perpetual motion

Noun

 * 1)  The motion of some hypothetical device that continues forever with no external input of energy, in violation of the laws of thermodynamics.

Usage notes

 * In the literal sense, perpetual motion can exist in an ideal isolated system, such as a single photon moving through empty space. However, a perpetual motion machine which produces work while retaining its kinetic energy is impossible under the known laws of physics.

Translations

 * Finnish: ikuinen liike
 * French:
 * Latin: mōtus perpetuus
 * Polish: wieczny ruch, nieustanny ruch
 * Russian: ве́чное движе́ние