I have an idea of what Gravitons might be and why we may never detect them.
gravitons are the place holders of spacetime, like pins in a notice board. They do not actually move with respect to space, but are the force of movement in spacetime, facilitating the quantum tunneling of energy from one location in spacetime to another. They are each composed of a elastic closed energy string intervoven with it's adjacent neighbours. When energy or mass enters into the same spacetime as the gravitron, the gravitron responds by facilitating it's movement onto it's neighbouring gravitron in a manner that corresponds to it's stress energy tensor and it's spin state.
The maximum speed at which a gravitron can turnaround this change is c the speed of light, and thus it is the speed of gravitons that put a top speed limit on the universe.
Massless bosons can thus be moved along at the speed of gravity c, whereas massive particles require more graviton turn arounds per unit time to movealong in spacetime, and thus the more massive the more difficult it is to achieve c.
Could this idea hold water? Is it a valid theory?