انگارهی ِ کانت-لاپلاس engâre-ye Kant-Laplace
*Fr.: hypothèse de Kant-Laplace*
The hypothesis of the origin of the solar system proposed first by Kant
(1755) and later by Laplace (1796). According to this hypothesis, the solar system
began as a nebula of tenuous gas. Particles collided and gradually, under the influence
of gravitation, the condensing gas took the form of a disk. Larger bodies formed,
moving in circular orbits around the central condensation (the Sun). Named after the German prominent philosopher Immanuel Kant (1724-1804) and the French great
mathematician, physicist, and astronomer Pierre-Simon Marquis de Laplace (1749-1827);
→ *hypothesis*. |

لاپلاس Laplace
*Fr.: Laplace*
The French great mathematician, physicist, and astronomer Pierre-Simon Marquis de Laplace
(1749-1827).
→ *Laplace operator*;
→ *Laplace plane*;
→ *Laplace resonance*;
→ *Laplace transform*;
→ *Laplace's demon *;
→ *Laplace's equation *;
→ *Kant-Laplace hypothesis* |

آپارگر ِ لاپلاس âpârgar-e Laplace
*Fr.: opérateur de Laplace*
Same as → *Laplacian*. → *Laplace*; → *operator*. |

هامن ِ لاپلاس hâmon-e Laplace
*Fr.: plan de Laplace*
The plane normal to the axis about which the pole of a satellite's
orbit → *precess*es.
In his study of Jupiter's satellites, Laplace
(1805) recognized that the combined effects of the solar tide and
the planet's oblateness induced a "proper" inclination in satellite
orbits with respect to Jupiter's equator. He remarked that this
proper inclination increases with the distance to the planet, and
defined an orbital plane (currently called Laplace plane)
for circular orbits that lies between the
orbital plane of the planet's motion around the Sun and its equator
plane (Tremaine et al., 2009, AJ, 137, 3706). → *Laplace*; → *plane*. |

بازآوایی ِ لاپلاس bâzâvâyi-ye Laplace
*Fr.: résonance de Laplace*
An → *orbital resonance* that makes
a 4:2:1 period ratio among three bodies in orbit. The
→ *Galilean satellite*s
→ *Io*, → *Europa*,
→ *Ganymede* are in the
Laplace resonance that keeps
their orbits elliptical. This interaction prevents the orbits of the satellites
from becoming perfectly circular (due to tidal interactions
with Jupiter), and therefore permits → *tidal heating*
of Io and Europa.
For every four orbits of Io, Europa orbits
twice and Ganymede orbits once. Io cannot keep one side exactly facing
Jupiter and with the varying strengths of the tides because of its
elliptical orbit, Io is stretched and twisted over short time periods. This commensurability was first
pointed out by Pierre-Simon Laplace,
→ *Laplace*; → *resonance*. |

ترادیس ِ لاپلاس tarâdis-e Laplace (#)
*Fr.: transformée de Laplace*
An integral transform of a function obtained by multiplying the given
function *f(t)* by *e*^{-pt}, where *p* is a new variable, and integrating
with respect to *t* from *t = 0* to *t = ∞*. → *Laplace*; → *transform*. |

پری ِ لاپلاس pari-ye Laplace
*Fr.: démon de Laplace*
An imaginary super-intelligent being who knows all the laws of
nature and all the parameters describing the state of the Universe at a given moment
can predict all subsequent events by virtue of using physical laws.
In the introduction to his 1814 *Essai philosophique sur les probabilités*,
Pierre-Simon Laplace puts forward this concept to uphold
→ *determinism*, namely the belief that the past completely
determines the future. The relevance of this statement, however, has been called into
question by quantum physics laws and the discovery of
→ *chaotic system*s. → *Laplace*; → *demon*. |

هموگش ِ لاپلاس hamugeš-e Laplace
*Fr.: équation de Laplace*
A → *linear differential equation* of the second order
the solutions of which are important in many fields of science, mainly in electromagnetism,
fluid dynamics, and is often used in astronomy. It is expressed by:
∂^{2}*V*/ ∂*x*^{2} +
∂^{2}*V*/ ∂*y*^{2} +
∂^{2}*V*/ ∂*z*^{2} = 0.
Laplace's equation can more concisely expressed by: ∇^{2}*V* = 0.
The function *V* may, for example, be the potential at any point in the electric field where
there is no free charge. The general theory of solutions to Laplace's equation is
known as *potential theory*. → *Laplace*; → *equation*. |