History of energy

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Thomas Young - the first to use the term "energy" to refer to kinetic energy in its modern sense, in 1802. Thomas Young (scientist).jpg
Thomas Young - the first to use the term "energy" to refer to kinetic energy in its modern sense, in 1802.


In the history of physics, the history of energy examines the gradual development of energy as a central scientific concept. Classical mechanics was initially understood through the study of motion and force by thinkers like Galileo Galilei and Isaac Newton, the importance of the concept of energy was made clear in the 19th century with the principles of thermodynamics, particularly the conservation of energy which established that energy cannot be created or destroyed, only transformed. In the 20th century Albert Einstein's mass–energy equivalence expanded this understanding by linking mass and energy, and quantum mechanics introduced quantized energy levels. Today, energy is recognized as a fundamental conserved quantity across all domains of physics, underlying both classical and quantum phenomena.

Contents

Antiquity

The word energy derives from Greek word "energeia" (Greek : ἐνέργεια) meaning actuality, which appears for the first time in the 4th century BCE in various works of Aristotle [1] when discussing potentiality and actuality including Physics , Metaphysics, Nicomachean Ethics [2] and On the Soul .

Kinetic energy

The modern concept of kinetic energy emerged from the idea of vis viva (living force), which Gottfried Wilhelm Leibniz defined over the period 1676–1689 as the product of the mass of an object and its velocity squared he believed that total vis viva was conserved.[ citation needed ] To account for slowing due to friction, Leibniz claimed that heat consisted of the random motion of the constituent parts of matter — a view described by Francis Bacon in Novum Organon to illustrate inductive reasoning and shared by Isaac Newton, although it would be more than a century until this was generally accepted.

Émilie du Châtelet in her book Institutions de Physique ("Lessons in Physics"), published in 1740, incorporated the idea of Leibniz with practical observations of Willem 's Gravesande to show that the "quantity of motion" of a moving object is proportional to its mass and its velocity squared (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 to refer to kinetic energy in its modern sense, instead of vis viva . [3] In the 1807 publication of those lectures, he wrote,

The product of the mass of a body into the square of its velocity may properly be termed its energy. [4]

Gustave-Gaspard Coriolis described "kinetic energy" in 1829 in its modern sense,

Thermodynamics

It was argued for some years whether energy was a substance (the caloric) or merely a physical quantity.[ citation needed ]

The development of steam engines in the 18th century 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 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. [5] In 1853, Rankine coined the term "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. [5] In 1881, William Thomson stated before an audience that: [6]

The very name energy, though first used in its present sense by Dr Thomas 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 or energetics, but after the 1920s generally came to be known as thermodynamics, the science of energy transformations.

Time-translation symmetry

In 1918 Emmy Noether proved that the law of conservation of energy is the direct mathematical consequence of the time-translation symmetry.[ citation needed ] That is according to Noether's theorem relating symmetries and conserved quantity, energy is conserved because the laws of physics do not distinguish between different moments of time.

During a 1961 lecture [7] 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:

There is a fact, or if you wish, a law, governing natural phenomena that are known to date. There is no known exception to this law—it is exact so far we know. The law is called conservation of energy; it states that there is a certain quantity, which we call energy that does not change in manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle; it says that there is a numerical quantity, which does not change when something happens. It is not a description of a mechanism, or anything concrete; it is just a strange fact that we can calculate some number, and when we finish watching nature go through her tricks and calculate the number again, it is the same.

— The Feynman Lectures on Physics

See also

Related Research Articles

In physics, a conservation law states that a particular measurable property of an isolated physical system does not change as the system evolves over time. Exact conservation laws include conservation of mass-energy, conservation of linear momentum, conservation of angular momentum, and conservation of electric charge. There are also many approximate conservation laws, which apply to such quantities as mass, parity, lepton number, baryon number, strangeness, hypercharge, etc. These quantities are conserved in certain classes of physics processes, but not in all.

<span class="mw-page-title-main">Energy</span> Physical quantity

Energy is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light. Energy is a conserved quantity—the law of conservation of energy states that energy can be converted in form, but not created or destroyed. The unit of measurement for energy in the International System of Units (SI) is the joule (J).

<span class="mw-page-title-main">History of physics</span> Historical development of physics

Physics is a branch of science whose primary objects of study are matter and energy. Discoveries of physics find applications throughout the natural sciences and in technology. Historically, physics emerged from the scientific revolution of the 17th century, grew rapidly in the 19th century, then was transformed by a series of discoveries in the 20th century. Physics today may be divided loosely into classical physics and modern physics.

<span class="mw-page-title-main">Momentum</span> Property of a mass in motion

In Newtonian mechanics, momentum is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction. If m is an object's mass and v is its velocity, then the object's momentum p is: In the International System of Units (SI), the unit of measurement of momentum is the kilogram metre per second (kg⋅m/s), which is dimensionally equivalent to the newton-second.

The following outline is provided as an overview of and topical guide to physics:

<span class="mw-page-title-main">Thermodynamics</span> Physics of heat, work, and temperature

Thermodynamics is the branch of physics that studies 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. Thermodynamics plays a role in a wide variety of topics in science and engineering.

The following is a timeline of classical mechanics:

<span class="mw-page-title-main">Timeline of thermodynamics</span>

A timeline of events in the history of thermodynamics.

The law of conservation of energy states that the total energy of an isolated system remains constant; it is said to be conserved over time. In the case of a closed system the principle says that the total amount of energy within the system can only be changed through energy entering or leaving the system. Energy can neither be created nor destroyed; rather, it can only be transformed or transferred from one form to another. For instance, chemical energy is converted to kinetic energy when a stick of dynamite explodes. If one adds up all forms of energy that were released in the explosion, such as the kinetic energy and potential energy of the pieces, as well as heat and sound, one will get the exact decrease of chemical energy in the combustion of the dynamite.

<span class="mw-page-title-main">First law of thermodynamics</span> Law of thermodynamics establishing the conservation of energy

The first law of thermodynamics is a formulation of the law of conservation of energy in the context of thermodynamic processes. The law distinguishes two principal forms of energy transfer, heat and thermodynamic work, that modify a thermodynamic system containing a constant amount of matter. The law also defines the internal energy of a system, an extensive property for taking account of the balance of heat and work in the system. Energy cannot be created or destroyed, but it can be transformed from one form to another. In an isolated system the sum of all forms of energy is constant.

<span class="mw-page-title-main">Rudolf Clausius</span> German physicist and mathematician (1822–1888)

Rudolf Julius Emanuel Clausius was a German physicist and mathematician and is considered one of the central founding fathers of the science of thermodynamics. By his restatement of Sadi Carnot's principle known as the Carnot cycle, he gave the theory of heat a truer and sounder basis. His most important paper, "On the Moving Force of Heat", published in 1850, first stated the basic ideas of the second law of thermodynamics. In 1865 he introduced the concept of entropy. In 1870 he introduced the virial theorem, which applied to heat.

Scientific laws or laws of science are statements, based on repeated experiments or observations, that describe or predict a range of natural phenomena. The term law has diverse usage in many cases across all fields of natural science. Laws are developed from data and can be further developed through mathematics; in all cases they are directly or indirectly based on empirical evidence. It is generally understood that they implicitly reflect, though they do not explicitly assert, causal relationships fundamental to reality, and are discovered rather than invented.

<span class="mw-page-title-main">Heat death of the universe</span> Possible fate of the universe

The heat death of the universe is a hypothesis on the ultimate fate of the universe, which suggests the universe will evolve to a state of no thermodynamic free energy, and will therefore be unable to sustain processes that increase entropy. Heat death does not imply any particular absolute temperature; it only requires that temperature differences or other processes may no longer be exploited to perform work. In the language of physics, this is when the universe reaches thermodynamic equilibrium.

The word "mass" has two meanings in special relativity: invariant mass is an invariant quantity which is the same for all observers in all reference frames, while the relativistic mass is dependent on the velocity of the observer. According to the concept of mass–energy equivalence, invariant mass is equivalent to rest energy, while relativistic mass is equivalent to relativistic energy.

Vis viva is a historical term used to describe a quantity similar to kinetic energy in an early formulation of the principle of conservation of energy.

<span class="mw-page-title-main">History of thermodynamics</span>

The history of thermodynamics is a fundamental strand in the history of physics, the history of chemistry, and the history of science in general. Due to the relevance of thermodynamics in much of science and technology, its history is finely woven with the developments of classical mechanics, quantum mechanics, magnetism, and chemical kinetics, to more distant applied fields such as meteorology, information theory, and biology (physiology), and to technological developments such as the steam engine, internal combustion engine, cryogenics and electricity generation. The development of thermodynamics both drove and was driven by atomic theory. It also, albeit in a subtle manner, motivated new directions in probability and statistics; see, for example, the timeline of thermodynamics.

This timeline lists significant discoveries in physics and the laws of nature, including experimental discoveries, theoretical proposals that were confirmed experimentally, and theories that have significantly influenced current thinking in modern physics. Such discoveries are often a multi-step, multi-person process. Multiple discovery sometimes occurs when multiple research groups discover the same phenomenon at about the same time, and scientific priority is often disputed. The listings below include some of the most significant people and ideas by date of publication or experiment.

<i>Reflections on the Motive Power of Fire</i> Unique book of the French physicist Sadi Carnot

Reflections on the Motive Power of Fire and on Machines Fitted to Develop that Power is a scientific treatise written by the French military engineer Sadi Carnot. Published in 1824 in French as Réflexions sur la puissance motrice du feu et sur les machines propres à développer cette puissance, the short book sought to advance a rational theory of heat engines. At the time, heat engines had acquired great technological and economic importance, but very little was understood about them from the point of view of physics.

<span class="mw-page-title-main">Classical mechanics</span> Description of large objects physics

Classical mechanics is a physical theory describing the motion of objects such as projectiles, parts of machinery, spacecraft, planets, stars, and galaxies. The development of classical mechanics involved substantial change in the methods and philosophy of physics. The qualifier classical distinguishes this type of mechanics from physics developed after the revolutions in physics of the early 20th century, all of which revealed limitations in classical mechanics.

<span class="mw-page-title-main">Branches of physics</span> Overview of the branches of physics

Physics is a scientific discipline that seeks to construct and experimentally test theories of the physical universe. These theories vary in their scope and can be organized into several distinct branches, which are outlined in this article.

References

  1. ↑ OUP V, 240, 1991[ clarification needed ]
  2. ↑ Aristotle, "Nicomachean Ethics", 1098a, at Perseus
  3. ↑ Smith, Crosbie (1998). The Science of Energy - a Cultural History of Energy Physics in Victorian Britain. The University of Chicago Press. ISBN   0-226-76420-6.
  4. ↑ Thomas Young (1807). A Course of Lectures on Natural Philosophy and the Mechanical Arts, p. 52.
  5. 1 2 Smith, Crosbie (1998). The Science of Energy - a Cultural History of Energy Physics in Victorian Britain. The University of Chicago Press. ISBN   0-226-76421-4.
  6. ↑ 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.
  7. ↑ Feynman, Richard (1964). The Feynman Lectures on Physics; Volume 1 . U.S.A: Addison Wesley. ISBN   0-201-02115-3.

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