Right at the moment of the Big Bang, positive space, the space we are in macroscopically, was only two-dimensional...when the inflationary epoch began, space was two-dimensional...by the time the inflationary epoch ended, positive space fully gained its three-dimensional characteristics....I believe that the decoupling of the GE forces initiated the inflationary epoch in positive space.
Think about it, why are the only two forces that show acceleration (besides the time particle I think) in our normal positive space are gravity and electromagnetic forces. They exhibit actions that point away from their common origin in positive space. The force particles show action tangential to their common origin in positive space. And my new idea is that the gravitons are lightspeed-traveling particles that show momentum in two-dimensions (photons only show momentum in one dimension)...so each mass particle has two gravity particles in them, each two-dimensional (I think). The gravitons might be intertwined when they act...each of them showing momentum in two dimensions only.