Why do we love roller coasters? They are almost a perversion of the pleasure-pain principle. We are drawn to them even as they incite fear, get our hearts racing, turn our knuckles white and toss us around mercilessly. Then we get off and jump right back in line. Beginning in the early 1990s, roller coasters began their second Golden Age (the first was during the Jazz-Age 1920s when the wooden lattices dotted the U.S. landscape) and their numbers and variety show no signs of letting up. Why do we love roller coasters? Who knows? But, it seems, we can't get enough of them.