Lecture

Statistical Definition of Entropy

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In course

PHYS-106(h): General physics : thermodynamics

Le but du cours de Physique générale est de donner à l'étudiant les notions de base nécessaires à la compréhension des phénomènes physiques. L'objectif est atteint lorsque l'étudiant est capable de prévoir quantitativement les conséquences de ces phénomène ...

Description

This lecture explores the statistical definition of entropy, revealing the true reason behind the second law of thermodynamics and discussing the third principle of thermodynamics. By analyzing the microscopic interpretation of Joule's expansion, the instructor explains the concept of entropy as a measure of multiplicity and probability of macroscopic states. The lecture demonstrates the equivalence between macroscopic and microscopic entropy, highlighting the importance of maximizing probability in natural processes. Through examples like Joule's expansion and coin tossing, the lecture elucidates why improbable events never occur in nature due to the vast number of particles involved. Additionally, it delves into the concept of zero entropy, which corresponds to absolute zero temperature according to the Nernst principle, the third law of thermodynamics.

Instructor

Ivo Furno

Teaching & PhD PhD Students Jules Amédée Aristobule Schadt, Renat Karimov, Amélie Renggli, Yuri Asnis, Michael Goddijn, Vanni Jonas Meier, Cyrille Sepulchre, Francesco D'Angelo Past EPFL PhD Students Federico Nespoli, Oulfa Chellai, Thibaut François Hugo Richard, Fabian Manke, Riccardo Agnello, Alexandra Waskow, Lorenzo Ibba, Agus Rita, Kadi Lyes Roland Past EPFL PhD Students as codirector Davoud Iraji, Christian Gabriel Theiler, Alexandre Dominique Bovet, Fabio Avino Courses General physics : thermodyn

Official source

Ontological neighbourhood

Physics

Thermodynamics: Statistical mechanics

Related concepts (32)

Thermodynamics

Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of thermodynamics which convey a quantitative description using measurable macroscopic physical quantities, but may be explained in terms of microscopic constituents by statistical mechanics.

Second law of thermodynamics

The second law of thermodynamics is a physical law based on universal experience concerning heat and energy interconversions. One simple statement of the law is that heat always moves from hotter objects to colder objects (or "downhill"), unless energy in some form is supplied to reverse the direction of heat flow. Another definition is: "Not all heat energy can be converted into work in a cyclic process." The second law of thermodynamics in other versions establishes the concept of entropy as a physical property of a thermodynamic system.

Laws of thermodynamics

The laws of thermodynamics are a set of scientific laws which define a group of physical quantities, such as temperature, energy, and entropy, that characterize thermodynamic systems in thermodynamic equilibrium. The laws also use various parameters for thermodynamic processes, such as thermodynamic work and heat, and establish relationships between them. They state empirical facts that form a basis of precluding the possibility of certain phenomena, such as perpetual motion.

Entropy (statistical thermodynamics)

The concept entropy was first developed by German physicist Rudolf Clausius in the mid-nineteenth century as a thermodynamic property that predicts that certain spontaneous processes are irreversible or impossible. In statistical mechanics, entropy is formulated as a statistical property using probability theory. The statistical entropy perspective was introduced in 1870 by Austrian physicist Ludwig Boltzmann, who established a new field of physics that provided the descriptive linkage between the macroscopic observation of nature and the microscopic view based on the rigorous treatment of large ensembles of microstates that constitute thermodynamic systems.

Probability

Probability is the branch of mathematics concerning numerical descriptions of how likely an event is to occur, or how likely it is that a proposition is true. The probability of an event is a number between 0 and 1, where, roughly speaking, 0 indicates impossibility of the event and 1 indicates certainty. The higher the probability of an event, the more likely it is that the event will occur. A simple example is the tossing of a fair (unbiased) coin.

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