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: 18 Search : symmetry
asymmetry
  ناهمامونی   
nâhamâmuni

Fr.: asymétrie   

Lack of symmetry; not symmetrical.

Gk. asymmetria "lack of proportion," from asymmetros "ill-proportioned," from → a- "not" + symmetros "commensurable, symmetrical."

Nâhamâmuni, from nâ- "not" + hamâmuni "symmetry," from ham- "together = syn" + -â-, euphonic affix, + mun "measure" + -i, noun affix.

axial symmetry
  همامونی ِ آسه‌ای   
hamâmuni-ye âse-yi

Fr.: symmétrie axiale   

A symmetry with respect to a line. A geometric configuration is said to have axial symmetry if it remains unchanged when rotated about a given line.

axial; → symmetry.

axisymmetry
  همامونی ِ آسه‌ای، آسه-همامونی   
hamâmuni-ye âse-yi, âse-hamâmuni

Fr.: axisymétrie   

Same as → axial symmetry.

baryon asymmetry
  ناهمامونی ِ باریون   
nâhamâmuni-ye bariyon

Fr.: asymmétrie baryonique   

The observation that in the present → Universe there is → matter but not much → antimatter. Observations do not show the presence of galaxies made of antimatter, nor gamma rays are observed that would be produced if large entities of antimatter would undergo → annihilation with matter. However, the → early Universe could have been baryon symmetric, and for some reason the matter excess has been generated, through some process called → baryogenesis. → Sakharov conditions.

baryon; → asymmetry.

C-symmetry
  همامونی ِ بار   
hamâmuni-ye bâr

Fr.: symétrie de charge   

Same as → charge conjugation and → charge symmetry.

charge; → symmetry.

charge symmetry
  همامونی ِ بار   
hamâmuni-ye bâr

Fr.: symétrie de charge   

Same as → charge conjugation and → C-symmetry.

charge; → symmetry.

charge-parity symmetry
  همامونی ِ بار-همالی   
hamâmuni-ye bâr-hamâli

Fr.: symétrie charge-parité   

The laws of physics should be the same if a particle is interchanged with its → antiparticle (→ charge conjugation), or swapped for its mirror image (→ parity symmetry). It is known that charge-parity (CP) symmetry holds for interactions involving → electromagnetism, → gravitation, and → strong interactions, but CP violation is known to occur during → weak interactions involved in → radio decay. Same as → CP-symmetry.

charge; → parity; → symmetry.

CP-symmetry
  همامونی ِ بار-همالی   
hamâmuni-ye bâr-hamâli

Fr.: symétrie charge-parité   

Same as → charge-parity symmetry.

charge; → parity; → symmetry.

dissymmetry
  ناهمامونی   
nâhmâmuni

Fr.: dissymétrie   

Absence or lack of symmetry

From → dis- + → symmetry.

Nâhmâmuni, from nâ- "non, un-," → a- + hmâmunisymmetry.

gauge symmetry
  همامونی ِ گز   
hamâmuni-ye gaz

Fr.: symétrie de jauge   

A principle underlying the quantum-mechanical description of the three non-gravitational forces. It allows a system to behave in the same way even though it has undergone various transformations. The earliest physical theory which had a gauge symmetry was Maxwell's electrodynamics.

gauge; → symmetry.

P-symmetry
  همامونی ِ همالی   
hamâmuni-ye hamâli

Fr.: symétrie de parité   

Same as → parity symmetry.

parity; → symmetry.

parity symmetry
  همامونی ِ همالی   
hamâmuni-ye hamâli

Fr.: symétrie de parité   

The invariance of physical laws under a transformation that changes the sign of the space coordinates. Parity symmetry is sometimes called mirror symmetry. It is known that the parity symmetry is violated in some weak interactions, while it is well preserved in all other three interactions (gravitational, electromagnetic, strong). Same as → P-symmetry and → parity conservation.

parity; → symmetry.

spherical symmetry
  همامونی ِ کُره‌ای   
hamâmuni-ye kore-yi

Fr.: symétrie sphérique   

A configuration in which the constituting parts are arranged concentrically around the center of a sphere.

spherical; → symmetry.

spontaneous symmetry breaking
  شکست ِ سرخود ِ همامونی   
šekast-e sarxod-e hamâmuni

Fr.: brisure spontanée de symétrie   

A physical phenomenon whereby a symmetric system becomes permanently asymmetric. A simple example is a ball lying on top of a hill in equilibrium. The hill-ball system is symmetric about the vertical axis through the top of the hill. Moreover, there is no preferred horizontal direction to the system. However, its state is unstable, since the slightest perturbing force will cause the ball to roll down the hill in some particular direction. The system becomes permanently asymmetric because the ball will not roll uphill by itself. Symmetry breaking is found in several fields of physics, for example in → magnetism (→ ferromagnetism), → thermodynamics (→ crystallization), and → particle physics, where it constitutes the basis of → electroweak interactions. In cosmology, according to the → Big Bang model, the fundamental forces of the Universe split off from one another in a form of spontaneous symmetry braking. If a single, unified force existed with a certain symmetry just after the Big Bang, if that symmetry were somehow broken so that the unified force were fractured, then the result might be several fundamental forces. See also → grand unified theory, → theory of everything, → phase transition.

spontaneous; → symmetry; → break.

supersymmetry
  اَبَر-همامونی   
abar-hamâmuni

Fr.: supersymétrie   

A class of theories that seek to unify the four fundamental forces of nature. It proposes symmetrical relationships linking fermions and bosons (particles of half integer spin, like electrons, protons, and neutrinos) with particles of integral spin (like photons and gluons).

super; → symmetry.

symmetry
  همامونی   
hamâmuni

Fr.: symétrie   

1) A quality of a geometric figure that has exactly similar parts with respect to a point, a line, or a plane of its own.
2) A geometric transformation that does not alter neither the shape nor the size of a figure.
3) A property of a mathematical function whose value does not change when its variables are interchanged.
4) Of physical phenomena, the property of remaining invariant under certain changes (as of rotation, reflection, inversion in space, the sign of the electric charge, parity, or the direction of time flow). See clso ⎒ Noether's theorem.
See also:
asymmetry, → axial symmetry, → axisymmetry, → baryon asymmetry, → charge-parity symmetry, → dissymmetry, → gauge symmetry, → parity symmetry, → spherical symmetry, → spontaneous symmetry breaking, → supersymmetry, → symmetry group, → T-symmetry.

From L. symmetria, from Gk. symmetria "agreement in dimensions, due proportion, arrangement," from symmetros "having a common measure, even, proportionate," from → syn- "together" + metron "meter;" PIE base *me- "to measure;" cf. O.Pers., Av. mā- "to measure;" Skt. mati "measures;" L. metri "to measure."

Hamâmun from ham-, → syn- "together," + -â- epenthetic vowel + mun, variant mân "measure," as in Pers. terms pirâmun "perimeter," âzmun "test, trial," peymân "measuring, agreement," peymâné "a measure; a cup, bowl," from O.Pers./Av. mā(y)- "to measure;" cf. Skt. mati "measures," matra- "measure;" Gk. metron "measure;" L. metrum; PIE base *me- "to measure."

symmetry group
  گروه ِ همامونی   
goruh-e hamâmuni

Fr.: groupe de symétrie   

A group of symmetry-preserving operations composed of all rigid motions or similarity transformations of some geometric object onto itself.

symmetry; → group.

T-symmetry
  همامونی ِ زمانی   
hamâmuni-ye zamâni

Fr.: symétrie T   

The symmetry of physical laws under a time reversal transformation.

T for → time; → symmetry.