Imagine thinking all your life that you had an amazing and spacious house, and that it occupied your entire sense of everything there was. Then one day you discover it’s actually only the bottom five floors in a one-hundred-story luxury apartment building. Suddenly, your living situation just got more complicated. Twenty-seven of those other floors belong to something heavy but invisible that we’re calling dark matter. They might be cool neighbors or they might be weird neighbors. For some reason, they keep avoiding you in the hallways. Fully sixty-eight of the other floors are nearly a
...more
