StarTalk Radio - #ICYMI: Cosmic Queries: The Physics of Soccer

Episode Date: June 1, 2017

In this week’s off-season episode of Playing with Science, hosts Gary O’Reilly and Chuck Nice answer fan-submitted questions about soccer, with a little help on the science of “the beautiful game” from returning fan-favorite physicist John Eric Goff.Don’t miss an episode of Playing with Science. Subscribe to our channels on:TuneIn: http://www.tunein.com/playingwithscienceApple Podcasts: https://itunes.apple.com/us/podcast/playing-with-science/id1198280360?mt=2Stitcher: http://www.stitcher.com/podcast/startalk/playing-with-scienceSoundCloud: https://soundcloud.com/startalk_playing-with-scienceGooglePlay Music: https://play.google.com/music/listen?u=0#/ps/Iimke5bwpoh2nb25swchmw6kzjqNOTE: StarTalk All-Access subscribers can watch or listen to this entire episode commercial-free. Find out more at https://www.startalkradio.net/startalk-all-access/ Subscribe to SiriusXM Podcasts+ on Apple Podcasts to listen to new episodes ad-free and a whole week early.

I'm Gary O'Reilly. And I'm Chuck Nice. And this is Playing With Science. Because of the constant requests from so many of our listeners for a soccer-based show, we decided to speak to the boss, yes, Neil deGrasse Tyson, and ask him if we could give it the cosmic query treatment and let you, the listeners, decide which direction the show should take with your questions. And bringing the science in to answer those questions will be our good

friend, physics professor Eric Goff from Lynchburg College in Virginia, author of Gold Medal Physics and all-around sports guru and super soccer fan. Yes. So stick around because we are going to get to grips with probably the greatest free kick of all time, bring you the science of that and plenty more. And for once, I get to play in my own backyard, which should be fun. I know. This is your show, my friend. Yes.

We'll see. I'm just going to sit back and learn something here, you know. We got Eric Goff who will give us the physics, and then we have a professional footballer here who will give us the experience. And, you know, I'm just going to go home. No, no, no, no, no. Be good. Be good.

You're all part of the team here. And speaking of Eric Goff, Professor Eric Goff, how are you, my friend? I'm doing great. How are you? It's good to have you back, sir. You are indeed a big time, huge soccer fan, right? I really, I didn't get into soccer much as a kid, but I got into it when I started doing sports physics as an adult and I really enjoyed it in the last, I'd say, 15, 16 years that I've been doing this. Ah, that's long enough to be considered a fan. 15 years of dedication to a sport is enough. And there's lots of physics in the sport. It's just if you're new to the sport, you don't quite realize it's there. But hopefully by the time the show finishes, our listeners will understand just

how much is going on within what they call the beautiful game. The beautiful game, that is. Yeah. All right. Well, let's get straight into a little bit of action. Aaron from Connecticut has asked, can you explain the Roberto Carlos goal against France in 97? As he puts it, probably the best free kick goal ever. And I'm not in a position where I can argue to that. I think it is probably the best free kick goal ever. And I'm not in a position where I can argue to that. I think it is probably the best free kick goal ever. So, Chuck, let's set this one up and get to a clip. Okay. I definitely want to hear.

I just definitely want to see what this is because I'm not familiar with this 97 free kick goal. So why don't we just take a look at what you are now. If you're saying this is the best free kick goal ever, I can't wait to see it. Let's do it. So the commentary is in French. Roberto Carlos is a left-footed player. This is for Brazil against France. He's what, 35 yards from goal?

Okay. This thing is going to do stuff that Eric can explain. He kicks it. Whoa. Whoa. Yeah, it's not stuff that Eric can explain. He kicks it. Whoa. Whoa. Yeah, it's not just that angle. Okay, here's the... Wow, that was amazing.

Watch the goalkeeper. He barely moves. The goalkeeper puts his hands on his hips like, what the hell was that? Yeah, and the goalkeeper is Fabian Barthez, one of the world's greatest goalkeepers, a World Cup-winning goalkeeper. Right, now watch how wide of a goalkeepers, a World Cup-winning goalkeeper. Right.

Now, watch how wide of a goal it goes. And then it comes back in. That's why the goalkeeper doesn't move. The goalkeeper doesn't move. No, because Barthez is thinking, watch this. This is out towards the corner flag and down into the parking lot. Okay. And that's what it's all about. It's so far outside of the goalpost that the goalkeeper doesn't move

because he says, this guy just kicked the ball into the stands. He doesn't expect it to cut back in that much. But then it cut back in and drops like a rock at the same time. This is like a baseball pitch. That's what it was like. Only slightly slower. Yeah.

But, I mean, Roberto Carlos is a a fullback so he's a shorter player but if you ever meet him and i've done on several occasions he has such powerful quads and the power that he puts through this ball now professor please explain in the physics what is going on when roberto carlos slams this into the back of the net so he's about 38 yards out maybe 35 meters out from the goal of course you see the the wall set up to defend against this kick think of it like a screwball pitcher in in baseball so that he's coming at it with his left foot and he's going to kick it in such a way that if you were to look down on the ball from the sky, you'd see it spinning counterclockwise. So what it's actually doing is as the ball leaves the boot, it's got this counterclockwise spin at a fairly hefty speed. We were looking at about 60 miles an hour coming off the foot.

And the ball is going to start deflecting to the left and if there was no pitch uh we would see the ball simply spiral down at a smaller and smaller radius but uh what we're getting is the the first part of that spiral which is that nice uh banana kick that you're you're used to seeing in in soccer So for Chuck right now, if you imagine you just came up and kicked the ball on the very outside of it, it would end up going almost laterally on a 90-degree angle. So what Roberto Carlos has to do is understand exactly where it is on the ball,

and it's a small space, maybe a couple of inches across, where he has to drive through it. But as the boot makes contact with the ball ball he's now got to flip his foot to ensure he gets enough rotation on the ball to bring it out and then at the end drag it back in so you're saying that because i noticed in the beginning he places it down very meticulously he puts the ball down in like a very specific spot and then twist the ball so you're saying that the spot that he kicks it, he gives foot action kind of like wrist action

when you're pitching a baseball? Yeah. Oh my, that's amazing. This is, when you watch a pitcher and you see just how they manipulate fingers, thumbs and everything. So now you don't have such dexterity in the foot, but you are able once you are practiced at the art.

And by the way, Roberto is very well practiced at the art of curving and swerving a ball. He can do stuff that very few players can do. So maybe we should have been saying bend it like Roberto instead of bend it like Beckham. Well, bend it like Beckham kind of came before. Oh, okay. A couple of years before that. All right. Okay. Beckham's got came before. Oh, okay. A couple of years before that. Yeah. All right. Okay. Beckham's got all the hoopla. Roberto just is special, is absolutely incredible. I mean,

I don't know if you agree, Eric, but that for me is number one free kick I have ever seen. And I've seen quite a few. I think that's the best. And I think the goalkeeper's reaction to it is priceless because he just doesn't move. I mean, he's not that far from the goalpost. He could have easily gotten that ball deflected out of the goal. He just never moved. I mean, he thought that ball was going well wide and it's got that nice bite curve right at the end. You know, if Carlos kicks the ball a little bit more toward the center, it's too fast. It's going to be wide. If he kicks it a little bit more out, it's got a little too much spin and a little less speed. It's going to curl into the ground. I mean, it was just the perfect foot placement.

So let me just ask you before we move on from this, the way the ball drops like that at the very end, what causes that to happen, Eric? Well, that's certainly the gravitational pull. I mean, the drop was about three quarters is going to happen in the last half of the flight. So it's no different from any other projectile. I mean, it's got a little bit of a topspin component to the sidespin, but mostly sidespin. of a top spin component to the side spin, but mostly side spin. So, but, but so I guess because it's such a long curve, such a, such a wide arc, the drop looks more dramatic because you're seeing it drop and move laterally at the same time. Is that what it is? Like more of a visual effect? Yes. And if the, if, as I said before, if the pitch wasn't there, I mean, you just see the ball continue to spiral at ever shorter and shorter radius. Gotcha. Gotcha. OK, cool.

All right. So we touched on the David Beckham, bend it like Beckham thing. And we have another question. And I love this name. Who he who is nobody from Google Plus has thrown a question. Can you explain bend It Like Beckham? Now, for me, the free kick we've just seen by Roberto Carlos is with the outside of his boot. Beckham's stock in trade was with the inside of the boot. So can you explain the difference and power and energy

that is going to be transmitted by using the outside and the inside of the boot, please? Before you do that, so let me ask you, Gary, is that, you said that Roberto's left-footed, so is Beckham right-footed? Beckham's right-footed. The thing is, you get more control. You're able to control the ball better

with the inside of your boot as to being accurate as opposed to the outside of it, which makes the Roberto Carlos thing so special. So much more impressive. He has taken the level of execution up. So, Professor, Beckham versus Roberto Carlos, one's outside of the boot, one's inside of the boot. How much difference in terms of energy and control

would you expect them to be able to bring to a free kick? The path of the Beckham ball is going to be very similar to the Carlos ball because Beckham's kicking with his right boot. It's more like a curve ball that a pitcher would throw, whereas Carlos was throwing like a screwball. It's going the opposite direction of a pitcher's curve ball. So the inside that Beckham is using is going to curve to his left. So it's going to make a big sweeping arc out to the right and then typically bite in back toward his left or toward the goalkeeper's right,

right at the end toward the goal. See, the thing is, Chuck, for you who are not familiar with Roberto Carlos, I've seen Roberto Carlos, right, drill from 40, 35, 40 yards so far away from the goal with a free kick because it's just completely gone wrong and busted. Wow.

Because he hasn't made the right connection in the spot. With David Beckham, because he's using the inside of the boot, and he had a sports manufacturer that developed a boot that helped with the precision. So his sports manufacturer was Adidas, and they had a boot arranged that helped them but he was all about accuracy of free kicks so they'd be a bit like a quarterback

throwing the pass to a planned target a wide receiver in a certain spot or he would look at the space that he wanted that player to be in he would aim the free kick

to that space knowing that player would be there when that ball arrived. So that was the whole control thing with Beckham, which is why Beckham is so special. All right. While we've got the professor thinking about curling free kicks, Joe Baggett on Facebook. Thank you, by the way, for every single one of your questions.

What is the Magnus force and how does it work on a curling football at a free kick, say? Magnus force and how does it work on a curling football at a free kick say so the you know Magnus effect was actually noticed by Isaac Newton back around the 1670s well-known soccer fan tennis well he's actually watching tennis I was kidding I was kidding sorry Magnus uh was working in the mid 19th century uh when he got his effect named after him But the idea is when the ball is spinning, and I'll take my bazooka ball here, when it's spinning, the air is being whipped around the ball. And if you're looking at the ball coming at you, the side that's spinning away is kind of pulling the air with it, and the side that's spinning toward you is changing the path of the air separating off the ball.

you is changing the path of the air separating off the ball. So what happens is when you look down on the ball, like a David Beckham kick, if it's spinning in a counterclockwise manner, it's going to go from right to left. So the way the boat rudder works is exactly the same. It's deflecting water off to one side, while a spinning ball is deflecting air off to one side. Oh, that's funny. I love the boat rudder analogy because that's perfect. It's like the air becomes, the ball itself becomes its own rudder, deflecting the air, and it moves in the opposite direction. That's Newton's third law. That's Newton's third law. There you go. Wow, look at that. Super cool, man. All right, Chuck, this one's for you. Alright, so Adam JDS and he says, Chuck,

if you are pronouncing my name, it's Marinas. And I gotta tell you, Adam JDS Marinas, you spelled your name wrong, okay? And he is coming to us from Brisbane, Australia and he says this, hey gang,

as a soccer player from junior days to adult, I'm wondering how much force or I guess the average amount of force, energy that goes from foot to ball to generate some of the absolutely impressive goals we see from players like Lionel Messi and Cristiano Ronaldo. We're talking big power shots, of course. Thanks. And thank you, Adam JDS Marinas, who spells your name wrong. So, Eric, what's... What happens... We're going to get an email, aren't we?

Oh, I'm sure we are. Yeah, yeah. What happens there? What Adam is talking about? How much force are we talking about? And what happens to the ball when it encounters that kind of force? Well, I love the fact this question's from Brisbane. That's where our next sports engineering conference is going to be in March.

So I hope to be down there next year. But the great thing about these long kicks is you're talking about leg muscles releasing enormous amounts of energy in only about a tenth or so of a second. Wow. And the type of power that's generated here is of order 10 horsepower. Now, what that is is about seven and a half. That's about seven and a half kilowatts. You're looking at about five or six microwave ovens kind of working together here for about a tenth of a second. I was going to say 10 horsepower.

That is like three, that's like three lawnmowers. I've never thought of legs as lawnmowers, but here we go. Right. Yeah. Like, no,

but if you take the blade of a lawnmower and figure, and figure it's spinning and you see how much force that takes, like then how fast that's going, that's three horsepower. Like you're a little lawnmower and figure it's spinning, and you see how much force that takes, like how fast that's going. That's three horsepower, like you're a little lawnmower. So that's like three lawnmowers. That's a lot. What I'm saying is that's a lot of force for a leg to create. It's a lot of power, but remember, this is only happening over about a tenth of a second. The athlete could not sustain it like your lawnmower could. Right. So the accelerations are going to be somewhere between 30 and 50 Gs, depending on how hard this kick is.

And given the fact that ball's about a pound in weight, that's 30 to 50 pounds hitting on the ball. Wow. What sort of speeds are we clocking the hardest sort of free kicks out of the moment? Well, I did a study for the Wall Street Journal back in 2010 of the World Cup. And I remember Manuel Neuer, the German goalkeeper, one of the best in the world, had a 82-yard kick from his goal. And launch speed, I had calculated, was about 78 miles an hour. Wow.

Whoops. That's going somewhere. That's serious. Yeah. He's about 70 miles an hour. So he's kicking it above the terminal speed of the ball. Yeah. Wow.

That's incredible, man. Links into another question. Ali Thierry on Twitter has asked, and it links back into the Manuel Neuer point that you made there. How powerful a goalkeeper's kick should it be to score a goal from his, her goal kick? And he's talking about across the field. Now, I remember back...

You mean her. Him or her. What? What are you talking about? Dumb start. That's so crazy. No. Girls play soccer?

Oh, naughty step. Naughty step again. Over there, naughty step. Okay, you guys are just making stuff up now. Come on. Come on. All right. We all know Chuck knows the truth.

Right. So back in the 70s, a very famous goalkeeper playing for Tottenham called Pat Jennings, who went on to play in the World Cup for Northern Ireland. He took a goal kick at Old Trafford against Manchester United and promptly delivered it straight into their goal. So the whole length of the field. Goal to goal, goal? Yeah. Yeah.

So how do we deal with that? I mean, I think there might have been a little bit of wind assistance, but that's awesome. That does happen. It's not impossible to do. How long is the soccer field? It's not a constant distance. It can be 100, 110, I think. Is that the longest?

100 to 110 meters for the World Cup pitches. Okay. So where are we going, Eric? What sort of forces are required to drill a ball that distance and be that accurate? And wouldn't you have to have a certain trajectory, like in terms of the launch angle in order to actually just make it the entire length of the field? Sure. And you probably need a little bit of backspin on the ball to get a little lift. It's the same Magnus effect we were talking about with side spin, but you get a little bit of backspin on the ball and you get

an upward component from the Magnus force that helps it stay in the air a little bit longer um so the noir kick i talked about was about 78 miles an hour but it was still about 25 yards short of the goal uh the kick that gary was talking about i mean this thing's going to have to be launched uh probably well over 80 miles an hour off the boot and maybe have a little bit of a backspin. If there's weather, if you've got some good wind at the back, you may need to dial the speed dial a bit. I didn't see the kick. Was it in the air the entire time? I think it may have bounced in front of the goalkeeper who gets dragged off of his goal line and then has the pleasure to watch it bounce over his head and into the net so it does bounce but it's got to

bounce from the six yard line into the 18 yard area at the other end of the field so it's still got some serious distance on it that's right so he's probably close to nars speed probably about 80 80 mile an hour launch speed at that point. And I'd love to know what the weather was like to see if he did get any assistance from the air. Well, it was Manchester, so it's likely to be gray slash raining. That is standard issue weather for Manchester. That's the way it goes. Everybody who's been to Manchester knows it rains. That's it. There's a weather report for Manchester for the rest of the century. There you go. I like that.

West of the Peak District. It's pretty out there. Is that how the weathermen work in Manchester? They just go, you know what it is. Got a window. You don't need me for this. Yeah, that's the way it is. I'm stealing money. All right. We are going to keep the professor with us, but we are going to take our first break. And afterwards

we'll take on more of your questions about the physics of soccer with the good professor on Playing with science don't go away we'll be right back welcome back i am gary o'reilly still chuck nice and this is still playing with science and today we are taking your questions about the physics of soccer and with us by video call is Professor Eric Goff, author of the fabulous book, Gold Medal Physics. As always, we recommend you go and grab a copy. And it's all about the science of sports. So, all right, let's have another question.

This is from Travis Sherman on Facebook, relating to World Cups. Right, in 2014, we used a ball called the Adidas Brazuca in 2010. They used... Eric has one of those, right? He does, yeah. And it's a smart little piece of kit, by the way. You can see he's holding it up.

In 2010, Adidas brought out the Jabulani for the World Cup in South Africa. Both balls were complained about for different reasons. One ball, says Travis, I recall, said that they floated like a beach ball when kicked, making it hard on strikers. Another made it hard for goalkeepers by having a tendency to curve. So, Professor, what are the dynamics

that made these balls behave so differently? And why did people hate the South? I've never, as much as I don't watch soccer, to be honest, I'm not going to, you know. That's fine. But I do always watch the World Cup,

as most Americans. Good. So I, but I can't ever remember complaints about a ball as much as that South African ball. Two things, that Vazouza.

Oh, the Vuvuzelas. Vuvuzelas. And the... And the... Hated them. People hated that. Yes. Just hearing the stadium all day.

It was just like, oh my God. It's like, are you guys having sex with a beehive? What is happening? And the other thing was the ball. Every single game, every day that I watched, somebody complained about that ball. And they had every right to. But then again, Eric, just for our listeners,

the World Cup in 2010 with the Jubilani took place in South Africa, but stadiums were at sea level. Some were at 1,500 metres. Half of them, yeah. Yeah. Some were a mile high in terms of altitude. And then not only do you have a ball that's a different kind of ball and flies differently, but you've also got altitude.

So, Professor, let's talk to all of those different components. World Cup footballs have changed over the years. And 2002 was the Ferva Nova. And that was the last time that we had a 32 panel ball. So these nice panel balls. So these have 20 hexagons, 12 pentagons. If they were flat panels, you'd call it a truncated icosahedron. But then 2006... Just go back to that ball for a second. The panels aren't the same size, are they, Professor? I mean, we have the privilege of seeing that ball you're holding it up for us and the panels themselves are stitched so there's there's ridges yes and so that that will affect the the aerodynamics

and the panels themselves being different shapes are different sizes yes and the key thing to note is everywhere where you see a seam you kind of think of that as a rough area on the ball. And when you see a patch, you think of it as a smooth area. So you've got a lot of rough areas with these seams. Well, when the 2006 World Cup rolls around in Germany, you had the Team Geist. And they used a 14-panel ball that was actually thermally bonded. And the panels in there were smooth. So when 2010 rolls around, the Javalani ball, they went down to eight panels. And Adidas has

had the contract since 1970. So they're the ones spitting these balls out. So you've got the eight-panel ball. And when the Brazuca came out for 2014 in south america down in brazil you had a six panel ball so they keep reducing the number of panels and javolani was the first time that they realized wait there aren't enough stitches there aren't enough panel uh seams we need to actually intentionally texture the ball to give it a little bit of roughness. So the panels, the fact that they actually had those more panels and created that unintentional aerodynamic roughness, they realized that they'd taken away what was an intrinsic quality of the ball itself. That's right.

And Giavolani had to be intentionally textured. The Brazuca is intentionally textured. If you feel the Brazuca, it's got little, almost like little dimples on it, or pimples, I guess, they're sticking out. So this is like a golf ball that's got all the different dimples on it. And there's a key piece of physics with the aerodynamics with this ball, and the flow around the ball at low speeds is what we call laminar. And the separation of the air in the back is actually fairly wide. When the speed gets larger, the separation moves back and separates at a much narrower angle off the back. And that transition, a colleague of mine in Japan and I were the first to actually publish the paper that definitively showed why

the Javolani ball was so terrible. That transition is what we like to call the drag crisis. And it happens for the Javolani ball right in the middle of where all the soccer kicks are taking place. So you have these kicks that are happening. So you have these kicks that are happening, and the leveling off of this, what we call a drag coefficient, is at about 54 miles an hour for the Javolani ball. But that's where all the great kicks are happening. Exactly. For the Brazuca, that leveling off happened at about 38 miles an hour, which was back before so the smaller little passing kicks and stuff it wasn't noticed but the hard kicks the free kicks the corner kicks well above 38 miles an hour so the bazooka performed

a whole lot better gotcha so from the point of view as a soccer player right when you and the thing is remember we did the show with jeff blum and he said about each bat had a different sweet spot on it yes you'd be sitting there holding bat, you'd throw one down because he'd found. The same is with a soccer ball. And soccer players are so in tune with each ball. They'll know that there'll be a different technique which they have to kick and strike a ball if they want to hit for power and pace or hit for distance. Now with the Jubilani, all of a sudden they were kicking it with power

and that power for some reason professor just ended up a bit like a beach ball it just if you've ever kicked a beach ball it travels about a couple of yards in the direction you intended it then it just goes off up into the atmosphere yeah and this is this is the thing so they had to relearn a technique to kick that particular ball or as just the professor highlighted there shorten the num the distance of which they kicked so that the ball itself has changed the way the game was played because you can't kick it a certain distance which is why it was hated so much by the players that's amazing that's that's pretty cool and just to let you know uh professor um a drag crisis in new york city i knew you were going to go there.

I knew you were going to go there. When a queen forgets her lasses for a show. I just knew you couldn't resist that. If you really want to see the drag crisis in action, Kisuke Honda's free kick goal against Denmark in the group stage match. If you just Google Honda's free kick goal against Denmark in the group stage match. If you just Google Honda's free kick against Denmark in 2010, you just see this wonderful knuckling action as the air around the ball is transitioning between turbulent and laminar and back and forth. And the ball just

wobbles like this beach ball we've been talking about. I I tell you, one of my ex-teammates coached Kasuki. Isn't that his, Kasuki Honda? Yes. Right. He said his left foot is so good, he could open a tin of beans with it. Wow. And he's right.

The guy is just, when you talk about being able to caress the ball and make it do things that other players, that's exactly how good he is. So I'm not surprised that that happened. Right. We have another question from Carter in San Diego. Oh, I like San Diego.

What would be the most beneficial element to have in a soccer ball? And how would it act differently? Oh, I like this. If there was a vacuum inside the ball. Professor, all yours. Interesting. Well, you certainly want a good bladder in the ball. The thermally bonded seams

really help keep the water outside of it. You don't want to get the water adding to the mass of the ball. As far as a vacuum inside, that would probably cause what we would call an implosion. Yeah, I was going to say that.

The ball would just suck into itself, right? The atmospheric air pressure is putting about, you know, on a square inch, nearly 15 pounds. So about the weight of a bowling ball and each square inch of the ball. But you have to balance that from a similar pressure on the inside. You know, that works also for the cells in our body. They have an internal pressure that's comparable to the atmospheric pressure. They have an internal pressure that's comparable to the atmospheric pressure.

And, you know, the tires, we do overpressure, 30-some PSI, but that's because the rigidity of the rubber keeps it stable. So if you had a vacuum inside, I mean, the ball would simply implode. Are we looking at new materials? I mean, we've gone from the ancient hand-stitched leather footballs with 32 panels, all the rest of it, to what we have now. We're down to six panels. Are we going to be seeing space-age materials? Are they in the composition of the ball so far? Well, I have no idea what the next World Cup ball is going to be.

I can't wait to get my hands on it and start testing it. But the reduction in panel number is going to be interesting to see if they can go below six. And what is the purpose of reducing the panels? I mean, I understand when you, I understand what happens. You just explained what happens when you have a reduction in these rough areas. But why is there a quest to keep going with a lower amount of panels? Well, the idea is to create a perfect sphere. And this kind of buckyball pattern that we've maybe grew up with, the 32-panel ball, it's a very good try at a sphere. But of course, you've got all these different seams on it. So you keep reducing the panels to essentially make a more perfect sphere. The great thing about the Javalani ball

is that its total seam length, despite having two fewer panels, is actually longer than the seam length on the Javalani. I'm sorry, the Brazuca has got a longer seam length than the javolani even though it's got two fewer panels i mean the the seams on the brazuca just wrap themselves around um and when the media was getting a hold of our work i liken some of these panels to helicopter blades my colleague in japan was a little more media savvy and he likened it to a ninja star. So then all of a sudden these articles were written about the ninja technology helping the soccer ball, which was completely silly, but it certainly helped to advertise the work. All right.

Nike manufactured a ball some years ago. They just advertised it as it's rounder. It's rounder. That's it. That's right. That's the whole thing. They realized that they could reinvent the wheel, or in this case, the ball. Christopher Mass on Facebook, and he says this.

Is there a small plus or minus range on the ball pressure that favors the home team? And I don't know why it would favor the home team, because if everyone is playing with the exact same ball, whatever advantages come from the ball are available to both teams. But that being said... I think it depends on your style of play. If you're a team like maybe Spain who's just got precision passing and is not looking to make a lot of long shots,

maybe a little less pressure keeps the speed down a little bit. If you're like Germany and you want your goalkeeper to kick the ball three quarters of the length of the pitch, maybe you want a little extra pressure on the ball. I tell you what you do. I take it back then, Christopher Moss. That was an excellent question. The pressure of the ball may benefit a team, but because during the course of a game, any phase of play,

the ball is exchanged between each team so frequently it kind of balances itself. What will happen is inside the game for you. If you knew you had a team like Spain that's a lot of short, sharp, quick passing, leave the grass longer. Really? Yeah. Yeah, but that makes sense.

Because that drags. That drags the pass. That slows it down. That slows it down. The other thing to do. See the team playing. Playing in drags. That drags the pass. That slows it down. The other thing to do. See the team playing in high weeds. Knees are sneaked. Oh, man, it was terrible.

We used to play at one stadium back in London, Fulham. The groundsman had really long hair, an old hippie kind of hairstyle, and the grass was equally as long. And you couldn't pass on the pitch because the grass was so long it just slowed the ball down. The other thing is do not water the field because it gets bumpy and bobbly and you try and pass on stuff like that and then you cut the grass really it just anything you do to take a home field advantage and up the ante so it's really a home field advantage in soccer you can you literally home field there will be head coaches will give the groundsman, the staff,

direct instructions to cut at a certain height of grass and not above that because they want it super short. Then they're going to water that thing forever and then the grass holds on to that moisture so passing becomes super slick. And this is the little tricks of the trade that come with high-level soccer. You just think it's grass. You just think it's green with white lines.

It ain't just that simple. Wow, look at that. Who knew groundskeeper Willie was so important to the game of soccer? That's awesome. It's all about that. Right, we are going to take another break. Stay with us. More inside tricks of the trade, maybe.

We'll certainly have the professor and we'll be back shortly. Welcome back. I'm Gary O'Reilly. And I'm Chuck Nice. And this, of course, is still Playing With Science. And during the break, I exchanged a little story with the professor, Eric Goff, and Chuck about a stadium in

Yorkshire we used to play in. Terrible. Just terrible. You guys are psychological gangsters. The away team locker room, right? You'd go in, the team, all the equipment would come in, all the staff, all the players, coaches, et cetera, et cetera. You'd sit down and you would need to answer the call of nature.

There are no toilet facilities in the locker room. You have to come out of the locker room into a public area. So you've got all your uniform on, you've got your soccer boots on, everything. You walk down the corridor and into a facility to do what you need to do, then come back. Amongst their fans. Yeah, so this is psychological warfare. Anything you do to get the merest advantage you take. It's taking home field advantage to a very, very different level.

It's cold and unusual, man. That's terrible. It's all about winning. All about winning. There you go. Right, next question up, I think. Yeah, let's go to Vinvalent on Instagram, which is Vincent from LA. He says, how does different geography affect the playing experience, be it weather, elevation,

or latitude on Earth? And what would be the ideal location to play? Interesting. Professor. Wouldn't that change for different teams? Like, are there teams

that are better in the rain than teams that are not? Some teams that are better at, you know, does it work that way? Oh yeah,

there's, when you want to take, I'm going to do this quite literally, take home field advantage to a new level. Bolivia. You are playing

at such a ridiculous altitude. Yeah. I can't, off the top of my head, I don't know the stats, but I don't believe they've lost many games in the last 50 years

in Bolivia, no matter who they've played, Brazil or Argentina, no matter how good they were. Once you go that far up, boom, all the odds are stacked for the home team

because they are acclimatized quite literally. Not to mention, they put cocaine in the water of the visiting team. Good old conspiracy theories. I couldn't answer that, but there we are. So, Professor, an ideal, is there a Goldilocks zone for a soccer stadium? I don't know that I would identify an ideal location.

I mean, certainly elevation is going to affect the air density. I mean, here in the U.S., we've got mile-high Denver that's got about 80% of the air density of sea level. You go to places like Mexico City or half the venues of the South African World Cup or Bolivia, you said. I mean, you go to these high elevation places where the air density goes down. That has an impact on the flight of the ball, much like the teams playing in Colorado, like the Colorado Rockies. I mean, you've got lower air drag, so the ball can go faster, but you've also got a smaller magnus force. So you mean you get less curve. So the ball is going to, it's going to move faster,

but it's going to have less curve on it. Gotcha. Plus, the thing is, you don't want it too hot and too humid because you're going to stress the players themselves that much sooner. Again, with altitude, it's not so much the effect on the ball that you will notice. It's the effect on the players because if you're not acclimatized, say you're going to go and play one game at altitude, you're there, you play, you come away. You're not really going to have an opportunity to to get to groups with with the uh with the lack of oxygen up there so you'll see a different style of gameplay because the guys are fighting

quite literally to get breath and oxygen into their lungs so that that again that's that's a home field advantage absolutely i mean it's why you see a lot of the African runners that win a lot of the marathon races are training at high altitudes. Yeah. So when they're down at sea level, it's like, oh, this is a walk in a park. Oh, gosh, yeah. Yeah. I mean, there isn't a continent where there is not a soccer field. I mean, I've played in Asia, Africa, the Arctic Circle, the Americas,

the Caribbean, and it's just, you just try and find a way to deal with the, whatever, the geography, the field, the grass is different. You go to different parts of the world. It's not standard issue grass for every soccer field. You've got domestic grasses and they're different to Europe as they are to Asia and to the Americas. So you come to terms with just about everything that's confront, that confronts you. Wow. That's fascinating stuff.

It truly is the world's sport. Absolutely. It's, it's, is it, I'm going to say it's the only global sport like that's played in every single country on the globe. Is there any sport that's played on it played in every single country on the

globe other than soccer? Maybe basketball. You know, basketball is pretty popular. on the globe. Is there any sport that's played in every single country on the globe other than soccer? Maybe basketball. Basketball's pretty popular. Basketball's pretty popular. Right on. See, the thing is, you can just drop

a couple of sweaters and there's a goal. In a little area of scrubland, it doesn't have to be pristine grass. And you can go anywhere into deepest, darkest Africa, the Amazon. There'll be a soccer field.

There'll be somebody kicking a ball around. That's it. All right, next question. All right. David's from Mexico. Which place will be the worst to play soccer? That would be the neighbors, which you hate. For you, it would be the Giants, wouldn't it?

Yes, exactly. So that would be that one answer. And can you explain the Chilena, which was made famous by the superb Mexican striker Hugo Sanchez? The Chilena would translate to me in English as the bicycle kick or the scissor kick. It is the most spectacular way, basically, to score a goal as an overhead kick. So I actually think we've got a clip of that. Made very popular.

I mean, everybody knows the bicycle kick from Pele. Yeah. That's how we know it here in the States. I mean, Pele, there's no way you can argue against him. But Hugo Sanchez just gave it that little bit more flair and maybe just executed at an even quicker rate. But I think we've got a clip of Hugo doing his thing there. So let's have a look at this.

All right, you're going to watch this cross come over and then... Pow! Snap! Yeah. That is amazing. See, I mean, if you watch here, it's a lovely slow motion replay.

Look, he pulls away from his mark and gives himself space. Oh, that is gorgeous. Yeah. That is absolutely gorgeous. So two things happen there that I noticed. Number one, the pass, the inlet kick. Yeah, the cross that comes in. The cross that comes in is on a curve back to him.

Yeah, and if you watch what he does, as he sees... That's what you want. That's what you want, okay. As his cross, as he notes it, he's like a hitter watching a pitch in baseball, right? So, and I'll just do this before the professor kicks in with the physics.

He's watching the flight of the cross. So watch him then. He moves out away from goal to get himself in a position to do his thing. So, professor, exactly what goes on with the physics of Hugo Sanchez there So watch him then. He moves out away from goal to get himself in a position to do his thing. So, Professor, exactly what goes on with the physics of Hugo Sanchez there and that incredible goal. So you'd rather have the ball coming at you, much like when you're setting up a corner kick or something. You want the ball coming at you so that it's like hitting a ball with a bat. I mean, you're going to be able to get a lot greater launch speed than if it's moving away from you.

the bat. I mean, you're going to be able to get a lot greater launch speed than if it's moving away from you. And the idea behind the bicycle kick, you need an incredibly strong core. He's going to generate an enormous torque on his body to get that rotation. And as soon as he's off the pitch, of course, the ability to create that torque is gone. Now he's got to start moving his arms and legs to actually rotate his body, much like a cat in the air. If a cat's dropped upside down, you know, the cat can move the arms and legs in such a way to right itself. Not if you tie those legs together. I'm just saying. Not that I've tried it. Not that I've just saying. We don't try that. Go ahead. Go ahead. So the PETA approved bicycle kicks would keep the arms and legs.

I like what you did there, Professor. Nice job. I like what you did there. Nice job, Eric. The PETA-approved. Go ahead. Yeah, so you need an incredibly strong core. I mean, the interior stomach muscles are going to be very strong to keep the legs bicycling like that.

And it's a great play because the goalkeeper initially sees the player with the back to him. So there's a slight delay with the goalkeeper to really process what's happening because the player's back is to him. And once that kick happens in a fraction of a second, all of a sudden the ball is just flying right in the direction of the goal. So the initial reaction to the player kicking just isn't there for the goalkeeper. Oh, thank you for that. Because I was just about to ask you guys, aside from the aesthetics, why the hell do you want to make that move in the first place?

Because it just seems like I'm showing off. Yeah. But the way you just explained it. Welcome to the game. You're like, hey. Watch this. Ever seen, you know, anyone who's had a kick around with friends,

one kid will go, hey, watch this. Right. The thing is, Hugo Sanchez isn't on a kick around with his friends in the backyard. He's doing it in the major stadiums. I mean, this guy played for Real Madrid. He actually played for both Madrid clubs, which is almost impossible to do because of the hatred between them.

But that makes sense, though. So what you're saying, Eric, is that because you have your back to the goalkeeper, the goalkeeper is not able to process what you're doing because you're blocking his vision from what you're doing. So by the time he sees it happening, it's already happening. So the goalkeeper will need to set himself in position to make the save. But to set himself, he's got to be able to read the picture of everything

that's happening. And he will not see that. I mean, I'm interested if you can, a little bit of guesswork, and I appreciate you'd like to be exact about things.

What sort of speed, what sort of exit velocity have we got once Sanchez rotates and levers that left foot and then the ball hits i mean what sort of speeds are we talking about generated here well the ball is going to be able to leave at 50 or 60 miles an hour off the foot it's going to be like any other great kick and in fact you can elevate that speed if you can

really torque that leg around in a you know almost a quarter to a half circle before it makes contact with the ball. And see, that's another dimension that the goalkeeper's got to face. Not only does he not see, but once he does see it, he's got 60 mile an hour ball coming his way. His reaction times are going to be nowhere near sharp enough. That's amazing. All right. So thank you for reminding me about Hugo Sanchez. That's, yeah, David from Mexico.

That's brilliant. Right. The first part of his question was asking about the worst place to play soccer. And I'm just wondering if the 2022 World Cup in Qatar might be a good candidate for that. Oh, yeah. Because it's going to be 8,000 degrees. Well, they're playing it in November and December of that year. Oh, so only 4,000 degrees.

Only 4,000. It'll be a balmy 86 or so. That's not bad. It's going to be tough. And by the way, didn't they have the entire thing moved? Like, so that, is this the first time that we're having a winter World Cup? Yes, it is.

And I mean, this, Eric, you may agree or disagree here. The big soccer clubs in Europe will not take kindly to that because that is smack bang in the middle of their season and they are the big powerhouses. So you might have nailed it

with the worst place, and that game hasn't even taken place yet. Hey, that's right. Welcome to the 2022 World Cup here in Satan's butthole. All right. That might be edited. The devil's in the details, right? There you go.

I'm just saying it's hot. That's all. It's hot, people. Hey, let's take our last question. Yeah. This is from CyberZen from Twitter who says, how far would a pro kick a ball doing a goal kick on Mars? Wow.

So, Eric, you have any idea? We've got Manuel Neuer, the German goalkeeper, which the professor has clocked at around 78, 80 miles an hour. Yes. So the launch speed of the ball is not going to be that much different on Mars. You got two big things on Mars to help you kick farther. There's not a whole lot of atmosphere. You still have atmosphere, but you don't have a whole lot of atmosphere on Mars compared to the Earth. The acceleration due to gravity is only about, I think it's 38% what it is on the Earth. So if there were no air around on Earth, the added range is going to be about three times farther on Mars. But because of the air resistance on Earth, Mars, you can kick it maybe four to six times farther on Mars.

Okay. That's pretty cool. Four to six times is not a bad deal. So I wonder if that means you – well, no, you wouldn't have a larger field because guys would just die of – how much conditioning would you need if you had a soccer field four to six times bigger than the soccer field is now? All the soccer players would be Iron Men.

Exactly. It's a marathon. You'd have to wear something to breathe, yeah. Yeah, for sure. It'd be a marathon. That's cool. All right, so there you go. Four to six times longer is what you're getting on Mars if you get a goal kick like that.

All right. Super cool. It is. Professor, thank you. This is great. Yeah, I mean, that's All right. Super cool. It is. Professor, thank you. This is great. Yeah, I mean, that's an awful lot of insight into the physics

behind and within soccer. And I get a feeling we've only just begun to scratch the surface. So thanks once again, Professor Eric Goff. I'm sorry, before we leave,

I just thought... You want to keep... More questions. No, something just dawned on me because when you brought up the next World Cup, do you have any predictions of what, since we've changed in the ball every single World Cup, you got any predictions of what they might do to the next one? It'll be more expensive than the previous one, I can tell you that. Oh, you don't buy them anyway, Professor.

You get given those. This is $160, 100 pounds in the UK. So these things are not cheap and they fly off the shelves. You sound like Gary with a conspiracy theory now that the only reason they changed the ball is for merchandising purposes. That's a pretty good reason for it. Well, I am on record as saying, but by the time I leave this mortal coil, the ball will be square and the goals will be round because the governing body FIFA seem to have this desire to change something no matter what it does.

So who knows? A square ball in the next World Cup? Probably not, but don't be surprised if it is. There you have it. Sorry about that. Thanks, Doc. That's all right. That's great.

Professor, thank you so much for your time. Professor Eric Goff, physics professor at Lynchburg College in Virginia. Got a feel for soccer now. Oh, man, I got to tell you, I'm very excited. This was an exciting show. I learned a great deal. I mean, who knew that it's really, it is the beautiful game, my friend. It can be a ballet at times.

Depends if that's your kind of dance. Then we have one thing to say. I'm Gary O'Reilly. I'm Chuck Nice. And this has been Playing With Science. See you all soon.