Assertion: gravity's theory | /r/HasProperty | kaluza–klein theories
Facets:
value: sometimes
type: TEMPORAL
Source sentences:
text: The resulting theories were sometimes referred to as Kaluza–Klein theories as Kaluza and Klein constructed in 1919 a 5-dimensional gravitational theory, that when dimensionally reduced on a circle, its 4-dimensional non-massive modes describe electromagnetism coupled to gravity.