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Lie algebra representation
A Lie algebra representation is a way of realizing a Lie algebra as linear operators on a vector space, via a bracket-preserving homomorphism into endomorphisms.
Lie bialgebra
A Lie bialgebra, or Poisson-Hopf algebra, is a Lie algebra with a compatible cobracket, introduced by Vladimir Drinfeld in 1983 as the structure underlying Poisson-Lie groups.
Lie derivative
The Lie derivative is an operator on a differentiable manifold that measures the rate of change of a tensor field along the flow of a vector field.
Lie group
A Lie group is a set carrying compatible structures of a group and a smooth manifold, named for Sophus Lie and central to continuous symmetry in mathematics and physics.
Lie group analysis
Lie group analysis is a mathematical method that finds and exploits continuous symmetry groups of differential equations to produce similarity solutions, reduce order or variables, and derive conservation laws.
Lie superalgebra
A Lie superalgebra is a ℤ₂-graded algebra with even and odd parts whose bracket obeys graded symmetry and Jacobi identities, generalizing a Lie algebra and underlying supersymmetry in physics.
Lie symmetry analysis
Lie symmetry analysis is a mathematical method that finds continuous transformation groups leaving a differential equation invariant, then uses those symmetries to construct exact solutions and reduce the order of equations.
Lies, damned lies, and statistics
"Lies, damned lies, and statistics" is a phrase describing the persuasive power of statistics to bolster weak arguments, popularized by Mark Twain, who credited Disraeli in 1907.
Life on Mars
Life on Mars is the scientific question of whether life exists or ever existed on Mars; none has been confirmed, though organic molecules and potential biosignatures have been found.
Life on Titan
Life on Titan, also called Titanian life, is a hypothesized possibility studied in astrobiology: Saturn's moon Titan has liquid methane lakes and a possible subsurface ocean.
Life on Venus
Life on Venus, also known as habitability of Venus, is the scientific question of whether life exists or ever existed there, focusing on microbial life in the clouds.
Life table
A life table, also called a mortality table or actuarial table, is a statistical table describing a population's mortality by age, showing death probabilities, survivors, and remaining life expectancy.
Lifeng Chi
Lifeng Chi (迟力峰, born 1957) is a Chinese surface physical chemist known for on-surface chemical reactions and molecular self-assembly, a Chinese Academy of Sciences academician elected in 2021.
Lift (force)
Lift, also called aerodynamic lift, is the component of aerodynamic force perpendicular to the oncoming flow, the force that supports an aircraft in flight and acts on wings, propellers, and sails.
Lift coefficient
The lift coefficient, or coefficient of lift, is a dimensionless number that combines the effects of wing shape, angle of attack, and flow conditions on lift in the lift equation.
Lift-to-drag ratio
The lift-to-drag ratio, abbreviated L/D and also called lift over drag, is the ratio of aerodynamic lift to drag and the standard measure of aircraft aerodynamic efficiency.
Lifted condensation level
The lifted condensation level (LCL) is the altitude at which a rising unsaturated air parcel cools to saturation and condensation begins, used to estimate convective cloud bases.
Lifted index
The lifted index (LI) is a meteorological stability index measuring lower-troposphere instability by lifting a surface air parcel to 500 mb; negative values indicate instability and stronger updrafts.
Lifting scheme
The lifting scheme is a method for constructing wavelets and computing the discrete wavelet transform through split, predict, and update steps, introduced by Wim Sweldens in 1995.
Ligand
A ligand is an atom, ion, or molecule that binds to a central atom or molecule, such as a metal in a coordination compound or a receptor.
Ligand (biochemistry)
In biochemistry, a ligand, or biological ligand, is a molecule, ion, or group that binds specifically to another molecule, usually a protein or nucleic acid, including hormones, drugs, and inhibitors.
Ligand effect
The ligand effect is the modification of a catalyst's surface electronic structure by dissimilar neighboring atoms, typically subsurface alloying atoms in bimetallic nanoparticles, changing adsorbate binding and catalytic activity.
Ligand field theory
Ligand field theory (LFT) is a bonding model for transition-metal complexes that describes metal–ligand bonds with molecular orbitals, explaining the colors, magnetism, spectra, and structures of coordination compounds.
Ligand-enabled C–H activation
Ligand-enabled C–H activation is a strategy in transition-metal catalysis where chosen ligands direct or accelerate selective carbon–hydrogen bond cleavage, pioneered by Murai's 1993 ruthenium-catalyzed reaction.
Ligand-enabled Pd-catalyzed C(sp3)–H activation
Ligand-enabled Pd-catalyzed C(sp3)–H activation is a family of palladium-catalyzed reactions in which bifunctional ligands, chiefly MPAAs, allow Pd(II) to functionalize unactivated methyl and methylene C–H bonds.
Ligand-to-metal charge transfer
Ligand-to-metal charge transfer (LMCT) is a photochemical excitation that moves an electron from a coordinated ligand to a metal center, generating ligand-centered radicals used in C–H functionalization catalysis.
Ligand-to-metal charge transfer catalysis
Ligand-to-metal charge transfer (LMCT) catalysis is a photochemical method that uses light on earth-abundant metals like cerium and iron to generate radicals for C–H activation.
Ligand-to-metal charge transfer photocatalysis
Ligand-to-metal charge transfer (LMCT) photocatalysis is a photochemical strategy in which a substrate coordinates to a metal center and light-induced homolysis generates radicals, notably alkoxy radicals from alcohols.
Light
Light, also called visible light, is electromagnetic radiation the human eye can sense; it travels at 299,792,458 m/s and behaves as both wave and photon.
Light clock
A light clock is a thought-experiment timepiece with two parallel mirrors and a light pulse bouncing between them, whose geometry directly yields the time-dilation factor of special relativity.