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

1) General: A thin cord, usually made of twisted fibers, used for fastening, hanging, or tying. Something that resembles string in form or texture.
2) Music: A cord stretched across a musical instrument and vibrated to produce sound.
3) Subatomic string; → string theory.
4) → cosmic string.

M.E. string, streng; O.E. streng "line, cord, thread;" Du. streng,Ger. Strang "rope, cord;" PIE base *strenk- "stiff, tight."

Târ "thread, warp, string" (related to tur "net, fishing net, snare," tâl "thread" (Borujerdi dialect), tân "thread, warp of a web," from tanidan, tan- "to spin, twist, weave;" Mid.Pers. tanitan; Av. tan- to stretch, extend;" cf. Skt. tan- to stretch, extend;" tanoti "stretches," tántra- "warp; essence, main point;" Gk. teinein "to stretch, pull tight;" L. tendere "to stretch;" Lith. tiñklas "net, fishing net, snare," Latv. tikls "net;" PIE base *ten- "to stretch").
Rismân "thread, string, cord" variants rasan, ras, ris, razé, rajé, rijé, rešmé, Mid.Pers. rasan, cf. Skt. rajju- "rope, cord," L. restis "cord," Lith. resgis, rekstis "wicker basket," O.L.G. risch; PIE base *rezg- "to plait."

The latest theory of fundamental physics in which the basic entity is a one-dimensional → brane rather than the "zero-dimensional" point of conventional elementary particle physics. The one-dimensional string-like objects exist in the normal four dimensions of → space-time plus additional dimensions, the total dimensions being ten, eleven, or twenty-six depending on the version of the theory. Particles are strings that vibrate in different ways to account for their various properties.

→ string; → theory.

Hydrology: A freshwater spring that emerges off the seashore.

→ submarine; → spring.

Grouping of galaxies in supercluster structure.

→ super-; → clustering

Same as → last scattering surface.

→ surface; → last; → scattering.

The classical, → non-relativistic scattering of photons by free charged particles. When an electromagnetic wave is incident on a charged particle, the electric and magnetic components of the wave exert a force on the particle, setting it into motion. As it accelerates, it in turn radiates in all directions. Such scattering is independent of wavelength and equal numbers of photons are scattered forward and backward. Thomson scattering occurs in stellar atmospheres and in any non-relativistic → plasma. Thomson scattering is normally taken as the minimum → opacity.

→ Thomson; → scattering.

A highly → magnetized vacuum behaving as a prism for the propagation of light, as predicted by → quantum electrodynamics (QED). Attempts to detect this phenomenon in the laboratory have not yet succeeded in the 80 years since it was predicted (Heisenberg & Euler, 1936, Z. Physik, 98, 714). This effect can be detected only in the presence of enormously strong → magnetic fields, such as those around → neutron stars. Owing to the large inferred magnetic fields (B ~ 10¹³ G, → gauss), radiation from these sources is expected to be substantially polarized, independently of the mechanism actually responsible for the → thermal emission. The strongest magnetic field so far created in a laboratory is less than 10⁶ G lasting only for several tens of milliseconds. A large observed → polarization degree is, however, expected only if QED polarization effects are present in the magnetized vacuum around the star. The detection of a strongly → linearly polarized signal would therefore provide the observational evidence of QED effects in the strong-field regime. Recently a team of astrophysicists (Mignani et al. 2016, arXiv/1610.08323) have detected → linear polarization toward the neutron star RXJ1856.5-3754 (at a significant degree of around 16%). This finding is likely due to the boosting effect of vacuum birefringence occurring in the area of empty space surrounding the neutron star.

→ vacuum; → birefringence.

Geology: The various processes, such as the actions of wind, rain, temperature changes and so forth, which mechanically and chemically cause exposed rocks to decompose.

From → weather + → -ing.

Sâyand, from sâyidan "to touch, to rub," variants sâbidan, pasâvidan; Khotanese sauy- "to rub;" Sogdian ps'w- "to touch;" ultimately Proto-Iranian *sau- "to rub."