Activities in sailing, rock climbing, construction require the tightening of ropes and some knots are stronger than others. But, until now, what exactly makes one knot more stronger than another was still uncertain. Now, with the help of color-changing fibers, MIT mathematicians and engineers have developed a mathematical model to predict a knot’s stability, based on several key attributes, including the number of crossings involved and the direction in which the rope segments rotate as we pull the knot tightly. The newly developed model will allow the researchers to look at two almost identical knots and be able to say which is better and stronger.