All articles starting with G
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Gravitational wave echo
A gravitational wave echo is a hypothesized delayed, repeating pulse of gravitational radiation following a merger's ringdown if the remnant lacks a true event horizon.
Gravitational-wave astronomy
Gravitational-wave astronomy studies cosmic sources through gravitational waves, ripples in spacetime predicted by Einstein and first detected by the LIGO detectors in 2015, when they recorded the binary black hole merger GW150914.
Gravitational-wave early warning alert
A gravitational-wave early warning alert is a notice from the LIGO–Virgo–KAGRA detectors sent before a compact binary merger, giving telescopes a head start on the flash that follows.
Gravitational-wave echoes
Gravitational-wave echoes are hypothetical delayed pulses of gravitational radiation after a merger that would appear if the remnant is an exotic compact object rather than a black hole.
Gravitational-wave lensing
Gravitational-wave lensing is the deflection, delay, and distortion of gravitational waves by massive objects like galaxies and black holes; no lensed signal has yet been confirmed.
Gravitational-wave memory
Gravitational-wave memory is a permanent, non-oscillatory change in spacetime left behind by a burst of gravitational waves, first predicted by Zel'dovich and Polnarev in 1974 and still undetected.
Gravitational-wave polarizations
Gravitational-wave polarizations are the independent strain patterns a passing wave imposes on matter; general relativity allows two tensor modes, while general metric theories allow up to six.
Gravitational-wave recoil
Gravitational-wave recoil is the kick a compact-object merger remnant receives when gravitational waves emit momentum anisotropically; black hole kicks can reach thousands of kilometers per second.
Gravitational-wave strain calibration
Gravitational-wave strain calibration is the process by which interferometric detectors such as LIGO, Virgo, and KAGRA convert raw photodetector output into gravitational-wave strain, enabling every estimate of source masses, distances, and sky positions.
Gravitational-wave transient catalog
The Gravitational-Wave Transient Catalog (GWTC) is the running list of gravitational-wave signals detected by the LIGO, Virgo, and KAGRA collaborations, growing from 11 events in 2019 to hundreds of compact binary mergers.
Gravitationally induced entanglement
Gravitationally induced entanglement (GIE) is the predicted entanglement between two masses interacting only through gravity, proposed in 2017 as a laboratory test of whether the gravitational field is quantum.
GravitHy
GravitHy is a French low-carbon iron producer founded in 2022 and based in Marseille, planning a €2.2 billion hydrogen-based direct reduced iron plant at Fos-sur-Mer near Marseille.
Gravitino
The gravitino is the hypothetical spin-3/2 superpartner of the graviton predicted by supergravity. It is extremely weakly coupled, possibly stable dark matter, and has never been observed.
Gravitoelectromagnetism
Gravitoelectromagnetism, also called gravitomagnetism, is a weak-field, slow-motion approximation of general relativity rewritten in a form resembling Maxwell's equations, with mass current generating frame dragging, the Lense–Thirring effect.
Graviton
The graviton is the hypothetical quantum particle of the gravitational field, a massless spin-2 boson whose exchange would mediate gravity; no graviton has ever been detected, and 2024 proposals suggest single-graviton detection may be within reach.
Graviton (comics)
Graviton (comics) is a Marvel supervillain, Franklin Hall, who first appeared in 1977. He is known for his immense power to mentally manipulate gravity, lifting Manhattan Island.
Gravitron
Gravitron (also Starship, Old Blue, Trip to Mars) is an enclosed spinning-cylinder amusement ride, descended from the Rotor, that pins standing riders to the wall by centrifugal force; Wisdom Industries builds the 24 RPM, 45-passenger version.
Gravity
Gravity, also called gravitation, is the mutual attraction between masses, the force that keeps the Moon in orbit and gives objects near Earth a downward acceleration.
Gravity (2013 film)
Gravity (2013) is a science fiction thriller directed by Alfonso Cuarón, starring Sandra Bullock and George Clooney as astronauts stranded after debris destroys their shuttle; it won 7 Oscars from 10 nominations and scored 96% on Rotten Tomatoes.
Gravity (wrestler)
Gravity is a Mexican masked professional wrestler from Torreón, Coahuila, who wrestles for AEW and Ring of Honor, and is the younger brother of ROH World Champion Bandido.
Gravity and Grace
Gravity and Grace (La pesanteur et la grâce) is a 1947 collection of short reflective passages by French philosopher Simone Weil, the first book published under her name.
Gravity anomaly
A gravity anomaly is the difference between measured gravity, reduced to sea level, and the theoretical gravity of a uniform ellipsoidal Earth, revealing rock density variations.
Gravity assist
A gravity assist, also known as a swing-by or gravity slingshot, is a maneuver in which a spacecraft flies close past a moving planet to gain or lose speed without spending propellant.
Gravity bong
Gravity bong (G-B, geeb): a homemade cannabis smoking device using water displacement to fill a chamber with concentrated smoke pushed in under positive pressure; commercialized as GRAV's all-glass Gravitron (2004).
Gravity casting
Gravity casting is a metal casting process in which molten metal fills a mold under gravity alone, producing castings in sand molds or reusable metal dies.
Gravity compensation
Gravity compensation is a robotics technique that cancels the torques and forces gravity exerts on a mechanism, so actuators or users need not work against its weight.
Gravity dam
A gravity dam is a dam that resists water pressure by its own weight, typically built as a straight wall of mass concrete on a rock foundation.
Gravity darkening
Gravity darkening is the variation of brightness and temperature across a rotating star, with hotter, brighter poles and a cooler equator, formulated by von Zeipel in 1924.
Gravity Falls
Gravity Falls is an American animated mystery-comedy series created by Alex Hirsch for Disney, aired 2012–2016 over two seasons. Twins Dipper and Mabel Pines (Jason Ritter, Kristen Schaal) spend summer with Grunkle Stan in a supernatural Oregon town; ended with the three-part Weirdmageddon finale.
Gravity Falls: Journal 3
Gravity Falls: Journal 3, also known as Journal Three, is a 2016 tie-in book by Alex Hirsch and Rob Renzetti reproducing the fictional journal from the animated series Gravity Falls.