Lambda (}, ''lám(b)da'') is the 11th letter of the
Greek alphabet
The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BCE. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as we ...
, representing the
voiced alveolar lateral approximant
The voiced alveolar lateral approximant is a type of consonantal sound used in many Speech, spoken languages. The symbol in the International Phonetic Alphabet that represents Dental consonant, dental, Alveolar consonant, alveolar, and Postalv ...
. In the system of
Greek numerals
Greek numerals, also known as Ionic, Ionian, Milesian, or Alexandrian numerals, are a system of writing numbers using the letters of the Greek alphabet. In modern Greece, they are still used for ordinal numbers and in contexts similar to tho ...
, lambda has a value of 30. Lambda is derived from the
Phoenician Lamed
Lamedh or Lamed is the twelfth letter of the Semitic abjads, including Hebrew Lāmed , Aramaic Lāmadh , Syriac Lāmaḏ ܠ, Arabic , and Phoenician Lāmed . Its sound value is .
The Phoenician letter gave rise to the Greek Lambda (Λ), Latin ...
![Phoenician lamedh](https://upload.wikimedia.org/wikipedia/commons/3/3b/Phoenician_lamedh.svg)
. Lambda gave rise to the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
L and the
Cyrillic
, bg, кирилица , mk, кирилица , russian: кириллица , sr, ћирилица, uk, кирилиця
, fam1 = Egyptian hieroglyphs
, fam2 = Proto-Sinaitic
, fam3 = Phoenician
, fam4 = G ...
El (Л). The ancient
grammarians and dramatists give evidence to the pronunciation as () in
Classical Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
times. In
Modern Greek
Modern Greek (, , or , ''Kiní Neoellinikí Glóssa''), generally referred to by speakers simply as Greek (, ), refers collectively to the dialects of the Greek language spoken in the modern era, including the official standardized form of the ...
, the name of the letter, Λάμδα, is pronounced .
In
early Greek alphabets, the shape and orientation of lambda varied. Most variants consisted of two straight strokes, one longer than the other, connected at their ends. The angle might be in the upper-left, lower-left ("Western" alphabets) or top ("Eastern" alphabets). Other variants had a vertical line with a horizontal or sloped stroke running to the right. With the general adoption of the
Ionic alphabet
The history of the Greek alphabet starts with the adoption of Phoenician letter forms in the 9th–8th centuries BC during early Archaic Greece and continues to the present day. The Greek alphabet was developed during the Iron Age centuries af ...
, Greek settled on an angle at the top; the Romans put the angle at the lower-left.
The HTML 4 character entity references for the Greek capital and small letter lambda are
Λ
and
λ
respectively. The Unicode code points for lambda are U+039B and U+03BB.
Symbol
Upper-case letter Λ
Examples of the symbolic use of uppercase lambda include:
* The
lambda particle
The lambda baryons (Λ) are a family of subatomic hadron particles containing one up quark, one down quark, and a third quark from a higher flavour generation, in a combination where the quantum wave function changes sign upon the flavour of any ...
is a type of
subatomic particle
In physical sciences, a subatomic particle is a particle that composes an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a pr ...
in
subatomic particle physics.
* Lambda is the set of logical axioms in the
axiomatic method
In mathematics and logic, an axiomatic system is any set of axioms from which some or all axioms can be used in conjunction to logically derive theorems. A theory is a consistent, relatively-self-contained body of knowledge which usually contains ...
of logical deduction in
first-order logic
First-order logic—also known as predicate logic, quantificational logic, and first-order predicate calculus—is a collection of formal systems used in mathematics, philosophy, linguistics, and computer science. First-order logic uses quantifie ...
.
* There is a poetical allusion to the use of Lambda as a
shield blazon by the
Spartans
Sparta (Doric Greek: Σπάρτα, ''Spártā''; Attic Greek: Σπάρτη, ''Spártē'') was a prominent city-state in Laconia, in ancient Greece. In antiquity, the city-state was known as Lacedaemon (, ), while the name Sparta referred t ...
.
* Lambda is the
von Mangoldt function
In mathematics, the von Mangoldt function is an arithmetic function named after German mathematician Hans von Mangoldt. It is an example of an important arithmetic function that is neither multiplicative nor additive.
Definition
The von Mangold ...
in mathematical
number theory
Number theory (or arithmetic or higher arithmetic in older usage) is a branch of pure mathematics devoted primarily to the study of the integers and arithmetic function, integer-valued functions. German mathematician Carl Friedrich Gauss (1777 ...
.
* Lambda denotes the
de Bruijn–Newman constant
The de Bruijn–Newman constant, denoted by Λ and named after Nicolaas Govert de Bruijn and Charles M. Newman, is a mathematical constant defined via the zero of a function, zeros of a certain function (mathematics), function ''H''(''λ'', ...
which is closely connected with
Riemann's hypothesis
In mathematics, the Riemann hypothesis is the conjecture that the Riemann zeta function has its zeros only at the negative even integers and complex numbers with real part . Many consider it to be the most important unsolved problem in pu ...
.
* In
statistics
Statistics (from German language, German: ''wikt:Statistik#German, Statistik'', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of ...
, lambda is used for the
likelihood ratio
The likelihood function (often simply called the likelihood) represents the probability of random variable realizations conditional on particular values of the statistical parameters. Thus, when evaluated on a given sample, the likelihood functi ...
.
* In statistics,
Wilks's lambda is used in multivariate analysis of variance (
MANOVA
In statistics, multivariate analysis of variance (MANOVA) is a procedure for comparing multivariate sample means. As a multivariate procedure, it is used when there are two or more dependent variables, and is often followed by significance tests i ...
analysis) to compare group means on a combination of dependent variables.
* In the
spectral decomposition of matrices, lambda indicates the
diagonal matrix
In linear algebra, a diagonal matrix is a matrix in which the entries outside the main diagonal are all zero; the term usually refers to square matrices. Elements of the main diagonal can either be zero or nonzero. An example of a 2×2 diagonal ma ...
of the
eigenvalues
In linear algebra, an eigenvector () or characteristic vector of a linear transformation is a nonzero vector that changes at most by a scalar factor when that linear transformation is applied to it. The corresponding eigenvalue, often denoted b ...
of the
matrix
Matrix most commonly refers to:
* ''The Matrix'' (franchise), an American media franchise
** ''The Matrix'', a 1999 science-fiction action film
** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...
.
* In
computer science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...
, lambda is the time window over which a process is observed for determining the working memory set for a
digital computer
A computer is a machine that can be programmed to carry out sequences of arithmetic or logical operations ( computation) automatically. Modern digital electronic computers can perform generic sets of operations known as programs. These pro ...
's
virtual memory
In computing, virtual memory, or virtual storage is a memory management technique that provides an "idealized abstraction of the storage resources that are actually available on a given machine" which "creates the illusion to users of a very l ...
management.
* In
astrophysics
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the h ...
, lambda represents the likelihood that a small body will encounter a
planet
A planet is a large, rounded astronomical body that is neither a star nor its remnant. The best available theory of planet formation is the nebular hypothesis, which posits that an interstellar cloud collapses out of a nebula to create a you ...
or a
dwarf planet
A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to p ...
leading to a deflection of a significant magnitude. An object with a large value of lambda is expected to have
cleared its neighbourhood, satisfying the current
definition of a planet
The definition of ''planet'', since the word was coined by the ancient Greeks, has included within its scope a wide range of celestial bodies. Greek astronomy, Greek astronomers employed the term (), 'wandering stars', for star-like objects wh ...
.
* In
crystal optics
Crystal optics is the branch of optics that describes the behaviour of light in '' anisotropic media'', that is, media (such as crystals) in which light behaves differently depending on which direction the light is propagating. The index of refrac ...
, lambda is used to represent a lattice period.
* In
NATO
The North Atlantic Treaty Organization (NATO, ; french: Organisation du traité de l'Atlantique nord, ), also called the North Atlantic Alliance, is an intergovernmental military alliance between 30 member states – 28 European and two No ...
military operations, a
chevron
Chevron (often relating to V-shaped patterns) may refer to:
Science and technology
* Chevron (aerospace), sawtooth patterns on some jet engines
* Chevron (anatomy), a bone
* ''Eulithis testata'', a moth
* Chevron (geology), a fold in rock lay ...
(a heraldic symbol which looks like a capital letter lambda or inverted V) is painted on the vehicles of this military alliance for identification.
* In
electrochemistry
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outco ...
, lambda denotes the "equivalent
conductance" of an
electrolyte
An electrolyte is a medium containing ions that is electrically conducting through the movement of those ions, but not conducting electrons. This includes most soluble salts, acids, and bases dissolved in a polar solvent, such as water. Upon dis ...
solution.
* In
cosmology
Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe. The term ''cosmology'' was first used in English in 1656 in Thomas Blount (lexicographer), Thomas Blount's ''Glossographia'', and in 1731 taken up in ...
, lambda is the symbol for the
cosmological constant
In cosmology, the cosmological constant (usually denoted by the Greek capital letter lambda: ), alternatively called Einstein's cosmological constant,
is the constant coefficient of a term that Albert Einstein temporarily added to his field equ ...
, a term added to some dynamical equations to account for the
accelerating expansion of the universe
Observations show that the expansion of the universe is accelerating, such that the velocity at which a distant galaxy recedes from the observer is continuously increasing with time. The accelerated expansion of the universe was discovered durin ...
.
* In optics, lambda denotes the grating pitch of a
Bragg reflector
A distributed Bragg reflector (DBR) is a reflector used in waveguides, such as optical fibers. It is a structure formed from multiple layers of alternating materials with varying refractive index, or by periodic variation of some characteristi ...
. Also in optics, it denotes wavelength of light.
* In
politics
Politics (from , ) is the set of activities that are associated with making decisions in groups, or other forms of power relations among individuals, such as the distribution of resources or status. The branch of social science that studies ...
, the lambda is the symbol of
Identitarianism
The Identitarian movement or Identitarianism is a pan-European nationalist, far-right political ideology asserting the right of European ethnic groups and white peoples to Western culture and territories claimed to belong exclusively to them ...
, a
white nationalist
White nationalism is a type of racial nationalism or pan-nationalism which espouses the belief that white people are a raceHeidi Beirich and Kevin Hicks. "Chapter 7: White nationalism in America". In Perry, Barbara. ''Hate Crimes''. Greenwoo ...
movement that originated in
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
before spreading out to the rest of
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
and later on to
North America
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
,
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
and
New Zealand
New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...
. The Identitarian lambda represents the
Battle of Thermopylae
The Battle of Thermopylae ( ; grc, Μάχη τῶν Θερμοπυλῶν, label=Greek, ) was fought in 480 BC between the Achaemenid Persian Empire under Xerxes I and an alliance of Greek city-states led by Sparta under Leonidas I. Lasting o ...
.
Lower-case letter λ
![Greek lc lamda thin](https://upload.wikimedia.org/wikipedia/commons/3/3a/Greek_lc_lamda_thin.svg)
Examples of the symbolic use of lowercase lambda include:
* Lambda indicates the
wavelength
In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats.
It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tro ...
of any
wave
In physics, mathematics, and related fields, a wave is a propagating dynamic disturbance (change from equilibrium) of one or more quantities. Waves can be periodic, in which case those quantities oscillate repeatedly about an equilibrium (res ...
, especially in
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
,
electronic engineering
Electronics engineering is a sub-discipline of electrical engineering which emerged in the early 20th century and is distinguished by the additional use of active components such as semiconductor devices to amplify and control electric current ...
, and
mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics ...
.
* In
evolutionary algorithm
In computational intelligence (CI), an evolutionary algorithm (EA) is a subset of evolutionary computation, a generic population-based metaheuristic optimization algorithm. An EA uses mechanisms inspired by biological evolution, such as reproduc ...
s, λ indicates the number of offspring that would be generated from μ current population in each generation. The terms μ and λ are originated from
Evolution strategy
In computer science, an evolution strategy (ES) is an optimization technique based on ideas of evolution. It belongs to the general class of evolutionary computation or artificial evolution methodologies.
History
The 'evolution strategy' optimizat ...
notation.
* Lambda indicates the
radioactivity decay constant in
nuclear physics
Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter.
Nuclear physics should not be confused with atomic physics, which studies the ...
and
radioactivity. This constant is very simply related (by a multiplicative constant) to the
half-life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
of any radioactive material.
* In
probability theory
Probability theory is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expressing it through a set o ...
, lambda represents the density of occurrences within a time interval, as modelled by the
Poisson distribution
In probability theory and statistics, the Poisson distribution is a discrete probability distribution that expresses the probability of a given number of events occurring in a fixed interval of time or space if these events occur with a known co ...
.
* In
mathematical logic
Mathematical logic is the study of logic, formal logic within mathematics. Major subareas include model theory, proof theory, set theory, and recursion theory. Research in mathematical logic commonly addresses the mathematical properties of for ...
and
computer science
Computer science is the study of computation, automation, and information. Computer science spans theoretical disciplines (such as algorithms, theory of computation, information theory, and automation) to Applied science, practical discipli ...
, lambda is used to introduce
anonymous function
In computer programming, an anonymous function (function literal, lambda abstraction, lambda function, lambda expression or block) is a function definition that is not bound to an identifier. Anonymous functions are often arguments being passed to ...
s expressed with the concepts of
lambda calculus
Lambda calculus (also written as ''λ''-calculus) is a formal system in mathematical logic for expressing computation based on function abstraction and application using variable binding and substitution. It is a universal model of computation ...
.
* Lambda indicates an
eigenvalue
In linear algebra, an eigenvector () or characteristic vector of a linear transformation is a nonzero vector that changes at most by a scalar factor when that linear transformation is applied to it. The corresponding eigenvalue, often denoted b ...
in the mathematics of
linear algebra
Linear algebra is the branch of mathematics concerning linear equations such as:
:a_1x_1+\cdots +a_nx_n=b,
linear maps such as:
:(x_1, \ldots, x_n) \mapsto a_1x_1+\cdots +a_nx_n,
and their representations in vector spaces and through matrices.
...
.
* In the physics of
electric field
An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...
s, lambda sometimes indicates the linear
charge density
In electromagnetism, charge density is the amount of electric charge per unit length, surface area, or volume. Volume charge density (symbolized by the Greek letter ρ) is the quantity of charge per unit volume, measured in the SI system in co ...
of a uniform line of
electric charge
Electric charge is the physical property of matter that causes charged matter to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative'' (commonly carried by protons and electrons respe ...
(measured in
coulomb
The coulomb (symbol: C) is the unit of electric charge in the International System of Units (SI).
In the present version of the SI it is equal to the electric charge delivered by a 1 ampere constant current in 1 second and to elementary char ...
s per meter).
* Lambda denotes a
Lagrange multiplier
In mathematical optimization, the method of Lagrange multipliers is a strategy for finding the local maxima and minima of a function subject to equality constraints (i.e., subject to the condition that one or more equations have to be satisfied ex ...
in
multi-dimensional calculus.
* In
solid-state electronics
Solid-state electronics means semiconductor electronics: electronic equipment using semiconductor devices such as transistors, diodes and integrated circuits (ICs). The term is also used as an adjective for devices in which semiconductor electr ...
, lambda indicates the
channel length modulation
Channel length modulation (CLM) is an effect in field effect transistors, a shortening of the length of the inverted channel region with increase in drain bias for large drain biases. The result of CLM is an increase in current with drain bias an ...
parameter of a
MOSFET
The metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, or MOS FET) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which d ...
.
* In
ecology
Ecology () is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers organisms at the individual, population, community, ecosystem, and biosphere level. Ecology overlaps wi ...
, lambda denotes the long-term intrinsic growth rate of a population. This value is often calculated as the dominant eigenvalue of the age/size class
matrix
Matrix most commonly refers to:
* ''The Matrix'' (franchise), an American media franchise
** ''The Matrix'', a 1999 science-fiction action film
** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...
.
* In
formal language theory
In logic, mathematics, computer science, and linguistics, a formal language consists of words whose letters are taken from an alphabet and are well-formed according to a specific set of rules.
The alphabet of a formal language consists of symb ...
and in computer science, lambda denotes the
empty string
In formal language theory, the empty string, or empty word, is the unique string of length zero.
Formal theory
Formally, a string is a finite, ordered sequence of characters such as letters, digits or spaces. The empty string is the special cas ...
.
* Lambda is a nonstandard symbol in the
International Phonetic Alphabet
The International Phonetic Alphabet (IPA) is an alphabetic system of phonetic transcription, phonetic notation based primarily on the Latin script. It was devised by the International Phonetic Association in the late 19th century as a standa ...
for the
voiced alveolar lateral affricate
The voiced alveolar lateral affricate is a type of consonantal sound, used in some spoken languages. The symbol in the International Phonetic Alphabet is (often simplified to ).
Features
Features of the voiced alveolar lateral affricate:
...
.
* Lambda denotes the
Lebesgue measure
In measure theory, a branch of mathematics, the Lebesgue measure, named after French mathematician Henri Lebesgue, is the standard way of assigning a measure to subsets of ''n''-dimensional Euclidean space. For ''n'' = 1, 2, or 3, it coincides wit ...
in
mathematical set theory
Set theory is the branch of mathematical logic that studies sets, which can be informally described as collections of objects. Although objects of any kind can be collected into a set, set theory, as a branch of mathematics, is mostly concern ...
.
* The
Goodman and Kruskal's lambda
In probability theory and statistics, Goodman & Kruskal's lambda (\lambda) is a measure of proportional reduction in error in cross tabulation analysis. For any sample with a nominal independent variable and dependent variable (or ones that can be ...
in
statistics
Statistics (from German language, German: ''wikt:Statistik#German, Statistik'', "description of a State (polity), state, a country") is the discipline that concerns the collection, organization, analysis, interpretation, and presentation of ...
indicates the
proportional reduction in error
Proportional reduction in loss (PRL) is a general framework for developing and evaluating measures of the reliability of particular ways of making observations which are possibly subject to errors of all types. Such measures quantify how much havin ...
when one variable's values are used to predict the values of another variable.
* Lambda denotes the
oxygen sensor
An oxygen sensor (or lambda sensor, where lambda refers to air–fuel equivalence ratio, usually denoted by λ) or probe or sond, is an electronic device that measures the proportion of oxygen (O2) in the gas or liquid being analysed.
It was ...
in a vehicle that measures the
air-to-fuel ratio in the exhaust
gases
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
of an
internal-combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal combust ...
.
* A
Lambda 4S
The Lambda 4S or L-4S was an experimental Japanese expendable carrier rocket. It was produced by Nissan and the Institute of Space and Astronautical Science and launched five times between 1966 and 1970 with Ohsumi technology demonstration satelli ...
solid-fuel rocket was used to launch
Japan's first orbital satellite in 1970.
* Lambda denotes the
failure rate
Failure rate is the frequency with which an engineered system or component fails, expressed in failures per unit of time. It is usually denoted by the Greek letter λ (lambda) and is often used in reliability engineering.
The failure rate of a ...
of devices and systems in
reliability theory
Reliability engineering is a sub-discipline of systems engineering that emphasizes the ability of equipment to function without failure. Reliability describes the ability of a system or component to function under stated conditions for a specifi ...
, and it is measured in failure events per hour. Numerically, this lambda is also the reciprocal of the
mean time between failure
Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a mechanical or electronic system during normal system operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a syste ...
s.
* In criminology, lambda denotes an individual's frequency of
offences.
* In
electrochemistry
Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outco ...
, lambda also denotes the
ion
An ion () is an atom or molecule with a net electrical charge.
The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...
ic conductance of a given ion (the composition of the ion is generally shown as a subscript to the lambda character).
* In
neurobiology
Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, development ...
, lambda denotes the
length constant
In neurobiology, the length constant (''λ'') is a mathematical constant used to quantify the distance that a graded electric potential will travel along a neurite via passive electrical conduction. The greater the value of the length constant, t ...
(or exponential rate of decay) of the
electric potential
The electric potential (also called the ''electric field potential'', potential drop, the electrostatic potential) is defined as the amount of work energy needed to move a unit of electric charge from a reference point to the specific point in ...
across the
cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
along a length of a nerve cell's
axon
An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action po ...
.
* In the science and technology of
heat transfer
Heat transfer is a discipline of thermal engineering that concerns the generation, use, conversion, and exchange of thermal energy (heat) between physical systems. Heat transfer is classified into various mechanisms, such as thermal conduction, ...
, lambda denotes the
heat of vaporization
The enthalpy of vaporization (symbol ), also known as the (latent) heat of vaporization or heat of evaporation, is the amount of energy (enthalpy) that must be added to a liquid substance to transform a quantity of that substance into a gas. T ...
per
mole
Mole (or Molé) may refer to:
Animals
* Mole (animal) or "true mole", mammals in the family Talpidae, found in Eurasia and North America
* Golden moles, southern African mammals in the family Chrysochloridae, similar to but unrelated to Talpida ...
of material (a.k.a. its "latent heat").
* In the technology and science of
celestial navigation
Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space (or on the surface of ...
, lambda denotes the
longitude
Longitude (, ) is a geographic coordinate that specifies the east–west position of a point on the surface of the Earth, or another celestial body. It is an angular measurement, usually expressed in degrees and denoted by the Greek letter l ...
as opposed to the Roman letter "L", which denotes the
latitude
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
.
* A block style lambda is used as a recurring symbol in the
Valve
A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings ...
computer game series ''
Half-Life
Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...
'', referring to the Lambda complex of the fictional
Black Mesa Research Facility
The Black Mesa Research Facility (also simply called Black Mesa) is a fictional underground laboratory complex that serves as the primary setting for the video game ''Half-Life'' and its expansions, as well as its remake, '' Black Mesa''. It als ...
, as well as making appearances in the sequel ''Half-Life 2'', and its subsequent prequel ''Half-Life: Alyx'' as an in universe logo.
* In 1970, a lowercase lambda was chosen by
Tom Doerr
Thomas L. Doerr (1947 – August 2, 1987) was an American gay activist. In 1970, he introduced the lambda symbol into the gay rights movement when the image was used to represent the political work of the Gay Activists Alliance. The lambda became " ...
as the symbol of the New York chapter of the
Gay Activists Alliance
The Gay Activists Alliance (GAA) was founded in New York City on December 21, 1969, almost six months after the Stonewall riots, by dissident members of the Gay Liberation Front (GLF). In contrast to the Liberation Front, the Activists Alliance s ...
. The lambda symbol became associated with
Gay Liberation
The gay liberation movement was a social and political movement of the late 1960s through the mid-1980s that urged lesbians and gay men to engage in radical direct action, and to counter societal shame with gay pride.Hoffman, 2007, pp.xi-xiii. ...
and recognized as an
LGBT symbol
Over the course of its history, the LGBT community has adopted certain symbols for self-identification to demonstrate unity, pride, shared values, and allegiance to one another. These symbols communicate ideas, concepts, and identity both with ...
for some time afterwards, being used as such by the International Gay Rights Congress in Edinburgh.
Litra symbol
The
Roman
Roman or Romans most often refers to:
*Rome, the capital city of Italy
*Ancient Rome, Roman civilization from 8th century BC to 5th century AD
*Roman people, the people of ancient Rome
*''Epistle to the Romans'', shortened to ''Romans'', a letter ...
''libra'' and
Byzantine
The Byzantine Empire, also referred to as the Eastern Roman Empire or Byzantium, was the continuation of the Roman Empire primarily in its eastern provinces during Late Antiquity and the Middle Ages, when its capital city was Constantinopl ...
''lítra'' (), which served as both the pound mass unit and liter volume unit, were abbreviated in Greek using lambda with modified forms of the
iota subscript
The iota subscript is a diacritic mark in the Greek alphabet shaped like a small vertical stroke or miniature iota placed below the letter. It can occur with the vowel letters eta , omega , and alpha . It represents the former presence of an ...
(as λͅ). These are variously encoded in Unicode. The
Ancient Greek Numbers
Ancient Greek Numbers is a Unicode block containing acrophonic numerals
The Attic numerals are a symbolic number notation used by the ancient Greeks. They were also known as Herodianic numerals because they were first described in a 2nd- ...
Unicode block
A Unicode block is one of several contiguous ranges of numeric character codes (code points) of the Unicode character set that are defined by the Unicode Consortium for administrative and documentation purposes. Typically, proposals such as the ad ...
includes 10183 (𐆃) as well as 𐅢, which is described as 10162 but was much more common as a form of the litra sign. A variant of the sign can be formed from 0338 and either 039B (Λ̸) or 03BB (λ̸).
Character encodings
Unicode uses the (Modern Greek-based) spelling "lamda" in character names, instead of "lambda", due to "the pre-existing names in ISO 8859-7, as well as preferences expressed by the Greek National Body".
* Greek Lambda / Coptic Laula
* Mathematical Lambda
These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.
See also
*
Barred lambda
The barred lambda ƛ, (in Unicode ), also called running man,
(strictly speaking, this refers to the glottalized version, ) is a mo ...
- ƛ
*
El (Cyrillic)
El (Л л; italics: ) is a letter of the Cyrillic script.
El commonly represents the alveolar lateral approximant . In Slavic languages it may be either palatalized or slightly velarized; see below.
Allography
In some typefaces the Cyrillic ...
– Л, л
*
Fraser alphabet#Consonants
*
Greek letters used in mathematics, science, and engineering
Greek letters are used in mathematics, science, engineering, and other areas where mathematical notation is used as symbols for constants, special functions, and also conventionally for variables representing certain quantities. In these cont ...
References
{{Reflist
Greek letters
LGBT symbols