What makes you think this cant apply to gravitons, or more generally, what makes you think that gravitons are relevant over large distance scales? > Do you hav

What makes you think this cant apply to gravitons, or more generally, what makes you think that gravitons are relevant over large distance scales? > Do you have any examples of the numbers of particles being different in different frames or coordinate systems that works at all distance scales? Sure, it’s called the Unruh effect. Any accelerated frame (or observer in a gravitational field) will see a different particle vacuum than observers in a inertial frame. This means that if you start in empty space and then accelerate, the space will suddenly not look so empty and will be at a higher temperature with more fluctuating particles.