Okay Tennis. This has been a long time on my list. I don't like the sport but it is fascinating to me. I remember my dad watching it on TV, reminiscing about his own past as a fit 30 something year old who used to be on par with successful professional players. That must have been in the 70s. I myself found tennis matches boring, especially men's tennis. It takes such a long time and is incredibly repetitive if you don't know what you're looking at. As grandparents who try to undo some of the lax attitude of the actual parents ought to do, my grandpa took me on a tour to acquire basic skills in various skills, among which of course skiing and tennis. Granddad was like 70 years old at the time and I never beat him. At some point I was part of a club, went a couple of times and then whined because I would have preferred staying home with my gameboy. Now I am 39 years old and workout is actually my favorite meditative past time. Looking back on tennis I understand why I didn't like to play it myself: it's gruesome cardio. In preparation you do calf raises, jumps, lunges, skater jumps. I find those cool because I saw a martial arts guy transmuting his body to steel this way. One thing I always hated is that the tennis court was this brutally barren stretch of land that you had to run around it like a hamster in order to play. If getting to the adjacent rectangle or the net is already a challenge in itself, you are not playing the game, the court like a desert to the thirsty wretch. It's like playing Beethoven while runs are not yet muscle memory or attempting to write fiction at B2 language proficiency. I am able to imagine now how things would have involved rather quickly: over about half a year you'd do daily conditioning for 30 minutes, you'd repeat the actual technical skills endlessly for another 30. You would master the space and automate the movements of the game and now you would be ready for the actual beauty of gameplay. The duration of a typical match aside, meant to challenge endurance, the dynamics of one set are highly exciting. The space of tennis is simple, like that of billiard or an old school shooter game. With technical and physical mastery players reach a point where they can precisely move themselves and the ball through the allowed area. Skill is dominant and visible and just as classical geometry makes natural shapes discreet and precise, practice makes a set of movements comprehensible. A good tennis match reduces the amount of randomness and maximizes control over kinetic physics. The player movement, materials, the color of the ball, the sounds and even the placement of cameras and the actual audience emphasize the constantly shifting burden of power transfer. It is only interrupted by clearly understandable superior skill or mistake. Some shots are impossible to counter, especially serving ones. One sound, one swift move and one line etch the logical ordering by skill into your consciousness, like anime martial art or indeed the terrifying targeting of a fired shot, at least in fiction. Good plays are quasi synonymous to straight lines because any larger degree of curvature exposes you to the danger of a more tactically calculated shot by your opponent. The balls movement is taught like the muscles of the players, everything is under tension and it only snaps right before a game is decided. The farther apart the players are, the more the game is under their control. More time to react to the movement of the ball, more leverage for your shot, more options for conscious targeting. Going to the net is a risk reward play. You gain a wider possible arc to position your shots, but pay for it with mechanical disadvantage should the opponent be able to respond. This tension is again expressed by geometry: a ball sent at a small angle to the net will leave the allowed area extremely quickly so it's rule-relevant movement speed (meters per allowed distance) is dramatically accelerated. This situation somewhat accentuates the importance of chance the closer you get to the net up to the paroxysmal point where the ball collides with it. It being a non-rigid, elastic band, the actual direction vector it will impart on the ball is unpredictable. The presence of controlled chance in the game puts even more emphasis of the control the contestants are able to typically exert. For the spectator, the rigid body physics of the ball impart a natural rhythm of tension and release to the game that is easy to read and to identify with the symbolic understanding of the game as a decision making algorithm to determine the better player. Good is fast, slow announces decision and uncertainty is so localized that it acts as a dramatic focus. Even without cameras you would hold your breath and squint your eyes to follow the ball randomly spinning off the top of the net. I mentioned pool or shooter games that are similarly designed. Pool is a precision game for collisions of 2 balls while three-body collisions are already famously chaotic. Shooter games reward precision in aiming with uncertainty being variously introduced as gun statistics, weather effects on ballistic paths or complex maps. But these as well as other tennis-likes (badminton, padel), are dexterity based or generally more chaotic. Tennis emphasizes strength and momentum transfer. It emphasizes skill precision and regularity. And it might be the game where the perception of the viewer and the spectator are most similar. The spectator follows the ball and imagines the actions needed to cause them. The player performs them willingly but also follows the ball. In his short story "Tennis, Trigonometry and Tornados", David Foster Wallace talks about the point where enough training and repetition allow the players to focus entirely on the optically-yellow ball and react instinctively to it. The perceived rhythms are the same but shifted by one: a well placed, fast shot makes it easier for a player to anticipate the next because their opponent has less options to counter and lowers tension, slower shots mean more unpredictability and more tension. Interestingly Wallace also mentioned that the boy who had learned tennis on uneven and imperfect terrain finds himself like a fish out of water on a professional court. Tennis could be intentionally played on natural ground but it isn't. It would immediately introduce randomness and lower clarity to a point where those settings are completely different games. Let's for example imagine a set up where every game is played on a different court, like a sequence of holes in golf. Irregularities could of course be controlled, court sizes could differ, wind conditions introduced. We would now emphasize reaction and adaptivity. The general rhythm of fast and slow would still be there but because a huge portion of outcomes would now depend on factors that are obscure to the audience and only imperfectly mastered by players, we would lose the direct association we are able to do between the different elements of tennis: sound - outcome, speed - mastery, consistency - skill and linearity as a proxy for all of them. Tennis derives historically from the *Jeu de Paume*, which has been around since antiquity, played by hitting the ball with the hand first and only since the 16th century with a racket. The ball is heavy and doesn't bounce back nearly as well and it can rebound twice. All of these make the game much slower. Service is also dependent on the game: the ball can rebound twice, that's called a *chasse*. If that happens twice in one game, service changes. The ball can also rebound on the walls and on inclined surfaces above and behind each player, creating interesting slingshots. All of this is slow, chance dependent, difficult to anticipate. Most notably, Jeu de Paume is a 3D game, sending the ball high up and playing with the walls is an integral part. In tennis whenever the third dimension gets involved by sending the ball high up, it's actually a clearly visible error, easily exploitable by the opponent. Tennis is a 2D game and everything is streamlined to be as abstractly geometric as possible. I think this is the reason why it is able to express so much meaning with lines. It's as if someone took projective geometry and made it into a pasttime. Is it an accident that this happened in the 15th century, shortly after the perspective studies of the renaissance?