In quantum computing, a qubit or quantum bit (sometimes qbit) is the basic unit of quantum information: G

Gamma ray

A gamma ray, or gamma radiation (symbol γ or {\displaystyle \gamma }\gamma ), is a penetrating form of electromagnetic radiation arising from the radioactive decay of atomic nuclei. It consists of the shortest wavelength electromagnetic waves and so imparts the highest photon energy. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter; in 1900 he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power.

Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts (keV) to approximately 8 megaelectronvolts (~8 MeV), corresponding to the typical energy levels in nuclei with reasonably long lifetimes. The energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 teraelectronvolt (TeV) range have been observed from sources such as the Cygnus X-3 microquasar.

Natural sources of gamma rays originating on Earth are mostly as a result of radioactive decay and secondary radiation from atmospheric interactions with cosmic ray particles. However, there are other rare natural sources, such as terrestrial gamma-ray flashes, which produce gamma rays from electron action upon the nucleus. Notable artificial sources of gamma rays include fission, such as that which occurs in nuclear reactors, and high energy physics experiments, such as neutral pion decay and nuclear fusion.

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A gluon (/ˈɡluːɒn/) is an elementary particle that acts as the exchange particle (or gauge boson) for the strong force between quarks. It is analogous to the exchange of photons in the electromagnetic force between two charged particles. In layman’s terms, they “glue” quarks together, forming hadrons such as protons and neutrons.

In technical terms, gluons are vector gauge bosons that mediate strong interactions of quarks in quantum chromodynamics (QCD). Gluons themselves carry the color charge of the strong interaction. This is unlike the photon, which mediates the electromagnetic interaction but lacks an electric charge. Gluons therefore participate in the strong interaction in addition to mediating it, making QCD significantly harder to analyze than quantum electrodynamics (QED).


The gluon is a vector boson, which means, like the photon, it has a spin of 1. While massive spin-1 particles have three polarization states, massless gauge bosons like the gluon have only two polarization states because gauge invariance requires the polarization to be transverse to the direction that the gluon is traveling. In quantum field theory, unbroken gauge invariance requires that gauge bosons have zero mass. Experiments limit the gluon’s rest mass to less than a few meV/c2. The gluon has negative intrinsic parity.

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Gravity (from Latin gravitas ‘weight’), or gravitation, is a natural phenomenon by which all things with mass or energy—including planets, stars, galaxies, and even light—are brought toward (or gravitate toward) one another. On Earth, gravity gives weight to physical objects, and the Moon’s gravity causes the ocean tides. The gravitational attraction of the original gaseous matter present in the Universe caused it to begin coalescing and forming stars and caused the stars to group together into galaxies, so gravity is responsible for many of the large-scale structures in the Universe. Gravity has an infinite range, although its effects become increasingly weaker as objects get further away.

Gravity is most accurately described by the general theory of relativity (proposed by Albert Einstein in 1915), which describes gravity not as a force, but as a consequence of masses moving along geodesic lines in a curved spacetime caused by the uneven distribution of mass. The most extreme example of this curvature of spacetime is a black hole, from which nothing—not even light—can escape once past the black hole’s event horizon. However, for most applications, gravity is well approximated by Newton’s law of universal gravitation, which describes gravity as a force causing any two bodies to be attracted toward each other, with magnitude proportional to the product of their masses and inversely proportional to the square of the distance between them.

Gravity is the weakest of the four fundamental interactions of physics, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a consequence, it has no significant influence at the level of subatomic particles. In contrast, it is the dominant interaction at the macroscopic scale, and is the cause of the formation, shape and trajectory (orbit) of astronomical bodies.

Current models of particle physics imply that the earliest instance of gravity in the Universe, possibly in the form of quantum gravity, supergravity or a gravitational singularity, along with ordinary space and time, developed during the Planck epoch (up to 10−43 seconds after the birth of the Universe), possibly from a primeval state, such as a false vacuum, quantum vacuum or virtual particle, in a currently unknown manner. Attempts to develop a theory of gravity consistent with quantum mechanics, a quantum gravity theory, which would allow gravity to be united in a common mathematical framework (a theory of everything) with the other three fundamental interactions of physics, are a current area of research.

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Gustave Trouvé

Gustave Pierre Trouvé (2 January 1839 – 27 July 1902) was a French electrical engineer and inventor in the 19th century.

Trouvé was born on 2 January 1839 in La Haye-Descartes (Indre-et-Loire, France) and died on 27 July 1902 in Paris. A polymath, he was highly respected for his innovative skill in miniaturization.

Gustave Trouvé was born into a modest family, his father, Jacques Trouvé, was a cattle dealer.[1] In 1850, he studied to be a locksmith in Chinon College, then in 1854-55 at the École des Arts et Métiers in Angers.[2] His studies incomplete through poor health, he left his local region for Paris where he obtained a job with a clockmaker.[3]

From 1865 Trouvé set up a workshop in central Paris where he innovated and patented many widely differing applications of electricity, regularly reported on by popular science magazines of the time such as La Nature.[4] He invented a carbon-zinc pocket-sized battery to power his miniature electric automata which soon became very popular. [5][6] A similar battery was invented and widely commercialized by Georges Leclanché.

Gustave Trouvé took part in the improvement in communication systems with several noteworthy innovations. In 1872 he developed a portable military telegraph whose cabling enabled rapid communication up to a distance of one kilometer, enabling the swift transmission of both orders and reports back from the Front.[7] In 1874, he developed a device for locating and extracting metal objects such as bullets from human patients, the prototype of today’s metal detector.[8] In 1878, he improved the sound intensity of Alexander Graham Bell’s telephone system by incorporating a double membrane. The same year he invented a highly sensitive portable microphone. Trouvé soon came to be known and respected by his talent for miniaturization. The same year, using a battery developed by Gaston Planté, and a small incandescent airtight bulb, he innovated a “polyscope”, the prototype of today’s endoscope.[9]

In 1880 Trouvé improved the efficiency of a small electric motor developed by Siemens and using the recently developed rechargeable battery, fitted it to an English James Starley tricycle, so inventing the world’s first electric vehicle.[10] Although this was successfully tested on 19 April 1881 along the Rue Valois in central Paris, he was unable to patent it.[11] Trouvé swiftly adapted his battery-powered motor to marine propulsion; to make it easy to carry his marine conversion to and from his workshop to the nearby River Seine, Trouvé made it portable and removable from the boat, thus inventing the outboard engine.[12] On 26 May 1881 the 5m Trouvé prototype, called Le Téléphone reached a speed of 1 m/s (3.6 km/h) going upstream at 2.5 m/s (9 km/h) downstream.[13]

Trouvé exhibited his boat (but not his tricycle) and his electro-medical instruments at the International Electrical Exhibition in Paris and soon after was awarded the Légion d’Honneur.[14] He also miniaturized his electric motor to power a model airship, a dental drill, a sewing machine and a razor.[15][16]

Gustave Trouvé next invented his “Photophore”, or battery-powered frontal headlamp, which he developed for a client, Dr Paul Hélot, an ear-nose-and throat specialist of Rouen. This wearable, direct shaft, lighting system could be oriented by head movements, so freeing the hands of its wearer. A file of correspondence between these two men enables one to place this invention during 1883. Trouvé soon modified their frontal headlamp both for use by miners, rescue workers, and later by speleologists, in dark surroundings, but also by tinting the light with various colors as theater jewelry for artiste troupes in Paris and Europe. The latter became known as “luminous electric jewels” and was the forerunner of today’s wearable technology.[17]

In 1884, Trouvé fitted an electric boat with both electric horn and a bow-mounted frontal headlamp, the first time such electrical accessories had ever been fitted on any mode of transport.[18] He developed a portable electric safety lamp.[19] In 1887, Trouvé, whose brand name was Eureka (Greek: εὕρηκα =“I have found”, translated into French “J’ai trouvé), developed his auxanoscope, an electric slide projector for itinerant teachers (1887). Around the same period, Trouvé, a confirmed bachelor uninterested in commercialization, turned his fertile mind skywards. Convinced that the future lay with heavier-the-air machines, he flew a tethered model electric helicopter, the ancestor of the Sikorsky Firefly.

He next built an ornithopter, the wings of which flapped using a rapid succession gun cartridges, enabling it to make a noisy but at the time unheard-of flight of 80 meters.[20]

In 1889, he also fitted the battery-electric rifle he had developed in 1866, with a frontal light enabling nocturnal hunting. He also developed a battery-electric alarm system for nocturnal fishing.

In 1891 Trouvé developed electric multi-colored fountains for domestic and outdoor use. Seeing the limitations of electrical supply without the reliable support of a national grid, in 1895 he took the recent discovery of acetylene light and had soon harnessed it for domestic lighting.[21] Among his 75 innovations,(see below) he also developed an electric massaging machine, an electric keyboard instrument based on Savart’s wheel, a battery-powered wearable lifejacket, a water-jet propelled boat and a streamlined bicycle, as well as several children’s toys.

In 1902, Trouvé was working on his latest innovation, a small portable device which used ultra-violet light to treat skin diseases, the prototype of PUVA therapy when he accidentally cut his thumb and index finger. Neglecting the wound, sepsis set in and after amputations at the Saint-Louis Hospital, Paris, the 63-year-old inventor died on 27 July 1902.

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