42,772 articles
Graphite furnace atomic absorption spectrometry
Graphite furnace atomic absorption spectrometry (GFAAS), or electrothermal atomization AAS, is an analytical technique that atomizes microliter samples in a heated graphite tube, measuring trace metals at parts-per-billion levels.
Graphite intercalation compound
A graphite intercalation compound (GIC) is a material in which atoms, ions, or molecules are inserted between graphite's graphene layers, first reported in 1841 and now central to lithium-ion batteries.
Graphite oxide
Graphite oxide, also known as graphitic oxide, is a layered material made by oxidizing graphite, first prepared in 1859 and now the main precursor for producing graphene oxide and graphene.
Graphitic carbon nitride photocatalysis
Graphitic carbon nitride photocatalysis uses g-C3N4, a metal-free polymeric semiconductor activated by visible light, to drive reactions such as hydrogen production, CO2 reduction, and pollutant degradation.
Graphoid
A graphoid is an abstract relation capturing the behavior of conditional independence, defined by five axioms introduced by Judea Pearl and Azaria Paz in 1985.
Graphon
A graphon is a symmetric measurable function on the unit square serving as the limit object for convergent sequences of dense graphs, introduced by Lovász and Szegedy in 2004.
Graphviz
Graphviz is open source graph visualization software that turns textual descriptions of abstract graphs into automatically arranged diagrams; it originated at AT&T Bell Laboratories and is used in software engineering, bioinformatics, and machine learning.
Grasberg mine
The Grasberg mine is a copper and gold mine at Tembagapura, near Puncak Jaya in Papua, Indonesia, operated by PT Freeport Indonesia and holding the world's largest gold reserves.
Grashof number
The Grashof number (Gr) is a dimensionless number measuring the ratio of buoyancy to viscous forces in natural convection, playing the role Reynolds number plays in forced convection.
Grassmannian
The Grassmannian, also called the Grassmann manifold, is the space of k-dimensional linear subspaces of a vector space, fundamental to algebraic geometry and named for Hermann Grassmann.
Grassy ELM
The grassy ELM regime is an operating regime in H-mode tokamak plasmas where large type-I ELM bursts are replaced by small, frequent edge instabilities, first observed on JT-60U.
Grating-based phase-contrast imaging
Grating-based phase-contrast imaging is an X-ray technique using transmission gratings arranged as an interferometer to capture attenuation, refraction, and small-angle scattering signals simultaneously, and it works with ordinary laboratory X-ray tubes rather than requiring synchrotron radiation.
Graupel
Graupel, also called soft hail or snow pellets, is precipitation of small, fragile, white ice grains under 5 mm that forms when supercooled droplets freeze onto snowflakes.
Gravastar
A gravastar, short for gravitational vacuum condensate star, is a hypothetical compact object proposed by Mazur and Mottola in 2001 as an alternative to black holes.
Gravel
Gravel is a loose granular material of rock fragments larger than sand, one of the two main sources of natural aggregate for concrete, asphalt, and road base.
Gravel-bed river
A gravel-bed river is an alluvial river whose bed is gravel and cobble, 2 to 256 mm, common in steep mountain terrain, where sediment moves mainly as bedload.
Graveyard orbit
A graveyard orbit is an orbit above geostationary altitude where retired satellites are parked at end of mission so they no longer interfere with operating spacecraft.
Gravimetric analysis
Gravimetric analysis, or gravimetry, is a quantitative chemical analysis method in which the analyte is separated in a weighable form and determined from mass measurements.
Gravimetry
Gravimetry is the measurement of gravitational acceleration and its variations in space and time, using instruments on the ground, ships, aircraft, or satellites to infer Earth's mass distribution.
Gravitation (book)
Gravitation, known in physics as MTW, is a 1973 graduate-level textbook on general relativity by Charles Misner, Kip Thorne, and John Wheeler, emphasizing the geometric view and applications from stars to black holes.
Gravitation and Cosmology (book)
Gravitation and Cosmology: Principles and Applications of the General Theory of Relativity is a 1972 graduate textbook by Nobel laureate Steven Weinberg that bases relativity on the principle of equivalence rather than geometry.
Gravitation of the Moon
The gravitation of the Moon, or lunar gravity, is the field generated by the Moon's mass, which accelerates surface objects at about one sixth of Earth's rate.
Gravitational acceleration
Gravitational acceleration, also called acceleration of free fall, is the acceleration of a body under gravity alone, ranging on Earth from 9.78 m/s² at the equator to 9.83 at the poles.
Gravitational anomaly
A gravitational anomaly is a quantum field theory effect in which curved spacetime breaks a chiral conservation law, first observed experimentally in the Weyl semimetal NbP in 2017.
Gravitational behavior of antimatter
Gravitational behavior of antimatter concerns whether it falls or rises in a gravitational field. In 2023, CERN's ALPHA collaboration directly showed antihydrogen atoms fall downward like ordinary matter, excluding antigravity.
Gravitational collapse
Gravitational collapse is the contraction of a region of matter under its own gravity when supporting pressure is insufficient, first analyzed by James Jeans in 1902.
Gravitational constant
The gravitational constant, or Newton's constant, is the constant G in Newton's law of universal gravitation, which fixes the strength of gravity between any two masses anywhere in the universe.
Gravitational decoherence
Gravitational decoherence is the loss of quantum coherence in low-energy quantum systems caused by gravitation, including metric fluctuations and gravity-induced wave function collapse, testable in table-top experiments.
Gravitational energy
Gravitational energy, also known as gravitational potential energy, is the potential energy stored in a system of masses by virtue of their positions in each other's gravitational field.
Gravitational field
A gravitational field is a vector field giving the gravitational force per unit mass at every point in space, equal to the local free-fall acceleration.