Skateboarders call it “pumping,” and it’s a skill that both Olympic medalists and aspiring thrashers use to build launch speed from what seems like thin air.

But what separates the steeziest pro from the sketchiest beginner is the years’ worth of practice it takes to develop the know-how to execute the cleanest pump — or at least that was the case until now.

In a paper published Monday in the journal Physical Review Research, scientists have revealed the secret of achieving serious airtime.

With a bit of coding, researchers were able to describe the optimal technique for pumping — a tactic where skateboarders crouch down low momentarily and then push their body upright on inclines. To get the highest jump, they need to do it once as they descend into the bowl, and then again as they shoot back up toward the sky.

The trick is knowing when and where to execute the maneuver.

“Pumping is the foundation of skateboarding in skate parks,” said professional skater Haden McKenna, during a morning session at the Venice Beach Skatepark. “You build off of that and learn tricks. Then the pumping just becomes something in the back of your brain.”

However, the likeliest users of the researchers’ perfect pump equation are non-humans.

After skateboarding’s Olympic debut at the Tokyo Games, a research arm of the Japanese government reached out to Shigeru Shinomoto, a scientist at the Advanced Telecommunications Research Institute International in Japan. The organization had wondered if it was possible to build a skateboarding robot that could compete in the X Games.

The robot is still a ways off — right now it’s more like a toy that rides back and forth on a mini half-pipe — but the researchers discovered that the mechanics for good skateboarding technique can be surprisingly simple (well, at least compared to the complex fluid dynamics and neuroscience that they’re normally working on).

“It’s just this cute little project which became much bigger than we expected,” said Florian Kogelbauer, an author on the paper and a mechanical engineering professor at the public university ETH Zürich. “People like it — it’s a fun topic. It’s easy to explain, but some serious math and computational work went into it.”

To test their calculations, study authors recruited an expert skater with over a decade of experience, and a novice with just two years under their belt. They told the skaters to catch as much air as possible on a half-pipe erected in a research lab.

The result: The pro much more closely matched their calculated optimal motion than the amateur. (Ideally the skater would pop up instantaneously, but the researchers conceded that humans lack the unlimited muscle strength to do this — plus it would send the skater flying off their board.)

“The experiment seems to agree well,” said Frank Feng, a mechanical engineering professor at the University of Missouri who was not involved with the paper, but studied similar motions in half-pipe snowboarding.

Feng said the simple physics model gets researchers most of the way there, then the computer optimization is able to account for complexities that the physics equations can’t handle.

While the study was mostly just for fun, it snowballed into a fairly big project, and ended up getting published in one of the world’s premier physics journals. Part of the reason is that it may have some serious implications for how to get robots to move effectively without face-planting all the time.

It could help human skateboarders, too. Feng said the results could be used as a straightforward guide to help skateboarders train.

However, some question whether skaters would be able to use the information in the moment.

“This graph, showing the mass going up, is very helpful for somebody that can understand that,” said pro skater McKenna, who was not involved in the research. “But when you’re teaching kids and you’re trying to teach somebody that’s focused in the moment of skateboarding, they’re not going to be able to bring math into the equation.”

Also, out in the complex terrain of the park, the technique gets a bit more nuanced than a simple model the physicists developed. You need to flow as “one with the wall,” said McKenna. “Like what Bruce Lee says, ‘Be like water.’”

Skateboarder Greyson Godfrey, 20, of Rancho Santa Margarita drops into the bowl at Etnies Skate Park Lake Forest.

(Allen J. Schaben / Los Angeles Times)

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While the researchers’ optimal solution may not always be the best suited for real-world conditions, it does help to illustrate the physics behind the technique.

Studio Gutierrez, who teaches skateboarding as a sports instructor to middle schoolers in the Los Angeles Unified School District, finds understanding the science helpful for new skaters. “I explain it to them in physics motions,” he said. “The more motion, the faster you go, the higher you get.”

The physics works similarly to how ice skaters increase the speed of their spinning in the Winter Olympics, said Kogelbauer. They start out spinning slow with their limbs extended outward. Then, they tuck their arms and legs in, causing them to spin faster.

Skateboarders also gain speed by using this technique on curved surfaces.

When a skateboarder hits the circular section of the half-pipe, they start crouched down, positioning their center of mass further from the center of rotation above their head. As they climb the curved ramp, they pop up and bring their center of mass closer to the center of rotation, and they speed up.

While the pumping paper is one of the first to capture the physics of pumping, its authors aren’t the only ones studying the motion of skateboarding.

Google has also taken a stab at a more complex understanding with its Project Skate. It’s using AI to identify different tricks and motions — but AI requires a lot of computing power that many researchers who aren’t Google don’t have access to.

“They have [essentially] unlimited resources. If they want to, they can take a new server farm and then run trajectories as much as they want.” said Kogelbauer. “That’s what Google does. We’re not Google.”

If you’d like to study pumping physics on your own, you can tune in to the Paris Olympics. The women skateboarders are scheduled to compete in the park event (as opposed to the street event, which has fewer curved surfaces for pumping) Tuesday morning. The men are scheduled for Wednesday.

McKenna has always seen skating more as an art form and community than a sport, but he’s stoked to watch nonetheless. “When I was a kid, which doesn’t seem that long ago, skateboarding was a crime, literally,” he said. “Now we’re winning gold medals in the Olympics.”

A Summer Olympics that hoped to champion inclusivity — choosing “Games Wide Open” as its slogan — has become embroiled in loud, angry debates over who should and should not be allowed to compete as a woman.

The dispute has triggered conflicting official statements, pointed comments and unhinged social media posts, all whirling around two athletes in the women’s boxing competition at Arena Paris Nord.

This isn’t about how Imane Khelif of Algeria and Lin Yu Ting of Taiwan identify. By all accounts, they were born as women but appear to have unusual body chemistry that triggered gender tests and caused them to be disqualified from last year’s world championships.

The Olympics, however, have broader eligibility rules.

“I think we all have a responsibility to dial down this and not turn it into some kind of witch hunt,” International Olympic Committee spokesman Mark Adams told reporters. “These are regular athletes who have competed for many years in boxing, they are entirely eligible and they are women on their passports.”

His plea has been overshadowed by a Thursday afternoon bout in which Khelif punched an opponent hard enough to make her quit after 46 seconds. Paris has been lumped in the same category as previous controversies involving South African runner Caster Semenya and U.S. collegiate swimmer Lia Thomas.

This case might be more incendiary because, instead of running or swimming fast, Khelif and Lin are delivering potentially lethal blows. Italian boxer Angela Carini said she conceded to Khelif because “I had to safeguard my life.”

Experts wonder if the sports world has reached an inflection point.

“We really have not come up with a consensus on how we define sex,” said Jaime Schultz, author of a new book titled “Regulating Bodies: Elite Sport Policies and Their Unintended Consequences.” “People have to learn how to talk about this.”

Over the last 24 hours, much of the public discourse has inaccurately described Khelif and Lin as transgender. Former President Donald Trump posted on Truth Social: “I WILL KEEP MEN OUT OF WOMEN’S SPORTS!”

There is no evidence that either boxer is transgender or has chromosomal abnormalities. Though purposefully vague, officials have described what appear to be “differences of sex development,” a designation that applies to women who are androgen-sensitive or have naturally occurring testosterone levels in the male range.

The international track federation used this standard to demand that 800-meter star Semenya either take medication to alter her body chemistry or race against men. She fought the decision, losing in the Federal Supreme Court of Switzerland.

Sports have a long and troubled history with gender testing.

Early on, female athletes were forced to disrobe for physical inspections. Chromosome tests came into fashion for a while but were successfully challenged by Spanish runner Maria Jose Martinez-Patino in the 1980s because they could not account for rare conditions.

Though testosterone is now a common measure, there is continued disagreement over its validity.

Italy’s Angela Carini, left, cries after her loss to Algeria’s Imane Khelif at the Paris Olympics on Thursday.

(John Locher / Associated Press)

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“These criteria keep folding under the weight of closer scrutiny,” said Schultz, who is also a kinesiology professor at Penn State. “None of them have held up over time.”

Veterans on the amateur scene, Khelif finished fifth in the 60 kilogram event and Lin finished ninth at 57 kilograms in the Tokyo Olympics in 2021. The Algerian won silver at the International Boxing Assn.’s 2022 world championships. The Taiwanese athlete earned gold at that tournament in 2018 and 2022.

But last year, the IBA took action against both women.

Khelif was disqualified shortly before her gold-medal bout and Lin after her bronze-medal victory. The IBA stated the boxers did not “undergo a testosterone examination but were subject to a separate and recognized test, whereby the specifics remain confidential.”

The situation grew more complicated when the IOC suspended its recognition of the IBA after years of dispute between the organizations. With the IOC temporarily in control of boxing at the Games, Khelif and Lin have had their eligibility restored.

It came as no surprise when Khelif’s bout on Thursday prompted dueling responses.

First the IBA condemned Olympic officials for letting Khelif and Lin compete, stating: “We absolutely do not understand why any organization would put a boxer at risk with what could bring a potential serious injury.”

The IOC fired back by saying: “Every person has the right to practice sport without discrimination.” It further noted the IBA disqualifications were “based entirely on this arbitrary decision, which was taken without any proper procedure.”

Algeria’s Imane Khelif, right, walks beside Italy’s Angela Carini after their women’s 66kg preliminary boxing match.

(John Locher / Associated Press)

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On Friday morning, when questioned about the Olympics’ apparent struggle with gender rules, Adams said: “There is still neither scientific nor political consensus on this issue. It’s not a black and white issue. And we at the IOC would be very interested to hear of such a solution, such a consensus on this, and we would be the first to act on this should a common understanding be reached.”

Hours later, the media descended on a bout between Lin and Sitora Turdibekova of Uzbekistan. No devastating blows were landed during Lin’s victory, by unanimous decision, after which both athletes walked through the mixed zone without responding to questions.

Khelif’s next bout — against Anna Luca Hamori of Hungary — figures to attract similar attention on Saturday. The Hungarian Boxing Assn. has reportedly protested Khelif’s participation but Hamori did not seem as concerned. “I am not scared,” the boxer said. “If she or he is a man, it will be a bigger victory for me if I win. So let’s do it.”

Even Carini, who fell to her knees and cried after losing to Khelif, has been magnanimous. Her comments reflect the complexity of the issue.

“I am not in the position of saying this is right or wrong,” she told reporters. “I did my job as a boxer, entering the ring and fighting.”

After decades of mounting tension between scientists and native Hawaiians, Caltech has completed its removal of a telescope from the summit of Maunakea, a dormant volcano that is revered by the island’s Indigenous population.

The decommissioning of the Caltech Submillimeter Observatory in July follows the removal of a University of Hawaii observatory a month earlier, and comes amid a cultural resurgence among native Hawaiians.

“Nothing is forever,” said Gregory Chun, the executive director of the Center for Maunakea Stewardship at the University of Hawaii and a native Hawaiian.

“It was important for these two facilities to come down, not just because they were not productive anymore but because it’s an acknowledgment of the privilege of being up there. You were pau — you were done. So, you can go home now.”

Prized for its altitude, dark skies and low humidity, Maunakea still hosts 11 other telescopes. Although the facilities have brought Hawaii international acclaim in astronomy and have helped to boost the local economy, native Hawaiians have long regarded the summit as their spiritual connection to the heavens.

Protests erupted at the base of the mountain in 2019, when Caletch and the University of California proposed construction of another observatory called the Thirty Meter Telescope. The outcry led the state to shift oversight responsibilities from the University of Hawaii — which leased the land to Caltech — to the new Maunakea Stewardship Oversight Authority, which is composed of local, environmental and scientific stakeholders.

The closure of the Caltech observatory marks the end of a contentious era, as locals and the new authority debate what’s next for the mountain.

“I have incredible respect for the people at the University of Hawaii, who can audit their own actions,” said John De Fries, the executive director of the new authority. “If this authority can begin to pioneer a new model of leadership, that’s reason to be grateful, but the task of that remains ahead of us.”

In response to public criticism, the University of Hawaii created the Center for Maunakea Stewardship in 2020 to oversee operations on the mountain. It worked closely with Caltech to decommission the observatory.

Throughout the process, cultural observers were present to ensure deconstruction was done in a respectful way, and while the new authority was not involved in the decommissioning process, Caltech invited members to perform cultural ceremonies at its conclusion.

A senior member from the authority also inspected the site for final sign-off of completion, and reported that “the site had been restored to as near a pristine level that you can expect,” De Fries said.

Over its roughly three decades of observations, the Caltech Submillimeter Observatory has played a key role in several scientific breakthroughs in astrophysics.

The observatory was first designed to detect some of the most unexplored wavelengths of light, between a third of a millimeter and one millimeter — much longer than visible light.

The telescope, with its fellow Maunakea resident the James Clerk Maxwell Telescope, discovered that Earth is basking in light from excited molecules living quietly in interstellar space.

Since the Caltech Submillimeter Observatory started looking at the night sky in 1987, the telescope has played a key role in several scientific breakthroughs. It helped identify molecules in interstellar space and created maps of cosmic dust and galaxy clusters.

(Caltech Submillimeter Observatory)

Toward the turn of the century, an upgraded Caltech Submillimeter Observatory started making maps of the sky. It was a “quantum leap in capability,” said Sunil Golwala, director of the observatory and a physics professor at Caltech.

This allowed scientists to map everything from dust in the interstellar medium to the largest scale of structure in the universe, galaxy clusters.

Now, the Caltech telescope moves to Chile with a new name (the Leighton Chajnantor Telescope), new instruments and the opportunity to reestablish itself on the cutting edge of astronomy.

Golwala said the team has learned from their time on Maunakea and that the Chile site is farther from population centers and not regarded as sacred. They’ll also build near other observatories to reduce their environmental footprint.

In the aftermath of the observatory protests, finding the right balance between astronomy and preservation of the Maunakea sacred site remains a challenge.

Despite criticisms, the telescopes do help the state economically, and they support science and engineering on the islands as many of Hawaii’s young people are leaving to pursue degrees in these fields.

“You don’t have a unified consensus in the community — much less the Hawaiian community — about [Thirty Meter Telescope] or astronomy,” Chun said. “So, balance is not going to be something that’s easily found, but I think if the authority can come up with a vision where people see themselves in it, we have a better chance.”

Over his time heading the center, Chun has come to think empathy is the path toward reconciliation, and the authority is an opportunity to find it.

“We certainly have a lot of lessons learned and scars that we’ve accumulated over the years,” Chun said.

“I also think, however, that it’s not by happenstance that one of the most sacred lands here in Hawaii to native Hawaiians is also the premier place, certainly in the northern hemisphere if not in the world, for astronomy.”