The forces that act among atoms cause them to resist compression—if you don’t believe me, just try squeezing a balloon. But dark matter is different. Unlike atoms, it is effectively immune to such forces, allowing gravity to compress it much more quickly, and shaping it into the scaffolding that the rest of our universe’s structure would later be built upon. Long before there were any galaxies, the dark matter began to gather together into enormous clouds. It was the gravity of these dark clouds that attracted and pulled together the atoms that would ultimately go on to form galaxies
...more
