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

Same as → Raman scattering.

Named after the Indian physicist Sir Chandrasekhara Venkata Raman (1888-1970), who discovered the effect; recipient of the 1930 Nobel Prize in Physics; → effect.

The scattering of monochromatic light (visible or ultraviolet) by molecules in which the scattered light differs in wavelength from the incident light. It is caused by the light's interaction with the vibrational or rotational energy of the medium's scattering molecules.

→ Raman effect; → scattering.

The small circular patch of light visible in the back focal plane of an eyepiece.

Named after Jesse Ramsden (1735-1800), English maker of astronomical instruments; → disk.

An eyepiece consisting of two planoconvex lenses of the same focal length, placed with the convex sides facing each other and with a separation between the lenses of about two-thirds of the focal length of each.

Named after Jesse Ramsden (1735-1800), English maker of astronomical instruments; → eyepiece.

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.

1) Physics: The maximum distance a projectile travels.
2) Math.: The → set of values that actually comes out of a → function. The range is a → subset of the → codomain.
3) Statistics: The interval between the largest and smallest values in a statistical distribution.

M.E., from O.Fr. range "range, rank," from rangier "to place in a row, arrange," from reng "row, line."

1) Bord past stem of bordan "to carry, transport" (Mid.Pers. burdan, O.Pers./Av. bar- "to bear, carry," barəθre "to bear (infinitive)," Skt. bharati "he carries," Gk. pherein, L. fero "to carry;" PIE base *bher- "to carry").
2) Gostaré, from gostar, gostardan "to expand; to spread; to diffuse" (Mid.Pers. wistardan "to extend; to spread;" Proto-Iranian *ui.star-; Av. vi- "apart, away from, out" (O.Pers. viy- "apart, away;" cf. Skt. vi- "apart, asunder, away, out;" L. vitare "to avoid, turn aside") + Av. star- "to spread," starati "spreads;" cf. Skt. star- "to spread out, extend, strew," strnati "spreads;" Gk. stornumi "I spread out," strotos "spread, laid out;" L. sternere "to spread;" Ger. Strahlung "radiation," from strahlen "to radiate," from Strahl "ray;" from M.H.G. strāle; from O.H.G. strāla "arrow," stripe; PIE base *ster- "to spread").

Position, in a series arranged in order, on the basis of some principle of arrangement, with reference to the other items or values in the series.

M.E., from O.E. ranc "proud, overbearing, showy," from O.Fr. renc, ranc, rang "row, line;" cf. Dan. rank "right, upright," Ger. rank "slender," O.N. rakkr "straight, erect," perhaps from PIE *reg- "to stretch, straighten," cognate with Pers. râst, → right.

Rotbé, loan from Ar. ratbat "rank."

A temperature scale in which the degree intervals are the same size as in the → Fahrenheit scale, but 0 is set at absolute zero, -459.69 °F. Therefore, 1 degree Rankine is equal to exactly 5/9 → kelvin. It was formerly used by engineers in English-speaking countries, but is now obsolete. See also → Celsius scale, → Kelvin scale, → Reaumur scale.

Named for the British physicist and engineer William John Rankine (1820-1872); → scale.