An Etymological Dictionary of Astronomy and Astrophysics
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An act or instance of contracting; the quality or state of being contracted.
→ gravitational contraction, → Kelvin-Helmholtz contraction, → length contraction, → Lorentz contraction.

Verbal noun of → contract.

Decrease in the volume of an astronomical object under the action of a dominant, central gravitational force.

→ gravitational; → contraction.

The contraction of a volume of gas under its → gravity, accompanied by the → radiation of the lost → potential energy as → heat.

After the Scottish physicist William Thomson, also known as Lord Kelvin (1824-1907) and the German physicist and physician Hermann Ludwig Ferdinand von Helmholtz (1821-1894), who made important contributions to the thermodynamics of gaseous systems; → contraction.

Same as → Lorentz contraction.

→ length; → contraction.

The decrease in the length of a body moving in the direction of its length as measured by an observer situated in that direction. The shortening factor is [1 - (v/c)²]^1/2, where v is the relative velocity and c light speed.

→ Lorentz; → contraction.

An operation of tensor algebra that is obtained by setting unlike indices equal and summing according to a summation convention.

→ contraction; → tensor.