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

1) General: Made or occurring without a definite pattern, plan, or system; haphazard arrangement as if due to pure chance.
2) Statistics: Of or characterizing a process of selection in which each item of a population has an equal probability of being chosen.
See also:
→ random access memory, → random error, → random experiments, → random noise, → random sample, → random structure, → random thermal motion, → random variable , → independent random variables, → random walk, → randomization, → randomize, → randomness.

M.E. raundon, random "impetuosity, speed," from O.Fr. randon "rush, disorder, impetuosity," from randir "to run fast."

Kâturé originally "dazzled, confused," variants katré "disorderly, ragged, tattered, babble, meaningless or incoherent speech," katreyi "disorderly, at random;" maybe from kat- "to fall;" → case.

In computer technique, a configuration of memory cells that hold data for processing by a central processing unit (CPU). The term random derives from the fact that the CPU can retrieve data from any individual location, or address, within RAM.

→ random; → access; → memory.

The fluctuating part of the overall error that varies from measurement to measurement. Normally, the random error is defined as the deviation of the total error from its mean value; opposite of → systematic error.

→ random; → error.

Statistics: Experiments in which results will not be essentially the same even though conditions may be nearly identical.

→ random; → experiment.

Unpredictable noise comprising large numbers of frequent, transient impulses occurring at statistically random time intervals. Thermal noise is a form of random noise.

→ random; → noise.

A sample selected at random from a population.

→ random; → sample.

Crystalline arrangement in which equivalent positions are not necessarily occupied by atoms of a single kind.

→ random; → structure.

The agitated motion of molecular, atomic, or → subatomic particles in all possible directions at any temperature, except at → absolute zero, where → thermal motion would cease.

→ random; → thermal; → motion.

A quantity that takes different real values as a result of the → outcomes of a → random event or experiment involving specified probabilities.

→ random; → variable.

The trajectory consisting of a series of successive moves in which the direction and size of each move is randomly determined.

→ random; → walk.

Arrangement of data in such a way as to simulate chance occurrence.

Verbal noun of → randomize.

To arrange or select in a random manner in order to reduce bias and interference caused by irrelevant variables.

Verbal form of → random.

The property of being random.

State, condition noun of → random.

Systematic activity combining both basic and applied research, and aimed at discovering solutions to problems or creating new goods and knowledge. (BusinessDictionary.com).

→ research; → development.

See → Fleming's rules.

→ right; → hand; → rule.

A rule that gives the direction of the resultant vector in a → vector product: A x B = C. It is the direction of advance of a right-hand screw whose axis, held perpendicular to the plane of A and B, is rotated in the same sense that rotates the first-named vector (A) into the second-named vector B through the smaller angle.

→ right; → hand; → screw; → rule.

Using the right hand with greater skill or ease than the left.

→ right; → hand + -ed.

Râstâl, from râst, → right, + -al→ -al. Râstdast, with dast, → hand.

The → opacity of a gas of given composition, temperature, and density averaged over the various wavelengths of the radiation being absorbed and scattered. The radiation is assumed to be in → thermal equilibrium with the gas, and hence have a → blackbody spectrum. Since → monochromatic opacity in stellar plasma has a complex frequency dependence, the Rosseland mean opacity facilitates the analysis. Denoted κ_R, it is defined by: 1/κ_R = (π/4σT³) ∫(1/k_ν) (∂B/∂T)_νdν, summed from 0 to ∞, where σ is the → Stefan-Boltzmann constant, T temperature, B(T,ν) the → Planck function, and k_ν monochromatic opacity (See Rogers, F.J., Iglesias, C. A. Radiative atomic Rosseland mean opacity tables, 1992, ApJS 79, 507).

Named after Svein Rosseland (1894-1985), a Norwegian astrophysicist, who obtained the expression in 1924; → mean; → opacity.

The only supernova seen to date in the Andromeda galaxy and the first supernova observed beyond our own Galaxy. It was recorded on Aug. 20, 1885, by Ernst Hartwig (1851-1923) at Dorpat Observatory (Tartu) in Estonia and independently by other astronomers. S Andromedae reached magnitude 6 between Aug. 17 and 20, and had faded to magnitude 16 by February 1890. It is now believed that S Andromedae was a Type Ia supernova. Also known as SN 1885A.

S, from the second variable star to be discovered in constellation → Andromeda

Hard granular powder, consisting of fine grains of rock or minerals, usually quartz fragments, found on beaches, in deserts, and in soil.

O.E. sand; cf. O.N. sandr, O.Fris. sond, M.Du. sant, Ger. Sand; PIE base *samatha- (cf. Gk. psammos "sand," L. sabulum).

Mâsé "sand," of unknown origin.