And one does not know how physics behaves out in the void, nor in another galaxy.
Umm, yes we do, as far as we can work out what we know of physics appears to apply uniformly across the universe. Different laws of physics applying in the Andromeda galaxy even in a way that may appear minor, would lead to large scale effects that would be obvious even to us this far away, "Ye cannae change laws of physics" as a well known Scotsman once said.
Now no doubt there are quite a few things we don't know, but for instance if we were to fiddle with the inverse square law of gravity even a little bit there would be no stars, or a single gigantic star, take your pick. yes the laws of physics do apply across the universe, even the ones we don't yet understand or know about.