Physical world and mathematics

Gradient

The gradient, also called the gradient vector, is a vector calculus operator that collects a scalar function's partial derivatives and points in the direction of fastest increase.

Gradient elution is a chromatography technique that changes the mobile-phase composition continuously during separation, solving the general elution problem of isocratic elution for complex mixtures such as peptides.

Gradient magnetic separation

Gradient magnetic separation is a separation method that uses a high field gradient to capture fine, weakly magnetic particles from a slurry on a magnetized matrix.

Oct 22, 2026

Gradient nanograined metals

Gradient nanograined (GNG) metals are metals with grain size graded from tens of nanometers at the surface to micrometers inside, combining high strength with good ductility.

Gradient wind

The gradient wind is a horizontal wind blowing parallel to curved isobars, balancing the pressure gradient, Coriolis, and centrifugal forces; it generalizes the geostrophic wind to curved flow.

Grading in education

Grading in education, measured by grade point average, assigns standardized letters or numbers to student performance, with the A–F scale dominant in United States higher education.

Gradual typing

Gradual typing is a programming language design approach where parts of a program are statically type checked and others dynamically, introduced by Jeremy Siek and Walid Taha in 2006.

Gradualism

Gradualism is the view that large changes in nature result from the accumulation of small, incremental steps over long periods, rather than from sudden, large-scale events.

Graduated cylinder

A graduated cylinder, also called a measuring cylinder, is tall, narrow laboratory glassware or plasticware marked with a volume scale and used to measure liquid volumes with moderate accuracy.

Graeco-Latin square

A Graeco-Latin square, also called an Euler square, is an n × n array formed by superimposing two orthogonal Latin squares, named by Euler in 1782.

Graeme Henkelman

Graeme Henkelman is a Canadian-born computational materials chemist at the University of Texas at Austin, known for the climbing-image nudged elastic band and dimer methods for finding saddle points.

Graeme Moad

Graeme Moad is an Australian chemist and CSIRO Fellow who co-invented RAFT polymerization at CSIRO in 1996, a controlled radical technique used by over 100 companies worldwide, and was elected to the Royal Society in 2023.

Graeme Segal

Graeme Segal is an Australian-born mathematician working in algebraic topology and quantum field theory, known for the Segal conjecture, Segal spaces, and the Chern Medal in 2026.

Graeme Stephens

Graeme L. Stephens is an Australian atmospheric scientist known for research on clouds, radiation, and climate, and for creating and leading NASA's CloudSat satellite mission.

Graft copolymerization

Graft copolymerization chemically attaches side chains of one monomer onto a preformed polymer backbone to modify properties like wettability and fouling resistance, using routes called grafting-from, grafting-onto, and grafting-through.

Graft polymerization

Graft polymerization is a polymer synthesis method in which side chains are grown from or attached to a polymer backbone, tuning surface wettability, antifouling behavior, and biocompatibility.

Grafting density

Grafting density is the average number of polymer chains tethered to a unit area of a surface, and it determines whether attached chains behave as isolated coils or stretched polymer brushes.

Graham Feingold

Graham Feingold is a South African-born atmospheric scientist at NOAA's Chemical Sciences Laboratory in Boulder, known for his 2009 and 2010 Nature papers on aerosol-cloud interactions.

Graham Higman

Graham Higman (1917–2008) was a British group theorist, Waynflete Professor at Oxford from 1960 to 1984, known for the Higman embedding theorem, HNN extensions, and the PORC conjecture.

Sep 20, 2026

Graham J. Hutchings

Graham J. Hutchings, also known as G. J. Hutchings, is a British chemist and Regius Professor at Cardiff University, a pioneer of catalysis by gold.

Graham Pearson

D. Graham Pearson, born 1965, is a British isotope geochemist at the University of Alberta known for using diamonds and mantle xenoliths to study the continental mantle.

Sep 20, 2026

Graham R. Fleming

Graham R. Fleming, born in Barrow, England, in 1949, is a physical chemist at UC Berkeley known for developing two-dimensional electronic spectroscopy and applying it to photosynthesis.

Graham Ross (theoretical physicist)

Graham Ross (1944–2021) was a British theoretical particle physicist at the University of Oxford, a Fellow of the Royal Society and winner of the 2012 Dirac Medal.

Graham Sutton

Graham Sutton (Oliver Graham Sutton) was a Welsh mathematician and meteorologist known for work on atmospheric diffusion and for directing the Meteorological Office, 1953 to 1965.

Graham's law

Graham's law, or Graham's law of effusion, states that a gas's rate of effusion or diffusion is inversely proportional to the square root of its molar mass.

Graham's number

Graham's number is an enormous integer, built from Knuth's up-arrow notation, that arose as a Ramsey theory upper bound and was popularized by Martin Gardner in 1977.

Grain (unit)

The grain (gr), also called the troy grain, is a unit of mass equal to 64.79891 milligrams, shared by the avoirdupois, troy, and apothecaries' systems.

Grain boundary

A grain boundary is the internal interface where two crystals of different orientation meet within a polycrystalline solid, and it strongly affects hardness, brittleness, creep, and corrosion resistance.