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eponym An eponym is a person, a place, or a thing after whom or which someone or something is, or is believed to be, named. The adjectives which are derived from the word eponym include ''eponymous'' and ''eponymic''. Usage of the word The term ''epon ...
ous laws provides links to articles on
laws Law is a set of rules that are created and are enforceable by social or governmental institutions to regulate behavior,Robertson, ''Crimes against humanity'', 90. with its precise definition a matter of longstanding debate. It has been vari ...
, principles, adages, and other succinct observations or predictions named after a person. In some cases the person named has coined the law – such as Parkinson's law. In others, the work or publications of the individual have led to the law being so named – as is the case with Moore's law. There are also laws ascribed to individuals by others, such as Murphy's law; or given eponymous names despite the absence of the named person.


A–B

* Acton's dictum: "Power tends to corrupt, and absolute power corrupts absolutely. Great men are almost always bad men .. * Aitken's law describes how
vowel length In linguistics, vowel length is the perceived length of a vowel sound: the corresponding physical measurement is duration. In some languages vowel length is an important phonemic factor, meaning vowel length can change the meaning of the word, ...
in Scots and
Scottish English Scottish English ( gd, Beurla Albannach) is the set of varieties of the English language spoken in Scotland. The transregional, standardised variety is called Scottish Standard English or Standard Scottish English (SSE). Scottish Standard ...
is conditioned by environment. Named for Professor A. J. Aitken, who formulated it. * Alder's razor: See
Newton's flaming laser sword Michael D. Alder is an Australian mathematician, formerly an assistant professor at the University of Western Australia. Alder is known for his popular writing, such as sardonic articles about the lack of basic arithmetic skills in young adults. ...
below. *
Allen's rule Allen's rule is an ecogeographical rule formulated by Joel Asaph Allen in 1877, broadly stating that animals adapted to cold climates have thicker limbs and bodily appendages than animals adapted to warm climates. More specifically, it states that ...
: Endotherms from colder climates usually have shorter limbs (or appendages) than the equivalent animals from warmer climates. * Amagat's law describes the behaviour and properties of mixtures of ideal gases. Named for Émile Amagat. * Amara's law: "We tend to overestimate the effect of a technology in the short run and underestimate the effect in the long run." Named after
Roy Amara Roy Charles Amara (7 April 1925 – 31 December 2007) was an American researcher, scientist, futurist and president of the Institute for the Future best known for coining Amara's law on the effect of technology. He held a BS in Management, an MS i ...
(1925–2007). *
Amdahl's law In computer architecture, Amdahl's law (or Amdahl's argument) is a formula which gives the theoretical speedup in latency of the execution of a task at fixed workload that can be expected of a system whose resources are improved. It states tha ...
is used to find out the maximum expected improvement to an overall system when only a part of it is improved. Named after
Gene Amdahl Gene Myron Amdahl (November 16, 1922 – November 10, 2015) was an American computer architect and high-tech entrepreneur, chiefly known for his work on mainframe computers at IBM and later his own companies, especially Amdahl Corporation ...
(1922–2015). * Ampère's circuital law, in physics, relates the circulating magnetic field in a closed loop to the electric current through the loop. Discovered by André-Marie Ampère. *
Anderson's rule Anderson's rule is used for the construction of energy band diagrams of the heterojunction between two semiconductor materials. Anderson's rule states that when constructing an energy band diagram, the vacuum levels of the two semiconductors on e ...
is used for the construction of energy band diagrams of the heterojunction between two semiconductor materials. Named for R. L. Anderson. * Andy and Bill's law describes how, when a computer chip is released, new software will be released to use up all of its power. Named for
Andy Grove Andrew Stephen Grove (born András István Gróf; 2 September 193621 March 2016) was a Hungarian-American businessman and engineer who served as the third CEO of Intel Corporation. He escaped from Communist-controlled Hungary at the age of 20 ...
, then CEO of
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
, and
Bill Gates William Henry Gates III (born October 28, 1955) is an American business magnate and philanthropist. He is a co-founder of Microsoft, along with his late childhood friend Paul Allen. During his career at Microsoft, Gates held the positions ...
, then CEO of
Microsoft Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...
. *
Archie's law In petrophysics, Archie's law relates the ''in-situ'' electrical conductivity (C) of a porous rock to its porosity (\phi\,\!) and fluid saturation (S_w) of the pores: :C_t = \frac C_w \phi^m S_w^n Here, \phi\,\! denotes the porosity, C_t th ...
, in
petrophysics Petrophysics (from the Greek πέτρα, ''petra'', "rock" and φύσις, ''physis'', "nature") is the study of physical and chemical rock properties and their interactions with fluids. A major application of petrophysics is in studying reservo ...
, relates the in-situ electrical conductivity of
sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
to its
porosity Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measur ...
and brine
saturation Saturation, saturated, unsaturation or unsaturated may refer to: Chemistry * Saturation, a property of organic compounds referring to carbon-carbon bonds **Saturated and unsaturated compounds ** Degree of unsaturation **Saturated fat or fatty aci ...
. Named for Gus Archie (1907–1978). *
Archimedes' principle Archimedes' principle (also spelled Archimedes's principle) states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces. Archimedes' ...
indicates that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces. Named for Archimedes. *
Artin reciprocity law The Artin reciprocity law, which was established by Emil Artin in a series of papers (1924; 1927; 1930), is a general theorem in number theory that forms a central part of global class field theory. The term "reciprocity law" refers to a long line ...
is a general theorem in number theory that forms a central part of global
class field theory In mathematics, class field theory (CFT) is the fundamental branch of algebraic number theory whose goal is to describe all the abelian Galois extensions of local and global fields using objects associated to the ground field. Hilbert is credit ...
. Named after Emil Artin. * Ashby's law of requisite variety, that the number of states of its control mechanism must be greater than or equal to the number of states in the system being controlled. * Asimov's
Three Laws of Robotics The Three Laws of Robotics (often shortened to The Three Laws or known as Asimov's Laws) are a set of rules devised by science fiction author Isaac Asimov. The rules were introduced in his 1942 short story " Runaround" (included in the 1950 colle ...
formulated by Isaac Asimov: ** A robot may not injure a human being or, through inaction, allow a human being to come to harm. ** A robot must obey the orders given it by human beings, except where such orders would conflict with the First Law. ** A robot must protect its own existence as long as such protection does not conflict with the First or Second Laws. (Asimov later added what became known as the "Zeroth Law", to precede the initial three: A robot may not harm humanity, or, by inaction, allow humanity to come to harm.) * The Asimov corollary to Parkinson's law: In ten hours a day you have time to fall twice as far behind your commitments as in five hours a day. * Atwood's law: Any software that can be written in
JavaScript JavaScript (), often abbreviated as JS, is a programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. As of 2022, 98% of websites use JavaScript on the client side for webpage behavior, of ...
will eventually be written in JavaScript. * Augustine's laws on air force management. Named for Norman R. Augustine. *
Avogadro's law Avogadro's law (sometimes referred to as Avogadro's hypothesis or Avogadro's principle) or Avogadro-Ampère's hypothesis is an experimental gas law relating the volume of a gas to the amount of substance of gas present. The law is a specific c ...
, one of the
gas laws The gas laws were developed at the end of the 18th century, when scientists began to realize that relationships between pressure, volume and temperature of a sample of gas could be obtained which would hold to approximation for all gases. Boyl ...
, states that: "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules." *
Babinet's principle In physics, Babinet's principle states that the diffraction pattern from an opaque body is identical to that from a hole of the same size and shape except for the overall forward beam intensity. It was formulated in the 1800s by French physicist Ja ...
, in
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, states that the diffraction pattern from an opaque body is identical to that from a hole of the same size and shape except for the overall forward beam intensity. Named for
Jacques Babinet Jacques Babinet (; 5 March 1794 – 21 October 1872) was a French physicist, mathematician, and astronomer who is best known for his contributions to optics. Biography His father was Jean Babinet and mother, Marie‐Anne Félicité Bonneau d ...
. *
Baldwin's rules Baldwin's rules in organic chemistry are a series of guidelines outlining the relative favorabilities of ring closure reactions in alicyclic compounds. They were first proposed by Jack Baldwin in 1976. Baldwin's rules discuss the relative rates ...
predict feasibility of ring-closing reactions in organic synthesis, proposed by Jack Baldwin. * Barlow's law was an incorrect physical law proposed by Peter Barlow in 1825 to describe the ability of wires to conduct electricity. * Bayes' theorem describes the probability of an event, based on prior knowledge of conditions that might be related to the event. *
Beckstrom's law In economics, Beckstrom's law is a model or theorem formulated by Rod Beckstrom. It purports to answer "the decades-old question of 'how valuable is a network'", and states in summary that "The value of a network equals the net value added to each ...
, in
economics Economics () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyzes ...
, states that the value of a network equals the net value added to each user's transactions conducted through that network, summed over all users. Named for
Rod Beckstrom Rod Beckstrom (born February 1961) is an American author, high-tech entrepreneur, and former CEO and President of ICANN. He previously served as Director of the National Cybersecurity Center. Education and early work Beckstrom received his BA ...
. *
Beer–Lambert law The Beer–Lambert law, also known as Beer's law, the Lambert–Beer law, or the Beer–Lambert–Bouguer law relates the attenuation of light to the properties of the material through which the light is travelling. The law is commonly applied t ...
: in
optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultrav ...
, the empirical relationship of the absorption of
light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 te ...
to the properties of the material through which the light is traveling. Independently discovered (in various forms) by Pierre Bouguer in 1729,
Johann Heinrich Lambert Johann Heinrich Lambert (, ''Jean-Henri Lambert'' in French; 26 or 28 August 1728 – 25 September 1777) was a polymath from the Republic of Mulhouse, generally referred to as either Swiss or French, who made important contributions to the subject ...
in 1760 and August Beer in 1852. *
Benford's law Benford's law, also known as the Newcomb–Benford law, the law of anomalous numbers, or the first-digit law, is an observation that in many real-life sets of numerical data, the leading digit is likely to be small.Arno Berger and Theodore ...
: In many collections of data, a given data point has roughly a 30% chance of starting with the digit 1. *
Benford's law of controversy Gregory Benford (born January 30, 1941) is an American science fiction author and astrophysicist who is professor emeritus at the Department of Physics and Astronomy at the University of California, Irvine. He is a contributing editor of ''Reaso ...
: Passion is
inversely proportional In mathematics, two sequences of numbers, often experimental data, are proportional or directly proportional if their corresponding elements have a constant ratio, which is called the coefficient of proportionality or proportionality constan ...
to the amount of real information available. *
Bennett's laws Bennett's laws of quantum information are: # 1 qubit \geqslant 1 bit (classical), # 1 qubit \geqslant 1 ebit ( entanglement bit), # 1 ebit + 1 qubit \geqslant 2 bits (i.e. superdense coding In quantum information theory, superdense coding (als ...
are principles in
quantum information Quantum information is the information of the state of a quantum system. It is the basic entity of study in quantum information theory, and can be manipulated using quantum information processing techniques. Quantum information refers to both t ...
theory. Named for Charles H. Bennett. * Bergmann's rule: within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, and species of smaller size are found in warmer regions. *
Bernoulli's principle In fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy. The principle is named after the Swiss mathematici ...
, in fluid dynamics, describes the effect that flow has on pressure contributing
lift Lift or LIFT may refer to: Physical devices * Elevator, or lift, a device used for raising and lowering people or goods ** Paternoster lift, a type of lift using a continuous chain of cars which do not stop ** Patient lift, or Hoyer lift, mobil ...
to airfoils. *
Betteridge's law of headlines Betteridge's law of headlines is an adage that states: "Any headline that ends in a question mark can be answered by the word ''no''." It is named after Ian Betteridge, a British technology journalist who wrote about it in 2009, although the princ ...
: "any
headline The headline or heading is the text indicating the content or nature of the article below it, typically by providing a form of brief summary of its contents. The large type ''front page headline'' did not come into use until the late 19th centur ...
which ends in a
question mark The question mark (also known as interrogation point, query, or eroteme in journalism) is a punctuation mark that indicates an interrogative clause or phrase in many languages. History In the fifth century, Syriac Bible manuscripts used que ...
can be answered by the word 'no. *
Betz's law Betz's law indicates the maximum power that can be extracted from the wind, independent of the design of a wind turbine in open flow. It was published in 1919 by the German physicist Albert Betz. The law is derived from the principles of conserva ...
: No wind turbine can capture more than 16/27 (59.3%) of the kinetic energy in wind, independent of the design of the turbine, in open flow. *
Biot–Savart law In physics, specifically electromagnetism, the Biot–Savart law ( or ) is an equation describing the magnetic field generated by a constant electric current. It relates the magnetic field to the magnitude, direction, length, and proximity of the ...
describes the magnetic field set up by a steady current density. Named for
Jean-Baptiste Biot Jean-Baptiste Biot (; ; 21 April 1774 – 3 February 1862) was a French physicist, astronomer, and mathematician who co-discovered the Biot–Savart law of magnetostatics with Félix Savart, established the reality of meteorites, made an early ba ...
and
Félix Savart Félix Savart (; ; 30 June 1791, Mézières – 16 March 1841, Paris) was a French physicist and mathematician who is primarily known for the Biot–Savart law of electromagnetism, which he discovered together with his colleague Jean-Bapti ...
. *
Birch's law Birch's law, discovered by the geophysicist Francis Birch, establishes a linear relation between compressional wave velocity and density of rocks and minerals: : v_\mathrm = a( \bar M ) + b \rho where \, \bar M \, is the mean atomic mass in fo ...
, in
geophysics Geophysics () is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' so ...
, establishes a linear relation of the compressional wave velocity of rocks and minerals of a constant average atomic weight. Named after Francis Birch. * Born's law, in
quantum mechanics Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistr ...
, gives the probability that a measurement on a quantum system will yield a given result. Named after physicist Max Born. *
Boyle's law Boyle's law, also referred to as the Boyle–Mariotte law, or Mariotte's law (especially in France), is an experimental gas law that describes the relationship between pressure and volume of a confined gas. Boyle's law has been stated as: The ...
, in
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, one of the
gas laws The gas laws were developed at the end of the 18th century, when scientists began to realize that relationships between pressure, volume and temperature of a sample of gas could be obtained which would hold to approximation for all gases. Boyl ...
, states that the volume and pressure of an ideal gas of fixed mass held at a constant
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...
are inversely proportional, or, that the product of absolute pressure and volume of a fixed mass is always constant. Discovered by and named after
Robert Boyle Robert Boyle (; 25 January 1627 – 31 December 1691) was an Anglo-Irish natural philosopher, chemist, physicist, alchemist and inventor. Boyle is largely regarded today as the first modern chemist, and therefore one of the founders of ...
(1627–1691). * Bradford's law is a pattern described by Samuel C. Bradford in 1934 that estimates the exponentially diminishing returns of extending a library search. *
Bragg's law In physics and chemistry , Bragg's law, Wulff–Bragg's condition or Laue–Bragg interference, a special case of Laue diffraction, gives the angles for coherent scattering of waves from a crystal lattice. It encompasses the superposition of wave ...
, in physics, gives the angles for coherent and incoherent scattering from a crystal lattice. * Brandolini's law: The amount of energy needed to refute bullshit is an order of magnitude bigger than to produce it. Named after Italian programmer Alberto Brandolini. *
Brewster's law Brewster's angle (also known as the polarization angle) is an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with ''no reflection''. When ''unpolarized'' light ...
, an angle of incidence at which light with a particular polarization is perfectly transmitted through a transparent dielectric surface, with no reflection. Named after Scottish physicist David Brewster. * Briffault's law: "The female, not the male, determines all the conditions of the animal family. Where the female can derive no benefit from association with the male, no such association takes place." Named after
Robert Briffault Robert Stephen Briffault (, 1874 – 11 December 1948) was a French surgeon who found fame as a social anthropologist and later in life as a novelist. Biography Briffault was born in either France or London,Brooks's law Brooks' law is an observation about software project management according to which adding manpower to software project that is behind schedule delays it even longer.Frederick P. Brooks, Jr. '' The Mythical Man-Month''. 1995 975 Addison-Wesley. It ...
: "Adding manpower to a late software project makes it later." Named after
Fred Brooks Frederick Phillips Brooks Jr. (April 19, 1931 – November 17, 2022) was an American computer architect, software engineer, and computer scientist, best known for managing the development of IBM's System/360 family of computers and the O ...
, author of the well known book on
project management Project management is the process of leading the work of a team to achieve all project goals within the given constraints. This information is usually described in project documentation, created at the beginning of the development process. T ...
''
The Mythical Man-Month ''The Mythical Man-Month: Essays on Software Engineering'' is a book on software engineering and project management by Fred Brooks first published in 1975, with subsequent editions in 1982 and 1995. Its central theme is that adding manpower to a ...
''. *
Buys Ballot's law In meteorology, Buys Ballot's law () may be expressed as follows: In the Northern Hemisphere, if a person stands with their back to the wind, the atmospheric pressure is low to the left, high to the right. This is because wind travels counterc ...
is concerned with the notion that the wind travels
counterclockwise Two-dimensional rotation can occur in two possible directions. Clockwise motion (abbreviated CW) proceeds in the same direction as a clock's hands: from the top to the right, then down and then to the left, and back up to the top. The opposite ...
around low pressure zones in the Northern Hemisphere. Named for
C. H. D. Buys Ballot Christophorus Henricus Diedericus Buys Ballot (; October 10, 1817 – February 3, 1890) was a Dutch chemist and meteorologist after whom Buys Ballot's law and the Buys Ballot table are named. He was first chairman of the International Meteo ...
, who published an
empirical validation Empirical evidence for a proposition is evidence, i.e. what supports or counters this proposition, that is constituted by or accessible to sense experience or experimental procedure. Empirical evidence is of central importance to the sciences and ...
of an existing theory, in 1857. *
Byerlee's law In rheology, Byerlee's law, also known as Byerlee's friction law concerns the shear stress (τ) required to slide one rock over another. The rocks have macroscopically flat surfaces, but the surfaces have small asperities that make them "rough." F ...
gives the stress circumstances in the Earth's crust at which fracturing along a geological fault takes place.


C–D

* Campbell's law: "The more any quantitative social indicator is used for social decision making, the more subject it will be to corruption pressures and the more apt it will be to distort and corrupt the social processes it is intended to monitor." Named after Donald T. Campbell (1916–1996) * Casper's Dictum is a law in forensic medicine that states the ratio of time a body takes to putrefy in different substances – 1:2:8 in air, water and earth. *
Cassie's law Cassie's law, or the Cassie equation, describes the effective contact angle Theta, θc for a liquid on a chemically heterogeneous surface, i.e. the surface of a composite material consisting of different chemistries, that is non uniform throughout. ...
describes the effective contact angle θc for a liquid on a composite surface. *
Cassini's laws Cassini's laws provide a compact description of the motion of the Moon. They were established in 1693 by Giovanni Domenico Cassini, a prominent scientist of his time.For the original statement of the laws, see Refinements of these laws to include ...
provide a compact description of the motion of the Moon. Established in 1693 by
Giovanni Domenico Cassini Giovanni Domenico Cassini, also known as Jean-Dominique Cassini (8 June 1625 – 14 September 1712) was an Italian (naturalised French) mathematician, astronomer and engineer. Cassini was born in Perinaldo, near Imperia, at that time in the ...
. *
Celine's laws Celine's Laws are a series of three laws regarding government and social interaction attributed to the fictional character Hagbard Celine from Robert Anton Wilson's and Robert Shea's ''Illuminatus! Trilogy''. Celine, a gentleman anarchist, serve ...
are a series of three laws regarding government and social interaction attributed to the fictional character Hagbard Celine from Robert Anton Wilson's ''
The Illuminatus! Trilogy ''The Illuminatus! Trilogy'' is a series of three novels by American writers Robert Shea and Robert Anton Wilson, first published in 1975.''Illuminatus!'' was written between 1969 and 1971, but not published until 1975 according to Robert Anto ...
''. * Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. Discovered by Austrian chemist Erwin Chargaff. *
Charles's law Charles's law (also known as the law of volumes) is an experimental gas law that describes how gases tend to expand when heated. A modern statement of Charles's law is: When the pressure on a sample of a dry gas is held constant, the Kelvin t ...
, one of the
gas laws The gas laws were developed at the end of the 18th century, when scientists began to realize that relationships between pressure, volume and temperature of a sample of gas could be obtained which would hold to approximation for all gases. Boyl ...
in
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, states that at constant pressure the volume of a given mass of a gas increases or decreases by the same factor as its temperature (in kelvins) increases or decreases. Named after
Jacques Charles Jacques Alexandre César Charles (November 12, 1746 – April 7, 1823) was a French inventor, scientist, mathematician, and balloonist. Charles wrote almost nothing about mathematics, and most of what has been credited to him was due to mistaking ...
. *
Chekhov's gun Chekhov's gun (Chekhov's rifle; russian: Чеховское ружьё) is a narrative principle that states that every element in a story must be necessary, and irrelevant elements should be removed. Alternatively explained, suppose a writer featu ...
states that nonessential elements of a story must be removed. * Cheops law: Nothing ever gets built on schedule or within budget. * Chesterton's fence states that reforms should not be made until the reasoning behind the existing state of affairs is understood. * Child's law states that the space-charge limited current in a plane-parallel diode varies directly as the three-halves power of the anode voltage and inversely as the square of the distance separating the cathode and the anode. Named after Clement D. Child; also known as the Child–Langmuir law (after Irving Langmuir). See also Mott–Gurney law. * Chladni's law relates the frequency of modes of vibration for flat circular surfaces with fixed center as a function of the numbers of diametric (linear) nodes and of radial (circular) nodes. Named after
Ernst Chladni Ernst Florens Friedrich Chladni (, , ; 30 November 1756 – 3 April 1827) was a German physicist and musician. His most important work, for which he is sometimes labeled as the father of acoustics, included research on vibrating plates an ...
. *
Claasen's law Claasen's logarithmic law of usefulness{{cite web, first=Brian, last = Dipert, year =1999, url=http://www.edn.com/electronics-blogs/other/4361480/It-s-elementary, title =It's elementary, publisher= EDN Magazine, accessdate = 2009-01-06 is name ...
, or the logarithmic law of usefulness: usefulness = log(technology). * Clarke's three laws, formulated by Arthur C. Clarke. Several corollaries to these laws have also been proposed. ** First law: When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong. ** Second law: The only way of discovering the limits of the possible is to venture a little way past them into the impossible. ** Third law: Any sufficiently advanced technology is indistinguishable from magic. *
Conway's law Conway's law is an adage that states organizations design systems that mirror their own communication structure. It is named after the computer programmer Melvin Conway, who introduced the idea in 1967. His original wording was: The law is bas ...
: Any piece of software reflects the organizational structure that produced it. Named after Melvin Conway. *
Cooper Cooper, Cooper's, Coopers and similar may refer to: * Cooper (profession), a maker of wooden casks and other staved vessels Arts and entertainment * Cooper (producers), alias of Dutch producers Klubbheads * Cooper (video game character), in ...
's law: The number of radio frequency conversations which can be concurrently conducted in a given area doubles every 30 months. *
Cope's rule Cope's rule, named after American paleontologist Edward Drinker Cope, postulates that population lineages tend to increase in body size over evolutionary time. It was never actually stated by Cope, although he favoured the occurrence of linear ...
: Population lineages tend to increase in body size over evolutionary time. *
Coulomb's law Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law of physics that quantifies the amount of force between two stationary, electrically charged particles. The electric force between charged bodies at rest is convention ...
is an inverse-square law indicating the magnitude and direction of
electrostatic Electrostatics is a branch of physics that studies electric charges at rest ( static electricity). Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amb ...
force that one stationary, electrically charged object of small dimensions (ideally, a
point source A point source is a single identifiable ''localised'' source of something. A point source has negligible extent, distinguishing it from other source geometries. Sources are called point sources because in mathematical modeling, these sources ca ...
) exerts on another. It is named after
Charles-Augustin de Coulomb Charles-Augustin de Coulomb (; ; 14 June 1736 – 23 August 1806) was a French officer, engineer, and physicist. He is best known as the eponymous discoverer of what is now called Coulomb's law, the description of the electrostatic force of attra ...
. * Cramer's rule: In linear algebra, an explicit formula for the solution of a system of linear equations with as many equations as unknowns, valid whenever the system has a unique solution. Named after Swiss mathematician
Gabriel Cramer Gabriel Cramer (; 31 July 1704 – 4 January 1752) was a Genevan mathematician. He was the son of physician Jean Cramer and Anne Mallet Cramer. Biography Cramer showed promise in mathematics from an early age. At 18 he received his doctorate ...
. *
Cromwell's rule Cromwell's rule, named by statistician Dennis Lindley, states that the use of prior probabilities of 1 ("the event will definitely occur") or 0 ("the event will definitely not occur") should be avoided, except when applied to statements that ar ...
states that the use of
prior probabilities In Bayesian probability, Bayesian statistical inference, a prior probability distribution, often simply called the prior, of an uncertain quantity is the probability distribution that would express one's beliefs about this quantity before some e ...
of 0 ("the event will definitely not occur") or 1 ("the event will definitely occur") should be avoided, except when applied to statements that are logically true or false, such as 2+2 equaling 4 or 5. * Cunningham's law: The best way to get the right answer on the Internet is not to ask a question, but to post the wrong answer. Attributed to Ward Cunningham by
Steven McGeady Steven McGeady is a former Intel executive best known as a witness in the Microsoft antitrust trial. His notes and testimony contained colorful quotes by Microsoft executives threatening to "cut off Netscape's air supply" and Bill Gates' guess ...
. * Curie's law: In a
paramagnetic Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, ...
material the magnetization of the material is (approximately) directly proportional to an applied magnetic field. Named after
Pierre Curie Pierre Curie ( , ; 15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Curie, and Henri Becq ...
. * Curie-Weiss law: describes the magnetic susceptibility χ of a ferromagnet in the paramagnetic region above the Curie point. Named after
Pierre Curie Pierre Curie ( , ; 15 May 1859 – 19 April 1906) was a French physicist, a pioneer in crystallography, magnetism, piezoelectricity, and radioactivity. In 1903, he received the Nobel Prize in Physics with his wife, Marie Curie, and Henri Becq ...
and Pierre-Ernest Weiss. *
D'Alembert's principle D'Alembert's principle, also known as the Lagrange–d'Alembert principle, is a statement of the fundamental classical laws of motion. It is named after its discoverer, the French physicist and mathematician Jean le Rond d'Alembert. D'Alembert ...
: The sum of the differences between the forces acting on a system of mass particles and the time derivatives of the momenta of the system itself along any virtual displacement consistent with the constraints of the system, is zero. Named after
Jean le Rond d'Alembert Jean-Baptiste le Rond d'Alembert (; ; 16 November 1717 – 29 October 1783) was a French mathematician, mechanician, physicist, philosopher, and music theorist. Until 1759 he was, together with Denis Diderot, a co-editor of the '' Encyclopéd ...
. *
Dahl's law Dahl's law (German: ''Das Dahlsche Gesetz'') is a sound rule in some of the Northeast Bantu languages that illustrates a case of voicing dissimilation. In the history of these languages, a voiceless stop, such as , became voiced () when immediatel ...
, a sound rule of Northeast Bantu languages, a case of voicing dissimilation. *
Dale's principle In neuroscience, Dale's principle (or Dale's law) is a rule attributed to the English neuroscientist Henry Hallett Dale. The principle basically states that a neuron performs the same chemical action at all of its synaptic connections to other c ...
, in
neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developme ...
, states that a neuron is capable of producing and secreting only one neurotransmitter from its axon terminals. Named after
Henry Hallett Dale Sir Henry Hallett Dale (9 June 1875 – 23 July 1968) was an English pharmacologist and physiologist. For his study of acetylcholine as agent in the chemical transmission of nerve pulses (neurotransmission) he shared the 1936 Nobel Prize in Ph ...
but more recent data suggests it to be false. A more common interpretation of the original statement made by Dale is that neurons release the same set of transmitters at all of their synapses. *
Dalton's law Dalton's law (also called Dalton's law of partial pressures) states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. This empirical law was observed by Joh ...
, in chemistry and
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, states that the total
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
exerted by a
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
eous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture. Also called
Dalton's law of partial pressure Dalton's law (also called Dalton's law of partial pressures) states that in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases. This empirical law was observed by Joh ...
, and related to the
ideal Ideal may refer to: Philosophy * Ideal (ethics), values that one actively pursues as goals * Platonic ideal, a philosophical idea of trueness of form, associated with Plato Mathematics * Ideal (ring theory), special subsets of a ring considere ...
gas laws The gas laws were developed at the end of the 18th century, when scientists began to realize that relationships between pressure, volume and temperature of a sample of gas could be obtained which would hold to approximation for all gases. Boyl ...
, this empirical law was observed by John Dalton in 1801. *
Darcy's law Darcy's law is an equation that describes the flow of a fluid through a porous medium. The law was formulated by Henry Darcy based on results of experiments on the flow of water through beds of sand, forming the basis of hydrogeology, a branch of ...
, in
hydrogeology Hydrogeology (''hydro-'' meaning water, and ''-geology'' meaning the study of the Earth) is the area of geology that deals with the distribution and movement of groundwater in the soil and rocks of the Earth's crust (commonly in aqui ...
, describes the flow of a fluid (such as
water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...
) through a
porous medium A porous medium or a porous material is a material containing pores (voids). The skeletal portion of the material is often called the "matrix" or "frame". The pores are typically filled with a fluid ( liquid or gas). The skeletal material is us ...
(such as an
aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials ( gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characteris ...
). * Davis's law, in
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...
, describes how soft tissue models along imposed demands. Corollary to
Wolff's law Wolff's law, developed by the German anatomist and surgeon Julius Wolff (1836–1902) in the 19th century, states that bone in a healthy animal will adapt to the loads under which it is placed. If loading on a particular bone increases, the bon ...
. *
De Morgan's laws In propositional logic and Boolean algebra, De Morgan's laws, also known as De Morgan's theorem, are a pair of transformation rules that are both valid rules of inference. They are named after Augustus De Morgan, a 19th-century British math ...
apply to
formal logic Logic is the study of correct reasoning. It includes both formal and informal logic. Formal logic is the science of deductively valid inferences or of logical truths. It is a formal science investigating how conclusions follow from premis ...
regarding the negation of pairs of logical operators. * Dermott's law: The
sidereal period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets, ...
of major
satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioi ...
s tends to follow a geometric series. Named after Stanley Dermott. * De Vaucouleurs' law, in astronomy, describes how the surface brightness of an elliptical galaxy varies as a function of apparent distance from the center. Named after
Gérard de Vaucouleurs Gérard Henri de Vaucouleurs (25 April 1918 – 7 October 1995) was a French astronomer. Life and career Born in Paris, he had an early interest in amateur astronomy and received his undergraduate degree in 1939 at the Sorbonne in that city. ...
. *
Dilbert principle The Dilbert principle is a satirical concept of management developed by Scott Adams, creator of the comic strip ''Dilbert'', which states that companies tend to promote incompetent employees to management to minimize their ability to harm product ...
: "the most ineffective workers are systematically moved to the place where they can do the least damage: management." Coined by
Scott Adams Scott Raymond Adams (born June 8, 1957) is an American author and cartoonist. He is the creator of the syndicated '' Dilbert'' comic strip, and the author of several nonfiction works of satire, commentary, and business. ''Dilbert'' gained natio ...
. *
Doctorow's law Cory Efram Doctorow (; born July 17, 1971) is a Canadian-British blogger, journalist, and science fiction author who served as co-editor of the blog ''Boing Boing''. He is an activist in favour of liberalising copyright laws and a proponent of ...
: "Anytime someone puts a lock on something you own, against your wishes, and doesn't give you the key, they're not doing it for your benefit." *
Dolbear's law Dolbear's law states the relationship between the air temperature and the rate at which crickets chirp. It was formulated by Amos Dolbear and published in 1897 in an article called "The Cricket as a Thermometer". Dolbear's observations on the rela ...
is an empirical relationship between temperature and the rate of cricket chirping. *
Dollo's law Dollo's law of irreversibility (also known as Dollo's law and Dollo's principle), proposed in 1893 by Belgian paleontologist Louis Dollo states that, "an organism never returns exactly to a former state, even if it finds itself placed in condition ...
: "An organism is unable to return, even partially, to a previous stage already realized in the ranks of its ancestors." Simply put this law states that evolution is not reversible; the "law" is regarded as a generalisation as exceptions may exist. *
Dulong–Petit law The Dulong–Petit law, a thermodynamic law proposed by French physicists Pierre Louis Dulong and Alexis Thérèse Petit, states that the classical expression for the molar specific heat capacity of certain chemical elements is constant for tempe ...
states the classical expression for the
specific heat capacity In thermodynamics, the specific heat capacity (symbol ) of a substance is the heat capacity of a sample of the substance divided by the mass of the sample, also sometimes referred to as massic heat capacity. Informally, it is the amount of heat t ...
of a
crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...
due to its lattice vibrations. Named for
Pierre Louis Dulong Pierre Louis Dulong FRS FRSE (; ; 12 February 1785 – 19 July 1838) was a French physicist and chemist. He is remembered today largely for the law of Dulong and Petit, although he was much-lauded by his contemporaries for his studies into ...
and
Alexis Thérèse Petit Alexis Thérèse Petit (; 2 October 1791, Vesoul, Haute-Saône – 21 June 1820, Paris) was a French physicist. Petit is known for his work on the efficiencies of air- and steam-engines, published in 1818 (''Mémoire sur l’emploi du principe ...
. *
Dunbar's number Dunbar's number is a suggested cognitive limit to the number of people with whom one can maintain stable social relationships—relationships in which an individual knows who each person is and how each person relates to every other person. This ...
is a theoretical cognitive limit to the number of people with whom one can maintain stable social relationships. No precise value has been proposed for Dunbar's number, but a commonly cited approximation is 150. First proposed by British anthropologist
Robin Dunbar Robin Ian MacDonald Dunbar (born 28 June 1947) is a British anthropologist and evolutionary psychologist and a specialist in primate behaviour. He is currently head of the Social and Evolutionary Neuroscience Research Group in the Department ...
. *
Dunning–Kruger effect The Dunning–Kruger effect is a cognitive bias whereby people with low ability, expertise, or experience regarding a certain type of task or area of knowledge tend to overestimate their ability or knowledge. Some researchers also include in th ...
is a cognitive bias in which people who are unskilled in some area wrongly believe their ability is higher than average; they don't know enough about the subject to accurately measure their aptitude. People with well-above-average skills are acutely aware of how much they don't know of the subject, but less aware of the general ineptitude of others, so tend to underestimate their relative ability. * Duverger's law: Winner-take-all (or first-past-the-post) electoral systems tend to create a two-party system, while proportional representation tends to create a multiple-party system. Named for Maurice Duverger.


E–G

* Edholm's law predicts that bandwidth and data rates double every 18 months. Named for Phil Edholm. * Einasto's law relates the density of a galaxy to distance from the center. Named for
Jaan Einasto Jaan Einasto (born 23 February 1929) is an Estonian astrophysicist and one of the discoverers of the large-scale structure of the Universe. Born Jaan Eisenschmidt in Tartu, the name "Einasto" is an anagram of "Estonia" (it was chosen by his p ...
. * Elliott wave principle is a form of technical analysis that finance traders use to analyze financial market cycles and forecast market trends by identifying extremes in investor psychology, highs and lows in prices, and other collective factors. Named for American accountant
Ralph Nelson Elliott Ralph Nelson Elliott (28 July 1871 – 15 January 1948) was an American accountant and author, whose study of stock market data led him to develop the Wave Principle, a description of the cyclical nature of trader psychology and a form of techni ...
. *
El-Sayed rule Mostafa A. El-Sayed (Arabic: مصطفى السيد) is an Egyptian-American physical chemist, a leading nanoscience researcher, a member of the National Academy of Sciences and a US National Medal of Science laureate. He was the editor-in-chief ...
, in physical chemistry states that "the rate of intersystem crossing (same energy radiationless transition between two electronic states), e.g. from the lowest singlet state to the triplet manifold, is relatively large if it involves a change of molecular orbital type" * Emmert's law, in optics: objects that generate retinal images of the same size will look different in physical size (linear size) if they appear to be located at different distances. Named for Emil Emmert. * Engelbart's law: "The intrinsic rate of human performance is exponential." * Eroom's law, the observation that drug discovery is becoming slower and more expensive over time, despite improvements in technology. The name "Eroom" is "Moore" spelled backward, in order to contrast it with Moore's law. * Euler's laws of motion: extends
Newton's laws of motion Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows: # A body remains at rest, or in moti ...
for
point particle A point particle (ideal particle or point-like particle, often spelled pointlike particle) is an idealization of particles heavily used in physics. Its defining feature is that it lacks spatial extension; being dimensionless, it does not take up ...
to
rigid body In physics, a rigid body (also known as a rigid object) is a solid body in which deformation is zero or so small it can be neglected. The distance between any two given points on a rigid body remains constant in time regardless of external fo ...
motion. * Faraday's law of induction: a magnetic field changing in time creates a proportional electromotive force. Named for
Michael Faraday Michael Faraday (; 22 September 1791 – 25 August 1867) was an English scientist who contributed to the study of electromagnetism and electrochemistry. His main discoveries include the principles underlying electromagnetic inducti ...
, based on his work in 1831. *
Faraday's law of electrolysis Faraday's laws of electrolysis are quantitative relationships based on the electrochemical research published by Michael Faraday in 1833. First law Michael Faraday reported that the mass (m) of elements deposited at an electrode is directly prop ...
: the mass of a substance produced at an
electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials d ...
during electrolysis is proportional to the number of
moles Moles can refer to: * Moles de Xert, a mountain range in the Baix Maestrat comarca, Valencian Community, Spain * The Moles (Australian band) *The Moles, alter ego of Scottish band Simon Dupree and the Big Sound People *Abraham Moles, French engin ...
of electrons transferred at that electrode; again named for Michael Faraday. *
Faxén's law In fluid dynamics, Faxén's laws relate a sphere's velocity \mathbf and angular velocity \mathbf to the forces, torque, stresslet and flow it experiences under low Reynolds number (creeping flow) conditions. First law Faxen's first law was introduc ...
: In fluid dynamics, Faxén's laws relate a sphere's velocity and angular velocity to the forces, torque, stresslet and flow it experiences under low Reynolds number (creeping flow) conditions. * Fick's laws of diffusion describe
diffusion Diffusion is the net movement of anything (for example, atoms, ions, molecules, energy) generally from a region of higher concentration to a region of lower concentration. Diffusion is driven by a gradient in Gibbs free energy or chemica ...
, and define the ''diffusion coefficient'' ''D''. Derived by
Adolf Fick Adolf Eugen Fick (3 September 1829 – 21 August 1901) was a German-born physician and physiologist. Early life and education Fick began his work in the formal study of mathematics and physics before realising an aptitude for medicine. He th ...
in the year 1855. * Finagle's law: "Anything that can go wrong, will—at the worst possible moment." or "The perversity of the Universe tends towards a maximum." *
Fisher's fundamental theorem of natural selection Fisher's fundamental theorem of natural selection is an idea about genetic variance in population genetics developed by the statistician and evolutionary biologist Ronald Fisher. The proper way of applying the abstract mathematics of the theorem ...
states "The rate of increase in fitness of any organism at any time is equal to its genetic variance in fitness at that time." * Fitts's law is a principle of human movement published in 1954 by
Paul Fitts Paul Morris Fitts Jr. (May 6, 1912 – May 2, 1965) was a psychologist at the Ohio State University (later at the University of Michigan). He developed a model of human movement, Fitts's law, based on rapid, aimed movement, which went on to beco ...
which predicts the time required to move from a starting position to a final target area. Fitts's law is used to
model A model is an informative representation of an object, person or system. The term originally denoted the plans of a building in late 16th-century English, and derived via French and Italian ultimately from Latin ''modulus'', a measure. Models c ...
the act of pointing, both in the real world, e.g. with a hand or finger, and on a computer, e.g. with a mouse. *
Flynn effect The Flynn effect is the substantial and long-sustained increase in both fluid and crystallized intelligence test scores that were measured in many parts of the world over the 20th century. When intelligence quotient (IQ) tests are initially stand ...
describes the phenomenon of an increase in IQ test scores for many populations at an average rate of three IQ points per decade since the early 20th century. *
Fourier's law Conduction is the process by which heat is transferred from the hotter end to the colder end of an object. The ability of the object to conduct heat is known as its ''thermal conductivity'', and is denoted . Heat spontaneously flows along a te ...
, also known as the law of heat conduction, states that the time rate of
heat flow Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, ...
''Q'' through a slab (or a portion of a perfectly insulated wire) is proportional to the
gradient In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gr ...
of temperature difference; named for Joseph Fourier. *
Frege's principle In semantics, mathematical logic and related disciplines, the principle of compositionality is the principle that the meaning of a complex expression is determined by the meanings of its constituent expressions and the rules used to combine them. ...
: The meaning of a complex expression is determined by the meanings of its constituent expressions and the rules used to combine them. * Gall's law: "A complex system that works is invariably found to have evolved from a simple system that worked." * Gause's law, in
ecology Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overl ...
, the competitive exclusion principle: "complete competitors cannot coexist." *
Gauss's law In physics and electromagnetism, Gauss's law, also known as Gauss's flux theorem, (or sometimes simply called Gauss's theorem) is a law relating the distribution of electric charge to the resulting electric field. In its integral form, it sta ...
, in
physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
, gives the relation between the electric flux flowing out a closed surface and the
charge Charge or charged may refer to: Arts, entertainment, and media Films * '' Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * ''Charge!!'', an album by The Aqu ...
enclosed in the surface. It was formulated by
Carl Friedrich Gauss Johann Carl Friedrich Gauss (; german: Gauß ; la, Carolus Fridericus Gauss; 30 April 177723 February 1855) was a German mathematician and physicist who made significant contributions to many fields in mathematics and science. Sometimes refer ...
. See also
Gauss's law for gravity In physics, Gauss's law for gravity, also known as Gauss's flux theorem for gravity, is a law of physics that is equivalent to Newton's law of universal gravitation. It is named after Carl Friedrich Gauss. It states that the flux ( surface inte ...
, and
Gauss's law for magnetism In physics, Gauss's law for magnetism is one of the four Maxwell's equations that underlie classical electrodynamics. It states that the magnetic field has divergence equal to zero, in other words, that it is a solenoidal vector field. It is ...
. *
Gay-Lussac's law Gay-Lussac's law usually refers to Joseph-Louis Gay-Lussac's law of combining volumes of gases, discovered in 1808 and published in 1809. It sometimes refers to the proportionality of the volume of a gas to its absolute temperature at constant pr ...
: "The pressure of a fixed mass and fixed volume of a gas is directly proportional to the gas's temperature." * Gell-Mann amnesia effect: Believing newspaper articles outside one's area of expertise, even after acknowledging that neighboring articles in one's area of expertise are completely wrong. * Gérson's law: "An advantage should be taken in every situation, regardless of ethics." *
Gibrat's law Gibrat's law, sometimes called Gibrat's rule of proportionate growth or the law of proportionate effect, is a rule defined by Robert Gibrat (1904–1980) in 1931 stating that the proportional rate of growth of a firm is independent of its absolut ...
: "The size of a firm and its growth rate are independent." *
Gibson's law In public relations, and in the practice of law, Gibson's law holds that "For every PhD there is an equal and opposite PhD." The term specifically refers to the conflict between testimony of expert witnesses called by opposing parties in a trial un ...
: "For every PhD there is an equal and opposite PhD." *
Ginsberg's theorem Ginsberg's theorem is a parody of the laws of thermodynamics in terms of a person playing a game. The quote was first attributed to the poet Allen Ginsberg in a 1975 issue of the ''Coevolution Quarterly.'' It is possible that the quote originates ...
is a set of adages based on the
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 paramet ...
. * Godwin's law, an adage in
Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...
culture: "As an online discussion grows longer, the probability of a comparison involving
Nazis Nazism ( ; german: Nazismus), the common name in English for National Socialism (german: Nationalsozialismus, ), is the far-right totalitarian political ideology and practices associated with Adolf Hitler and the Nazi Party (NSDAP) in N ...
or
Hitler Adolf Hitler (; 20 April 188930 April 1945) was an Austrian-born German politician who was dictator of Nazi Germany, Germany from 1933 until Death of Adolf Hitler, his death in 1945. Adolf Hitler's rise to power, He rose to power as the le ...
approaches one." Coined by
Mike Godwin Michael Wayne Godwin (born October 26, 1956) is an American attorney and author. He was the first staff counsel of the Electronic Frontier Foundation (EFF), and he created the Internet adage Godwin's law and the notion of an Internet meme, as ...
in 1990. *
Gompertz–Makeham law of mortality The Gompertz–Makeham law states that the human death rate is the sum of an age-dependent component (the Gompertz function, named after Benjamin Gompertz), which increases exponentially with age and an age-independent component (the Makeham ter ...
: the death rate is the sum of an age-independent component and an age-dependent component. * Goodhart's law: When a measure becomes a target, it ceases to be a good measure. *
Gossen's laws Gossen's laws, named for Hermann Heinrich Gossen (1810–1858), are three laws of economics: * Gossen's First Law is the "law" of diminishing marginal utility: that marginal utilities are diminishing across the ranges relevant to decision-making. ...
are three laws in economics relating to utility and value, formulated by
Hermann Heinrich Gossen Hermann Heinrich Gossen (7 September 1810 – 13 February 1858) was a Prussian economist who is often regarded as the first to elaborate a general theory of marginal utility. Life and work Gossen studied in Bonn, then worked in the Prussian admin ...
. * Graham's law, a gas law in physics: the average
kinetic energy In physics, the kinetic energy of an object is the energy that 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 acc ...
of the molecules of two samples of different gases at the same temperature is identical. It is named for Thomas Graham (1805–1869), who formulated it. * Grassmann's law: A dissimilatory phonological process in Ancient Greek and Sanskrit which states that if an aspirated consonant is followed by another aspirated consonant in the next syllable, the first one loses the aspiration. Named after its discoverer
Hermann Grassmann Hermann Günther Grassmann (german: link=no, Graßmann, ; 15 April 1809 – 26 September 1877) was a German polymath known in his day as a linguist and now also as a mathematician. He was also a physicist, general scholar, and publisher. His mat ...
. * Grassmann's law (optics), an empirical result about human color perception: that chromatic sensation can be described in terms of an effective stimulus consisting of linear combinations of different light colors. * Greenspun's tenth rule: Any sufficiently complicated C or Fortran program contains an ad hoc, informally specified, bug-ridden, slow implementation of half of Common Lisp; coined by
Philip Greenspun Philip Greenspun (born September 28, 1963) is an American computer scientist, educator, early Internet entrepreneur, and pilot who was a pioneer in developing online communities like photo.net. Biography Greenspun was born on September 28, 1 ...
. *
Gresham's law In economics, Gresham's law is a monetary principle stating that "bad money drives out good". For example, if there are two forms of commodity money in circulation, which are accepted by law as having similar face value, the more valuable com ...
is typically stated as "Bad money drives good money out of circulation", but more accurately "Bad money drives good money out of circulation if their exchange rate is set by law." Coined in 1858 by British economist Henry Dunning Macleod, and named for Sir
Thomas Gresham Sir Thomas Gresham the Elder (; c. 151921 November 1579), was an English merchant and financier who acted on behalf of King Edward VI (1547–1553) and Edward's half-sisters, queens Mary I (1553–1558) and Elizabeth I (1558–1603). In 1565 G ...
(1519–1579). The principle had been stated before Gresham by others, including
Nicolaus Copernicus Nicolaus Copernicus (; pl, Mikołaj Kopernik; gml, Niklas Koppernigk, german: Nikolaus Kopernikus; 19 February 1473 – 24 May 1543) was a Renaissance polymath, active as a mathematician, astronomer, and Catholic canon, who formulated ...
. *
Grimm's law Grimm's law (also known as the First Germanic Sound Shift) is a set of sound laws describing the Proto-Indo-European (PIE) stop consonants as they developed in Proto-Germanic in the 1st millennium BC. First systematically put forward by Jacob Gr ...
explains correspondence between some consonants in Germanic languages and those in other Indo-European languages. Discovered by Jacob Grimm, (1785–1863),
German German(s) may refer to: * Germany (of or related to) ** Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...
philologist Philology () is the study of language in oral and written historical sources; it is the intersection of textual criticism, literary criticism, history, and linguistics (with especially strong ties to etymology). Philology is also defined as th ...
and mythology, mythologist and one of the Brothers Grimm. * Grosch's law: the economic value of computation increases with the square root of the increase in speed; that is, to do a calculation 10 times as cheaply you must do it 100 times as fast. Stated by Herb Grosch in 1965. * Grotthuss–Draper law: only that light which is absorbed by a system can bring about a photochemical change. Named for Theodor Grotthuss and John William Draper. * Gustafson's law (also known as Gustafson–Barsis's law) in computer engineering: any sufficiently large problem can be efficiently parallel computing, parallelized. Coined by John Gustafson in 1988.


H–K

* Haber's rule is a mathematical statement relating the concentration of a poisonous gas and how long it must be breathed to result in death. * Hagen–Poiseuille law: a physical law that gives the pressure drop in an incompressible and Newtonian fluid in laminar flow flowing through a long cylindrical pipe of constant cross section. Named after Gotthilf Hagen and Jean Poiseuille. * Haitz's law is an observation and forecast about the steady improvement, over many years, of light-emitting diodes (LEDs). * Hamilton's principle: the dynamics of a physical system is determined by a variational problem for a functional based on a single function, the Lagrangian, which contains all physical information concerning the system and the forces acting on it. Named after William Rowan Hamilton. * Hanlon's razor is a corollary of Finagle's law, named in allusion to Occam's razor, normally taking the form "Never attribute to malice that which can be adequately explained by stupidity." As with Finagle, possibly not strictly eponymous. Alternatively, "Do not invoke conspiracy as explanation when ignorance and incompetence will suffice, as conspiracy implies intelligence." * Hartley's law is a way to quantify information and its line rate in an analog communications channel. Named for Ralph Hartley (1888–1970). * Hasse principle is the idea that one can find an integer solution to an equation by using the Chinese remainder theorem to piece together solutions modulo powers of each different prime number. Named after Helmut Hasse. * Hauser's law is an empirical observation about U.S. tax receipts as a percentage of GDP, theorized to be a natural equilibrium. * Heaps' law describes the number of distinct words in a document (or set of documents) as a function of the document length. * Donald O. Hebb, Hebb's law: "Neurons that fire together wire together." * Uncertainty principle, Heisenberg's uncertainty principle: one cannot measure values (with arbitrary precision) of certain conjugate quantities, which are pairs of observables of a single elementary particle. The most familiar of these pairs is position and momentum. * Henry's law: The mass of a
gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
that dissolves in a definite volume of liquid is directly proportional to the
pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...
of the gas provided the gas does not react with the solvent. * Hess's law, in physical chemistry: the total enthalpy change during the complete course of a reaction is the same whether the reaction is made in one step or in several steps. * Hick's law, in psychology, describes the time it takes for a person to make a decision as a function of the number of possible choices. * Hickam's dictum, in medicine, is commonly stated as "Patients can have as many diseases as they damn well please" and is a counterargument to the use of Occam's razor. * Hitchens's razor is an epistemology, epistemological principle maintaining that the burden of evidence in a debate rests on the claim maker, and that the opponent can dismiss the claim if this burden is not met: "That which can be asserted without evidence can be dismissed without evidence." * Hofstadter's law: "It always takes longer than you expect, even when you take into account Hofstadter's law" (Douglas Hofstadter, ''Gödel, Escher, Bach'', 1979). * Hooke's law: The tension on a spring or other elastic object is proportional to the displacement from the equilibrium. Frequently cited in Latin as "Ut tensio sic vis." Named after Robert Hooke (1635–1703). * Hotelling's law in
economics Economics () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyzes ...
: Under some conditions, it is rational for competitors to make their products as nearly identical as possible. * Hubble's law: Galaxies recede from an observer at a rate proportional to their distance to that observer. Formulated by Edwin Hubble in 1929. * Hume's law, in meta-ethics: normative statements cannot be deduced exclusively from descriptive statements. * Hume-Rothery rules, named after William Hume-Rothery, are a set of basic rules that describe the conditions under which an element could dissolve in a metal, forming a solid solution. * Humphrey's law: conscious attention to a task normally performed automatically can impair its performance. Described by psychologist George Humphrey in 1923. * Hund's rules are three rules in atomic physics used to determine the term symbol that corresponds to the ground state of a multi-electron atom. Named after Friedrich Hund. * Hutber's law: "Improvement means deterioration." Coined by financial journalist Patrick Hutber. * Hyrum's Law: No matter what the documentation of some computer software's API, other programs will come to rely on the actual behaviour. * Isaac Bonewits#Contributions to Neopaganism, Isaac Bonewits's laws of magic are synthesized from a multitude of belief systems from around the world, collected in order to explain and categorize magical beliefs within a cohesive framework. * Jevons paradox: Increasing the efficiency with which a resource is used increases the usage of that resource. William Stanley Jevons * Joule's laws are heat laws related to electricity and to gasses, named for James Prescott Joule. * Joy's law (management), Joy's law in management: the principle that "no matter who you are, most of the smartest people work for someone else", attributed to Sun Microsystems co-founder Bill Joy. * Kepler's laws of planetary motion describe the motion of the planets around the sun. First articulated by Johannes Kepler. * Kerckhoffs's principle of secure cryptography: A cryptosystem should be secure even if everything about the system, except the key, is public. * Kirchhoff's laws are named after Gustav Kirchhoff and cover thermodynamics, thermochemistry, electrical circuits and spectroscopy (see Kirchhoff's laws (disambiguation)). * Klaiber's law: the silicon wafer size will dictate the largest diameter of ultrapure water supply piping needed within a semiconductor wafer factory. * Kluge's law: a sound law that purports to explain the origin of the Proto-Germanic long consonants. Named after Friedrich Kluge. * Koomey's law: the energy of computation is halved every year and a half. * Kopp's law: The molecular heat capacity of a solid compound is the sum of the atomic heat capacities of the elements composing it. Named for Hermann Franz Moritz Kopp. * Korte's law: The greater the length of a path between two successively presented stimuli, the greater the stimulus onset asynchrony must be for an observer to perceive the two stimuli as a single moving object. * Kranzberg's laws of technology: The first law states that technology is neither good nor bad; nor is it neutral. *Kryder's law: on growth of density of magnetic disk storage, compared to Moore's law.


L–M

* L'Hôpital's rule uses derivatives to find limits of indeterminate forms 0/0 or ±∞/∞, and only applies to such cases. * Jean-Baptiste Lamarck#L'influence des circonstances: The adaptive force, Lamarck's theory of evolution has two laws: The first can be paraphrased as "use it or lose it". The second is the more famous law of soft inheritance. * Lambert's cosine law describes the radiant intensity observed from an ideal diffusely reflecting surface or ideal diffuse radiator. * Lanchester's laws are formulae for calculating the relative strengths of predator/prey pair and application in military conflict. * Landauer's principle: there is a minimum possible amount of energy required to change one bit of information, known as the Landauer limit. * LaSalle's invariance principle is a criterion for the asymptotic stability of an autonomous (possibly nonlinear) dynamical system. Named for mathematician Joseph P. LaSalle. * Leavitt's law: In astronomy, a period-luminosity relation linking the luminosity of pulsating variable stars with their pulsation period. Named for American astronomer Henrietta Swan Leavitt. * Lehman's laws of software evolution * Identity of indiscernibles, Leibniz's law is a principle in metaphysics also known as the Identity of Indiscernibles. It states: "If two objects have all their properties in common, then they are one and the same object." * Lenz's law: An induced current is always in such a direction as to oppose the motion or change causing it. Named for Russian physicist Emil Lenz. * Lem's Law: "No one reads; if someone does read, he doesn't understand, if he understands, he immediately forgets." * Lewis's law: The comments on any article about feminism justify feminism. Named for English journalist Helen Lewis (journalist), Helen Lewis. * Lightwood's law: In medicine, states that bacterial infections will tend to localise while viral infections will tend to spread. * Liebig's law of the minimum: The growth or distribution of a plant is dependent on the one environmental factor most critically in demand. * Lindy's Law: the life expectancy of something is proportional to its current age. Something that has been around for a long time is likely to also remain around for a long time. * Linus's law: "Given enough eyeballs, all computer bug, bugs are shallow." Named for Linus Torvalds. * Little's law, in queuing theory: "The average number of customers in a stable system (over some time interval) is equal to their average arrival rate, multiplied by their average time in the system." The law was named for John Little (academic), John Little from results of experiments in 1961. * Littlewood's law: individuals can expect miracles to happen to them, at the rate of about one per month. Coined by John Edensor Littlewood, J. E. Littlewood, (1885–1977). * Liskov substitution principle in computer science is a particular definition of a subtyping relation, called (strong) behavioral subtyping. * Lorentz force, Lorentz force law defines the force on a moving charged particle in electric and magnetic fields. * Lotka's law, in infometrics: the number of authors publishing a certain number of articles is a fixed ratio to the number of authors publishing a single article. As the number of articles published increases, authors producing that many publications become less frequent. For example, there may be as many authors publishing two articles within a specified time period as there are single-publication authors, as many publishing three articles, as many publishing four articles, etc. Though the law itself covers many disciplines, the actual ratios involved are very discipline-specific. * Madelung rule: the order in which atomic orbitals are filled according to the aufbau principle. Named for Erwin Madelung. Also known as the Janet rule or the Klechkowski rule (after Charles Janet or Vsevolod Klechkovsky). * Maes–Garreau law: most favorable predictions about future technology will fall around latest possible date they can come true and still remain in the lifetime of the person making the prediction. * Malthusian growth model, also referred to as the ''Malthusian law'' or ''simple exponential'' growth model, is exponential growth based on a constant rate. The model is named after Thomas Robert Malthus, who wrote ''An Essay on the Principle of Population'' (1798), one of the earliest and most influential books on population. * Marconi's law empirically relates radio communication distance to antenna tower height. * Maxwell's equations a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, and electric circuits. * Meadow's law is a precept, now discredited, that since cot deaths are so rare, "One is a tragedy, two is suspicious and three is murder, until proved otherwise." It was named for Roy Meadow, a discredited paediatrician prominent in the United Kingdom in the last quarter of the twentieth century. * Mendelian inheritance, Mendel's laws are named for the 19th century Austrian monk Gregor Mendel who determined the patterns of inheritance through his plant breeding experiments, working especially with peas. Mendel's first law, or the law of segregation, states that each organism has a pair of genes; that it inherits one from each parent, and that the organism will pass down only one of these genes to its own offspring. These different copies of the same gene are called alleles. Mendel's second law, the law of independent assortment, states that different traits will be inherited independently by the offspring. * Menzerath's law, or Menzerath–Altmann law (named after Paul Menzerath and Gabriel Altmann), is a linguistic law according to which the increase of a linguistic construct results in a decrease of its constituents, and vice versa. * Metcalfe's law, in communications and network theory: the value of a system grows as approximately the square of the number of users of the system. Framed by Robert Metcalfe in the context of ethernet. * Miller's law, in communication: "To understand what another person is saying, you must assume that it is true and try to imagine what it could be true of." Named after George Armitage Miller. * Miller's rule (optics), Miller's rule, in optics, is an empirical rule which gives an estimate of the order of magnitude of the nonlinear coefficient. * Intracranial pressure, Monro-Kellie doctrine: The pressure–volume relationship between intracranial contents and cerebral perfusion pressure (CPP) states that the cranial compartment is inelastic and that the volume inside the cranium is fixed. The cranium and its constituents (blood, CSF, and brain tissue) create a state of volume equilibrium, such that any increase in volume of one of the cranial constituents must be compensated by a decrease in volume of another. ''*This concept only applies to adults, as the presence of fontanelles and open suture lines in infants that have not yet fused means there is potential for a change in size and intracranial volume.'' * Morgan's canon "In no case is an animal activity to be interpreted in terms of higher psychological processes if it can be fairly interpreted in terms of processes which stand lower in the scale of psychological evolution and development." * Mooers's law: "An information retrieval system will tend not to be used whenever it is more painful and troublesome for a customer to have information than for him not to have it." An empirical observation made by American computer scientist Calvin Mooers in 1959. * Moore's law is an empirical observation stating that the complexity of integrated circuits doubles every 24 months. Outlined in 1965 by Gordon Moore, co-founder of Intel Corporation. * Muller's ratchet where mutations in a species will tend to accumulate. * Muphry's law: "If you write anything criticizing, editing, or proofreading, there will be a fault of some kind in what you have written." The name is a deliberate misspelling of "Murphy's law". * Murray's law states that, in physiological systems such as blood flow, no matter the diameter of the vessel, it will be structured such that minimal work is required to enable the maintenance of a steady state. Named after Cecil D. Murray. * Murphy's law: "Anything that can go wrong will go wrong." Ascribed to Edward A. Murphy, Jr. See also Sod's law.


N–Q

* Naismith's rule is a rule of thumb that helps in the planning of a walking or hiking expedition by calculating how long it will take to walk the route, including ascents. * Navier–Stokes equations: In physics, these equations describe the motion of viscous fluid substances. Named after Claude-Louis Navier and George Gabriel Stokes. * Richard John Neuhaus, Neuhaus's law: Where orthodoxy is optional, orthodoxy will sooner or later be proscribed. This "law" had been expressed earlier. For example, Charles Porterfield Krauth wrote in his ''The Conservative Reformation'': "Truth started with tolerating; it comes to be merely tolerated, and that only for a time. Error claims a preference for its judgments on all disputed points." * Newton's flaming laser sword, also known as Alder's razor: What cannot be settled by experiment is not worth debating. * Newton's law of cooling: The rate of cooling (or heating) of a body due to convection is proportional to the difference between the body temperature and the ambient temperature. *
Newton's laws of motion Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it. These laws can be paraphrased as follows: # A body remains at rest, or in moti ...
, in physics, are three List of laws in Science, scientific laws concerning the behaviour of motion (physics), moving bodies, which are fundamental to classical mechanics (and since Albert Einstein, Einstein, which are valid only within inertial reference frames). Discovered and stated by Isaac Newton (1643–1727), they can be formulated, in modern terms, as follows: ** First law: A body remains at rest, or keeps moving in a straight line (at a constant velocity), unless acted upon by a net outside force. ** Second law: The acceleration of an object of constant mass is proportional to the net force acting upon it. ** Third law: Whenever one body exerts a force upon a second body, the second body exerts an equal and opposite force upon the first body. * Nielsen's law: A high-end user's internet connection speed grows by 50% per year. * Niven's laws: several aphorisms, including "If the universe of discourse permits the possibility of time travel and of changing the past, then no time machine will be invented in that universe." * Occam's razor: explanations should never multiply causes without necessity. ("Entia non sunt multiplicanda praeter necessitatem.") When two or more explanations are offered for a phenomenon, the simplest full explanation is preferable. Named after William of Ockham (c. 1285–1349). * Oddo–Harkins rule: elements with an even atomic number are more common than those with odd atomic number. Named after Giuseppe Oddo and William Draper Harkins. * Ohm's law, in physics: the ratio of the potential difference (or voltage drop) between the ends of a conductor (material), conductor (and resistor) to the current (electricity), current flowing through it is a constant. Discovered by and named after Georg Simon Ohm (1789–1854). * Ohm's acoustic law is an empirical approximation concerning the perception of musical tones, named for Georg Simon Ohm. * Okrent's law is Daniel Okrent's take on the argument to moderation. * Okun's law, in economics: when unemployment increases by 1%, the annual GDP decreases by 2%. * Orgel's rules, in evolutionary biology, are a set of axioms attributed to the evolutionary biologist Leslie Orgel: ** First rule: "Whenever a spontaneous process is too slow or too inefficient a protein will evolve to speed it up or make it more efficient." ** Second rule: "Evolution is cleverer than you are." * Ostrom's law, in
economics Economics () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyzes ...
and property law: resource arrangements in practice can be represented in theory, such as arrangements of the commons or shared property. * O'Sullivan's first law, in politics: "All organizations that are not actually right-wing will over time become left-wing." * Papert's principle: "Some of the most crucial steps in mental growth are based not simply on acquiring new skills, but on acquiring new administrative ways to use what one already knows." * Pareto principle: for many phenomena 80% of consequences stem from 20% of the causes. Named after Italian economist Vilfredo Pareto, but framed by management thinker Joseph M. Juran. * Parkinson's law: "Work expands to fill the time available for its completion." Corollary: "Expenditure rises to meet income." Coined by C. Northcote Parkinson (1909–1993). * Parkinson's law of triviality: "The time spent on any agenda item will be in inverse proportion to the sum of money involved." Also due to C. Northcote Parkinson. * Peltzman effect: Safety measures are offset by increased risk-taking. * Peter principle: "In a hierarchy, every employee tends to rise to his level of incompetence." Coined by Dr. Laurence J. Peter (1919–1990) in his book ''The Peter Principle''. In his follow-up book, ''The Peter Prescription'', he offered possible solutions to the problems his principle could cause. * Planck's law, in physics, describes the spectral radiance of a black body at a given temperature. After Max Planck. * Plateau's laws describe the structure of soap films. Named after Belgian physicist Joseph Plateau. * Poe's law (fundamentalism): "Without a winking smiley or other blatant display of humor, it is utterly impossible to parody a Creationist in such a way that someone won't mistake for the genuine article." Although it originally referred to creationism, the scope later widened to any form of extremism or fundamentalism. * Poisson's law of large numbers: For independent random variables with a common distribution, the average value for a sample tends to the mean as sample size increases. Named after Siméon Denis Poisson (1781–1840) and derived from ''Recherches sur la probabilité des jugements en matière criminelle et en matière civile'' (1837: ''Research on the Probability of Criminal and Civil Verdicts''). * Postel's law: Be conservative in what you do; be liberal in what you accept from others. Derived from RFC 761 (Transmission Control Protocol, 1980) in which Jon Postel summarized earlier communications of desired interoperability criteria for the Internet Protocol (cf. IEN 111) * Pournelle's iron law of bureaucracy: "In any bureaucracy, the people devoted to the benefit of the bureaucracy itself always get in control and those dedicated to the goals the bureaucracy is supposed to accomplish have less and less influence, and sometimes are eliminated entirely." * Premack's principle: More probable behaviors will reinforce less probable behaviors. Named for David Premack (1925–2015) * Price's law (Price's square root law) indicates that the square root of the number of all authors contribute half the publications in a given subject. * Putt's Law and the Successful Technocrat, Putt's law: Technology is dominated by two types of people: those who understand what they do not manage and those who manage what they do not understand. * Putt's Law and the Successful Technocrat, Putt's corollary: Every technical hierarchy, in time, develops a competence inversion. * Pythagorean theorem fundamental relation in Euclidean geometry among the three sides of a right triangle, that the square of the hypotenuse is equal to the square of the other two sides added together.


R–S

* Ramsey problem, the principle in economics that lower price elasticity of demand is optimally associated with greater markups or greater taxation. * Raoult's law, in chemistry: that the vapor pressure of mixed liquids is dependent on the vapor pressures of the individual liquids and the molar fraction of each present in solution. * Rayleigh–Jeans law: attempts to describe the spectral radiance of electromagnetic radiation at all wavelengths from a black body at a given temperature through classical arguments. Named after John William Strutt (Lord Rayleigh) and James Jeans. * Reed's law: the utility of large networks, particularly social networks, can exponential growth, scale exponentially with the size of the network. Asserted by David P. Reed. * Reilly's law of retail gravitation: People generally patronize the largest mall in the area. * Rent's rule: In computing logic, the relationship between the number of external signal connections to a logic block (i.e., the number of "pins") with the number of logic gates in the logic block. Named for IBM employee E. F. Rent. * Ribot's law: In amnesia, more recent memories are most affected. * Ricco's law: In human vision, the product of contrast and area is a constant for small targets below the resolution limit. * Roemer's law: A hospital bed built is a bed filled. * Pygmalion effect, Rosenthal effect, also known as the Pygmalion effect: Higher expectations lead to an increase in performance, or low expectations lead to a decrease in performance. Named after Robert Rosenthal (psychologist), Robert Rosenthal. * Rothbard's law: Everyone specializes in his own area of weakness. * Russell's teapot: the philosophic burden of proof lies upon a person making empirically unfalsifiable claims, rather than shifting the burden of disproof to others. To assert, without offering proof, that a teapot, too small to be seen by telescopes, orbits the Sun somewhere in space between the Earth and Mars, we could not expect anyone to believe solely because the assertion could not be proven wrong. * Sagan standard: Extraordinary claims require extraordinary evidence. * Saint-Venant's principle states: "the difference between the effects of two different but statically equivalent loads becomes very small at sufficiently large distances from load." Named after Adhémar Jean Claude Barré de Saint-Venant. * Sapir–Whorf hypothesis: the structure and scope of the language that people use influences people's worldview and cognition. * Sarnoff's law: The value of a broadcast network is proportional to the number of viewers. * Say's law, attributed to economist Jean-Baptiste Say by economist John Maynard Keynes: "supply creates its own demand", i.e., if businesses produce more output in a free market economy, the wages and other payment for productive inputs will provide sufficient demand so that there is no general glut. * Sayre's law: "In any dispute the intensity of feeling is inversely proportional to the value of the stakes at issue." By way of corollary, the law adds: "That is why academic politics are so bitter." Often attributed to Henry Kissinger. * Schneier's law: "Any person can invent a security system so clever that she or he can't think of how to break it." * Schottky–Mott rule predicts the Schottky barrier height based on the vacuum work function of the metal relative to the vacuum electron affinity (or vacuum ionization energy) of the semiconductor. Named for Walter H. Schottky and Nevill Francis Mott. * Segal's law: "A man with a watch knows what time it is. A man with two watches is never sure." * Shermer's last law: "Any sufficiently advanced extraterrestrial intelligence is indistinguishable from God". This is a corollary to Clarke's third law. * Shirky principle: "Institutions will try to preserve the problem to which they are the solution." * Sievers's law, in Indo-European linguistics, accounts for the pronunciation of a consonant cluster with a glide (*''w'' or *''y'') before a vowel as it was affected by the phonetics of the preceding syllable. Named after Germanic philologist Eduard Sievers (1859–1932). * Sieverts's law, in physical metallurgy, is a rule to predict the solubility of gases in metals. Named after German chemist Adolf Sieverts (1874–1947). * Smeed's law is an empirical rule relating traffic fatalities to traffic congestion as measured by the proxy of motor vehicle registrations and country population. After R. J. Smeed. * Snell's law is the simple formula used to calculate the refraction of light when travelling between two media of differing refractive index. It is named after one of its discoverers, Netherlands, Dutch mathematician Willebrord van Roijen Snell (1580–1626). * John F. Sowa#Sowa's law of standards, Sowa's law of standards: "Whenever a major organization develops a new system as an official standard for X, the primary result is the widespread adoption of some simpler system as a de facto standard for X." * Spearman's hypothesis: The magnitudes of the Race and intelligence#Test scores, black–white differences on tests of cognitive ability positively correlate with the tests' G factor (psychometrics), ''g''-loading. * Spearman's law of diminishing returns states that the g factor (psychometrics), ''g'' factor decreases in predictive power for high IQs. * Stang's law, in Proto-Indo-European phonology: when a word ends with a vowel followed by a laryngeal or a semivowel *''y'' or *''w'' followed by a nasal, the laryngeal or semivowel is dropped, with compensatory lengthening of a preceding vowel. Named after Norwegian linguist Christian Stang. * Stark–Einstein law: every photon that is absorbed will cause a (primary) chemical or physical reaction. Named after Johannes Stark and Albert Einstein. * Stefan–Boltzmann law: The total energy radiated per unit surface area of a black body in unit time is directly proportional to the fourth power of the black body's thermodynamic temperature. Named for Joseph Stefan, Jožef Stefan (1835–1893) and Ludwig Boltzmann. * Stein's law: If something cannot go on forever, it will stop. If a trend cannot go on forever, there is no need for action or a program to make it stop, much less to make it stop immediately; it will stop of its own accord. * Stevens's power law, in psychophysics, relates the intensity of a stimulus to its perceived strength. It supersedes the Weber–Fechner law, since it can describe a wider range of sensations. The theory is named after its inventor, S. Smith Stevens (1906–1973). * Stigler's law of eponymy, Stigler's law: No scientific discovery is named after its original discoverer. Named by statistician Stephen Stigler who attributes it to sociologist Robert K. Merton, making the law self-reference, self-referential. * Stokes's law is an expression for the frictional force exerted on spherical objects with very small Reynolds numbers, named for George Gabriel Stokes (1819–1903). * Stokes's law of sound attenuation is a formula for the attenuation of sound in a Newtonian fluid, such as water or air, due to the fluid's viscosity. * Streisand effect: Any attempt to hide, remove, or censor a piece of information has the unintended consequence of publicizing the information more widely. * Sturgeon's law: "Ninety percent of everything is crud." Derived from a quote by science fiction author Theodore Sturgeon (1918–1985). * Sutton's law: "Go where the money is." Often cited in medical schools to teach new doctors to spend resources where they are most likely to pay off. The law is named after bank robber Willie Sutton, who when asked why he robbed banks, is claimed to have answered "Because that's where the money is." * Swanson's law: solar cell prices fall 20% for every doubling of solar cell industry manufacturing capacity. The law is named after SunPower Corporation founder Richard Swanson. * Szemerényi's law, in Proto-Indo-European phonology: word-final clusters of vowels (V), resonants (R) and either *''s'' or *''h'' are simplified by dropping the word-final fricative (*''h'' was phonetically itself probably a back fricative), with compensatory lengthening of the preceding vowel. Named for Hungarian linguist Oswald Szemerényi.


T–Z

* Teeter's law: "The language of the family you know best always turns out to be the most archaic." A wry observation about the biases of historical linguists, explaining how different investigators can arrive at radically divergent conceptions of the proto-language of a family. Named after the American linguist Karl V. Teeter. *Tesler's law of conservation of complexity states that every Application software, application has an inherent amount of Programming complexity, complexity that cannot be removed or hidden. Named for Larry Tesler. * Thirlwall's Law, Thirlwall's law: under certain conditions, the long run growth of a country can be approximated by the ratio of the growth of exports to the income elasticity of demand for imports. * Titius–Bode law: "a hypothesis that the bodies in some orbital systems, including the Sun's, orbit at semi-major axes in a function of planetary sequence". Named for Johann Daniel Titius and Johann Elert Bode. * Tobler's first law of geography: "Everything is related to everything else, but near things are more related than distant things." Coined by Waldo R. Tobler (b. 1930). *Triffin dilemma, conflict of economic interests that arises between short-term domestic and long-term international objectives for countries whose currency serves as a global reserve currency; named for Belgian American economist Robert Triffin *Rent-seeking#Tullock paradox, Tullock Paradox: a rent-seeker wanting political favors can bribe politicians at a cost much lower than the value of the favor to the rent-seeker; named for American economist Gordon Tullock *Twyman's law: "Any figure that looks interesting or different is usually wrong", following the principle that "the more unusual or interesting the data, the more likely they are to have been the result of an error of one kind or another". * Van Loon's law: "The amount of mechanical development will always be in inverse ratio to the number of slaves that happen to be at a country's disposal." Named for Hendrik Willem van Loon. * Vegard's law, in metallurgy, is an approximate empirical rule which holds that a linear relation exists, at constant temperature, between the crystal lattice parameter of an alloy and the concentrations of the constituent elements. Named for Lars Vegard. * Verdoorn's law, in economics: faster growth in output increases productivity due to increasing returns. Named after Dutch economist Petrus Johannes Verdoorn. * Verner's law, stated by Karl Verner in 1875, describes a historical sound change in the Proto-Germanic language whereby voiceless fricatives *f, *þ, *s and *x, when immediately following an unstressed syllable in the same word, underwent voicing and became respectively *b, *d, *z and *g. * Vierordt's law states that, retrospectively, "short" intervals of time tend to be overestimated, and "long" intervals of time tend to be underestimated. Named after German physician Karl von Vierordt. * Vopěnka's principle, in mathematics, is a large cardinal axiom that states that the set-theoretical universe is so large that in every proper class, some members are similar to others, with this similarity formalized through elementary embeddings. Named after Petr Vopěnka. * Wagner's law predicts that the development of an industrial economy will be accompanied by an increased share of public expenditure in gross national product, and is named after the German economist Adolph Wagner (1835–1917). * Walras's law: budget constraints imply that the values of excess market demands must sum to zero. * Weber–Fechner law, named after the Germans Ernst Heinrich Weber and Gustav Fechner, Gustav Theodor Fechner, attempts to describe the human perception of various physical stimuli. In most cases, Stevens's power law gives a more accurate description. * Weyl law, in mathematics, describes the asymptotic behavior of eigenvalues of the Laplace-Beltrami operator. Named for Hermann Weyl. * The Wiedemann–Franz law, in physics, states that the ratio of the electronic contribution of the thermal conductivity (''κ'') to the electrical conductivity (''σ'') of a metal is proportional to the
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measurement, measured with a thermometer. Thermometers are calibrated in various Conversion of units of temperature, temp ...
(''T''). Named for Gustav Wiedemann (1826–1899) and Rudolph Franz (1826–1902). * Wien's displacement law states that the black body radiation curve for different temperatures peaks at a wavelength inversely proportional to the temperature. Named for Wilhelm Wien. (See also Wien approximation.) * Wiio's laws: The fundamental Wiio's law states that "Communication usually fails, except by accident". * Wike's law of low odd primes: "If the number of experimental treatments is a low odd prime number, then the experimental design is unbalanced and partially confounded." * Winter's law: A sound law operating on Balto-Slavic short vowels. Named after Werner Winter (linguist), Werner Winter * Wirth's law: Software gets slower more quickly than hardware gets faster. * Wiswesser's rule gives a simple method to determine the energetic sequence of electron shells. See also Aufbau principle. *
Wolff's law Wolff's law, developed by the German anatomist and surgeon Julius Wolff (1836–1902) in the 19th century, states that bone in a healthy animal will adapt to the loads under which it is placed. If loading on a particular bone increases, the bon ...
: Bone adapts to pressure, or a lack of it. * Woodward–Hoffmann rules, in organic chemistry, predict the stereochemistry of pericyclic reactions based on orbital symmetry. * ''Wright's law'' also known as Experience curve effects was probably first quantified in the industrial setting sometime in 1936 and postulates that as production doubles the cost of production will decline by a constant percentage. Named after aerospace engineer Theodore Paul Wright (no relation to the Wright brothers) who was working for Curtiss-Wright aircraft during explosive growth in the Aviation between the World Wars, "Golden Age of Aviation". * Yao's principle, in computational complexity theory: the expected cost of any randomized algorithm for solving a given problem, on the worst case input for that algorithm, can be no better than the expected cost, for a worst-case random probability distribution on the inputs, of the deterministic algorithm that performs best against that distribution. Named for Andrew Yao. * Yerkes–Dodson law, an empirical relationship between arousal and performance, originally developed by psychologists Robert M. Yerkes and John Dillingham Dodson. * Zawinski's law: Every program attempts to expand until it can read mail. Those programs which cannot expand are replaced by ones which can. * Zeeman effect: Splitting of a spectral line into several components in the presence of a static magnetic field. * Zipf's law, in linguistics, is the observation that the frequency of use of the ''n''th-most-frequently-used word in any natural language is approximately inversely proportional to ''n'', or, more simply, that a few words are used very often, but many or most are used rarely. Named after George Kingsley Zipf (1902–1950), whose statistical body of research led to the observation. More generally, the term ''Zipf's law'' refers to the probability distributions involved, which is applied by statisticians not only to linguistics but also to fields remote from that. See also Zipf–Mandelbrot law.


See also

* * * * * * * * *


References

{{DEFAULTSORT:Eponymous laws, List of Lists of eponyms, Laws Adages, * Principles, * Law-related lists, eponymous