I don’t have a l;ink, but I think one of them is called Antlia 2. Galaxies don’t really collide, they more or less just co-mingle. IF they are of more or less equal size, they then form a globular galaxy.
I think gravity is a force. On earth, gravity is the force that is accelerating us towards the center of the planet. Since the earth is spinning, we would fly off without this force holding us down. What else could be accelerating us in that direction?
Yes, Einstein said that mass curves space, and this is when we call gravity. Then again, he also thought that mass is an inherent property of matter. The discovery of the Higgs boson in 2012 kinda disproved this. So what is gravity? Is it an exchange of virtual particles called gravitons? Some differential in the gluon field? Eh, nobody knows!
I don’t think space itself is moving, at least not expanding uniformly. It can get distorted, twisted, and so on, but is generally static-ish. Basically, an anti-de Sitter space.
I don’t want to hijack this thread any more than we have. Start a new thread and I’ll tell you the way I think it works… The Big-ish Kersplat hypothesis.