Coming to grips with a world of knots

Sometimes just when you think the world has gone off the deep end, a little sparkle shines through the darkness and revives your hope in humanity.

Forget for a moment first-quarter figures for China out this week that have people who swear by tea-leaf reading wetting their pants; forget the so-called mother of all bombs - a travesty of a name if ever there was one - that is now apparently going to make the world a safer place; and forget about chocolate cake and its pivotal role in world diplomacy.

Now bring on the mechanical engineers at the University of California, Berkeley, who must surely be on a shortlist for a Nobel Prize this year. Their contribution to humanity's knowledge: discovering why your shoelaces keep coming undone.