Why haven't gravitons been discovered yet?

[AstrophysicsX]

The four forces of nature: gravity, electromagnetic, strong, and weak: each have a particle. Strong force has gluon, weak force has weak gauge bosons, electromagnetic force has photons, and it is predicted that gravity has gravitons, though experiments haven't confirmed this. Why haven't gravitons been discovered?

 

[Drakkith]

Hrmm. I would think it is because we have not way of observing them yet, if they exist. All the others can be directly observed or indirectly through particle accelerators and whatnot, but so far we have nothing that can detect a graviton. I'm sure if we went back in time and asked the same thing about gluons we would get a similar answer.