I remember the first time I went to a salsa club about 20 years ago. I remember feeling very excited when I saw people dancing, laughing, smiling, and having a great time. At that moment, I decided to be part it and began to take salsa dance lessons.

Andreas Wahl, a Norwegian physicist, tied himself to the side of building forty-five feet off the ground to demonstrate a basic property of physics.  The only thing keeping him from falling and potentially breaking a body part, or several, was a cable with a weight attached to the end.   At first,