Physical world and mathematics

Grain refinement

Grain refinement is the reduction of crystal grain size in a metal or alloy, achieved by inoculation during solidification or by deformation, improving strength and castability.

Grain rotation-mediated plasticity in nanocrystalline metals

Grain rotation-mediated plasticity is a deformation mechanism in nanocrystalline metals, seen below roughly 15 nm grain size, where rotating grains rather than dislocations carry plastic strain.

Grain size

Grain size is the diameter of the individual grains in a sediment or soil, the most basic attribute used to describe and classify sediments into gravel, sand, silt, and clay.

Grain-oriented electrical steel

Grain-oriented electrical steel (GOES, also called CRGO, cold-rolled grain-oriented steel) is a silicon-iron soft magnetic sheet with grains aligned along the rolling direction, giving low core loss in transformer cores.

Grainstone

A grainstone is a mud-free, grain-supported carbonate rock from Robert J. Dunham's 1962 classification, forming in agitated shallow water with high initial porosity and serving as a prolific petroleum reservoir rock.

Gram

The gram (symbol g) is an SI unit of mass equal to one thousandth of a kilogram; the kilogram, not the gram, is the SI base unit.

Gram matrix

The Gram matrix is a square matrix whose entries are the pairwise inner products of a set of vectors, encoding lengths, angles, and linear dependence; it is always positive semidefinite.

Gramicidin S

Gramicidin S is a cyclic decapeptide antibiotic produced by Bacillus brevis, isolated in Moscow in 1942 and used topically for skin and throat infections because hemolytic toxicity rules out systemic use.

Gran Telescopio Canarias

The Gran Telescopio Canarias (GranTeCan) is a 10.4 m optical and infrared telescope at the Roque de los Muchachos Observatory on La Palma, Spain, the world's largest since 2007.

Granat (satellite)

Granat, formally the International Astrophysical Observatory, was a Soviet-led X-ray and gamma-ray observatory launched in 1989 that carried seven instruments from four countries and studied the Galactic center until 1998.

Grand Accélérateur National d'Ions Lourds

The Grand Accélérateur National d'Ions Lourds, or GANIL, is a French heavy-ion accelerator laboratory in Caen, Normandy, where more than 100 nuclei have been discovered.

Grand canonical ensemble

The grand canonical ensemble is a statistical-mechanical description of an open system at fixed temperature, volume, and chemical potential, where energy and particle number fluctuate.

Sep 29, 2026

Grand canonical Monte Carlo simulation

Grand canonical Monte Carlo, introduced by D.J. Adams in 1974, is a simulation method with fluctuating particle number at fixed chemical potential, used for adsorption isotherms.

Grand design spiral galaxy

A grand design spiral galaxy is a spiral galaxy with a few long, continuous, sharply defined spiral arms that dominate its appearance, unlike the patchy arms of flocculent spirals.

Grand potential

The grand potential, also called the Landau potential, is a thermodynamic state function for systems at fixed temperature, volume, and chemical potential, defined as Ω = F − μN.

Grand Staircase

The Grand Staircase is a 100-mile sequence of sedimentary rock layers in southern Utah and northern Arizona, ascending from the Grand Canyon to Bryce Canyon.

Grand Tack hypothesis

The Grand Tack hypothesis is a 2011 model of early Solar System evolution in which Jupiter migrated inward to about 1.5 AU, then reversed course and returned outward.

Grand Unified Theory

A grand unified theory (GUT), also called grand unification, is a particle-physics framework merging the strong and electroweak forces under one gauge symmetry at extremely high energy.

Grand-canonical DFT

Grand-canonical DFT (GC-DFT) is a formulation of density functional theory that fixes the electron electrochemical potential, matching the constant electrode potential used in electrochemistry experiments.

Grandfather paradox

The grandfather paradox is a thought experiment in which a time traveler prevents their own birth by killing their grandfather, first clearly stated by René Barjavel in 1943.

Granger causality

Granger causality is a statistical test, proposed by Clive Granger in 1969, where one time series causes another if its past values improve prediction of it.

Granite

Granite is a coarse-grained, light-colored intrusive igneous rock that forms when silica-rich magma cools slowly at depth, and it is quarried widely as dimension and crushed stone.

Granodiorite

Granodiorite is a coarse-grained intrusive igneous rock intermediate between granite and diorite, defined by more plagioclase than potassium feldspar; the Rosetta Stone is a famous example.

Grant H. Stokes

Grant H. Stokes is an American physicist at MIT Lincoln Laboratory who directs the LINEAR program, which has found about half of near-Earth asteroids discovered since 1998.

Granular aluminum Josephson junctions

Granular aluminum Josephson junctions are the superconducting tunnel contacts between nanoscale aluminum grains in granular aluminum, a self-assembled junction network used as high-impedance superinductors in qubits, amplifiers, and resonators.

Granular chain solitons

Granular chain solitons are non-dispersive pulses traveling along chains of elastic grains like steel spheres, predicted by Vitalii Nesterenko, with a fixed width of about five grain diameters.

Granular convection

Granular convection, known as the Brazil nut effect, is the circulation of shaken granular material, where particles rise in the center and sink along the walls.

Granular jamming

Granular jamming is the reversible transition of granular material like coffee grounds from a fluid-like to a solid-like state under vacuum, used widely in soft robotic grippers.

Granular material

A granular material, or granular matter, is a collection of macroscopic solid particles like sand, salt, and powders that interact through contact forces and behave as solids, liquids, or gases.