How Does Snooker Work? Angles, Spin and the Physics of the Cue Ball
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A snooker table is twelve feet by six, its pockets are barely wider than the balls, and the game is played by potting a red, then a colour, then a red, until the table is clear, which the best players do in a single visit of 147 points about once a career. The potting is the visible skill and the lesser one; the game is won by the position of the white ball after each shot, which the player controls with spin, speed and the angle off the cushions, and the physics of a rolling, sliding, spinning sphere on cloth is what a professional has spent twenty thousand hours learning to feel.
The game
Fifteen reds, six colours and a white cue ball are set on the table, and a player scores by potting a red, worth one, then any colour, worth two to seven and returned to its spot, then another red, alternating until the reds are gone, after which the colours are potted in order of value and stay down. A break is the run of points in one visit, the maximum being 147, and a frame ends when the balls are gone or a player concedes; matches are the best of a set number of frames, up to 35 for the world final. A foul, missing the ball on, potting the white, or touching a ball, gives the opponent points and often a free ball, and a snooker, from which the game takes its name, is leaving the opponent no straight path to the ball they must hit, so that they must play off a cushion and risk a foul.
The cue ball
Striking the white in the centre sends it sliding and then, as friction with the cloth takes hold, rolling; striking it above centre makes it roll at once with topspin, so that after hitting the object ball it follows through, and striking it below centre makes it spin backward, so that it stops dead on contact, the stun, or draws back toward the player, the screw. Striking it to one side puts side spin on it, which does little until the ball hits a cushion, off which it then rebounds at a different angle and speed, and which also deflects the ball's initial path slightly, the swerve and the throw that players allow for. The effects in use:
- •Stun: a low, firm strike so the white stops where it hits the object ball; the basic positional shot
- •Screw: lower and firmer, so the white comes back, up to several feet on a full-ball contact
- •Topspin, or run-through: the white follows the object ball's line after contact
- •Side: alters the angle off the cushion, widening or narrowing it, and is used to steer the white to the next ball
- •Speed: since the angle the white leaves the object ball depends on how much it is rolling at contact, pace alone changes position
The angles
A pot is a matter of contact point: the white must hit the object ball on the point exactly opposite the pocket, and a professional judges that point to within a millimetre at eight feet. After a contact the two balls separate along paths that are, for a sliding cue ball, at right angles to each other, and a rolling one follows a curve forward from that line; the player reads the angle of the pot and knows, from the physics and from memory, where the white will go, and chooses the spin and pace to put it where the next shot is easiest. Cushions return a rolling ball at roughly the angle it arrived, less some speed, and a ball with side at a different one, so that a positional shot may be planned off two or three cushions. The cloth, brushed and ironed so that its nap runs from the baulk end, drags a slow ball toward the top of the table and bends it slightly, which the players call the nap effect and allow for.
Why it is hard
The pockets are cut so that a ball travelling at pace along the cushion will not drop, the balls are small relative to the table and a long pot is a shot at a target the width of a coin from across a room, and every shot must do two things at once, sink one ball and place another. A break of a hundred requires twenty-five consecutive shots each within the margin, and the game punishes the error that ends a break with the opponent's visit. The mental side is famous, since a player sits and watches while the other scores and must return cold to the table; the finals at the Crucible theatre in Sheffield, played to a silent audience over two days, are the sport's test of both, and the greatest players, Davis, Hendry, O'Sullivan, have been distinguished as much by temperament as by cue.
Where it came from
Billiards, potting and cannoning with three balls, was the game of the European aristocracy from the seventeenth century, and snooker was invented by British army officers in India in 1875, when a colonel in Jubbulpore added coloured balls to a pool game and named it for the slang term for a first-year cadet, a snooker being what a novice was; it spread through the officers' messes and the clubs of Britain, was codified in 1900, and became a mass sport through television, whose colour broadcasts from 1969 finally let viewers see which ball was which. The world championship has been played since 1927, and the game is now played professionally in China, where a boy from Guangdong named Ding Junhui made it a national enthusiasm, on tables of the same slate, cloth and dimensions that the colonel's mess had.
The takeaway
Snooker is scored by potting reds and colours in sequence on a twelve-foot table, and won by controlling where the cue ball comes to rest, which the player does with topspin, screw, stun, side and pace, reading the right-angle separation of the balls and the rebound off the cushions to place the white for the next shot. The pockets are tight and every shot must both pot and position, which is why a century break needs twenty-five faultless strokes and why the game, invented by British officers in India in 1875, rewards nerve as much as touch.