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

Without variations; identical, always the same in quality, degree, character, or manner.

→ uni- + → form.

Yekdis, from yek, → uni-, + dis, → form; yeknavâxt, literally "with one rhythm," from yek, → one, + navâxt "rhythm," from navâxtan, navâzidan "to play an instrument; to gratify," navâ "music, song, melody" (Mid.Pers. nw'c "to treat kindly, honour," niwag "music, melody;" Proto-Iranian *ni-uac-, from ni- "down; into," → ni- (PIE), + *uac- "to speak, treat kindly").

The motion of an object around a fixed point at a constant angular speed, and at constant radius.

→ uniform; → circular; → motion.

A field that at a given instant has the same value at all points within a specified region of interest.

→ uniform; field.

A → magnetic field whose direction does not change and whose strength is constant at every point.

→ uniform; → magnetic; → field.

Motion at a constant → velocity. The state of rest is a special case of uniform motion. → accelerated motion; → inertial motion.

→ uniform; motion.

1) Of, characterized by, or conforming to → uniformity.
2) Of or relating to → uniformitarianism.

→ uniformity + -arian.

The doctrine whereby geologic processes (→ erosion, → deposition, → compaction, and → uplift) observed at Earth's surface now are the same that have shaped Earth's landscape over long periods of time in the past. The term uniformitarianism was first used in 1832 by William Whewell, to present an alternative explanation for the origin of the Earth. The prevailing view at that time was that the Earth was created through supernatural means and had been affected by a series of catastrophic events such as the biblical Flood. This theory is called → catastrophism. The ideas behind uniformitarianism originated with the work of Scottish geologist James Hutton. In 1785, Hutton presented at the meetings of the Royal Society of Edinburgh that the Earth had a long history and that this history could be interpreted in terms of processes currently observed. For example, he suggested that deep soil profiles were formed by the weathering of bedrock over thousands of years. He also suggested that supernatural theories were not needed to explain the geologic history of the Earth (PhysicalGeography.net).

→ uniformitarian; → -ism.

The state or quality of being uniform.

→ uniform; → -ity.

A transformation whose reciprocal is equal to its Hermitian conjugate.

→ unitary; → transformation.

The concept of star formation pertaining to a variety of systems (OB associations, giant H II regions, H II galaxies, massive star clusters, etc.) that are believed to have formed large numbers of stars in a very short time.

→ violent; → star formation.

A graphical representation of the shape of a wave for a given instant in time.

→ wave; → form.

The resolution of a complex waveform into a sum of simple periodic waves, usually by computer means.

→ waveform; → analysis.

A → semiempirical → equation which describes the → binding energy of the → atomic nucleus. It is essentially a nuclear mass formula that provides the total binding energy per → nucleon as the sum of five terms:
E_b = a_VA - a_SA^2/3 - a_CZ²/A^1/3 - a_A(N -Z)²/A + δ(A,Z),
where the terms in the right-hand side of this equation are called the volume term, surface term, Coulomb term, asymmetry term, and pairing term, respectively. A, Z, and N are the number of nucleons, → protons, and → neutrons, respectively (see, e.g., Alexi M. Frolov, 2013, arxiv.org/pdf/1212.6768). Also called Bethe-Weizacker formula and → semiempirical binding energy formula.

Named after Carl Friedrich von Weizäcker (1912-2007), German physicist, who derived the formula in 1935, Z. für Physik 96, 431; → formula.

A string of → symbols from the alphabet of the → formal language that conforms to the grammar of the formal language. → closed wff, → open wff.

Wff, pronounced whiff; → well; → form; → formula.