Does space have some kind of buoyancy that prevents stuff from falling down? for instance, why doesn't the Sun fall downward eternally? Like, it is clear why the moon doesn't fall out of the sky but what is holding the Sun up in space? If you say the galaxy what is holding it up? what is the support structure for this stuff ... dark matter? Else it seems everything is just floating in space. is the entire universe everywhere filled with this support structure to prevent everything from falling? Or is everything falling in the same frame of reference and it appears to be static? what happens if the support structure fails or becomes too diluted due to expansion?