An Etymological Dictionary of Astronomy and Astrophysics
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فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 2 Search : rigorous
rigorous
  فرسخت   
farsaxt (#)

Fr.: rigoureux   

1) Severely exact or accurate; precise.
2) Logic, Math.: Logically valid. See also: → accurate, → exact, → precise.

M.E., from M.L. rigorosus, from rigor "stiffness, rigor," from rigere "to be stiff."

Farsaxt, from far- intensive prefix "much, abundant; elegantly" (Mid.Pers. fra- "forward, before; much; around;" O.Pers. fra- "forward, forth;" Av. frā, fərā-, fra- "forward, forth; excessive;" cf. Skt. prá- "before; forward, in fron;" Gk. pro "before, in front of;" L. pro "on behalf of, in place of, before, for;" PIE *pro-) + saxt "hard, strong, firm, secure, solid, vehement, intense" (Mid.Pers. saxt "hard, strong, severe;" Av. sak- "to understand or know a thing, to mark;" cf. Skt. śakta- "able, strong," śaknoti "he is strong," śiksati "he learns").

rigorous selection rule
  رزن ِ گزینش ِ فرسخت   
razan-e gozineš-e farsaxt

Fr.: règle de sélection rigoureuse   

A → selection rule obeyed by → discrete transitions. Among them are: rigorous selection rules for → electric dipole transitions (→ permitted) requiring: 1) ΔJ must be 0 or ± 1 with J = 0 ↔ 0 forbidden. 2) ΔMJ = 0, ± 1. 3) → Parity change, i.e. even ↔ odd.

rigorous; → selection; → rule.