- History of energy
The word 'energy' derives from Greek "ἐνέργεια" ("energeia"), which appears for the first time in the work
Nicomachean Ethics [ [http://www.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus%3aabo%3atlg%2c0086%2c010%3a1098b%3a33&vers=original&word=e%29ne%2frgeia#word1 Aristotle, "Nicomachean Ethics", 1098b33, at Perseus] ] ofAristotle in the 4th century BC. In 1021 AD, the Arabian physicist, Alhazen, in the "Book of Optics ", heldlight rays to be streams of minute energy particles, stating that "the smallest parts of light" retain "only properties that can be treated by geometry and verified byexperiment " and that "they lack all sensible qualities except energy." [Citation |last=Rashed |first=Roshdi |year=2007 |title=The Celestial Kinematics of Ibn al-Haytham |journal=Arabic Sciences and Philosophy |volume=17 |pages=7–55 [19] |publisher=Cambridge University Press ] In 1121,Al-Khazini , in "The Book of the Balance of Wisdom", proposed that thegravitational potential energy of a body varies depending on its distance from the centre of the Earth. [Mariam Rozhanskaya and I. S. Levinova (1996), "Statics", p. 621, in Harvard reference |last1=Rashed |first1=Roshdi |last2=Morelon |first2=Régis |year=1996 |title=Encyclopedia of the History of Arabic Science |volume=1 & 3 |publisher=Routledge |isbn=0415124107 |pages=614-642 ]The concept of energy emerged out of the idea of
vis viva , whichLeibniz defined as the product of the mass of an object and its velocity squared; he believed that total vis viva was conserved. To account for slowing due to friction, Leibniz claimed that heat consisted of the random motion of the constituent parts of matter — a view shared byIsaac Newton , although it would be more than a century until this was generally accepted.Emilie marquise du Châtelet in her book Institutions de Physique (“Lessons in Physics”), published in 1740, incorporated the idea of Leibniz with practical observations of Gravesande to show that the energy of a moving object is proportional to its mass and the square of its velocity (not the velocity itself as Newton believed).
In 1807, Thomas Young was the first to use the term "energy", instead of
vis viva , in its modern sense. [cite book | last = Smith | first = Crosbie | title = The Science of Energy - a Cultural History of Energy Physics in Victorian Britain | publisher = The University of Chicago Press | year = 1998 | id = ISBN 0-226-76420-6]Gustave-Gaspard Coriolis described "kinetic energy " in 1829 in its modern sense, and in 1853, William Rankine coined the term "potential energy ."It was argued for some years whether energy was a substance (the caloric) or merely a physical quantity.
The development of
steam engines required engineers to develop concepts and formulas that would allow them to describe the mechanical and thermal efficiencies of their systems. Engineers such as Sadi Carnot, physicists such asJames Prescott Joule , mathematicians such asÉmile Clapeyron andHermann von Helmholtz , and amateurs such asJulius Robert von Mayer all contributed to the notion that the ability to perform certain tasks, called work, was somehow related to the amount of energy in the system. In the 1850s, Glasgow professor of natural philosophyWilliam Thomson and his ally in the engineering scienceWilliam Rankine began to replace the older language ofmechanics with terms such as "actual energy", "kinetic energy ", and "potential energy ".cite book | last = Smith | first = Crosbie | title = The Science of Energy - a Cultural History of Energy Physics in Victorian Britain | publisher = The University of Chicago Press | year = 1998 | id = ISBN 0-226-76421-4] William Thomson (Lord Kelvin ) amalgamated all of these laws into the laws ofthermodynamics , which aided in the rapid development of explanations of chemical processes using the concept of energy byRudolf Clausius ,Josiah Willard Gibbs andWalther Nernst . It also led to a mathematical formulation of the concept ofentropy by Clausius, and to the introduction of laws ofradiant energy byJožef Stefan .Rankine, coined the term "potential energy".cite book | last = Smith | first = Crosbie | title = The Science of Energy - a Cultural History of Energy Physics in Victorian Britain | publisher = The University of Chicago Press | year = 1998 | id = ISBN 0-226-76421-4] In 1881, William Thomson stated before an audience that: [Thomson, William. (1881). "On the sources of energy available to man for the production of mechanical effect." "BAAS Rep". 51: 513-18 (Quote: pg. 513); "PL 2": 433-50.]cquote|The very name energy, though first used in its present sense by DrThomas Young about the beginning of this century, has only come into use practically after the doctrine which defines it had ... been raised from mere formula of mathematical dynamics to the position it now holds of a principle pervading all nature and guiding the investigator in the field of science.Over the following thirty years or so this newly developing science went by various names, such as the dynamical
theory of heat orenergetics , but after the 1920s generally came to be known asthermodynamics , the science of energy transformations.Stemming from the 1850s development of the first two
laws of thermodynamics , the science of energy have since branched off into a number of various fields, such asbiological thermodynamics andthermoeconomics , to name a couple; as well as related terms such asentropy , a measure of the loss of useful energy, or power, an energy flow per unit time, etc. In the past two centuries, the use of the word energy in various "non-scientific" vocations, e.g. social studies, spirituality and psychology has proliferated the popular literature.In 1918 it was "proved" that the law of
conservation of energy is the direct mathematical consequence of thetranslational symmetry of the quantityconjugate to energy, namelytime . That is, energy is conserved because the laws of physics do not distinguish between different moments of time (seeNoether's theorem ).
Wikimedia Foundation. 2010.
