(April 28, 2022 at 4:02 pm)Jehanne Wrote: I think that you would be best served by reading more Wikipedia articles; here's one on the expansion of the Universe:
Wikipedia -- Expansion of the Universe
As for the graviton, it's a hypothetical particle. If it exists, it must be a spin-2 particle.
One of my physics professors said that is pretty much the only thing we know about gravitons.