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Théophile De Donder
Théophile Ernest de Donder (; 19 August 1872 – 11 May 1957) was a Belgian mathematician and physicist famous for his work (published in 1923) in developing correlations between the Newtonian concept of chemical affinity and the Gibbsian concept of free energy. Education He received his doctorate in physics and mathematics from the Université Libre de Bruxelles in 1899, for a thesis entitled ''Sur la Théorie des Invariants Intégraux'' (''On the Theory of Integral Invariants''). Career He was professor between 1911 and 1942, at the Université Libre de Bruxelles. Initially he continued the work of Henri Poincaré and Élie Cartan. From 1914 on, he was influenced by the work of Albert Einstein and was an enthusiastic proponent of the theory of relativity. He gained significant reputation in 1923, when he developed his definition of chemical affinity. He pointed out a connection between the chemical affinity and the Gibbs free energy. He is considered the father of thermodyn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solvay Conference
The Solvay Conferences (french: Conseils Solvay) have been devoted to outstanding preeminent open problems in both physics and chemistry. They began with the historic invitation-only 1911 Solvay Conference on Physics, considered a turning point in the world of physics, and continue to the present day. Following the initial success of 1911, they have since been organised by the International Solvay Institutes for Physics and Chemistry, founded by the Belgian industrialist Ernest Solvay in 1912 and 1913, and located in Brussels. The institutes coordinate conferences, workshops, seminars, and colloquia. Recent Solvay Conferences usually go through a three year cycle: the Solvay Conference on Physics, followed by a gap year, followed by the Solvay Conference on Chemistry. Notable Solvay conferences First conference Hendrik Lorentz was chairman of the first Solvay Conference on Physics, held in Brussels from 30 October to 3 November 1911. The subject was ''Radiation and the Quan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gibbs Free Energy
In thermodynamics, the Gibbs free energy (or Gibbs energy; symbol G) is a thermodynamic potential that can be used to calculate the maximum amount of work that may be performed by a thermodynamically closed system at constant temperature and pressure. It also provides a necessary condition for processes such as chemical reactions that may occur under these conditions. The Gibbs free energy change , measured in joules in SI) is the ''maximum'' amount of non-expansion work that can be extracted from a closed system (one that can exchange heat and work with its surroundings, but not matter) at fixed temperature and pressure. This maximum can be attained only in a completely reversible process. When a system transforms reversibly from an initial state to a final state under these conditions, the decrease in Gibbs free energy equals the work done by the system to its surroundings, minus the work of the pressure forces. The Gibbs energy is the thermodynamic potential that is minim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Belgian Physicists
{{Disambiguation ...
Belgian may refer to: * Something of, or related to, Belgium * Belgians, people from Belgium or of Belgian descent * Languages of Belgium, languages spoken in Belgium, such as Dutch, French, and German *Ancient Belgian language, an extinct language formerly spoken in Gallia Belgica *Belgian Dutch or Flemish, a variant of Dutch *Belgian French, a variant of French *Belgian horse (other), various breeds of horse *Belgian waffle, in culinary contexts * SS ''Belgian'', a cargo ship in service with F Leyland & Co Ltd from 1919 to 1934 *''The Belgian'', a 1917 American silent film See also * *Belgica (other) *Belgic (other) Belgic may refer to: * an adjective referring to the Belgae, an ancient confederation of tribes * a rarer adjective referring to the Low Countries or to Belgium * , several ships with the name * Belgic ware, a type of pottery * Belgic Confession, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1957 Deaths
1957 (Roman numerals, MCMLVII) was a Common year starting on Wednesday, common year starting on Tuesday of the Gregorian calendar, the 1957th year of the Common Era (CE) and ''Anno Domini'' (AD) designations, the 957th year of the 2nd millennium, the 57th year of the 20th century, and the 8th year of the 1950s decade. Events January * January 1 – The Saarland joins West Germany. * January 3 – Hamilton Watch Company introduces the first electric watch. * January 5 – South African player Russell Endean becomes the first batsman to be Dismissal (cricket), dismissed for having ''handled the ball'', in Test cricket. * January 9 – British Prime Minister Anthony Eden resigns. * January 10 – Harold Macmillan becomes Prime Minister of the United Kingdom. * January 11 – The African Convention is founded in Dakar. * January 14 – Kripalu Maharaj is named fifth Jagadguru (world teacher), after giving seven days of speeches before 500 Hindu scholars. * January 15 – The film ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1872 Births
Year 187 ( CLXXXVII) was a common year starting on Sunday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Quintius and Aelianus (or, less frequently, year 940 '' Ab urbe condita''). The denomination 187 for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Roman Empire * Septimius Severus marries Julia Domna (age 17), a Syrian princess, at Lugdunum (modern-day Lyon). She is the youngest daughter of high-priest Julius Bassianus – a descendant of the Royal House of Emesa. Her elder sister is Julia Maesa. * Clodius Albinus defeats the Chatti, a highly organized German tribe that controlled the area that includes the Black Forest. By topic Religion * Olympianus succeeds Pertinax as bishop of Byzantium (until 198). Births * Cao Pi, Chinese emperor of the Cao Wei state (d. 226) * G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
De Donder–Weyl Theory
In mathematical physics, the De Donder–Weyl theory is a generalization of the Hamiltonian formalism in the calculus of variations and classical field theory over spacetime which treats the space and time coordinates on equal footing. In this framework, the Hamiltonian formalism in mechanics is generalized to field theory in the way that a Field (physics), field is represented as a system that varies both in space and in time. This generalization is different from the Canonical form, canonical Hamiltonian formalism in field theory which treats space and time variables differently and describes classical fields as infinite-dimensional systems evolving in time. De Donder–Weyl formulation of field theory The De Donder–Weyl theory is based on a change of variables known as Legendre transformation. Let ''xi'' be spacetime coordinates, for ''i'' = 1 to ''n'' (with ''n'' = 4 representing 3 + 1 dimensions of space and time), and ''ya'' field variables, for ''a'' = 1 to ''m'', and ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harmonic Coordinate Condition
The harmonic coordinate condition is one of several coordinate conditions in general relativity, which make it possible to solve the Einstein field equations. A coordinate system is said to satisfy the harmonic coordinate condition if each of the coordinate functions ''x''α (regarded as scalar fields) satisfies d'Alembert's equation. The parallel notion of a harmonic coordinate system in Riemannian geometry is a coordinate system whose coordinate functions satisfy Laplace's equation. Since d'Alembert's equation is the generalization of Laplace's equation to space-time, its solutions are also called "harmonic". Motivation The laws of physics can be expressed in a generally invariant form. In other words, the real world does not care about our coordinate systems. However, for us to be able to solve the equations, we must fix upon a particular coordinate system. A coordinate condition selects one (or a smaller set of) such coordinate system(s). The Cartesian coordinates used in spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schrödinger Equation
The Schrödinger equation is a linear partial differential equation that governs the wave function of a quantum-mechanical system. It is a key result in quantum mechanics, and its discovery was a significant landmark in the development of the subject. The equation is named after Erwin Schrödinger, who postulated the equation in 1925, and published it in 1926, forming the basis for the work that resulted in his Nobel Prize in Physics in 1933. Conceptually, the Schrödinger equation is the quantum counterpart of Newton's second law in classical mechanics. Given a set of known initial conditions, Newton's second law makes a mathematical prediction as to what path a given physical system will take over time. The Schrödinger equation gives the evolution over time of a wave function, the quantum-mechanical characterization of an isolated physical system. The equation can be derived from the fact that the time-evolution operator must be unitary, and must therefore be generated by t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extent Of Reaction
In physical chemistry and chemical engineering, extent of reaction is a quantity that measures the extent to which the reaction has proceeded. Often, it refers specifically to the value of the extent of reaction when equilibrium has been reached. It is usually denoted by the Greek letter ξ. The extent of reaction is usually defined so that it has units of amount (moles). It was introduced by the Belgian scientist Théophile de Donder. Definition Consider the reaction :A ⇌ 2 B + 3 C Suppose an infinitesimal amount dn_i of the reactant A changes into B and C. This requires that all three mole numbers change according to the stoichiometry of the reaction, but they will not change by the same amounts. However, the extent of reaction \xi can be used to describe the changes on a common footing as needed. The change of the number of moles of A can be represented by the equation dn_A = - d\xi, the change of B is dn_B = + 2 d\xi, and the change of C is dn_C = + 3 d\xi. The change in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Thermodynamics
Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics. Chemical thermodynamics involves not only laboratory measurements of various thermodynamic properties, but also the application of mathematical methods to the study of chemical questions and the ''spontaneity'' of processes. The structure of chemical thermodynamics is based on the first two laws of thermodynamics. Starting from the first and second laws of thermodynamics, four equations called the "fundamental equations of Gibbs" can be derived. From these four, a multitude of equations, relating the thermodynamic properties of the thermodynamic system can be derived using relatively simple mathematics. This outlines the mathematical framework of chemical thermodynamics. History In 1865, the German physicist Rudolf Clausius, in his ''Mechanical Theory of Heat'', suggested that the principles of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Affinity
In chemical physics and physical chemistry, chemical affinity is the electronic property by which dissimilar chemical species are capable of forming chemical compounds. Chemical affinity can also refer to the tendency of an atom or compound to combine by chemical reaction with atoms or compounds of unlike composition. History Early theories The idea of ''affinity'' is extremely old. Many attempts have been made at identifying its origins. The majority of such attempts, however, except in a general manner, end in futility since "affinities" lie at the basis of all magic, thereby pre-dating science. Physical chemistry, however, was one of the first branches of science to study and formulate a "theory of affinity". The name ''affinitas'' was first used in the sense of chemical relation by German philosopher Albertus Magnus near the year 1250. Later, those as Robert Boyle, John Mayow, Johann Glauber, Isaac Newton, and Georg Stahl put forward ideas on elective affinity in attempts ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theory Of Relativity
The theory of relativity usually encompasses two interrelated theories by Albert Einstein: special relativity and general relativity, proposed and published in 1905 and 1915, respectively. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to the forces of nature. It applies to the cosmological and astrophysical realm, including astronomy. The theory transformed theoretical physics and astronomy during the 20th century, superseding a 200-year-old Classical mechanics, theory of mechanics created primarily by Isaac Newton. It introduced concepts including 4-dimensional spacetime as a unified entity of space and time in physics, time, relativity of simultaneity, kinematics, kinematic and gravity, gravitational time dilation, and length contraction. In the field of physics, relativity improved the science of elementary particles and their fundamental interactions, along with ushering in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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