42,772 articles
Geological Survey of Ireland
The Geological Survey of Ireland (GSI), founded in 1845, is Ireland's national earth science center, providing free maps and data on groundwater, geohazards, and the seabed.
Geologist
A geologist is a scientist who studies the solid Earth, including its composition, structure, processes, and history, and applies that knowledge to locating resources and assessing hazards.
Geology
Geology, also known as geoscience or Earth science, is the study of the Earth's composition, structure, processes, and history since its origin, read from a rock record spanning roughly 4,500 million years.
Geology of India
The geology of India spans Archean cratons over 3 billion years old, the Deccan Traps flood basalts, and the Himalaya built by India's collision with Eurasia.
Geology of Pluto
The geology of Pluto is the study of the dwarf planet's landforms, revealed by NASA's New Horizons flyby in 2015: nitrogen glaciers, methane mountains, and tectonics.
Geology of the Moon
The geology of the Moon, also known as lunar geology, is the study of the Moon's layered interior, highlands, maria, and impact craters, which preserve early solar-system history.
Geomagnetic reversal
A geomagnetic reversal, also called a magnetic pole reversal, is a change of Earth's magnetic field to the opposite polarity; the last occurred about 780,000 years ago.
Geomagnetic secular variation
Geomagnetic secular variation is the slow change in Earth's core-generated main magnetic field over years to centuries, at rates up to about 200 nanotesla per year.
Geomagnetic storm
A geomagnetic storm, or magnetic storm, is a major disturbance of Earth's magnetosphere, driven by the solar wind, that can disrupt power grids, satellites, and radio communication.
Geomagnetically induced current
A geomagnetically induced current (GIC) is an electric current driven through long conductors such as power lines by geomagnetic storms; it caused the 1989 Québec blackout.
GEOMAR Helmholtz Centre for Ocean Research Kiel
GEOMAR Helmholtz Centre for Ocean Research Kiel (GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel) is a German marine research institute in Kiel studying the ocean from seafloor to atmosphere.
Geometric albedo
Geometric albedo is the ratio of a celestial body's brightness at full phase to that of a perfectly reflecting, diffusely scattering disk of the same apparent size.
Geometric algebra
Geometric algebra is the geometric interpretation of Clifford algebra, which Clifford combined with Grassmann's exterior algebra in 1878. It defines vectors and volumes as elements within a unified system.
Geometric Brownian motion
Geometric Brownian motion, also known as exponential Brownian motion, is a continuous-time stochastic process, always positive, that serves as the standard model for asset prices and underlies the Black–Scholes option pricing model.
Geometric calculus (Grossman–Katz)
Geometric calculus, also known as multiplicative calculus, is a non-Newtonian calculus created by Michael Grossman and Robert Katz in which the derivative and integral are multiplicative rather than additive.
Geometric complexity theory
Geometric complexity theory is a program in computational complexity theory, founded by Ketan Mulmuley and Milind Sohoni in 2001, that uses algebraic geometry and representation theory to prove lower bounds such as P ≠ NP.
Geometric dimensioning and tolerancing
Geometric dimensioning and tolerancing (GD&T), also called geometric tolerancing, is a standardized symbolic language used on engineering drawings to define allowable variation in part geometry.
Geometric distribution
The geometric distribution is a discrete probability distribution modeling the number of independent trials until the first success, with fixed success probability p and mean 1/p.
Geometric graph theory
Geometric graph theory is the branch of graph theory that studies graphs drawn in the plane with straight-line or curved edges, focusing on crossings and extremal edge counts.
Geometric group theory
Geometric group theory studies groups as geometric objects through Cayley graphs and word metrics, drawing on topology and hyperbolic geometry; its modern form dates to Gromov's 1987 paper Hyperbolic groups.
Geometric invariant theory
Geometric invariant theory (GIT) is a framework in algebraic geometry introduced by David Mumford in 1965 for constructing quotients of algebraic varieties by group actions, notably moduli spaces.
Geometric Langlands program
The geometric Langlands program restates the Langlands correspondence as a statement in algebraic geometry, proved in 2024 by a team led by Dennis Gaitsgory and Sam Raskin.
Geometric lattice
A geometric lattice is a finite lattice in which every element is a join of atoms, equivalently the lattice of flats of a simple matroid.
Geometric logic
Geometric logic is a fragment of infinitary first-order logic allowing finite conjunctions, arbitrary set-indexed disjunctions, and existential quantification; it underlies the theory of classifying toposes.
Geometric mean
The geometric mean, also called the geometric average, is the n-th root of the product of n positive numbers, used for averaging growth rates and ratios.
Geometric phase
The geometric phase, also called the Berry phase, is a phase acquired by a quantum system over cyclic evolution that depends on the path's geometry, not its duration.
Geometric phase analysis
Geometric phase analysis is a Fourier-domain method for measuring strain fields from high-resolution electron microscope images, developed by Martin J. Hÿtch and colleagues in 1998.
Geometric phase metasurface
A geometric phase metasurface, or Pancharatnam–Berry (PB) metasurface, is an ultrathin optical device whose rotated anisotropic nanostructures give converted light a phase of twice the local rotation angle, dispersion-free in origin.
Geometric progression
A geometric progression, also called a geometric sequence, is a sequence of numbers where each term is the previous term multiplied by a fixed common ratio.
Geometric quantization
Geometric quantization is a mathematical procedure that builds a quantum Hilbert space of states from a classical system whose phase space is a symplectic manifold, first reported by Souriau in 1966.