Full Idea
String theory works as a quantum theory of gravity because string vibrations can describe gravitons, the hypothetical carriers of the gravitational force.
Gist of Idea
String theory offers a quantum theory of gravity, by describing the graviton
Source
New Scientist writers (Why the Universe Exists [2017], 09)
Book Reference
New Scientist writers: 'Why the Universe Exists' [John Murray 2017], p.169
A Reaction
Presumably the main aim of a quantum theory of gravity is to include gravitons within particle theory. This idea has to be a main attraction of string theory. Compare Idea 21166.
Related Ideas
Idea 21166 Standard antineutrinos have opposite spin and opposite lepton number [New Sci.]
Idea 21194 The Standard Model omits gravity, because there are no particles involved [Hesketh]