Monday, April 28, 2008


Welcome to training camp! The preparation and the exams have been demanding; congratulations on coming through with flying colors. Our thanks to your families and schools and to the teachers who helped you.

You’ll have plenty to think about during the next few weeks. However, if you have a minute, here’s a question that you won’t find on any exam. It’s about elevators. Last week there was an interesting article about them in the New Yorker magazine: Author Nick Paumgarten was surprised to learn that the maximum possible height to which elevators can go is limited by the weight of rope.

"The big ideas tend to falter on the laws of physics," he says. "A single elevator can climb no higher than seventeen hundred feet. A hoist rope any longer is too heavy to be practical; at thirty-two hundred feet, it will snap, like a stream of spit in a stairwell." According to him, that’s the case even if the rope is made of the latest high-tech materials.

Is he right? What if you taper the rope? What if you use carbon fibers? Got any other ideas for improvements?

Harold Stone of Harvard and I are thinking of writing a short piece for the "Quick Study" section of Physics Today that shows interesting uses of dimensional analysis. Can we use dimensional analysis to estimate how long a rope will be before it breaks of its own weight?

We look forward to sharing ideas about physics, about the training experience, about life - maybe even about elevators.

See you soon,
Charlie Holbrow
Executive Officer, AAPT