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

The ordinary Newtonian energy conservation equation when expressed in expanding cosmological coordinates. More specifically, it is the relation between the → kinetic energy per unit mass associated with the motion of matter relative to the general → expansion of the Universe and the → gravitational potential energy per unit mass associated with the departure from a homogeneous mass distribution. In other words, it deals with how the energy of the → Universe is partitioned between kinetic and potential energy. Also known as → cosmic energy equation. In its original form, the Layzer-Irvine equation accounts for the evolution of the energy of a system of → non-relativistic particles, interacting only through gravity, until → virial equilibrium is reached. But it has recently been generalized to account for interaction between → dark matter and a homogeneous → dark energy component. Thus, it describes the dynamics of local dark matter perturbations in an otherwise homogeneous and → isotropic Universe (P. P. Avelino and C. F. V. Gomes, 2013, arXiv:1305.6064).

W. M. Irvine, 1961, Ph.D. thesis, Harvard University; D. Layzer, 1963, Astrophys. J. 138, 174; → equation.

A silicate mineral of magnesium (Mg₂SiO₄) and iron (Fe₂SiO₄,) found commonly in basalt and in carbonaceous chondrites.

From Ger. Olivin, from olive, because of its olive-green to gray-green color, + -in equivalent to -ine a noun suffix used in chemical and mineralogical nomenclature.

Any of various plants, especially the grapevine, having long flexible stems that creep along the ground or climb by clinging to a support by means of tendrils, leafstalks, etc (Dictionary.com).

M.E., from O.Fr. vigne "vine, vinyard," from L. vinea "vine, vineyard," from vinum "wine," from PIE *win-o- "wine."

Mow, tâk, raz "vine," Persian words of unknown origin.