badminton

Physics of badminton’s new killer spin serve

badminton, computational fluid dynamics, fluid dynamics, Physics, physics of sports, Science, sports science / Mike M. / August 19, 2025

Serious badminton players are constantly exploring different techniques to give them an edge over opponents. One of the latest innovations is the spin serve, a devastatingly effective method in which a player adds a pre-spin just before the racket contacts the shuttlecock (aka the birdie). It’s so effective—some have called it “impossible to return“—that the Badminton World Federation (BWF) banned the spin serve in 2023, at least until after the 2024 Paralympic Games in Paris.

The sanction wasn’t meant to quash innovation but to address players’ concerns about the possible unfair advantages the spin serve conferred. The BWF thought that international tournaments shouldn’t become the test bed for the technique, which is markedly similar to the previously banned “Sidek serve.” The BWF permanently banned the spin serve earlier this year. Chinese physicists have now teased out the complex fundamental physics of the spin serve, publishing their findings in the journal Physics of Fluids.

Shuttlecocks are unique among the various projectiles used in different sports due to their open conical shape. Sixteen overlapping feathers protrude from a rounded cork base that is usually covered in thin leather. The birdies one uses for leisurely backyard play might be synthetic nylon, but serious players prefer actual feathers.

Those overlapping feathers give rise to quite a bit of drag, such that the shuttlecock will rapidly decelerate as it travels and its parabolic trajectory will fall at a steeper angle than its rise. The extra drag also means that players must exert quite a bit of force to hit a shuttlecock the full length of a badminton court. Still, shuttlecocks can achieve top speeds of more than 300 mph. The feathers also give the birdie a slight natural spin around its axis, and this can affect different strokes. For instance, slicing from right to left, rather than vice versa, will produce a better tumbling net shot.

Chronophotographies of shuttlecocks after an impact with a racket. Credit: Caroline Cohen et al., 2015

The cork base makes the birdie aerodynamically stable: No matter how one orients the birdie, once airborne, it will turn so that it is traveling cork-first and will maintain that orientation throughout its trajectory. A 2015 study examined the physics of this trademark flip, recording flips with high-speed video and conducting free-fall experiments in a water tank to study how its geometry affects the behavior. The latter confirmed that shuttlecock feather geometry hits a sweet spot in terms of an opening inclination angle that is neither too small nor too large. And they found that feather shuttlecocks are indeed better than synthetic ones, deforming more when hit to produce a more triangular trajectory.

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Scientists built a badminton-playing robot with AI-powered skills

AI, ai in sports, badminton, robot, Science / Beth Washington / June 11, 2025

It also learned fall avoidance and determined how much risk was reasonable to take given its limited speed. The robot did not attempt impossible plays that would create the potential for serious damage—it was committed, but not suicidal.

But when it finally played humans, it turned out ANYmal, as a badminton player, was amateur at best.

The major leagues

The first problem was its reaction time. An average human reacts to visual stimuli in around 0.2–0.25 seconds. Elite badminton players with trained reflexes, anticipation, and muscle memory can cut this time down to 0.12–0.15 seconds. ANYmal needed roughly 0.35 seconds after the opponent hit the shuttlecock to register trajectories and figure out what to do.

Part of the problem was poor eyesight. “I think perception is still a big issue,” Ma said. “The robot localized the shuttlecock with the stereo camera and there could be a positioning error introduced at each timeframe.” The camera also had a limited field of view, which meant the robot could see the shuttlecock for only a limited time before it had to act. “Overall, it was suited for more friendly matches—when the human player starts to smash, the success rate goes way down for the robot,” Ma acknowledged.

But his team already has some ideas on how to make ANYmal better. Reaction time can be improved by predicting the shuttlecock trajectory based on the opponent’s body position rather than waiting to see the shuttlecock itself—a technique commonly used by elite badminton or tennis players. To improve ANYmal’s perception, the team wants to fit it with more advanced hardware, like event cameras—vision sensors that register movement with ultra-low latencies in the microseconds range. Other improvements might include faster, more capable actuators.

“I think the training framework we propose would be useful in any application where you need to balance perception and control—picking objects up, even catching and throwing stuff,” Ma suggested. Sadly, one thing that’s almost certainly off the table is taking ANYmal to major leagues in badminton or tennis. “Would I set up a company selling badminton-playing robots? Well, maybe not,” Ma said.

Science Robotics, 2025. DOI: 10.1126/scirobotics.adu3922

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What do planet formation and badminton have in common?

astronomy, astrophysics, badminton, dust, planet-forming disk, planetary formation, protoplanetary disks, Science / Mike M. / October 15, 2024

It might not come as a surprise to learn that Lin is a badminton player. “The experience of playing badminton is really the thing that kick-started the idea and led me to ask the right questions,” he said.

Previous explanations attribute the dust alignment to the magnetic influence of the central star, the physics of which can be complicated and not always intuitive. The beauty of the proposed birdie mechanism is its simplicity. “It’s a very good first step,” said Bing Ren, an astronomer at France’s Côte d’Azur Observatory who wasn’t involved in the study.

Still, the birdie-alignment hypothesis is just that—a hypothesis. To confirm whether it holds water, scientists will need to throw their full observational arsenal at protoplanetary disks, such as viewing them at different wavelengths, to sniff out the finer details of particle-gas interactions.

Tracing invisible gas

Real-life protoplanetary disks are likely more complicated than a uniform squadron of space potatoes suspended in thin air. Ren suspects that the grains come in various shapes, sizes, and speeds. Nevertheless, he says Lin’s study is a good foundation for computer models of interstellar clouds, onto which scientists can tack layers of complexity.

The new research points a way forward for probing protoplanetary disks, particularly gas behavior. Given that the grains trace the gas direction, studying dust organization using existing tools like polarized light can allow scientists to map a disk’s aerodynamic flow. Essentially, these grains are tiny flags that signal where the wind blows.

As granular as the details are, the dust alignment is a small but key step in a grand journey of particle-to-planet progression. The nitty-gritty of a particle’s conduct will determine its fate for millions of years—perhaps the primordial seed will hoover up hydrogen and helium to become a gas giant or amass dust to transform into a terrestrial world like Earth. It all starts with it flailing or keeping steady amid a sea of other specks.

Monthly Notices of the Royal Astronomical Society, 2024. DOI: 10.1093/mnras/stae2248 (About DOIs)

Shi En Kim is a DC-based freelance journalist who writes about health, the environment, technology, and the physical sciences. She and three other journalists founded Sequencer Magazine in early 2024. Occasionally, she creates art to accompany her writings or does it simply for fun. Follow her on Twitter at @goes_by_kim, or see more of her work on her personal website.

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