amount of energy in a physical system which cannot be used to do work.
He defined the change in entropy of a thermodynamic system, during a reversible process in which an amount of heat δQ is applied at constant absolute temperature T, as [\delta S = \frac{\delta Q}{T}] Clausius gave the quantity S the name "entropy", from the Greek word τρoπη, "transformation".
Entropy change in heat engines Clausius' identification of S as a significant quantity was motivated by the study of reversible and irreversible thermodynamic transformations.
www.relan.net /Chemistry/Entropy.html   (2463 words)

 Entropy - Thermodynamic Properties - Engineers Edge   (Site not responding. Last check: 2007-10-21)
Because entropy is a property, changes in it can be determined by knowing the initial and final conditions of a substance.
Entropy quantifies the energy of a substance that is no longer available to perform useful work.
Entropy is sometimes referred to as a measure of the inability to do work for a given heat transferred.
www.engineersedge.com /thermodynamics/entropy_defintion.htm   (148 words)

 JCE 1999 (76) 1385 [Oct] Shuffled Cards, Messy Desks, and Disorderly Dorm Rooms - Examples of Entropy Increase? ...   (Site not responding. Last check: 2007-10-21)
The thermodynamic entropy change from human-defined order to disorder in the giant Egyptian stones themselves, in the clothing and books in a room or papers on a desk, and in the millions of cards in the world's casinos is precisely the same: Zero.
Entropy is increased in the shuffler's and in the billiard cue holder's muscles, in the tornado's wind and the earthquake's stressnot in the objects shifted.
Thermodynamic entropy changes are dependent on changes in the dispersal of energy in the microstates of atoms and molecules.
jchemed.chem.wisc.edu /Journal/Issues/1999/Oct/abs1385.html   (2401 words)

 Thermodynamic Asymmetry in Time
Thermodynamics is a ‘phenomenal’ science, in the sense that the variables of the science range over macroscopic parameters such as temperature and volume.
With all the current activity of physicists being focused on the thermodynamics of fl holes in general relativity and quantum gravity, it is amusing to note that special relativistic thermodynamics is still a field with many open questions, both physically and philosophically.
Thermodynamics is a science with very precise and definite restrictions on the applicability of its concepts.
plato.stanford.edu /entries/time-thermo   (10527 words)

There may be metaphors for entropy, which may be useful in information theory or in other approaches to understanding complex systems, but if we label these with the word "entropy," which has a very specific physical meaning, we lose sight of any real value of the term.
The maximum possible increase in entropy for a given system is found when all of the thermal energy flowing in as heat from the high temperature source, is also flowing out as heat to the low temperature sink.
From a thermodynamic standpoint it is impossible to say where in this sequence life actually begins, even though from a biochemical, or at least from a biological standpoint it might be clear that such a system could not yet be said to contain life.
www.geoman.com /jim/entropy.html   (4350 words)

 welcome to entropysite.com
In the October 2002 Journal I urged that entropy be presented as the quantity of dispersal of energy/T or by change in the number of microstates.
Their 2004 “Thermodynamics” completely omits the references to “disorder” of “messy desks” in a previous trial edition and replaces them with viewing entropy as related to how energy can be spread out in a system.
"Entropy is disorder" is an archaic, misleading definition of entropy dating from the late 19th century before knowledge of molecular behavior, of quantum mechanics and molecular energy levels, or of the Third Law of thermodynamics.
www.entropysite.com   (3643 words)

 Entropy Is Simple...If You Avoid The Briar Patches!
Entropy is the quantitative measure of that kind of spontaneous process: how much energy has flowed from being localized to becoming more widely spread out (at a specific temperature).
Entropy change is enabled in chemistry by the motional energy of molecules (or from bond energy change in a chemical reaction) but thermodynamic entropy is only actualized if the process itself (expansion, heating, mixing, reaction) makes available a larger number of microstates, a maximal Boltzmann probability at the specific temperature.
This means that, of the sunlight that strikes the plant, 70% is dispersed to the environment (an entropy increase in slightly heating the leaf and the atmosphere), while 30% is absorbed by the plant in the initial steps of photosynthesis of new complex "high-energy" substances (entropy decreased in the plant).
www.entropysimple.com /content.htm   (7966 words)

 Entropy   (Site not responding. Last check: 2007-10-21)
The thermodynamic entropy S, often simply called the entropy in the context of thermodynamics, is a measure of the amount of energy in a physical system that cannot be used to do work.
Thermodynamic entropy is closely related to information entropy.
In 1877, Boltzmann realised that the entropy of a system may be related to the number of possible "microstates" (microscopic states) consistent with its thermodynamic properties.
www.worldhistory.com /wiki/E/Entropy.htm   (2483 words)

 [No title]
Entropy has been launched as a scientific journal to provide an advanced forum for the community of entropy and information researchers.
A famous thermodynamic entropy theory is Dr. Ilya Prigogine's dissipative structure theory.
Nevertheless, diversity is good in another sense: the very diverse areas involved in the adaption and the application of the entropy concept and of those various good theories of entropy will definitely generate a very active scientific forum.
www.mdpi.org /entropy/htm/e1010001.htm   (732 words)

 [No title]
The change in thermodynamic entropy of the gas as a result of the compression depends on the distribution of the particles over the L and R compartments.
For this purpose one has to consider the behaviour of entropies at the infinite limit, and then at the limit demonstrate that the decrease in thermodynamic entropy is exactly compensated by the increase in the Von Neumann entropy.
The increase of thermodynamic entropy due to the volume increase  EMBED Equation.3  is exactly compensated by the decrease of thermodynamic mixing entropy  EMBED Equation.3  (where wk is the relative frequency of molecules of type k) due to the separation.
philsci-archive.pitt.edu /archive/00002256/01/Hemmo_Shenker_on_Von_Neumann_Entropy_Jan_2005.doc   (8191 words)

 The Second Law of Thermodynamics. by Brig Klyce
He discussed thermodynamic entropy in the section called "Entropy" of his Lectures on Physics published in 1963 (7), using physical units, joules per degree, and over a dozen equations (vol I section 44-6).
Entropies calculated in this way depend on the size-scale decided upon, in direct contradiction with thermodynamics in which entropy changes are fully objective.
Yet in his section entitled "Second Law of Thermodynamics," he says that as a thermodynamic system is put into contact with another one at a lower temperature, and thermal equilibrium is reached, the total entropy of the combined ensemble "stays constant" (p 99).
www.panspermia.org /seconlaw.htm   (4895 words)

 Cowley Lecture 20 - Thermodynamics and Chemical Equilibrium   (Site not responding. Last check: 2007-10-21)
The entropy of a pure crystal (single substance) at a temperature of 0° K is 0.
Discipline of thermodynamics was one of the triumphs of nineteenth century science.
Entropy is a measure of the probability of a system, so the second law says any system will change naturally to reach its most probable state.
www.astro.lsa.umich.edu /users/cowley/lecture20   (4185 words)

 THERMODYNAMIC ENTROPY   (Site not responding. Last check: 2007-10-21)
Some waste may be utilized in processes other than those generating it (see recycling) but the ultimate waste which can no longer support any process is energy in the form of dispersed heat (see second law of thermodynamics).
All physical process, despite any local and temporal concentration of energy they may achieve, contribute to the increased overall dispersion of heat.
Entropy therefore irreversibly increases in the known universe.
pespmc1.vub.ac.be /ASC/THERMO_ENTRO.html   (95 words)

 AMS Glossary
—A thermodynamic state variable denoted by S (s denotes specific entropy, entropy per unit mass).
The rate of change of entropy of a thermodynamic system is defined as
The entropy of an isolated system cannot decrease in any real physical process, which is one statement of the second law of thermodynamics.
amsglossary.allenpress.com /glossary/search?id=entropy1   (130 words)

 Relation to thermodynamic entropy
In thermodynamics, the change in entropy in a reversible process which transforms the system from state 1 to state 2 is
We can now ask if the entropy obtained starting from the microscopic description agrees with the standard thermodynamic definition.
These two examples illustrate that the statistical approach agrees exactly with the standard thermodynamic definition of entropy.
www.nyu.edu /classes/tuckerman/stat.mech/lectures/lecture_6/node3.html   (199 words)

 Mailing List complex-science@necsi.org Message 3471
Entropy that is numerically equal to the Thermodynamic entropy given
> >to an entropy measure that is identical to thermodynamic entropy
>to an entropy measure that is identical to thermodynamic entropy
necsi.org:8100 /Lists/complex-science/Message/3471.html   (1765 words)

 PCC - Philosophy, Cosmology & Consciousness News   (Site not responding. Last check: 2007-10-21)
The Benard cell experiment is carried out in a flat circular dish filled with a thin layer of water, which is uniformly heated from below in a controlled manner.
While this may be a very useful critique of the 19th century idea that all physical systems tend toward a state of greater disorder, it really has very little to do with the thermodynamic behavior of living systems.
Thus, the claim that the Benard cell creates increased entropy as rapidly as possible├Žoften erroneously referred to as "efficiently"├Žappears to be a correct (Swenson, 1989/1997).
www.ciis.edu /pcc/STUDENTS/fournier.html   (4379 words)

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