(Shoe) String Theory

[Yazata]

We've always wondered. They are securely tied one moment, and loose the next. What happened?

Well, an international team of scientists at UC Berkeley and Aston University in the UK are on the case.

And no MR, it isn't Gremlins.

http://www.laboratoryequipment.com/news/...ome-untied

They enlisted volunteers on treadmills and robots that stomped and swung mechanical legs. Neither stomping or swinging by themselves caused shoes to come untied.

But a combination of stomping and swinging did. Apparently stomping causes the knot to become tied less tightly so that slippage becomes possible in it. The swinging of the leg imparts lateral forces that pull on the laces. After enough of that a catastrophic failure ensues and the knot unravels very rapidly.

This research topic may seem kind of insignificant (the kind of thing that might win a Ig Nobel Prize) but it is part of a bigger project to investigate the dynamical properties of various kinds of knots under different kinds of mechanical forces and stresses.

[C C]

The "Brazil nut effect" finally has a partner to make a bookend set.

[Zinjanthropos]

I've refereed thousands of basketball games in my life. Seen many a shoelace come untied during play. No doubt in my mind that younger player's shoes come untied more often than older kids. So I think you have to figure in the relative strength of the shoe owner, their age, making a tied shoe a priority before playing(taking more care) and the gradual knowledge of how to tie a shoe properly. Also since older players wear higher quality shoes I presume the laces are of better quality too. So the older one gets, the less chance of a shoelace malfunction...the way I see it anyways.