42,772 articles
Holy Week
Holy Week, Latin hebdomada sancta, officially "great week", is the week of the Christian liturgical year commemorating the passion, death, and resurrection of Jesus Christ.
Hom functor
The Hom functor is the category theory construction assigning to each pair of objects the set of morphisms between them, contravariant in the first argument.
Homeomorphism
A homeomorphism, also called a topological equivalence, is a continuous bijection between topological spaces whose inverse is continuous; homeomorphic spaces are identical from topology's standpoint.
HomePod
HomePod, also known as Apple HomePod, is a line of smart speakers by Apple combining Siri voice control with room-adapting audio. The original model launched in 2018, followed by the HomePod mini in 2020.
Homer Burton Adkins
Homer Burton Adkins (1892–1949) was an American organic chemist at the University of Wisconsin, the leading authority on catalytic hydrogenation and developer of the copper chromite catalyst.
Homestake experiment
The Homestake experiment, also known as the Davis Experiment, was the first solar neutrino detector, operated by Raymond Davis Jr. in a South Dakota gold mine from the mid-1960s to 1994.
Homi J. Bhabha (હોમી જહાંગીર ભાભા)
Homi J. Bhabha (હોમી જહાંગીર ભાભા) was an Indian nuclear physicist, founder of the Tata Institute of Fundamental Research and first chairman of India's Atomic Energy Commission.
Homi Jehangir Bhabha
Homi Jehangir Bhabha (1909–1966) was an Indian nuclear physicist who calculated Bhabha scattering and founded the Tata Institute of Fundamental Research and India's atomic energy program.
HOMO–LUMO gap
The HOMO–LUMO gap is the energy difference between a molecule's highest occupied and lowest unoccupied molecular orbitals, marking its lowest possible electronic excitation and the light wavelengths it absorbs.
Homoallylic alcohol
A homoallylic alcohol is an organic compound with a hydroxyl group one methylene away from its alkene, widely used in synthesis and found in macrolides and polyether antibiotics.
Homochirality
Homochirality, or biochirality, is the preference of living systems for one mirror-image molecular form, using L-amino acids in proteins and D-sugars in DNA and RNA.
Homoclinic orbit
A homoclinic orbit is a trajectory of a dynamical system that approaches the same equilibrium as time tends to both plus and minus infinity, first identified by Henri Poincaré.
Homocoupling
Homocoupling is a chemical reaction in which two identical molecules or fragments are joined into a larger compound, most often a symmetric biaryl from two aryl halides.
Homodyne detection
Homodyne detection is an optical technique in quantum optics that mixes a weak signal with a strong phase-locked local oscillator to measure one quadrature of the field.
Homogeneity and heterogeneity
Homogeneity and heterogeneity describe whether a property or constituent is uniformly distributed throughout a material, classifying mixtures, determining sampling error in analysis, and distinguishing catalysts by phase.
Homogeneous broadening
Homogeneous broadening is spectral line broadening that affects every atom or molecule in a sample the same way, giving identical line shapes; its causes include lifetime, collisional, and thermal broadening, and its line shape is Lorentzian.
Homogeneous coordinates
Homogeneous coordinates, also called projective coordinates, represent points of projective space by tuples defined only up to a nonzero scalar, letting points at infinity be written as ordinary tuples.
Homogeneous differential equation
A homogeneous differential equation is an ordinary differential equation that is either first-order with right-hand side depending only on y/x, or linear with zero forcing term.
Homogeneous freezing
Homogeneous freezing is the spontaneous freezing of a supercooled liquid droplet without a solid particle, occurring below about −38 °C and driving ice formation in cirrus clouds.
Homogeneous function
A homogeneous function, also known as a homogeneous map, scales by a fixed power when all its arguments are scaled by the same factor, as in the Cobb–Douglas function.
Homogeneous isotropic turbulence
Homogeneous isotropic turbulence (HIT) is an idealized, simplest form of turbulence whose statistics are invariant under translation and rotation, serving as the theoretical baseline for real flows.
Homogeneous nucleation
Homogeneous nucleation is the spontaneous formation of crystal or droplet nuclei in the bulk of a supersaturated solution, supercooled melt, or vapor, without any foreign surface.
Homogeneous space
A homogeneous space is a space on which a group acts transitively, so any point can be carried to any other by some group element.
Homogenization (chemistry)
Homogenization in chemistry is a mechanical process that shrinks droplets or particles in an emulsion, most often by forcing fluid at high pressure through a narrow valve.
Homologation reaction
A homologation reaction, also called homologization, is a chemical transformation that lengthens a molecule's carbon skeleton by one carbon, typically a methylene group, as in the Arndt–Eistert synthesis.
Homological conjectures in commutative algebra
The homological conjectures are a web of related conjectures about homological properties of commutative rings, collected by Melvin Hochster in 1975; since 2016 perfectoid geometry has proved the direct summand conjecture.
Homologous series
A homologous series is a family of organic compounds sharing a functional group and general formula, each member differing from the next by one CH2 unit.
Homology (mathematics)
Homology is a construction in algebraic topology that assigns to each topological space homology groups recording, dimension by dimension, cycles such as loops and voids that are not boundaries.
Homomorphism
A homomorphism is a map between two algebraic structures of the same kind, such as groups or rings, that preserves their operations, making it algebra's basic tool for comparing structures.
Homophily
Homophily is the tendency of individuals to form social ties with similar others, defined by Lazarsfeld and Merton in 1954 and structuring marriage, friendship, and work ties.