An introduction to the entropy concept

A Simple Argument that is Simply Wrong Why is a page about thermodynamics in a website about origins? Because many young-earth creationists claim that evolution is thermodynamically impossible.

The macrostate of a system is what we know about the system, for example the temperaturepressureand volume of a gas in a box. For each set of values of temperature, pressure, and volume there are many arrangements of molecules which result in those values.

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The number of arrangements of molecules which could result in the same values for temperature, pressure and volume is the number of microstates.

The concept of entropy has been developed to describe any of several phenomena, depending on the field and the context in which it is being used. Information entropy takes the mathematical concepts of statistical thermodynamics into areas of probability theory unconnected with heat and energy.

Ice melting provides an example of entropy increasing Example of increasing entropy[ An introduction to the entropy concept ] Main article: Disgregation Ice melting provides an example in which entropy increases in a small system, a thermodynamic system consisting of the surroundings the warm room and the entity of glass container, ice and water which has been allowed to reach thermodynamic equilibrium at the melting temperature of ice.

It is important to realize that the entropy of the surrounding room decreases less than the entropy of the ice and water increases: This is always true in spontaneous events in a thermodynamic system and it shows the predictive importance of entropy: Later, the term came to acquire several additional descriptions, as more was understood about the behavior of molecules on the microscopic level.

In the late 19th century, the word "disorder" was used by Ludwig Boltzmann in developing statistical views of entropy using probability theory to describe the increased molecular movement on the microscopic level. That was before quantum behavior came to be better understood by Werner Heisenberg and those who followed.

Why Thermodynamics?

Descriptions of thermodynamic heat entropy on the microscopic level are found in statistical thermodynamics and statistical mechanics. For most of the 20th century, textbooks tended to describe entropy as "disorder", following Boltzmann's early conceptualisation of the "motional" i. More recently, there has been a trend in chemistry and physics textbooks to describe entropy as energy dispersal.

Thus there are instances where both particles and energy disperse at different rates when substances are mixed together.

The mathematics developed in statistical thermodynamics were found to be applicable in other disciplines. In particular, information sciences developed the concept of information entropy which lacks the Boltzmann constant inherent in thermodynamic entropy. Heat and entropy[ edit ] At a microscopic level, kinetic energy of molecules is responsible for the temperature of a substance or a system.

Assuming an ideal-gas model, average kinetic energy increases linearly with absolute temperatureso the average speed increases as the square root of temperature.

That amount of motional energy from the surroundings that is required for melting or boiling is called the phase-change energy, specifically the enthalpy of fusion or of vaporization, respectively. This phase-change energy breaks bonds between the molecules in the system not chemical bonds inside the molecules that hold the atoms together rather than contributing to the motional energy and making the molecules move any faster — so it does not raise the temperature, but instead enables the molecules to break free to move as a liquid or as a vapor.

Phase-change energy increases the entropy of a substance or system because it is energy that must be spread out in the system from the surroundings so that the substance can exist as a liquid or vapor at a temperature above its melting or boiling point.

When this process occurs in a 'universe' that consists of the surroundings plus the system, the total energy of the 'universe' becomes more dispersed or spread out as part of the greater energy that was only in the hotter surroundings transfers so that some is in the cooler system.

This energy dispersal increases the entropy of the 'universe'. Entropy or better, entropy change is the quantitative measure of that kind of a spontaneous process:2 attheheels.comuction The concept of entropy is not easy to grasp (even for physicists) and frequently entropy is seen as very mysterious quantity.

the concept of entropy in landscape evolution by luna b. leopold and walter b.

langbein theoretical papers in the hydrologic and geomorphic sciences geological survey professional paper a united states government printing office, washington: The author defends the position that an appropriate introduction to the concept of entropy can only be made from the Information Theory.

And indeed, the robust arguments exhibited by Prof. Ben-Naim through the present work in order to show it, are overwhelming. First, some intuition. Let’s say you had to determine whether a home is in San Francisco or in New attheheels.com machine learning terms, categorizing data points is a classification task..

Since San Francisco is relatively hilly, the elevation of a home may be a good way to distinguish the two cities. The concept of information entropy was introduced by Claude Shannon in his paper "A Mathematical Theory of Communication".

Introduction to entropy and information on Principia Cybernetica Web; Entropy an interdisciplinary journal on all aspect of the entropy concept. Open access. Entropy of the Playroom Andrew Vanden Heuvel explores the concept of entropy while cleaning the playroom.. Second Law of Thermodynamics.

In classical thermodynamics, the second law of thermodynamics states that the entropy of an isolated system always increases or remains constant.

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