âzmâyeš-e Michelson-Morley (#)
Fr.: expérience de Michelson-Morley
An experiment performed in 1887 to establish the presence or absence of an → ether, a medium through which light was supposed to travel. The experiment aimed to measure the speed of light coming from different directions. However no → ether drift was found. The null results obtained showed that the ether hypothesis was incorrect. Consequently, the theory of → special relativity, with its hypothesis that the speed of light is the same in all → inertial frames, reconciled the results of the Michelson-Morley experiment with the rest of physics.
→ Michelson interferometer; Michelson received the Nobel Prize in 1907 for his work, the first American to receive the Prize in science. Edward Williams Morley (1838-1923), an American chemist; → experiment.
Fr.: pleine lune d'apogée
Same as → apogee full Moon.
1) riz-; 2) mikro-
1) A combining form for "small."
From Gk. mikros "small."
Riz-, from riz "very small."
The area of computer science dealing with the use and development of microcomputers, and related peripheral devices and softwares. Also microinformatics.
Anything that is regarded as a world in miniature.
Fr.: effet de microlentille
A type of → gravitational lens, where the foreground → lensing object is of low mass, and the multiple images produced are too close together on the sky to be observed as separate images. Gravitational microlensing occurs when a foreground star happens to lie very close to our line of sight to a more distant background star. The foreground star acts as a lens, splitting the light from the background source star into two or more images, which are typically unresolved. However, these images of the source are magnified, by an amount that depends on the angular separation between the lens and source. If with the passage of time the lens moves across the Earth-source, the amount of brightening changes. Typically the source will appear to brighten, reach a maximum and then fade symmetrically back to normal over the course of a few weeks or months; this is called a → microlensing event. If the foreground star happens to host a planet with projected separation near the paths of these images, the planet will also act as a lens, further perturbing the images and resulting in a characteristic, short-lived signature of the planet. Microlensing is used in the search for → dark matter in the → Milky Way galaxy and its nearest neighbours, as well as for → extrasolar planets (e.g. B. S. Gaudi, 2010, arXiv:1002.0332).
Fr.: dégénérescence des paramètres de l'effet de microlentille
Determining the three various parameters of a microlensing event (the lens-source relative parallax and proper motion, and the mass of the lens) from only one physical parameter (the event time scale). Currently the microlensing degeneracy affects the vast majority of events and makes any individual event impossible to interpret with certainty.
Fr.: événement de microlentille
The effect arising whenever a source star and lens star pass each other at an angular separation involving the → Einstein radius (RE) of the lens. The time-scale for such an event is defined as tE = RE/v, where v is the magnitude of the relative transverse velocity between source and lens projected onto the lens plane.
A small grain sized meteorite which can only be positively identified under the microscope.
1) A screw thread device used to make accurate physical linear measurements.
A unit of length in the metric system equal to one millionth of a meter (10-6 m); symbol μ. Also called micrometer.
Coined 1880 in Fr. from Gk. mikron, neutral of mikros "small."
Any organism too small to be seen by the naked eye, e.g. bacteria, viruses, and protozoa.
Controlling unit of a microcomputer; laid out on a tiny silicon chip and containing the logical elements for handling data, performing calculations, carrying out stored instructions, etc.
A → binary system where an ordinary star orbits around a → neutron star or a → stellar-mass black hole that accretes the outer layers of the star's atmosphere. The accreted material falling on the → compact object warms up drastically and emits huge amounts of energy as → X-rays. The → accretion disk that emits this radiation also produces → relativistic jets of → plasma along the rotation axis of the compact object. The jets of material exhibit superluminal motion and resemble those emitted from → quasars, but on scales millions of times smaller. The first microquasar, 1E1740.7-2942, was discovered by F. Mirabel et al. 1992, Nature, 358, 215.
rizbin (#), mikroskop (#)
A magnifying optical instrument for inspecting objects too small to be seen or too small to be seen distinctly and in detail by the unaided eye.
From Mod.L. microscopium "an instrument for viewing what is small," from Gk. → micro- + -skopion "means of viewing," from skopein "look at."
Rizbin, from riz→ micro- + bin "to see; seer" (present stem of didan; Mid.Pers. wyn-; O.Pers. vain- "to see;" Av. vaēn- "to see;" Skt. veda "I know;" Gk. oida "I know," idein "to see;" L. videre "to see;" PIE base *weid- "to know, to see").
Fr.: état microscopique
Same as → microstate.
The Microscope. A minor constellation in autumn southern sky lying just south of → Capricornus at 21h right ascension, 37° south declination. The constellation contains only 4th magnitude or fainter stars. Abbreviation: Mic; genitive: Microscopii.
Microscopium was named by Abbé Nicolas Louis de Lacaille (1713-1762); → microscope.
Statistical physics: For a system made up of a large number of components, a state of the system which is specified by describing the current dynamical variables of each constituting component. For example, for a gas system composed of a large number of molecules, the microstate is defined by the set of quantities which defines the state of each molecule in the system (position, velocity, vibration, etc.). In practice, it is impossible to know perfectly the microstate of a system. The aim of → statistical physics is to relate the macroscopic (average ) observables (→ pressure, → temperature, → internal energy) to the microstate of the system. Also called → microscopic state. See also → macrostate and → multiplicity.