I was in the pub Friday evening, having a sneaky pint after walking the pooch. As is inevitable at the moment, talk was on the World Cup. We were discussing England’s chances (I believe!), the Balogun/Infantino/Trump controversy, amongst other football related things. One of the guys, I shall call him Dave (because that is his name) said “what about that goal from Pavard for France in the 2018 final against Argentina.” We all nodded agreeing it is probably one of the finest goals ever scored in World Cup history (it really is). Before someone else (who probably doesn’t like the French, don’t worry France, we don’t like him!), piped up and said, “Pah, it was just a wonder goal, no skill in that, just luck. You never see defenders scoring goals like that. Even Beckham as good as he was in his day, wouldn’t have scored that.”

Now, this made me cross, for a number of reasons. Firstly, I don’t like the guy who said it very much anyway. He doesn’t know much about footy, just repeats other people’s opinions. And secondly, he was wrong. On many counts.

Number one:
Of course he intended to score, he took the shot for goodness’ sake!!
Number Two:
There was a lot of skill involved in that shot. As a professional footballer, he knew instinctively what he was doing     
Number Three:
Beckham so could have made that shot, even on whim, have you ever seen him hit a ball to switch play across field?
Number Four:
Yes, there was bit of luck in it, he hit it perfectly. That was the lucky bit.

The wonder bit came when physics took over.

Me being me, I then went on to try and explain how and why to all who would listen. That’s when everyone in the pub’s eyes started to glass over. So, I said, “I’ll tell you what, if you promise to read my blog, I’ll explain it in an article.”

And that is how I have found myself breaking one of my own rules and writing over the weekend.

Now then, after that massive intro are you ready?

Picture this:

A free kick is awarded 25 yards from goal. The defenders build a wall. The goalkeeper shuffles nervously across his line, pointing and shouting, the striker takes a few steps back, raises his hand (why do they do this?), runs up, and hits the ball.

For a split second the fans groan as it looks like the shot is heading straight into Row Z.

Then the ball changes its mind.

It bends around the wall, curls towards the top corner, and sends the goalkeeper flying through the air in pursuit of a ball that had already made its appointment with the net the second it was kicked. And the fans go wild!!!

Now then, this piece of football wizardry is the called the Magnus Effect after the dude who investigated this amazing phenomenon back in the 19^th Century.

Most football fans often imagine a curling free kick as a battle between the player and the goalkeeper. Others are aware of the term Magnus Effect. And then you get people like me, who know far too much seemingly useless information that nobody wants to hear about in the pub when they’re discussing the footy.

It’s not a battle between the player and the keeper but against the air.

When a football is struck cleanly through the middle, it tends to travel fairly straight. But when it’s hit off-centre, it starts spinning, and as it spins, it drags air around with it, creating a pressure difference on either side of the ball. This results in one side of the ball ending up with lower pressure, and the other with higher pressure, which makes the ball get pushed sideways.

The result of which is you have a football that appears to have developed independent thought.

Players discovered this long before scientists explained that the spin is the power. If you add enough sidespin the ball curves left or right through the air.

This is why free-kick specialists are football’s equivalent of stage magicians. They know how to bend shots around walls, curl crosses into dangerous areas, shape passes around defenders, switch play so effectively as Beckham did and make highly skilled goalkeepers maybe question their career choices.

OK. There are three elements to this spin. There is sidespin, which is the classic freekick curve, hit the ball across its side and it swerves left or right through the air. It’s responsible for some of football’s most gorgeous goals. Think: David Beckham, Lionel Messi and pretty much every YouTube free-kick compilation that’s ever been made.

You have topspin, which makes the ball dive. The shot rises, clears the wall, and then suddenly plunges towards goal like it’s on its way to the World Cup and it remembers it’s left the oven on back home. This is the physics behind those infuriating shots that seem to drop out of the sky at the last possible moment.

And you have Backspin. It creates a lifting effect that helps the ball stay airborne longer, chip passes, floated crosses and delicate lobs often make use of it.

That was how Benjamin Pavard scored that amazing goal against Argentina back in 2018 when France beat them.

I don’t want to talk about that one though, I want to talk about another one, the one that Roberto Carlos hit against the French in 1997. This is the goal I asked you to imagine earlier, and no discussion of the Magnus Effect is complete without it.

In 1997, Roberto Carlos hit a free kick against France, in the Tournoi de France. A competition played in France with four international teams as a warm-up for the World Cup.

Now then, initially that free kick looked like it was going to go embarrassingly wide. It didn’t though, it turned out to be a 40 yard screamer into the back of the net, and is rightly considered one of the most famous and spectacular examples of the Magnus Effect in football.

For generations of football fans, this was the moment physics got a highlight reel, as it was all over the news with physicists explaining it. Just like I am now.

And this is why some players look like they have superpowers, as it gets stronger when players combine more spin, as this generally means more curve, more speed, as a faster moving ball experiences stronger aerodynamic forces, and technique.

And it is the technique that is the real secret here, and why elite players at the very top of their game don’t just hit the ball, they control exactly where, how, and what angle to strike it.

That’s why millions of Sunday-league footballers can understand the Magnus Effect, while the likes of Messi, can invoke it!

And there’s more! The Magnus Effect has a weird cousin, and that is the knuckleball which is where the fun really gets started.

Sometimes players try to do the opposite and hit the ball with almost no spin. So, instead of curving smoothly, the airflow becomes unstable and the ball wobbles unpredictably. The knuckleball is the famous free kick associated with players like Cristiano Ronaldo.

Where a Magnus free kick is a graceful ballerina, knuckleball is a shopping trolley with a faulty wheel. And that for me wins the ‘who’s better, Messi or Ronaldo’ debate.

The real magic involved with the Magnus Effect is that once you understand it, football somehow becomes even more impressive. Every curling free kick is a player manipulating air pressure, rotational velocity, aerodynamics, and fluid dynamics.

Where the crowd sees the magical, wizardly wondergoal, the physicist (and physics nerds like me) see pressure differentials, and the footballer sees a top corner that needs decorating with his mastery of the beautiful game.

And the ball? That’s the best bit, folks. The ball just follows the science.

The Magnus Effect is what turns football from a game of kicking a ball up and down the pitch into a game of mind-bending reality, just enough to make 60,000 people lose their minds!