  We study the formation of knots on a macroscopic ball-chain, which is shaken
on a horizontal plate at 12 times the acceleration of gravity. We find that
above a certain critical length, the knotting probability is independent of
chain length, while the time to shake out a knot increases rapidly with chain
length. The probability if finding a knot after a certain time is the result of
the balance of these two processes. In particular, the knotting probability
tends to a constant for long chains.
