How do Gravitons work?

Question

Gravitons are supposed to mediate the force of gravity, but wouldn't that require Earth, Sun and basically everything else is constantly sending out gravitons to everything else?

Answer 1

As Charlie said, interactions are not an exchange of real particles, and neither even an exchange of virtual particles, since the latter are in fact mathematical artifacts of quantum field theory. You can see gravitons as elementary perturbations/excitations of the metric field when it is treated perturbatively: \begin{equation} \underbrace{g_{\mu \nu}}_{\text{general metric}}=\underbrace{\eta_{\mu \nu}}_{\text{Minkowski metric}}+\underbrace{h_{\mu \nu}}_{\text{perturbation}}. \end{equation} Since gravitons are linked to the concept of metric, they are also linked to the concept of curvature of space-time. This is why one often read or hear that gravitons are quanta of the curvature of space-time. An interaction in QFT and QFT in curved space-time is nothing but a way the gauge fields are curved, leading the matter field perturbations to move accordingly. This is the same with gravitation, but the "field is curved" part is to be understood literally.