I'm a non-scientist - that watches way too many TV science programs - that is having trouble putting the pieces together. I am always hearing about how much visible matter is missing from the universe. I am also hearing about how (it is now believed) that every galaxy contains a massive black hole at it's center. I also recently read where it's believed that the black holes were simultaneouly created along with the galaxies. Here's what I'm not getting: 1. Billions of years ago, the galaxies were much closer to each other. Also, the galaxies were much more compact - the universe and galaxies hadn't expanded as greatly as today. 2. Since everything was so much closer, it would have been much easier for the black holes to feed on visible matter. 3. And, these black holes have been feeding on visible matter for billions of years. 4. Plus, how many invisible black holes are floating around the universe, of unimaginable mass, that totally consumed their galaxies billions of years ago. So, ... how can scientists be certain that the visible matter that is missing hadn't been gobbled up by massive black holes over billions of years? I can't understand how one could know. I also read where the missing matter is in the form of gases in the voids of the universe. ???