This list of eponymous laws provides links to articles on laws,

principle A principle is a proposition or value that is a guide for behavior or evaluation. In law, it is a Legal rule, rule that has to be or usually is to be followed. It can be desirably followed, or it can be an inevitable consequence of something, suc ...

adage An adage (; Latin: adagium) is a memorable and usually philosophical aphorism that communicates an important truth derived from experience, custom, or both, and that many people consider true and credible because of its longeval tradition, i.e. ...

s, 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 Moore's law is the observation that the number of transistors in a dense integrated circuit (IC) doubles about every two years. Moore's law is an observation and projection of a historical trend. Rather than a law of physics, it is an empir ...

. 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 John Emerich Edward Dalberg-Acton, 1st Baron Acton, 13th Marquess of Groppoli, (10 January 1834 – 19 June 1902), better known as Lord Acton, was an English Catholic historian, politician, and writer. He is best remembered for the remark he wr ...

: "Power tends to corrupt, and absolute power corrupts absolutely. Great men are almost always bad men .. *

Aitken's law The Scottish Vowel Length Rule (also known as Aitken's law after A. J. Aitken, the Scottish linguist who formulated it) describes how vowel length in Scots, Scottish English, and, to some extent, Ulster English and Geordie is conditioned by the ...

describes how vowel length in

Scots Scots usually refers to something of, from, or related to Scotland, including: * Scots language, a language of the West Germanic language family native to Scotland * Scots people, a nation and ethnic group native to Scotland * Scoti, a Latin na ...

and Scottish English is conditioned by environment. Named for Professor

A. J. Aitken Adam Jack Aitken (19 June 1921 – 11 February 1998) was a Scottish lexicographer and leading scholar of the Scots language. Education and military service Aitken was born on 19 June 1921 in Edinburgh, grew up in Bonnyrigg, Midlothian, a ...

, who formulated it. * Alder's razor: See Newton's flaming laser sword below. * Allen's rule: Endotherms from colder climates usually have shorter limbs (or appendages) than the equivalent animals from warmer climates. *

Amagat's law Amagat's law or the Law of Partial Volumes describes the behaviour and properties of mixtures of ideal (as well as some cases of non-ideal) gases. It is of use in chemistry and thermodynamics. It is named after Emile Amagat. Overview Amagat's la ...

describes the behaviour and properties of mixtures of ideal gases. Named for

Émile Amagat Émile Hilaire Amagat (2 January 1841, Saint-Satur – 15 February 1915) was a French physicist. His doctoral thesis, published in 1872, expanded on the work of Thomas Andrews, and included plots of the isotherms of carbon dioxide at high press ...

. * 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 (1925–2007). * Amdahl's law 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 (1922–2015). * Ampère's circuital law, in physics, relates the circulating

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

in a closed loop to the

electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...

through the loop. Discovered by

André-Marie Ampère André-Marie Ampère (, ; ; 20 January 177510 June 1836) was a French physicist and mathematician who was one of the founders of the science of classical electromagnetism, which he referred to as "electrodynamics". He is also the inventor of nu ...

. * Anderson's rule 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 Andy and Bill's law is a statement that new software will always consume any increase in computing power that new hardware can provide. The law originates from a humorous one-liner told in the 1990s during computing conferences: "what Andy giveth, ...

describes how, when a computer chip is released, new software will be released to use up all of its power. Named for Andy Grove, then CEO of Intel, and Bill Gates, then CEO of Microsoft. * Archie's law, 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 reservoi ...

, relates the in-situ

electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allow ...

of sedimentary rock to its porosity and

brine Brine is a high-concentration solution of salt (NaCl) in water (H2O). In diverse contexts, ''brine'' may refer to the salt solutions ranging from about 3.5% (a typical concentration of seawater, on the lower end of that of solutions used for br ...

saturation. Named for Gus Archie (1907–1978). * Archimedes' principle 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 Archimedes of Syracuse (;; ) was a Greek mathematician, physicist, engineer, astronomer, and inventor from the ancient city of Syracuse in Sicily. Although few details of his life are known, he is regarded as one of the leading scientists ...

. * Artin reciprocity law is a general theorem in number theory that forms a central part of global class field theory. Named after

Emil Artin Emil Artin (; March 3, 1898 – December 20, 1962) was an Austrian mathematician of Armenian descent. Artin was one of the leading mathematicians of the twentieth century. He is best known for his work on algebraic number theory, contributing lar ...

. *

Ashby's law In cybernetics, the term variety denotes the total number of distinguishable elements of a set, most often the set of states, inputs, or outputs of a finite-state machine or transformation, or the binary logarithm of the same quantity. Variet ...

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 formulated by

Isaac Asimov yi, יצחק אזימאװ , birth_date = , birth_place = Petrovichi, Russian SFSR , spouse = , relatives = , children = 2 , death_date = , death_place = Manhattan, New York City, U.S. , nationality = Russian (1920–1922)Soviet (192 ...

: ** 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 Jeff Atwood (1970) is an American software developer, author, blogger, and entrepreneur. He co-founded the computer programming question-and-answer website Stack Overflow and co-founded Stack Exchange, which extends Stack Overflow's question- ...

: Any software that can be written in JavaScript will eventually be written in JavaScript. *

Augustine's laws Augustine's laws were a series of tongue in cheek aphorisms put forth by Norman Ralph Augustine, an American aerospace businessman who served as Under Secretary of the Army from 1975 to 1977. In 1984 he published his laws. The book and several o ...

on air force management. Named for

Norman R. Augustine Norman (Norm) Ralph Augustine (born July 27, 1935) is a U.S. aerospace businessman who served as United States Under Secretary of the Army from 1975 to 1977. Augustine served as chairman and CEO of the Lockheed Martin Corporation. He was chair ...

. * Avogadro's law, one of the gas laws, states that: "equal volumes of all gases, at the same temperature and pressure, have the same number of molecules." * Babinet's principle, in physics, 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. * Baldwin's rules predict feasibility of ring-closing reactions in

organic synthesis Organic synthesis is a special branch of chemical synthesis and is concerned with the intentional construction of organic compounds. Organic molecules are often more complex than inorganic compounds, and their synthesis has developed into one o ...

, proposed by Jack Baldwin. *

Barlow's law Barlow's law was an incorrect physical law proposed by Peter Barlow in 1825 to describe the ability of wires to conduct electricity. It said that the strength of the effect of electricity passing through a wire varies inversely with the square root ...

was an incorrect physical law proposed by Peter Barlow in 1825 to describe the ability of wires to conduct electricity. *

Bayes' theorem In probability theory and statistics, Bayes' theorem (alternatively Bayes' law or Bayes' rule), named after Thomas Bayes, describes the probability of an event, based on prior knowledge of conditions that might be related to the event. For examp ...

describes the probability of an event, based on prior knowledge of conditions that might be related to the event. * Beckstrom's law, in economics, 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 wi ...

. * Beer–Lambert law: in optics, the

empirical relationship In science, an empirical relationship or phenomenological relationship is a relationship or correlation that is supported by experiment and observation but not necessarily supported by theory. Analytical solutions without a theory An empirical rel ...

of the

absorption Absorption may refer to: Chemistry and biology * Absorption (biology), digestion **Absorption (small intestine) *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a route by which ...

of light to the properties of the material through which the light is traveling. Independently discovered (in various forms) by

Pierre Bouguer Pierre Bouguer () (16 February 1698, Croisic – 15 August 1758, Paris) was a French mathematician, geophysicist, geodesist, and astronomer. He is also known as "the father of naval architecture". Career Bouguer's father, Jean Bouguer, one ...

in 1729, Johann Heinrich Lambert in 1760 and

August Beer August Beer (; 31 July 1825 – 18 November 1863) was a German physicist, chemist, and mathematician of Jewish descent. Biography Beer was born in Trier, where he studied mathematics and natural sciences. Beer was educated at the technical s ...

in 1852. * Benford's law : 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: Passion is inversely proportional to the amount of real information available. * Bennett's laws are principles in quantum information theory. Named for Charles H. Bennett. *

Bergmann's rule Bergmann's rule is an ecogeographical rule that states that within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, while populations and species of smaller size are found in warmer ...

: 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 In physics and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids— liquids and gases. It has several subdisciplines, including ''aerodynamics'' (the study of air and other gases in motion) an ...

, describes the effect that flow has on pressure contributing lift to

airfoils An airfoil (American English) or aerofoil (British English) is the cross-sectional shape of an object whose motion through a gas is capable of generating significant lift, such as a wing, a sail, or the blades of propeller, rotor, or turbine. A ...

. * Betteridge's law of headlines: "any headline which ends in a question mark can be answered by the word 'no. * Betz's law: 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 describes the

set up by a steady

current density In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional ar ...

. Named for Jean-Baptiste Biot and Félix Savart. * Birch's law, in geophysics, 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 The Born rule (also called Born's rule) is a key postulate of quantum mechanics which gives the probability that a measurement of a quantum system will yield a given result. In its simplest form, it states that the probability density of findi ...

, in quantum mechanics, gives the probability that a measurement on a quantum system will yield a given result. Named after physicist

Max Born Max Born (; 11 December 1882 – 5 January 1970) was a German physicist and mathematician who was instrumental in the development of quantum mechanics. He also made contributions to solid-state physics and optics and supervised the work of a n ...

. * Boyle's law, in physics, one of the gas laws, states that the volume and pressure of an ideal gas of fixed mass held at a constant temperature 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 (1627–1691). *

Bradford's law Bradford's law is a pattern first described by Samuel C. Bradford in 1934 that estimates the exponentially diminishing returns of searching for references in science journals. One formulation is that if journals in a field are sorted by number of ...

is a pattern described by

Samuel C. Bradford Samuel Clement Bradford (10 January 1878 in London – 13 November 1948) was a British mathematician, librarian and documentalist at the Science Museum in London. He developed " Bradford's law" (or the "law of scattering") regarding differences ...

in 1934 that estimates the exponentially diminishing returns of extending a library search. * Bragg's law, in physics, gives the angles for coherent and incoherent scattering from a crystal lattice. *

Brandolini's law Brandolini's law, also known as the bullshit asymmetry principle, is an internet adage coined in 2013 that emphasizes the effort of debunking misinformation, in comparison to the relative ease of creating it in the first place. The law states the ...

: 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, 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 Sir David Brewster KH PRSE FRS FSA Scot FSSA MICE (11 December 178110 February 1868) was a British scientist, inventor, author, and academic administrator. In science he is principally remembered for his experimental work in physical optics ...

. *

Briffault's law 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,Robert Briffault. * Brooks's law: "Adding manpower to a late software project makes it later." Named after Fred Brooks, author of the well known book on project management '' The Mythical Man-Month''. * Buys Ballot's law is concerned with the notion that the wind travels counterclockwise around low pressure zones in the Northern Hemisphere. Named for C. H. D. Buys Ballot, who published an empirical validation of an existing theory, in 1857. * Byerlee's law gives the stress circumstances in the Earth's crust at which fracturing along a geological fault takes place.

C–D

Campbell's law Campbell's law is an adage developed by Donald T. Campbell, a psychologist and social scientist who often wrote about research methodology, which states: Applications Campbell's law is related to the cobra effect, which is the sometimes uninte ...

: "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 Donald Thomas Campbell (November 20, 1916 – May 6, 1996) was an American social scientist. He is noted for his work in methodology. He coined the term ''evolutionary epistemology'' and developed a selectionist theory of human creativity. A ''R ...

(1916–1996) * Casper's Dictum is a law in

forensic medicine Forensic medicine is a broad term used to describe a group of medical specialties which deal with the examination and diagnosis of individuals who have been injured by or who have died because of external or unnatural causes such as poisoning, assa ...

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 describes the effective contact angle θc for a liquid on a composite surface. * Cassini's laws provide a compact description of the motion of the Moon. Established in 1693 by Giovanni Domenico Cassini. * 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 '' The Illuminatus! Trilogy''. * 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, one of the gas laws in physics, 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. * Chekhov's gun states that nonessential elements of a story must be removed. *

Cheops law Cheops' Law is an adage or epigram that is typically stated as, ''Nothing ever gets built on schedule or within budget.'' Written by Robert A. Heinlein; attributed to his fictitious character Lazarus Long in ''Time Enough for Love'' (1973)Robert A. ...

: Nothing ever gets built on schedule or within budget. *

Chesterton's fence Gilbert Keith Chesterton (29 May 1874 – 14 June 1936) was an English writer, philosopher, Christian apologist, and literary and art critic. He has been referred to as the "prince of paradox". Of his writing style, ''Time'' observed: " ...

states that reforms should not be made until the reasoning behind the existing state of affairs is understood. *

Child's law Space charge is an interpretation of a collection of electric charges in which excess electric charge is treated as a Continuum mechanics, continuum of charge distributed over a region of space (either a volume or an area) rather than distinct poi ...

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 Clement D. Child (1868 – 1933) was an American physicist and educator. He is noted particularly for "Child's law" (1911), which is an equation that describes the electric current that flows between the plates of a vacuum tube. Vacuum tubes were ...

; also known as the Child–Langmuir law (after

Irving Langmuir Irving Langmuir (; January 31, 1881 – August 16, 1957) was an American chemist, physicist, and engineer. He was awarded the Nobel Prize in Chemistry in 1932 for his work in surface chemistry. Langmuir's most famous publication is the 1919 art ...

). See also

Mott–Gurney law Space charge is an interpretation of a collection of electric charges in which excess electric charge is treated as a continuum of charge distributed over a region of space (either a volume or an area) rather than distinct point-like charges. This ...

. *

Chladni's law Chladni's law, named after Ernst Chladni, relates the frequency of modes of vibration for flat circular surfaces with fixed center as a function of the numbers ''m'' of diametric (linear) nodes and ''n'' of radial (circular) nodes. It is stated a ...

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. * Claasen's law, or the logarithmic law of usefulness: usefulness = log(technology). *

Clarke's three laws British science fiction writer Arthur C. Clarke formulated three adages that are known as Clarke's three laws, of which the third law is the best known and most widely cited. They are part of his ideas in his extensive writings about the future. ...

, formulated by

Arthur C. Clarke Sir Arthur Charles Clarke (16 December 191719 March 2008) was an English science-fiction writer, science writer, futurist, inventor, undersea explorer, and television series host. He co-wrote the screenplay for the 1968 film '' 2001: A Spac ...

. 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: Any piece of software reflects the organizational structure that produced it. Named after

Melvin Conway Melvin Edward Conway is an American computer scientist, computer programmer, and hacker who coined what is now known as Conway's law: "Organizations, who design systems, are constrained to produce designs which are copies of the communication stru ...

. *

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: Population lineages tend to increase in body size over evolutionary time. * Coulomb's law is an

inverse-square law In science, an inverse-square law is any scientific law stating that a specified physical quantity is inversely proportional to the square of the distance from the source of that physical quantity. The fundamental cause for this can be understo ...

indicating the magnitude and direction of electrostatic

force In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...

that one stationary, electrically charged object of small dimensions (ideally, a point source) exerts on another. It is named after Charles-Augustin de Coulomb. *

Cramer's rule In linear algebra, Cramer's rule is 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. It expresses the solution in terms of the determinants o ...

: 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. * Cromwell's rule states that the use of prior probabilities 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. *

Curie's law For many paramagnetic materials, the magnetization of the material is directly proportional to an applied magnetic field, for sufficiently high temperatures and small fields. However, if the material is heated, this proportionality is reduced. For ...

: In a paramagnetic material the magnetization of the material is (approximately) directly proportional to an applied magnetic field. Named after Pierre Curie. * Curie-Weiss law: describes the magnetic susceptibility χ of a ferromagnet in the paramagnetic region above the Curie point. Named after Pierre Curie and

Pierre-Ernest Weiss Pierre-Ernest Weiss (25 March 1865, Mulhouse – 24 October 1940, Lyon) was a French physicist who specialized in magnetism. He developed the domain theory of ferromagnetism in 1907. Weiss domains and the Weiss magneton are named after him. ...

. * D'Alembert's principle: 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. * Dahl's law, a sound rule of Northeast Bantu languages, a case of voicing dissimilation. * Dale's principle, in neuroscience, states that a neuron is capable of producing and secreting only one neurotransmitter from its axon terminals. Named after Henry Hallett Dale 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, in

chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

and physics, states that the total pressure exerted by a gaseous mixture is equal to the sum of the

partial pressure In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. The total pressure of an ideal gas ...

s of each individual component in a gas mixture. Also called Dalton's law of partial pressure, and related to the ideal gas laws, this

empirical 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 ...

law was observed by

John Dalton John Dalton (; 5 or 6 September 1766 – 27 July 1844) was an English chemist, physicist and meteorologist. He is best known for introducing the atomic theory into chemistry, and for his research into colour blindness, which he had. Colour b ...

in 1801. * Darcy's law, in hydrogeology, describes the flow of a

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shear ...

(such as water) through a porous medium (such as an aquifer). *

Davis's law Davis's law is used in anatomy and physiology to describe how soft tissue models along imposed demands. It is the corollary to Wolff's law, which applies to osseous tissue. It is a physiological principle stating that soft tissue heal according to ...

, in anatomy, describes how soft tissue models along imposed demands. Corollary to Wolff's law. * De Morgan's laws apply to formal logic regarding the negation of pairs of logical operators. * Dermott's law: The sidereal period of major satellites tends to follow a geometric series. Named after Stanley Dermott. *

De Vaucouleurs' law de Vaucouleurs's law, also known as the de Vaucouleurs profile or de Vaucouleurs model, describes how the surface brightness I of an elliptical galaxy varies as a function of apparent distance R from the center of the galaxy: : \ln I(R) = \ln I_ - ...

, 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. * Dilbert principle: "the most ineffective workers are systematically moved to the place where they can do the least damage: management." Coined by Scott Adams. * Doctorow's law: "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 is an empirical relationship between temperature and the rate of cricket chirping. * Dollo's law: "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 states the classical expression for the specific heat capacity of a crystal due to its lattice vibrations. Named for Pierre Louis Dulong and Alexis Thérèse Petit. * Dunbar's number 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. * Dunning–Kruger effect 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 Edholm's law, proposed by and named after Phil Edholm, refers to the observation that the three categories of telecommunication, namely wireless (mobile), nomadic (wireless without mobility) and wired networks (fixed), are in lockstep and gradually ...

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 ...

. *

Elliott wave principle The Elliott Wave Principle, or Elliott wave theory, 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 and price levels, such as hi ...

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. * El-Sayed rule, 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 Emmert's law states that 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. Specifically, the ''perceived linear size'' of an object increases ...

, 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

. *

Euler's laws of motion In classical mechanics, Euler's laws of motion are equations of motion which extend Newton's laws of motion for point particle to rigid body motion. They were formulated by Leonhard Euler about 50 years after Isaac Newton formulated his laws. O ...

: extends Newton's laws of motion for point particle to rigid body motion. *

Faraday's law of induction Faraday's law of induction (briefly, Faraday's law) is a basic law of electromagnetism predicting how a magnetic field will interact with an electric circuit to produce an electromotive force (emf)—a phenomenon known as electromagnetic inducti ...

: a

changing in time creates a proportional

electromotive force In electromagnetism and electronics, electromotive force (also electromotance, abbreviated emf, denoted \mathcal or ) is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical ''transd ...

. Named for Michael Faraday, based on his work in 1831. * Faraday's law of electrolysis: the mass of a substance produced at an electrode during

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...

is proportional to the number of moles 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 and angular velocity to the forces, torque, stresslet and flow it experiences under low Reynolds number (creeping flow) conditions. *

Fick's laws of diffusion Fick's laws of diffusion describe diffusion and were derived by Adolf Fick in 1855. They can be used to solve for the diffusion coefficient, . Fick's first law can be used to derive his second law which in turn is identical to the diffusion equ ...

describe diffusion, and define the ''diffusion coefficient'' ''D''. Derived by Adolf Fick in the year 1855. *

Finagle's law Finagle's law of dynamic negatives (also known as Melody's law, Sod's Law or Finagle's corollary to Murphy's law) is usually rendered as "Anything that can go wrong, will—at the worst possible moment." The term "Finagle's law" was first used ...

: "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 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 Fitts's law (often cited as Fitts' law) is a predictive model of human movement primarily used in human–computer interaction and ergonomics. The law predicts that the time required to rapidly move to a target area is a function of the ratio betw ...

is a principle of human movement published in 1954 by Paul Fitts which predicts the time required to move from a starting position to a final target area. Fitts's law is used to model the act of pointing, both in the real world, e.g. with a hand or finger, and on a

computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

, e.g. with a

mouse A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

. * Flynn effect 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, also known as the law of heat conduction, states that the time rate of heat flow ''Q'' through a slab (or a portion of a perfectly insulated wire) is

proportional Proportionality, proportion or proportional may refer to: Mathematics * Proportionality (mathematics), the property of two variables being in a multiplicative relation to a constant * Ratio, of one quantity to another, especially of a part compare ...

to the gradient of temperature difference; named for

Joseph Fourier Jean-Baptiste Joseph Fourier (; ; 21 March 1768 – 16 May 1830) was a French people, French mathematician and physicist born in Auxerre and best known for initiating the investigation of Fourier series, which eventually developed into Fourier an ...

. * Frege's principle: 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 John Gall (September 18, 1925 – December 15, 2014) was an American author and retired pediatrician. Gall is known for his 1975 book '' General systemantics: an essay on how systems work, and especially how they fail...'', a critique of systems t ...

: "A

complex system A complex system is a system composed of many components which may interact with each other. Examples of complex systems are Earth's global climate, organisms, the human brain, infrastructure such as power grid, transportation or communication ...

that works is invariably found to have evolved from a simple system that worked." *

Gause's law In ecology, the competitive exclusion principle, sometimes referred to as Gause's law, is a proposition that two species which compete for the same limited resource cannot coexist at constant population values. When one species has even the sligh ...

, in ecology, the

competitive exclusion principle In ecology, the competitive exclusion principle, sometimes referred to as Gause's law, is a proposition that two species which compete for the same limited resource cannot coexist at constant population values. When one species has even the sligh ...

: "complete competitors cannot coexist." * Gauss's law, in physics, gives the relation between the electric

flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications to physics. For transport ph ...

flowing out a closed surface and the charge enclosed in the surface. It was formulated by Carl Friedrich Gauss. See also Gauss's law for gravity, and Gauss's law for magnetism. * Gay-Lussac's law: "The pressure of a fixed mass and fixed volume of a gas is directly proportional to the gas's temperature." *

Gell-Mann amnesia effect John Michael Crichton (; October 23, 1942 – November 4, 2008) was an American author and filmmaker. His books have sold over 200 million copies worldwide, and over a dozen have been adapted into films. His literary works heavily feature tech ...

: 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: "The size of a firm and its growth rate are independent." * Gibson's law: "For every PhD there is an equal and opposite PhD." * Ginsberg's theorem is a set of adages based on the laws of thermodynamics. *

Godwin's law Godwin's law, short for Godwin's law (or rule) of Nazi analogies, is an Internet adage asserting that as an online discussion grows longer (regardless of topic or scope), the probability of a comparison to Nazis or Adolf Hitler approaches 1. P ...

, an adage in Internet 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 Na ...

or Hitler approaches one." Coined by Mike Godwin in 1990. * Gompertz–Makeham law of mortality: the death rate is the sum of an age-independent component and an age-dependent component. *

Goodhart's law Goodhart's law is an adage often stated as, "When a measure becomes a target, it ceases to be a good measure". It is named after British economist Charles Goodhart, who is credited with expressing the core idea of the adage in a 1975 article on mon ...

: When a measure becomes a target, it ceases to be a good measure. * Gossen's laws are three laws in economics relating to utility and value, formulated by Hermann Heinrich Gossen. *

Graham's law Graham's law of effusion (also called Graham's law of diffusion) was formulated by Scottish physical chemist Thomas Graham (chemist), Thomas Graham in 1848.Keith J. Laidler and John M. Meiser, ''Physical Chemistry'' (Benjamin/Cummings 1982), pp.&n ...

, a gas law in physics: the average kinetic energy 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. *

Grassmann's law (optics) Grassmann's laws describe empirical results about how the perception of mixtures of colored lights (i.e., lights that co-stimulate the same area on the retina) composed of different spectral power distributions can be algebraically related to one a ...

, 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. * Gresham's law 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 Henry Dunning Macleod (31 March 1821 – 16 July 1902) was a Scottish economist. Life Henry Dunning Macleod was born in Edinburgh, and educated at Eton, Edinburgh University, and Trinity College, Cambridge, where he graduated in 1843. Macleod ...

, and named for Sir Thomas Gresham (1519–1579). The principle had been stated before Gresham by others, including Nicolaus Copernicus. * Grimm's law explains correspondence between some consonants in Germanic languages and those in other Indo-European languages. Discovered by

Jacob Grimm Jacob Ludwig Karl Grimm (4 January 1785 – 20 September 1863), also known as Ludwig Karl, was a German author, linguist, philologist, jurist, and folklorist. He is known as the discoverer of Grimm's law of linguistics, the co-author of th ...

, (1785–1863), German philologist and 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 Photoelectrochemical processes are processes in photoelectrochemistry; they usually involve transforming light into other forms of energy. These processes apply to photochemistry, optically pumped lasers, sensitized solar cells, luminescence, and ...

: only that light which is absorbed by a system can bring about a photochemical change. Named for Theodor Grotthuss and

John William Draper John William Draper (May 5, 1811 – January 4, 1882) was an English-born American scientist, philosopher, physician, chemist, historian and photographer. He is credited with producing the first clear photograph of a female face (1839–40) and ...

. * Gustafson's law (also known as Gustafson–Barsis's law) in

computer engineering Computer engineering (CoE or CpE) is a branch of electrical engineering and computer science that integrates several fields of computer science and electronic engineering required to develop computer hardware and software. Computer engineers ...

: any sufficiently large problem can be efficiently

parallelized Parallel computing is a type of computation in which many calculations or processes are carried out simultaneously. Large problems can often be divided into smaller ones, which can then be solved at the same time. There are several different for ...

. Coined by John Gustafson in 1988.

H–K

Haber's rule In toxicology, Haber's rule or Haber's law is a mathematical statement of the relationship between the concentration of a poisonous gas and how long the gas must be breathed to produce death, or other toxic effect. The rule was formulated by German ...

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 Jean may refer to: People * Jean (female given name) * Jean (male given name) * Jean (surname) Fictional characters * Jean Grey, a Marvel Comics character * Jean Valjean, fictional character in novel ''Les Misérables'' and its adaptations * J ...

. * 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

, named in allusion to

Occam's razor Occam's razor, Ockham's razor, or Ocham's razor ( la, novacula Occami), also known as the principle of parsimony or the law of parsimony ( la, lex parsimoniae), is the problem-solving principle that "entities should not be multiplied beyond neces ...

, 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 In mathematics, Helmut Hasse's local–global principle, also known as the 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 di ...

is the idea that one can find an integer solution to an equation by using the

Chinese remainder theorem In mathematics, the Chinese remainder theorem states that if one knows the remainders of the Euclidean division of an integer ''n'' by several integers, then one can determine uniquely the remainder of the division of ''n'' by the product of thes ...

to piece together solutions modulo powers of each different prime number. Named after

Helmut Hasse Helmut Hasse (; 25 August 1898 – 26 December 1979) was a German mathematician working in algebraic number theory, known for fundamental contributions to class field theory, the application of ''p''-adic numbers to local class field theory and ...

. * 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. * Hebb's law: "Neurons that fire together wire together." * 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 that dissolves in a definite volume of

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...

is directly proportional to the pressure 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

. *

Hitchens's razor Hitchens's razor is an epistemological razor (a general rule for rejecting certain knowledge claims) that states "what can be asserted without evidence can also be dismissed without evidence." The razor was created by and named after author and ...

is an

epistemological Epistemology (; ), or the theory of knowledge, is the branch of philosophy concerned with knowledge. Epistemology is considered a major subfield of philosophy, along with other major subfields such as ethics, logic, and metaphysics. Episte ...

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 Douglas Richard Hofstadter (born February 15, 1945) is an American scholar of cognitive science, physics, and comparative literature whose research includes concepts such as the sense of self in relation to the external world, consciousness, an ...

, ''

Gödel, Escher, Bach ''Gödel, Escher, Bach: an Eternal Golden Braid'', also known as ''GEB'', is a 1979 book by Douglas Hofstadter. By exploring common themes in the lives and works of logician Kurt Gödel, artist M. C. Escher, and composer Johann Sebastian Bach, t ...

'', 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 Robert Hooke FRS (; 18 July 16353 March 1703) was an English polymath active as a scientist, natural philosopher and architect, who is credited to be one of two scientists to discover microorganisms in 1665 using a compound microscope that ...

(1635–1703). * Hotelling's law in economics: 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 Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an Americans, American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology. Hubble proved that many objects ...

in 1929. * Hume's law, in

meta-ethics In metaphilosophy and ethics, meta-ethics is the study of the nature, scope, and meaning of moral judgment. It is one of the three branches of ethics generally studied by philosophers, the others being normative ethics (questions of how one ought ...

normative statement In many disciplines, including economics and philosophy, a normative statement expresses a value judgment about the desirability of a situation. Whereas a descriptive statement (also known as a positive statement) is meant to describe the world '' ...

s 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 In atomic physics, Hund's rules refers to a set of rules that German physicist Friedrich Hund formulated around 1927, which are used to determine the term symbol that corresponds to the ground state of a multi- electron atom. The first rule is ...

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 Hutber's law states that "improvement means deterioration". It is founded on the cynical observation that a stated improvement actually hides a deterioration. The term has seen wide application in business, engineering, and risk analysis. It was fi ...

: "Improvement means deterioration." Coined by financial journalist

Patrick Hutber Patrick Hutber (18 May 1928 – 3 January 1980) was a British journalist.''The Times'' (4 January 1980), p. 12. He was educated at Ealing Grammar School for Boys and New College, Oxford, where he was librarian and secretary of the Union in 1951. ...

. *

Hyrum's Law An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software Interface (computing), interface, offering a service to other pieces of software. A document or standa ...

: No matter what the documentation of some computer software's API, other programs will come to rely on the actual behaviour. * 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 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 In astronomy, Kepler's laws of planetary motion, published by Johannes Kepler between 1609 and 1619, describe the orbits of planets around the Sun. The laws modified the heliocentric theory of Nicolaus Copernicus, replacing its circular orbits ...

describe the motion of the planets around the sun. First articulated by

Johannes Kepler Johannes Kepler (; ; 27 December 1571 – 15 November 1630) was a German astronomer, mathematician, astrologer, natural philosopher and writer on music. He is a key figure in the 17th-century Scientific Revolution, best known for his laws ...

. * 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 Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter wa ...

(see

Kirchhoff's laws (disambiguation) Kirchhoff's laws, named after Gustav Kirchhoff, may refer to: * Kirchhoff's circuit laws in electrical engineering * Kirchhoff's law of thermal radiation * Kirchhoff equations in fluid dynamics * Kirchhoff's three laws of spectroscopy * Kirch ...

). * 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 Kluge's law is a controversial Proto-Germanic sound law formulated by Friedrich Kluge. It purports to explain the origin of the Proto-Germanic long consonants ''*kk'', ''*tt'', and ''*pp'' (Proto-Indo-European lacked a phonemic length distinc ...

: a sound law that purports to explain the origin of the Proto-Germanic long consonants. Named after Friedrich Kluge. *

Koomey's law Koomey's law describes a trend in the history of computing hardware: for about a half-century, the number of computations per joule of energy dissipated doubled about every 1.57 years. Professor Jonathan Koomey described the trend in a 2010 pap ...

: the energy of computation is halved every year and a half. *

Kopp's law Kopp's law can refer to either of two relationships discovered by the German chemist Hermann Franz Moritz Kopp (1817–1892). #Kopp found "that the molecular heat capacity of a solid compound is the sum of the atomic heat capacities of the elemen ...

: 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 In psychophysics, Korte's third law of apparent motion is an observation relating the phenomenon of apparent motion to the distance and duration between two successively presented stimuli. Formulation Korte's four laws were first proposed in ...

: 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 Mark Howard Kryder (born October 7, 1943 in Portland, Oregon) was Seagate Corp.'s senior vice president of research and chief technology officer. Kryder holds a Bachelor of Science degree in electrical engineering from Stanford University and a ...

: on growth of density of magnetic disk storage, compared to

L–M

* L'Hôpital's rule uses derivatives to find limits of indeterminate forms 0/0 or ±∞/∞, and only applies to such cases. * 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 Joseph Pierre LaSalle (born 28 May 1916 in State College, Pennsylvania; died 7 July 1983 in Little Compton, Rhode Island) was an American mathematician specialising in dynamical systems and responsible for important contributions to stability theo ...

. *

Leavitt's law In astronomy, a period-luminosity relation is a relationship linking the luminosity of pulsating variable stars with their pulsation period. The best-known relation is the direct proportionality law holding for Classical Cepheid variables, sometime ...

: 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 In software engineering, the laws of software evolution refer to a series of laws that Lehman and Belady formulated starting in 1974 with respect to software evolution. The laws describe a balance between forces driving new developments on one han ...

* 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 Lem's Law ( pl, Prawo Lema) is an adage suggested by the Polish science-fiction writer and philosopher Stanisław Lem. It is best known from his faux review "Jedna Minuta" One Minute"of the non-existing book ''One Human Minute'' (1984),

: "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. *

Lightwood's law Lightwood's law is the principle that, in medicine, bacterial infections will tend to localise while viral Viral means "relating to viruses" (small infectious agents). Viral may also refer to: Viral behavior, or virality Memetic behavior l ...

: 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 Lindy effect (also known as Lindy's Law) is a theorized phenomenon by which the future life expectancy of some non-perishable things, like a technology or an idea, is proportional to their current age. Thus, the Lindy effect proposes the longe ...

: 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

bugs Bugs may refer to: * Plural of bug Arts, entertainment and media Fictional characters * Bugs Bunny, a character * Bugs Meany, a character in the ''Encyclopedia Brown'' books Films * ''Bugs'' (2003 film), a science-fiction-horror film * ''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 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

J. E. Littlewood John Edensor Littlewood (9 June 1885 – 6 September 1977) was a British mathematician. He worked on topics relating to mathematical analysis, analysis, number theory, and differential equations, and had lengthy collaborations with G. H. H ...

, (1885–1977). *

Liskov substitution principle The Liskov substitution principle (LSP) is a particular definition of a subtyping relation, called strong behavioral subtyping, that was initially introduced by Barbara Liskov in a 1988 conference keynote address titled ''Data abstraction and h ...

in computer science is a particular definition of a subtyping relation, called (strong) behavioral subtyping. *

Lorentz force law Lorentz is a name derived from the Roman surname, Laurentius, which means "from Laurentum". It is the German form of Laurence. Notable people with the name include: Given name * Lorentz Aspen (born 1978), Norwegian heavy metal pianist and keyboar ...

defines the force on a moving charged particle in electric and magnetic fields. * Lotka's law, in

infometrics Informetrics is the study of quantitative aspects of information, it is an extension and evolution of traditional bibliometrics and scientometrics. Informetrics uses bibliometrics and scientometrics methods to study mainly the problems of litera ...

: 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 The aufbau principle , from the German ''Aufbauprinzip'' (building-up principle), also called the aufbau rule, states that in the ground state of an atom or ion, electrons fill subshells of the lowest available energy, then they fill subshells o ...

. Named for Erwin Madelung. Also known as the Janet rule or the Klechkowski rule (after Charles Janet or Vsevolod Klechkovsky). *

Maes–Garreau law The Maes–Garreau law is the statement that "most favorable predictions about future technology will fall within the Maes–Garreau point", defined as "the latest possible date a prediction can come true and still remain in the lifetime of the per ...

: 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 An, AN, aN, or an may refer to: Businesses and organizations * Airlinair (IATA airline code AN) * Alleanza Nazionale, a former political party in Italy * AnimeNEXT, an annual anime convention located in New Jersey * Anime North, a Canadian an ...

'' (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

, form the foundation of classical electromagnetism, classical optics, and electric circuits. *

Meadow's law Now discredited, Meadow's Law was a precept much in use until recently in the field of child protection, specifically by those investigating cases of multiple cot or crib death – SIDS – within a single family. History The "law" has it that be ...

is a precept, now discredited, that since cot deaths are so rare, "One is a tragedy, two is suspicious and three is

murder Murder is the unlawful killing of another human without justification (jurisprudence), justification or valid excuse (legal), excuse, especially the unlawful killing of another human with malice aforethought. ("The killing of another person wit ...

, 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. *

Mendel's laws Mendelian inheritance (also known as Mendelism) is a type of biological inheritance following the principles originally proposed by Gregor Mendel in 1865 and 1866, re-discovered in 1900 by Hugo de Vries and Carl Correns, and later popularize ...

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 In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

; 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 Menzerath's law, or Menzerath–Altmann law (named after Paul Menzerath and Gabriel Altmann), is a linguistic law according to which the increase of the size of a linguistic construct results in a decrease of the size of its constituents, and vice ...

, or Menzerath–Altmann law (named after Paul Menzerath and

Gabriel Altmann In Abrahamic religions (Judaism, Christianity and Islam), Gabriel (); Greek: grc, Γαβριήλ, translit=Gabriḗl, label=none; Latin: ''Gabriel''; Coptic: cop, Ⲅⲁⲃⲣⲓⲏⲗ, translit=Gabriêl, label=none; Amharic: am, ገብር� ...

), 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 Network theory is the study of graphs as a representation of either symmetric relations or asymmetric relations between discrete objects. In computer science and network science, network theory is a part of graph theory: a network can be defi ...

: 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, in optics, is an empirical rule which gives an estimate of the order of magnitude of the nonlinear coefficient. * 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 Morgan's Canon, also known as Lloyd Morgan's Canon, Morgan's Canon of Interpretation or the principle or law of parsimony, is a fundamental precept of comparative (animal) psychology, coined by 19th-century British psychologist C. Lloyd Morgan. I ...

"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 A computer scientist is a person who is trained in the academic study of computer science. Computer scientists typically work on the theoretical side of computation, as opposed to the hardware side on which computer engineers mainly focus (al ...

Calvin Mooers in 1959. *

is an empirical observation stating that the complexity of

integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...

s doubles every 24 months. Outlined in 1965 by Gordon Moore, co-founder of

Intel Corporation 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 series ...

. * Muller's ratchet where mutations in a species will tend to accumulate. *

Muphry's law Muphry's law is an adage that states: "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". Names for variations on th ...

: "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. Edward Aloysius Murphy Jr. (January 11, 1918 – July 17, 1990) was an American aerospace engineer who worked on safety-critical systems. He is best known for his namesake Murphy's law, which is said to state, "Anything that can go wrong will g ...

N–Q

* Naismith's rule is a

rule of thumb In English, the phrase ''rule of thumb'' refers to an approximate method for doing something, based on practical experience rather than theory. This usage of the phrase can be traced back to the 17th century and has been associated with various t ...

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. * 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, in physics, are three scientific laws concerning the behaviour of moving bodies, which are fundamental to classical mechanics (and since

Einstein Albert Einstein ( ; ; 14 March 1879 – 18 April 1955) was a German-born theoretical physicist, widely acknowledged to be one of the greatest and most influential physicists of all time. Einstein is best known for developing the theory ...

, 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 Jakob Nielsen (born 5 October 1957) is a Danish web usability consultant, human–computer interaction researcher, and co-founder of Nielsen Norman Group. He was named the ''“guru of Web page usability”'' in 1998 by The New York Times and t ...

: 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." *

: 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 The Oddo–Harkins rule holds that an element with an even atomic number (such as carbon, element 6) is more abundant than both elements with the adjacently larger and smaller odd atomic numbers (such as boron, element 5, and nitrogen, element 7, ...

: elements with an even atomic number are more common than those with odd atomic number. Named after

Giuseppe Oddo Giuseppe Oddo (9 June 1865 – 5 November 1954) was an Italian chemist. The Oddo–Harkins rule The Oddo–Harkins rule holds that an element with an even atomic number (such as carbon, element 6) is more abundant than both elements with th ...

and William Draper Harkins. *

Ohm's law Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing the constant of proportionality, the resistance, one arrives at the usual mathematical equat ...

, in physics: the ratio of the potential difference (or voltage drop) between the ends of a

conductor Conductor or conduction may refer to: Music * Conductor (music), a person who leads a musical ensemble, such as an orchestra. * ''Conductor'' (album), an album by indie rock band The Comas * Conduction, a type of structured free improvisation ...

(and

resistor A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active el ...

) to the current flowing through it is a constant. Discovered by and named after Georg Simon Ohm (1789–1854). *

Ohm's acoustic law Ohm's acoustic law, sometimes called the acoustic phase law or simply Ohm's law, states that a musical sound is perceived by the ear as a set of a number of constituent pure harmonic tones. The law was proposed by physicist Georg Ohm in 1843. He ...

is an empirical approximation concerning the perception of musical tones, named for Georg Simon Ohm. *

Okrent's law Daniel Okrent (born April 2, 1948) is an American writer and editor. He is best known for having served as the first public editor of ''The New York Times'' newspaper, inventing Rotisserie League Baseball, and for writing several books (such as ...

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 rule Orgel's rules are a set of axioms attributed by Francis Crick to the evolutionary biologist Leslie Orgel. Orgel's First Rule "Whenever a spontaneous process is too slow or too inefficient a protein will evolve to speed it up or make it more efficie ...

s, 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 and

property law Property law is the area of law that governs the various forms of ownership in real property (land) and personal property. Property refers to legally protected claims to resources, such as land and personal property, including intellectual pro ...

: resource arrangements in practice can be represented in theory, such as arrangements of the commons or

shared property Communitarianism is a philosophy that emphasizes the connection between the individual and the community. Its overriding philosophy is based upon the belief that a person's social identity and personality are largely molded by community relati ...

. *

O'Sullivan's first law John O'Sullivan, CBE (born 25 April 1942) is a British conservative political commentator and journalist. From 1987 to 1988, he was a senior policy writer and speechwriter in 10 Downing Street for Margaret Thatcher when she was British prime mi ...

, 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 The Pareto principle states that for many outcomes, roughly 80% of consequences come from 20% of causes (the "vital few"). Other names for this principle are the 80/20 rule, the law of the vital few, or the principle of factor sparsity. Manage ...

: 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 Cyril Northcote Parkinson (30 July 1909 – 9 March 1993) was a British naval historian and author of some 60 books, the most famous of which was his best-seller ''Parkinson's Law'' (1957), in which Parkinson advanced Parkinson's law, stating t ...

(1909–1993). *

Parkinson's law of triviality The law of triviality is C. Northcote Parkinson's 1957 argument that people within an organization commonly or typically give disproportionate weight to trivial issues. Parkinson provides the example of a fictional committee whose job was to ap ...

: "The time spent on any agenda item will be in inverse proportion to the sum of money involved." Also due to

. *

Peltzman effect Risk compensation is a theory which suggests that people typically adjust their behavior in response to perceived levels of risk, becoming more careful where they sense greater risk and less careful if they feel more protected. Although usually ...

: 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, Planck's law describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature , when there is no net flow of matter or energy between the body and its environment. At ...

, 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 Joseph Antoine Ferdinand Plateau (14 October 1801 – 15 September 1883) was a Belgian physicist and mathematician. He was one of the first people to demonstrate the illusion of a moving image. To do this, he used counterrotating disks with repea ...

. * 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 Creationism is the religious belief that nature, and aspects such as the universe, Earth, life, and humans, originated with supernatural acts of divine creation. Gunn 2004, p. 9, "The ''Concise Oxford Dictionary'' says that creationism is 't ...

, the scope later widened to any form of extremism or fundamentalism. *

Poisson's law of large numbers In probability theory, the law of large numbers (LLN) is a theorem that describes the result of performing the same experiment a large number of times. According to the law, the average of the results obtained from a large number of trials shou ...

: 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 Jonathan Bruce Postel (; August 6, 1943 – October 16, 1998) was an American computer scientist who made many significant contributions to the development of the Internet, particularly with respect to standards. He is known principally for be ...

summarized earlier communications of desired interoperability criteria for the Internet Protocol (cf. IEN 111) *

Pournelle's iron law of bureaucracy Jerry Eugene Pournelle (; August 7, 1933 – September 8, 2017) was an American scientist in the area of operations research and human factors research, a science fiction writer, essayist, journalist, and one of the first bloggers. In the 1960s ...

: "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 Derek John de Solla Price (22 January 1922 – 3 September 1983) was a British physicist, historian of science, and information scientist. He was known for his investigation of the Antikythera mechanism, an ancient Greek planetary computer, and ...

(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 ''Putt's Law and the Successful Technocrat'' is a book, credited to the pseudonym Archibald Putt, published in 1981. An updated edition, subtitled ''How to Win in the Information Age'', was published by Wiley-IEEE Press in 2006. The book is bas ...

: 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 corollary: Every technical hierarchy, in time, develops a competence inversion. *

Pythagorean theorem In mathematics, the Pythagorean theorem or Pythagoras' theorem is a fundamental relation in Euclidean geometry between the three sides of a right triangle. It states that the area of the square whose side is the hypotenuse (the side opposite t ...

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 A good's price elasticity of demand (E_d, PED) is a measure of how sensitive the quantity demanded is to its price. When the price rises, quantity demanded falls for almost any good, but it falls more for some than for others. The price elastici ...

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 scale exponentially with the size of the network. Asserted by

David P. Reed David Patrick Reed (born January 31, 1952) is an American computer scientist, educated at the Massachusetts Institute of Technology, known for a number of significant contributions to computer networking and wireless communications networks. He ...

. * 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 Ribot's law of retrograde amnesia was hypothesized in 1881 by Théodule Ribot. It states that there is a time gradient in retrograde amnesia, so that recent memories are more likely to be lost than the more remote memories. Not all patients with ...

: 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 In health policy, Roemer's Law may be expressed as "in an insured population, a hospital bed built is a bed filled." The rule was deduced by the American health services researcher Milton Roemer, working at the UCLA School of Public Health. Roemer ...

: A hospital bed built is a bed filled. *

Rosenthal effect The Pygmalion effect, or Rosenthal effect, is a psychological phenomenon in which high expectations lead to improved performance in a given area. The effect is named for the Greek myth of Pygmalion, the sculptor who fell so much in love with the ...

, 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. *

Rothbard's law Murray Newton Rothbard (; March 2, 1926 – January 7, 1995) was an American economist of the Austrian School, economic historian, political theorist, and activist. Rothbard was a central figure in the 20th-century American libertarian m ...

: 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 Saint-Venant's principle, named after Adhémar Jean Claude Barré de Saint-Venant, a French elasticity theorist, may be expressed as follows: The original statement was published in French by Saint-Venant in 1855. Although this informal stateme ...

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 Adhémar Jean Claude Barré de Saint-Venant (23 August 1797 – 6 January 1886) was a mechanician and mathematician who contributed to early stress analysis and also developed the unsteady open channel flow shallow water equations, also known as ...

. *

Sapir–Whorf hypothesis The hypothesis of linguistic relativity, also known as the Sapir–Whorf hypothesis , the Whorf hypothesis, or Whorfianism, is a principle suggesting that the structure of a language affects its speakers' worldview or cognition, and thus people' ...

: the structure and scope of the language that people use influences people's worldview and cognition. *

Sarnoff's law David Sarnoff (February 27, 1891 – December 12, 1971) was an American businessman and pioneer of American radio broadcasting, radio and television. Throughout most of his career, he led the Radio Corporation of America (RCA) in various capaciti ...

: The value of a broadcast network is proportional to the number of viewers. * Say's law, attributed to economist

Jean-Baptiste Say Jean-Baptiste Say (; 5 January 1767 – 15 November 1832) was a liberal French economist and businessman who argued in favor of competition, free trade and lifting restraints on business. He is best known for Say's law—also known as the law of ...

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 Sayre's law states, in a formulation quoted by Charles Philip Issawi: "In any dispute the intensity of feeling is inversely proportional to the value of the issues at stake." By way of corollary, it adds: "That is why academic politics are so bitt ...

: "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 Segal's law is an adage that states: At surface level, the adage emphasizes the consistency that arises when information comes from a single source and points out the potential pitfalls of having too much conflicting information. However, the unde ...

: "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 British science fiction writer Arthur C. Clarke formulated three adages that are known as Clarke's three laws, of which the third law is the best known and most widely cited. They are part of his ideas in his extensive writings about the future. ...

. *

Shirky principle Clay Shirky (born 1964) is an American writer, consultant and teacher on the social and economic effects of Internet technologies and journalism. In 2017 he was appointed Vice Provost of Educational Technologies of New York University (NYU), a ...

: "Institutions will try to preserve the problem to which they are the solution." *

Sievers's law Sievers's law in Indo-European studies, Indo-European linguistics accounts for the pronunciation of a consonant cluster with a glide ( or ) before a vowel as it was affected by the phonetics of the preceding syllable. Specifically it refers to ...

, 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 Snell's law (also known as Snell–Descartes law and ibn-Sahl law and the law of refraction) is a formula used to describe the relationship between the angles of incidence and refraction, when referring to light or other waves passing through ...

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, Dutch mathematician

Willebrord van Roijen Snell Willebrord Snellius (born Willebrord Snel van Royen) (13 June 158030 October 1626) was a Dutch astronomer and mathematician, Snell. His name is usually associated with the law of refraction of light known as Snell's law. The lunar crater Sne ...

(1580–1626). * 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 black–white differences on tests of cognitive ability positively correlate with the tests' ''g''-loading. * Spearman's law of diminishing returns states that the ''g'' factor decreases in predictive power for high IQs. *

Stang's law Stang's law is a Proto-Indo-European (PIE) phonological rule named after the Norwegian linguist Christian Stang. Overview The law governs the word-final sequences of a vowel, followed by a semivowel ( or ) or a laryngeal ( or ), followed by a na ...

, in

Proto-Indo-European phonology The phonology of the Proto-Indo-European language (PIE) has been reconstructed by linguists, based on the similarities and differences among current and extinct Indo-European languages. Because PIE was not written, linguists must rely on the evi ...

: 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 Christian Schweigaard Stang (15 March 1900 – 2 July 1977) was a Norwegian linguist, Slavicist and Balticist, professor in Balto-Slavic languages at the University of Oslo from 1938 until shortly before his death. He specialized in the study of ...

. * 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

to the fourth power of the black body's thermodynamic temperature. Named for 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 Stanley Smith Stevens (November 4, 1906 – January 18, 1973) was an American psychologist who founded Harvard's Psycho-Acoustic Laboratory, studying psychoacoustics, and he is credited with the introduction of Stevens's power law. Stevens author ...

(1906–1973). * 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-referential. *

Stokes's law In 1851, George Gabriel Stokes derived an expression, now known as Stokes' law, for the frictional force – also called drag force – exerted on spherical objects with very small Reynolds numbers in a viscous fluid. Stokes' law is derived by s ...

is an expression for the frictional

exerted on spherical objects with very small

Reynolds number In fluid mechanics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. At low Reynolds numbers, flows tend to be domi ...

s, named for George Gabriel Stokes (1819–1903). *

Stokes's law of sound attenuation 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. It states that the amplitude of a plane wave decreases exponentially with distance traveled, at a ...

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 Attempts to hide, remove, or censor information often have the unintended consequence of increasing awareness of that information via the Internet. This is called the Streisand effect. It is named after American singer and actress Barbra Streis ...

: 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 Sutton's law states that when diagnosing, one should first consider the obvious. It suggests that one should first conduct those tests which could confirm (or rule out) the most likely diagnosis. It is taught in medical schools to suggest to medic ...

: "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 SunPower is an American provider of photovoltaic solar energy generation systems and battery energy storage products, primarily for residential customers. The company, headquartered in San Jose, California, was founded in 1985 by Richard Sw ...

founder

Richard Swanson Richard Swanson (born 1945) is an American electrical engineer and businessman, retired founder of SunPower, a solar photovoltaic cell manufacturer. Biography Swanson was born in Davenport, Iowa in 1945. He graduated in 1969 with Bachelor ...

. *

Szemerényi's law Szemerényi's law (or Szemerényi's lengthening) is both a sound change and a synchronic phonological rule that operated during an early stage of the Proto-Indo-European language (PIE). Though its effects are evident in many reconstructed as wel ...

, in

: 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 Teeter's law is 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: Although the law is named after the Americanist lin ...

: "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 Karl van Duyn Teeter (March 2, 1929 – April 20, 2007) was an American linguistics, linguist known especially for his work on the Algic languages. Life and work Teeter was born in Berkeley, California, to Charles Edwin Teeter, Jr., a college p ...

. *Tesler's

law of conservation of complexity The law of conservation of complexity, also known as Tesler's Law, or Waterbed Theory, is an adage in human–computer interaction stating that every application has an inherent amount of complexity that cannot be removed or hidden. Instead, it mus ...

states that every

application Application may refer to: Mathematics and computing * Application software, computer software designed to help the user to perform specific tasks ** Application layer, an abstraction layer that specifies protocols and interface methods used in a c ...

has an inherent amount of

complexity Complexity characterises the behaviour of a system or model whose components interaction, interact in multiple ways and follow local rules, leading to nonlinearity, randomness, collective dynamics, hierarchy, and emergence. The term is generall ...

that cannot be removed or hidden. Named for Larry Tesler. * 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 The Titius–Bode law (sometimes termed just Bode's law) is a formulaic prediction of spacing between planets in any given solar system. The formula suggests that, extending outward, each planet should be approximately twice as far from the Sun as ...

: "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 Waldo Rudolph Tobler (November 16, 1930 – February 20, 2018) was an American- Swiss geographer and cartographer. Tobler's idea that "Everything is related to everything else, but near things are more related than distant things" is referred ...

(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 *

Tullock Paradox Rent-seeking is the act of growing one's existing wealth without creating new wealth by manipulating the social or political environment. Rent-seeking activities have negative effects on the rest of society. They result in reduced economic effic ...

: 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 Lars Vegard (3 February 1880 – 21 December 1963) was a Norwegian physicist who is a pioneer in crystallography. He also made contributions to materials science and the science of aurora borealis. The Vegard's law in solid state chemistry and m ...

. * Verdoorn's law, in economics: faster growth in output increases productivity due to increasing returns. Named after Dutch economist

Petrus Johannes Verdoorn Verdoorn's law is named after Dutch economist Petrus Johannes Verdoorn (1949). It states that in the long run productivity generally grows proportionally to the square root of output. In economics, this law pertains to the relationship between the ...

. * Verner's law, stated by Karl Verner in 1875, describes a historical

sound change A sound change, in historical linguistics, is a change in the pronunciation of a language. A sound change can involve the replacement of one speech sound (or, more generally, one phonetic feature value) by a different one (called phonetic chang ...

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 Karl von Vierordt (1868) was the first to record a law of time perception The study of time perception or chronoception is a field within psychology, cognitive linguistics and neuroscience that refers to the subjective experience, or sense, of t ...

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 Karl von Vierordt (July 1, 1818 – November 22, 1884) was a German physiologist. Vierordt was born in Lahr, Baden. He studied at the universities of Berlin, Göttingen, Vienna, and Heidelberg, and began a practice in Karlsruhe in 1842. In ...

. *

Vopěnka's principle In mathematics, Vopěnka's principle is a large cardinal axiom. The intuition behind the axiom is that the set-theoretical universe is so large that in every proper class, some members are similar to others, with this similarity formalized through ...

, 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 Wagner's law, also known as the law of increasing state activity, is the observation that public expenditure increases as national income rises. It is named after the German economist Adolph Wagner (1835–1917), who first observed the effect in ...

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 Ernst Heinrich Weber (24 June 1795 – 26 January 1878) was a German physician who is considered one of the founders of experimental psychology. He was an influential and important figure in the areas of physiology and psychology during his lif ...

and 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 Hermann Klaus Hugo Weyl, (; 9 November 1885 – 8 December 1955) was a German mathematician, theoretical physicist and philosopher. Although much of his working life was spent in Zürich, Switzerland, and then Princeton, New Jersey, he is assoc ...

. * The Wiedemann–Franz law, in physics, states that the ratio of the electronic contribution of the thermal conductivity (''κ'') to the

(''σ'') of a metal is proportional to the temperature (''T''). Named for

Gustav Wiedemann Gustav Heinrich Wiedemann (; 2 October 1826 – 24 March 1899) was a German physicist and scientific author. Life Wiedemann was born in Berlin the son of a merchant who died two years later. Following the death of his mother in 1842 he lived wi ...

(1826–1899) and

Rudolph Franz Rudolph Franz (December 16, 1826 in Berlin – December 31, 1902 in Berlin) was a German physicist. Life Franz studied math and natural sciences at the University of Bonn and got his doctorate in 1850. He started working as a teacher in Berlin ...

(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 Wien's approximation (also sometimes called Wien's law or the Wien distribution law) is a law of physics used to describe the spectrum of thermal radiation (frequently called the blackbody function). This law was first derived by Wilhelm Wien ...

.) *

Wiio's laws Wiio's laws are ''humoristically'' formulated observations about how humans communicate. Wiio's laws are usually summarized with "Human communications usually fail except by accident", which is the main observation made by Professor Osmo Antero Wi ...

: 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 * Wirth's law: Software gets slower more quickly than hardware gets faster. *

Wiswesser's rule The aufbau principle , from the German ''Aufbauprinzip'' (building-up principle), also called the aufbau rule, states that in the ground state of an atom or ion, electrons fill subshells of the lowest available energy, then they fill subshells ...

gives a simple method to determine the energetic sequence of electron shells. See also

Aufbau principle The aufbau principle , from the German ''Aufbauprinzip'' (building-up principle), also called the aufbau rule, states that in the ground state of an atom or ion, electrons fill subshells of the lowest available energy, then they fill subshells o ...

. * Wolff's law: 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 In industry, models of the learning or experience curve effect express the relationship between experience producing a good and the efficiency of that production, specifically, efficiency gains that follow investment in the effort. The effect has ...

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 "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 John Dillingham Dodson (1879 in Allen County Ky – 1955 in Warren County Ky), was an American psychologist. In 1908, together with Robert Yerkes, Dodson proposed the Yerkes–Dodson Law relating motivation and habit. He obtained a master's degre ...

. * 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

. * 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 George Kingsley Zipf (; January 7, 1902 – September 25, 1950), was an American linguist and philologist who studied statistical occurrences in different languages.. Zipf earned his bachelors, masters, and doctoral degrees from Harvard Universi ...

(1902–1950), whose statistical body of research led to the observation. More generally, the term ''Zipf's law'' refers to the

probability distribution In probability theory and statistics, a probability distribution is the mathematical function that gives the probabilities of occurrence of different possible outcomes for an experiment. It is a mathematical description of a random phenomenon i ...

s involved, which is applied by statisticians not only to linguistics but also to fields remote from that. See also Zipf–Mandelbrot law.

References

{{DEFAULTSORT:Eponymous laws, List of Laws * * eponymous