A major new exhibition of mechanical puzzles is set to open next week at the Lilly Library at Indiana University. On display are many world-class examples of mathematical and physics-based puzzles. Apparently, in puritanical New England, the Sabbath was considered so sacred that one was not permitted any sort of entertainment, (games, dancing, music, or visiting friends) but creative types were able to find no mention in the bible regarding puzzles, and hence, a great tradition of puzzle solving evolved in that part of the US and provided an in-road to the rest of the country for a plethora of puzzles brought over from the Orient.

"Of all the puzzles on display, one of the most challenging was a deceptively simple-looking toy called Chinese rings. Its solution requires what mathematicians call a recursive sequence of moves.

The Chinese rings example in the library exhibition is particularly finely made. A set of rings are threaded over a long, thin loop with wires attached to each ring, tethering it below. Each ring can be taken off the loop or put back on only if the one next to it is on but the others farther down the chain are off. The goal is to get all the rings off.

According to legend, the puzzle was invented in the second century by a Chinese general who gave it to his wife to keep her busy while he was away at war. Logically, the puzzle is closely related to the Towers of Hanoi problem, which requires one to move a tower of increasingly smaller blocks from one peg to another.

In recursive puzzles like these, as the number of rings (or blocks) increases, the number of moves required to solve the puzzle increases exponentially.

Chinese rings make the problem tangible, and reveal in a hands-on fashion the exponential growth entailed. There are typically nine rings in a classic set of Chinese rings; if a player makes no mistakes, the puzzle requires 341 moves to solve.

But at the exhibit, there is a version with 65 rings. A perfect solution in that case would take 18,446,744,073,709,551,616 moves. Assuming one move every second, that would be 56 billion years, or four times the age of the universe."

As the White Queen said to to Alice "the more one practices, the better one gets at believing in impossible things." The more time I spend on this earth, the more true that sentiment becomes.

For more info on Chinese rings - http://www.daviddarling.info/encyclopedia/C/Chinese_rings.html