How to tie the shoelaces tight: the mystery still has no solution

Many people say that the tightness of shoelaces comes from the way we tie it. And the fact proves that the more buttons are tied, the more easily the shoelace will slip, however, not everyone understands why. Recently, a scientific article in Physical Review Letters has shed some light on this forgotten mystery.

Secrets of shoelaces

It seems like a joke but actually the tie knot is an area of ​​central research of abstract mathematics. So far, their physical characteristics are still difficult to describe in practice, even with computer simulations.

Not everyone understands the complexity behind shoe laces.

Khalid Jawed, a mechanical researcher from MIT, said: 'If you take a rope, knot it and start studying the shape of the knot with the naked eye, seemingly simple but it is an extreme thing. complicated '.

Each way of knotting produces a series of forces interacting with each other . And when becoming a mathematical model, researchers must list dozens of variables such as torsion, tension, friction, rigidity . And then the problem will have to be applied. For ropes, shoelaces, headphone wires, nylon, even protein fibers and DNA. Now a simple knot will also become complicated.

Back in the 2008, Basil Audoly, a French mathematician from the Sorbonne University, Paris said he could solve this problem. Audoly's solution works relatively well with simple buttons from 1 to 2 turns.

However, Jawed and his colleagues at MIT decided to retest Audoly's theory. They performed a number of experiments with increased number of buttons and using titanium nickel wire. The machine arm is used to tie the rope at the same time, the force is also measured after each loop. The results indicate that the magnitude of the force required to tighten the rope changes drastically after each knot increase.

It seems to be a simple knot but it is also very complicated with math.

Normally, most of us think that when knotting the second and third turns, we just need to use a little more force than the previous time. However, the results of MIT researchers show that to tighten the second node, you need four to eight times more force than the first. Calculations show that up to a complicated knot, you have to spend 1000 times more than the original button.

'This is very recognizable to your headphones ,' says Jawed. 'You tie a button and pull it, it seems easy to get it tight. The wire will become smaller immediately. But when it comes to the 5th or 6th turn, things start to get tough. The loop will come apart and until some time you can't even tie it. '

So what makes this strange? In all variables, friction is the most decisive factor . For a simple knot, the hardness of the material is a major influence variable, friction is negligible and can be neglected. However, when the number increases to 3 or 4 turns, 'you are increasing the contact area in the messy area of ​​the knots, the friction is very important now'.

New research by scientists at MIT has attracted the old author of the solution. Audoly also joined the research team to develop a better theory that could explain the secrets of knots. They came up with an equation that accurately describes how different forces are present in a knot that works based on friction, tension and rigidity of the wire.

Complex spiral molecules in biochemistry and chemistry.

The equation has shown its power in predicting the necessary force for certain knots under certain conditions. However, it has not been possible to complete a unified theory to apply to all cases. Even so, the researchers say this will be a great starting point. In the future, they will be able to expand their theory further when using a computer simulator.

It can be seen that just a knot also makes humanity to work hard. However, once the problem is solved, it will be a precursor to sophisticated technologies, such as surgery and stitches with wounded robots, fine-tuned shock absorbers and even the study of complex dissection. impurities of fibers during cell division.