History of energy
Encyclopedia
The word energy
derives from Greek
ἐνέργεια (energeia), which appears for the first time in the work Nicomachean Ethics
of Aristotle
in the 4th century BCE.
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The concept of energy emerged out of the idea of vis viva
(living force), which Leibniz 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 by Isaac 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 "quantity of motion" of a moving object is proportional to its mass and the square of its velocity (not the velocity itself as Newton taught—what was later called momentum
).
In 1802 lectures to the Royal Society, Thomas Young
was the first to use the term "energy" in its modern sense, instead of vis viva
. In the 1807 publication of those lectures, he wrote,
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.
and thermal efficiencies
of their systems. Engineers such as Sadi Carnot
, physicists such as James Prescott Joule
, mathematicians such as Émile Clapeyron and Hermann von Helmholtz
, and amateurs such as Julius 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 philosophy William Thomson
and his ally in the engineering science William Rankine began to replace the older language of mechanics
with terms such as "actual energy", "kinetic energy
", and "potential energy
". William Thomson (Lord Kelvin) amalgamated all of these laws into the laws of thermodynamics
, which aided in the rapid development of explanations of chemical processes using the concept of energy by Rudolf Clausius
, Josiah Willard Gibbs
and Walther Nernst
. It also led to a mathematical formulation of the concept of entropy
by Clausius, and to the introduction of laws of radiant energy
by Jožef Stefan.
Rankine, coined the term "potential energy". In 1881, William Thomson stated before an audience that:
Over the following thirty years or so this newly developing science went by various names, such as the dynamical theory of heat
or energetics
, but after the 1920s generally came to be known as thermodynamics
, 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 as biological thermodynamics
and thermoeconomics
, to name a couple; as well as related terms such as entropy
, 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.
is the direct mathematical consequence of the translational symmetry
of the quantity conjugate to energy, namely time
. That is, energy is conserved because the laws of physics do not distinguish between different moments of time (see Noether's theorem
).
During a 1961 lecture for undergraduate students at the California Institute of Technology
, Richard Feynman
, a celebrated physics teacher and Nobel Laureate, said this about the concept of energy:
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
derives from Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...
ἐνέργεια (energeia), which appears for the first time in the work Nicomachean Ethics
Nicomachean Ethics
The Nicomachean Ethics is the name normally given to Aristotle's best known work on ethics. The English version of the title derives from Greek Ἠθικὰ Νικομάχεια, transliterated Ethika Nikomacheia, which is sometimes also given in the genitive form as Ἠθικῶν Νικομαχείων, Ethikōn Nikomacheiōn...
of Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...
in the 4th century BCE.
Vis viva
In the history of science, vis viva is an obsolete scientific theory that served as an elementary and limited early formulation of the principle of conservation of energy...
(living force), which Leibniz 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 by Isaac Newton
Isaac Newton
Sir Isaac Newton PRS was an English physicist, mathematician, astronomer, natural philosopher, alchemist, and theologian, who has been "considered by many to be the greatest and most influential scientist who ever lived."...
, 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 "quantity of motion" of a moving object is proportional to its mass and the square of its velocity (not the velocity itself as Newton taught—what was later called momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
).
In 1802 lectures to the Royal Society, Thomas Young
Thomas Young (scientist)
Thomas Young was an English polymath. He is famous for having partly deciphered Egyptian hieroglyphics before Jean-François Champollion eventually expanded on his work...
was the first to use the term "energy" in its modern sense, instead of vis viva
Vis viva
In the history of science, vis viva is an obsolete scientific theory that served as an elementary and limited early formulation of the principle of conservation of energy...
. In the 1807 publication of those lectures, he wrote,
Gustave-Gaspard Coriolis described "kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
" in 1829 in its modern sense, and in 1853, William Rankine
William John Macquorn Rankine
William John Macquorn Rankine was a Scottish civil engineer, physicist and mathematician. He was a founding contributor, with Rudolf Clausius and William Thomson , to the science of thermodynamics....
coined the term "potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...
."
It was argued for some years whether energy was a substance (the caloric
Caloric theory
The caloric theory is an obsolete scientific theory that heat consists of a self-repellent fluid called caloric that flows from hotter bodies to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores in solids and liquids...
) or merely a physical quantity.
Thermodynamics
The development of steam engines required engineers to develop concepts and formulas that would allow them to describe the mechanicalMechanical efficiency
Mechanical efficiency measures the effectiveness of a machine in transforming the energy and power that is input to the device into an output force and movement...
and thermal efficiencies
Thermal efficiency
In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a boiler, a furnace, or a refrigerator for example.-Overview:...
of their systems. Engineers such as Sadi Carnot
Nicolas Léonard Sadi Carnot
Nicolas Léonard Sadi Carnot was a French military engineer who, in his 1824 Reflections on the Motive Power of Fire, gave the first successful theoretical account of heat engines, now known as the Carnot cycle, thereby laying the foundations of the second law of thermodynamics...
, physicists such as James Prescott Joule
James Prescott Joule
James Prescott Joule FRS was an English physicist and brewer, born in Salford, Lancashire. Joule studied the nature of heat, and discovered its relationship to mechanical work . This led to the theory of conservation of energy, which led to the development of the first law of thermodynamics. The...
, mathematicians such as Émile Clapeyron and Hermann von Helmholtz
Hermann von Helmholtz
Hermann Ludwig Ferdinand von Helmholtz was a German physician and physicist who made significant contributions to several widely varied areas of modern science...
, and amateurs such as Julius Robert von Mayer
Julius Robert von Mayer
Julius Robert von Mayer was a German physician and physicist and one of the founders of thermodynamics...
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 philosophy William Thomson
William Thomson, 1st Baron Kelvin
William Thomson, 1st Baron Kelvin OM, GCVO, PC, PRS, PRSE, was a mathematical physicist and engineer. At the University of Glasgow he did important work in the mathematical analysis of electricity and formulation of the first and second laws of thermodynamics, and did much to unify the emerging...
and his ally in the engineering science William Rankine began to replace the older language of mechanics
Mechanics
Mechanics is the branch of physics concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment....
with terms such as "actual energy", "kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
", and "potential energy
Potential energy
In physics, potential energy is the energy stored in a body or in a system due to its position in a force field or due to its configuration. The SI unit of measure for energy and work is the Joule...
". William Thomson (Lord Kelvin) amalgamated all of these laws into the laws of thermodynamics
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
, which aided in the rapid development of explanations of chemical processes using the concept of energy by Rudolf Clausius
Rudolf Clausius
Rudolf Julius Emanuel Clausius , was a German physicist and mathematician and is considered one of the central founders of the science of thermodynamics. By his restatement of Sadi Carnot's principle known as the Carnot cycle, he put the theory of heat on a truer and sounder basis...
, Josiah Willard Gibbs
Josiah Willard Gibbs
Josiah Willard Gibbs was an American theoretical physicist, chemist, and mathematician. He devised much of the theoretical foundation for chemical thermodynamics as well as physical chemistry. As a mathematician, he invented vector analysis . Yale University awarded Gibbs the first American Ph.D...
and Walther Nernst
Walther Nernst
Walther Hermann Nernst FRS was a German physical chemist and physicist who is known for his theories behind the calculation of chemical affinity as embodied in the third law of thermodynamics, for which he won the 1920 Nobel Prize in chemistry...
. It also led to a mathematical formulation of the concept of entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
by Clausius, and to the introduction of laws of radiant energy
Radiant energy
Radiant energy is the energy of electromagnetic waves. The quantity of radiant energy may be calculated by integrating radiant flux with respect to time and, like all forms of energy, its SI unit is the joule. The term is used particularly when radiation is emitted by a source into the...
by Jožef Stefan.
Rankine, coined the term "potential energy". In 1881, William Thomson stated before an audience that:
Over the following thirty years or so this newly developing science went by various names, such as the dynamical theory of heat
Theory of heat
In the history of science, the theory of heat or mechanical theory of heat was a theory, introduced predominantly in 1824 by the French physicist Sadi Carnot, that heat and mechanical work are equivalent. It is related to the mechanical equivalent of heat...
or energetics
Energetics
Energetics is the study of energy under transformation. Because energy flows at all scales, from the quantum level to the biosphere and cosmos, energetics is a very broad discipline, encompassing for example thermodynamics, chemistry, biological energetics, biochemistry and ecological energetics...
, but after the 1920s generally came to be known as thermodynamics
Thermodynamics
Thermodynamics is a physical science that studies the effects on material bodies, and on radiation in regions of space, of transfer of heat and of work done on or by the bodies or radiation...
, the science of energy transformations.
Stemming from the 1850s development of the first two laws of thermodynamics
Laws of thermodynamics
The four laws of thermodynamics summarize its most important facts. They define fundamental physical quantities, such as temperature, energy, and entropy, in order to describe thermodynamic systems. They also describe the transfer of energy as heat and work in thermodynamic processes...
, the science of energy have since branched off into a number of various fields, such as biological thermodynamics
Biological thermodynamics
Biological thermodynamics is a phrase that is sometimes used to refer to bioenergetics, the study of energy transformation in the biological sciences...
and thermoeconomics
Thermoeconomics
Thermoeconomics, also referred to as biophysical economics, is a school of heterodox economics that applies the laws of thermodynamics to economic theory. The term "thermoeconomics" was coined in 1962 by American engineer Myron Tribus, and developed by the statistician and economist Nicholas...
, to name a couple; as well as related terms such as entropy
Entropy
Entropy is a thermodynamic property that can be used to determine the energy available for useful work in a thermodynamic process, such as in energy conversion devices, engines, or machines. Such devices can only be driven by convertible energy, and have a theoretical maximum efficiency when...
, a measure of the loss of useful energy, or power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...
, 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.
Conservation of energy
In 1918 it was proved that the law of conservation of energyConservation of energy
The nineteenth century law of conservation of energy is a law of physics. It states that the total amount of energy in an isolated system remains constant over time. The total energy is said to be conserved over time...
is the direct mathematical consequence of the translational symmetry
Symmetry
Symmetry generally conveys two primary meanings. The first is an imprecise sense of harmonious or aesthetically pleasing proportionality and balance; such that it reflects beauty or perfection...
of the quantity conjugate to energy, namely time
Time
Time is a part of the measuring system used to sequence events, to compare the durations of events and the intervals between them, and to quantify rates of change such as the motions of objects....
. That is, energy is conserved because the laws of physics do not distinguish between different moments of time (see Noether's theorem
Noether's theorem
Noether's theorem states that any differentiable symmetry of the action of a physical system has a corresponding conservation law. The theorem was proved by German mathematician Emmy Noether in 1915 and published in 1918...
).
During a 1961 lecture for undergraduate students at the California Institute of Technology
California Institute of Technology
The California Institute of Technology is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering...
, Richard Feynman
Richard Feynman
Richard Phillips Feynman was an American physicist known for his work in the path integral formulation of quantum mechanics, the theory of quantum electrodynamics and the physics of the superfluidity of supercooled liquid helium, as well as in particle physics...
, a celebrated physics teacher and Nobel Laureate, said this about the concept of energy:
See also
- Timeline of thermodynamics, statistical mechanics, and random processesTimeline of thermodynamics, statistical mechanics, and random processesA timeline of events related to thermodynamics.- Before 1800 :* 1650 – Otto von Guericke builds the first vacuum pump* 1660 – Robert Boyle experimentally discovers Boyle's Law, relating the pressure and volume of a gas...
- History of physicsHistory of physicsAs forms of science historically developed out of philosophy, physics was originally referred to as natural philosophy, a term describing a field of study concerned with "the workings of nature".-Early history:...
- History of the conservation of energy principle
- History of thermodynamicsHistory of thermodynamicsThe history of thermodynamics is a fundamental strand in the history of physics, the history of chemistry, and the history of science in general...
- A Guide to the Scientific Knowledge of Things FamiliarA Guide to the Scientific Knowledge of Things FamiliarA Guide to the Scientific Knowledge of Things Familiar, also known as The Guide to Science or Brewer's Guide to Science, is a book by Ebenezer Cobham Brewer presenting explanations for common phenomena...
, a book by Ebenezer Cobham Brewer presenting explanations for common phenomena - Caloric theoryCaloric theoryThe caloric theory is an obsolete scientific theory that heat consists of a self-repellent fluid called caloric that flows from hotter bodies to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores in solids and liquids...
Further reading
- Eugene Hecht, “An Historico-Critical Account of Potential Energy: Is PE Really Real?” The Physics Teacher 41 (Nov 2003): 486-93.
- Katalin Martinás, “Aristotelian Thermodynamics,” Thermodynamics: history and philosophy: facts, trends, debates (Veszprém, Hungary 23-28 July 1990), 285-303.