An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

In ancient calendars, a year that contains an → embolismic month.

→ embolismic month; → year.

1) Philo.: The doctrine that all → knowledge of matters of fact derives from experience and that the mind is not furnished with a set of concepts in advance of experience.
2) The use of empirical methods (Dictionary.com).

From empiric, → empirical, + → -ism.

A → morphism from an → object to itself.

→ endo-; → morphism.

A → morphism f : Y → X if, for any two morphisms u,v : X → Z, u f = v f  implies u = v.

→ epi-; → morphism.

An inoffensive word or phrase substituted for one considered offensive or hurtful, especially one concerned with religion, sex, death, or excreta (TheFreeDictionary.com).

From Gk. euphemismos, from euphemizein "speak with fair words, use words of good omen," from → eu- "well," + pheme "speech, voice, talk," from phanai "to speak," ultimately from PIE *bha- "to speak, tell, say;" cf. Skt. bhanati "speaks;" L. fari "to say," fabula "tale, story," fama "talk, rumor, report; reputation;" Armenian ban, bay "word, term."

Xošguyi, xošzabâni, literally "pleasant talking, ~ speach," from xoš "well, pleasant," → eu- + guyi verbal noun of goftan "to say, talk, speak," → logic; zabâni, from zabân, → language.

A philosophical attitude associated especially with Heidegger, Jaspers, Marcel, and  Sartre, and opposed to → rationalism and  → empiricism, that stresses the individual's  unique position as a self-determining agent responsible for the authenticity of his or  her choices (Dictionary.com).

→ existential; → -ism.

1) Belief in the social, political, and economic freedom of women and equality of the sexes. Feminism is closely tied to democracy and → secularism.
2) The movement organized around this belief.

From Fr. féminisme, from féminin "feminine, female," from L. femininus "feminine" (originally in the grammatical sense), from femina "woman, female," literally "she who suckles," cognates fecund "fruitful, fertile," felix "happy," fetus "offspring, pregnancy;" PIE base *d^heh(i)- "to suck, suckle;" cf. Gk. thele "mother's breast;" Pers. dâyé "wet nurse."

Zâd-zan-bâvari, from zâdzan "free woman" (on the model of zâdmard "free man, valiant man, generous man," zâdsarv "tall and upright cypress tree"), from zâd, contraction of âzâd, → free, + zan, → woman, + bâvari, → -ism.

A property of certain substances which are enormously more magnetic than any other known substance. Ferromagnetic substances, such as the chemical elements iron, nickel, cobalt, some of the rare earths, and ceratin alloys, achieve maximum → magnetization at relatively low magnetic field strengths. Their large → magnetic permeabilityies (greater than unity) vary with the strength of the applied field. When the temperature of a ferromagnet is increased the property vanishes gradually due to randomizing effects of thermal agitation. Beyond a definite temperature for each substance ( → Curie temperature) it ceases to behave as a ferromagnet and becomes a → paramagnet. Ferromagnetism is due to the alignment of the → magnetic moments of uncompensated electrons in the crystal lattice. Under the influence of an external magnetizing field, all of the uncompensated electrons line up with their → spins in the direction of the field. In contrast with paramagnetic substances, in which spins interact only with an external magnetic field, in ferromagnets the spins interact with each others, each of them trying to align the others in its own direction. This coupling gives rise to a spontaneous alignment of the moments over macroscopic regions called domains. The domains undergo further alignment when the substance is subjected to an applied field. Ferromagnets retain their magnetisation even when the external magnetic field has been removed. See also → antiferromagnetism ; → diamagnetism; → magnetism.

→ ferro-; → magnetism.

1) Excessive adherence to prescribed forms.
2) Math., Logic: → Formalized expression of a set of elements; the nature of such expression.
3) A philosophical view of mathematics in which mathematics, including the logic used in proofs, can be based on the formal manipulation of symbols irrespective of their meaning.

From → formal + → -ism.

1) Geology: The process whereby a geologic section (subsurface model of one-, two-, or three dimensions) is transformed into a synthetic seismogram (synthetic seismic record).
2) In → asteroseismology, a model that takes the physical properties of a star as input parameters and predicts the star's oscillations. Then, by finding parameters that yield oscillation frequencies (ω_nlm) close to those observed, one can infer the properties of the observed star. The quantum numbers n, l, and m must be identified before any meaningful comparison between seismic data and model predictions can be made. That mode identification requires a physical interpretation of the measured frequencies.

→ forward; → seismic; → modeling.

An optical element consisting of two small angle → prisms, joined together at their bases, used to produce two → coherent sources. The thin double prism refracts the light from a source into two overlapping beams, which produce → interference fringes. With this experiment Fresnel was able to produce interference without relying upon → diffraction to bring the interfering beams together.

→ Fresnel diffraction; → bi-; → prism.

1) The production of electricity from a chemical reaction.
2) The therapeutic application of electricity to the human body.

From Fr. galvanisme, after Luigi Galvani (1737-1798), the Italian physiologist, who demonstrated (1790) muscular action due to contact with dissimilar metals.

A process which reinforces the → kappa mechanism in a → partial ionization zone. Because the temperature in the partial ionization zone is lower than in the adjacent stellar layers, heat tends to flow into the zone during compression, prompting further ionization.

γ, after the smaller ratio of → specific heats caused by the increased values of C_p and C_v; → mechanism.

The → magnetic flux through an arbitrary closed surface equals zero. Mathematically, in differential form: ∇ . B = 0 and in integral form: Φ_B = ∫B.dS = 0 (closed surface integral). This is one of the four → Maxwell's equations. This law expresses the fact that there are no free magnetic poles (→ monopoles) in nature and that all the lines of force of a magnetic field are closed curves.

→ gauss; → law; → magnetism.

A branch of geophysics concerned with the study of the Earth's → geomagnetic field, including its origin, spatial extent, and variations in time.

→ geo-; → magnetism.

An optical dispersing device used in a spectrograph. It is a combination of a prism and a grating, in the sense that the grating is placed side by side to one surface of a small-angle prism.

Grism, from gr(ating) + (pr)ism.

A reformulation of classical mechanics that predicts the same outcomes as classical mechanics. → Hamiltonian dynamics.

→ Hamiltonian; → mechanics.

The branch of astrophysics that investigates the interior structure of the Sun by studying its surface wave oscillations. See also → asteroseismology and → stellar pulsation. The surface of the Sun vibrates much like a bell. A piano has 88 keys or musical tones, whereas the Sun has millions of notes. These vibrations are the result of internal pressure waves that reflect off the → photosphere and repeatedly cross the solar interior. They are detected through the → Doppler shift of absorption lines formed in the photosphere. Because these vibrations make the solar surface move up and down, analysis of the surface patterns is used to study conditions far below the Sun's surface. The mean period of the vibrations is about five minutes, which corresponds to a speed of 0.5 km s^-1 or a frequency of about 3 mHz. See also → p mode.

From → helio- + → seismology.

Biology: For an animal or plant, the condition of having both male and female reproductive tissue or organs.

→ hermaphrodite; → -ism.

In the → standard model of → particle physics, a mechanism postulated to endow mass to → elementary particles. Simply put, a background field, called the → Higgs field, becomes locally distorted whenever a particle moves through it. The distortion generates the particle's mass.

→ Higgs boson; → mechanism.