Groovy Room Light
This page is the CodyCross answer for the clue below from Physics, Group 1889, Puzzle 4 (Space-Time Continuum).
Question is: Groovy Room Light
and the answer is: LAVALAMP
Word Meaning:
LAVA LAMP — A kind of lamp, typically used more for decoration than illumination, in which the gentle flow of randomly-shaped clumps of wax purportedly suggests the flowing of lava.
Definitions from Wiktionary.