(Roughly) Daily

It’s knot easy, but it’s important, to understand knots…

From whimsical flower crowns to carelessly tied shoelaces to hopelessly tangled headphones, knots are everywhere. 

That’s not surprising, as knots are quite ancient, predating both the use of the axe and of the wheel and potentially even the divergence of humans from other apes. After all, ropes and cords are practically useless without being tied to something else, making one of the most ancient technologies still remarkably relevant today.

But these tie-offs can be a problem, since knots actually decrease the strength of a rope. When a rope made up of multiple fibers is taut, those fibers all share equal portions of the load. However, the bending and compression where the knot forces the rope to curve (usually around itself, or around the thing it is tied to) create extra tension in only some of the fibers. That’s where the rope will break if yanked with too much force. And this isn’t a small effect: common knots generally reduce the strength of a rope by 20 percent for the strongest ones, to over 50 percent for a simple overhand knot.

Experience has taught surgeons, climbers, and sailors which knots are best for sewing up a patient, or rescuing someone from a ravine, or tying off a billowing sail, but until some recent research from a group at MIT it was hard to tell what actually makes one knot better than another… 

Which knot is the strongest? “The tangled physics of knots, one of our simplest and oldest technologies,” from Margaux Lopez (@margaux_lopez_).

See also: “The twisted math of knot theory can help you tell an overhand knot from an unknot.”

* Athanasius Kircher

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As we understand the over and under, we might send constructive birthday greetings to John “Blind Jack” Metcalf; he was born on this date in 1717. Blind from the age of six, he was an accomplished diver, swimmer, card player, and fiddler. But he is best remembered for his work between 1765 and 1792 when he emerged as the first professional road builder in the Industrial Revolution. He laid about 180 miles of turnpike road, mainly in the north of England– and became known as one of the “fathers of the modern road.”

Just before his death, he documented his remarkably eventful life; you can ready it here.

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