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

Any of the two theories put forward by Albert Einstein: → special relativity (1905) and → general relativity (1916).

→ theory; → relativity;

In → thermal conduction, the amount of heat passing across unit area per unit time and per unit → temperature gradient.

→ thermal; → conductivity.

The electricity produced by heat or temperature difference in a conductor.

→ thermo- + → electricity.

In a → rotating star, the sum of the → gravitational, → centrifugal, and → radiative accelerations. See also → effective gravity.

→ total; → gravity.

The period during a → solar eclipse when the → Sun is completely blocked by the → Moon. Totality for a → lunar eclipse is the period when the Moon is in the complete → shadow of the → Earth. For a solar eclipse totality can last from only several fractions of a second to a theoretical maximum of 7m 31s, depending on the → distance from the Moon to the Earth. For a lunar eclipse totality can last up to 1h 47m, also depending on the distance from the Moon to the Earth and on its → passage through the shadow. See also → totality path.

→ total; → -ity.

Of a → solar eclipse, the path of the → umbra across the → Earth. The totality path is usually about 100 km across, but under the most favorable conditions, when the → Moon is at its nearest → distance to Earth and the Earth is at its farthest distance from the Sun, the umbra can have a diameter of about 270 km.

→ totality; → path.

The probability that a quantum-mechanical system will make a transition from a given initial state to a given final state.

→ transition; → probability.

Same as → tangential velocity.

→ transverse; → velocity.

1) A theorem according to which any side of a triangle is always shorter than the sum of the other two sides.
2) The third requirement for a → distance function describing a → metric space.

→ triangle; → inequality.

The quality or state of being → trivial; something trivial.

→ trivial; → -ity;.

1) Meteo.: A measure of vertical extinction of solar radiation in the atmosphere. Turbidity is directly related to aerosol concentrations in the tropospheric and stratospheric layers. → visibility.
2) The cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye, similar to smoke in air.

→ turbid; → -ity.

The state or capacity of being everywhere, especially at the same time; omnipresence.

From M.Fr. ubiquité, from L. ubique "everywhere," → ubiquitous; → -ity.

Noun from visp-bâšandé, visp-bâš, visp-bâšâyi, → ubiquitous.

The state or quality of being uniform.

→ uniform; → -ity.

1) The condition of being → unitary.
2) → quantum unitarity.

→ unitary; → -ity.

The state or condition of being one.
Math.: One.

M.E. unite, from O.Fr., from L. unitatem "oneness, sameness, agreement," from unus, → one.

Yeki, noun from yek, → one.

The character or state of being universal.

→ universal; → -ity.

Same as → weak equivalence principle.

→ universality; → free; → fall.

The hypothesis whereby there exists a universal parent → distribution function which describes the stellar → initial mass function in individual star forming events. A consensus appears to have emerged in the community that the stellar IMF is largely invariant for star formation conditions as are found throughout the Local Group of galaxies at the present time. For details and discussion see Pavel Kroupa (2012), Recent advances on IMF research, arXiv.org/abs/astro-ph/1210.1211, and references therein.

→ universality; → initial mass function.

An institution of higher education composed of several faculties for teaching and research and authorized to grant academic degrees.

M.E., from O.Fr. universitei, from M.L. universitatem (nominative. universitas), in L.L. "corporation, society," from L., "the whole, aggregate," from universus "whole, entire," → universe.

Dânešgâh, from dâneš, → science, + -gâh "place; time" (Mid.Pers. gâh, gâs "time;" O.Pers. gāθu-; Av. gātav-, gātu- "place, throne, spot;" cf. Skt. gâtu- "going, motion; free space for moving; place of abode;" PIE *gwem- "to go, come").

The character of being → univocal. Same as → monosemy.

→ univocal; → ity.