How to configure the perfect knot

Science : Knot tying is important not just for fastening your shoes or mooring a boat but also for understanding structures on the molecular and atomic levels, such as proteins and DNA. To study the mechanics involved in tying a simple overhand knot, researchers used a highly elastic nickel titanium wire. They then developed a formula to calculate the amount of force needed to pull such a knot tight. They found that the force required depends on three variables: the wire’s thickness and stiffness and the knot’s topology, meaning the number of times the two ends are twisted around each other to form the knot. By plotting various combinations of those three variables on a graph, the researchers found that a 10-twist overhand knot needs a tug 1000 times as strong as a single-twist one. The researchers hope their findings will lead to studies of more complex knots and have many commercial applications, such as tunable shock absorbers or stretchier exercise bands.