[Opinión] Physics and Football: The Science of the Game

With the Qatar World Cup in full swing, soccer is getting the attention of the media. A sport that, due to its simple rules, can be played on improvised pitches and with a minimum of equipment. But this, as she became more professional, came under increasing pressure to improve various aspects of the game, allowing science and technology, in general, and physics, in particular, to have a lot to say about the game. “A beautiful sport.”

Physical knowledge of nature is also important on the soccer field. Every hit of the ball changes its trajectory, as Isaac Newton suggested 400 years ago: an object accelerates because a force acts on it.

Around this idea, Newton formulated three laws that are the basis of mechanics. The same equations that describe the motion of a soccer ball allow us to understand the fall of an apple, the return of a comet, or the tides. A unified idea quietly prevailed, until the cuts in the nineteenth century began to show signs of fatigue, forcing quantum mechanics and the theory of relativity into the field.

But just as physics has progressed, so has football, benefiting from scientific knowledge. Start for the ball. The first rubber tires for cars deteriorated easily in the heat of the roads. Then Charles Goodyear, in 1839, noticed that heating rubber could change its properties. Thus was born the process of vulcanization (from Vulcan, the Roman god of fire). In 1855, Goodyear himself made the first vulcanized rubber soccer ball. A ball made of this material will keep its shape longer, making its trajectory more predictable, resulting in a higher quality of play.

For this reason, research into the aerodynamics of the ball does not stop, trying to get a better knowledge of its behavior in flight. Details that aren’t details—such as the number of panels that make up the ball, how they are joined and the presence of grooves on the surface, among other things—affect the ball’s trajectory and are factors taken into account in the design. Nothing is left to chance.

A control that makes possible, with talented feet, unforgettable moments such as the magnificent free-kick of “Cotto” Sierra against Cameroon, in France 98, or even more impressive by Roberto Carlos against France, in a preparatory match for the same world. Glass. Interestingly, from time to time we come across reports of these types of goals, highlighting how they “defy the laws of physics”. But there is none of that. It is precisely these laws that allow us to understand it. In fact, Roberto Carlos’ achievement is a very clear example of a phenomenon known as the Magnus effect, which was described by physicist Heinrich Gustav Magnus in 1852, in which the rotation of an object affects its trajectory through a fluid, such as air, causing it to change its direction. Direction towards the opposite sector to which you set out.

In recent years, we’ve seen a greater use of technology to help “sports justice.” That supposed goal in the 1966 England final, or Maradona’s handball in Mexico 1986, are examples you don’t want to repeat.

Again, physics and its applications are there to help us. Ultra-high-speed cameras, derived from the latest developments in electronics and optical signal transmission, allow it to follow the trajectory of the ball with amazing accuracy, triangulating its position in real time and sending a signal to the referee’s watch as soon as the ball has acquired the ball. Completely crossed the line. Never again illegitimate targets, thanks to all we know about the behavior of light and matter on a microscopic scale. Certainly, in the near future, this ability will extend to the rest of the lines, quelling controversies such as Japan’s goal that qualified them to the Round of 16.

There are those who believe that these developments betray the essence of football. But what is the essence? Even in science it was a fickle concept. It has happened many times that physical models that are believed to be correct have had to be replaced by others. But that doesn’t question building physics, just the way it’s built. Like in football. Hungary in ’54 and the Netherlands in ’70 showed that there are other ways to play. They baffled everyone, dominating the scene, but the result was football, only more elaborate. It wasn’t just physics that influenced the development of soccer: they both have more in common than meets the eye.