I like Halloween. Not so much for the costumes and tropes of ghouls and goblins but more for my own personal reasons. Today is my birthday. And today, I get to share this planet with the 7,000,000,000th person. When I was born, there were about 4.1 Billion people. We've added almost 3 billion since I got here. There's a story about exponential growth here somewhere, but it eludes me at the moment.