This video of a line of swinging pendulums is simply mesmerizing. Watch it just for the fascinating pleasure of it.
[youtube]http://www.youtube.com/watch?v=yVkdfJ9PkRQ[/youtube]
Then, if you want to know more about the science behind it, check out the details page at the website of Harvard Natural Sciences Lecture Demonstrations -- they're the folks who created the video. As they tell it, the video shows:
As I tell it: Cool.
Via: Nathan Bransford