Since the galaxies are receeding with velocity propotional to distance, I'm curious what happens at or beyond the point where the velocities approach the speed of light & how that's possible. One source I looked at said the galaxies are invisible. Another source said the spacetime is what's stretching & there's no speed of light limit to that. Yet another source said the concept is incoherent because you can't compare vectors at different points in spacetime (in different tangent spaces). I don't know much about differential geometry yet, but I do know you physicists need to get your junk together. What is going on? Some math please.