What Color Is a Tennis Ball? The Answer Is Complicated—And Depends on Who You Ask

iStock.com/jujeecmu
iStock.com/jujeecmu

While there’s always some subjectivity in visual perception, some colors are supposed to be constant. Oranges are always orange. Fire trucks are always red. Tennis balls are always yellow.

Or maybe they’re always green.

In The Atlantic, Marina Koren explored the controversial debate over where the ubiquitous felt ball seen on courts or shooting out of serving machines falls on the color spectrum. After discovering that her colleagues perceived the ball different ways—either yellow or green—she attempted to understand why and if there was a definitive answer lurking in those ball cans.

By rule of tennis law—specifically, the International Tennis Federation, or ITF—a tennis ball should be yellow in color. The edict was handed down in 1972, after television viewers had trouble following the movement of white balls. Manufacturers like Gamma Sports also identify their product as yellow—in Gamma’s case, optic yellow.

So why do some people perceive the balls as green? For one thing, a yellow hue presented by itself can be hard for some people to describe. Yellow is easy to identify when contrasted with other colors—think paint swatches—but harder for people to articulate when there’s nothing to compare it to. Second, people tend to make color corrections based on lighting conditions. Some may discount warm colors like gold or cool colors like blue, changing how they perceive and interpret the color spectrum. If they discount cool colors, the ball might appear to be yellow. If they discount warm colors, green.

It’s possible that people who are active in the evenings under artificial light are more likely to discount warm colors, while people active in the daytime and under natural light would discard cool colors, further altering their perceptions.

Objectively, a tennis ball is yellow. But whether it appears that way to you depends on how you see the world.

[h/t The Atlantic]

103-Year-Old Julia 'Hurricane' Hawkins Just Set a New World Record for the 50-Meter Dash

Julia “Hurricane” Hawkins participates in the 2019 Senior Games,
Julia “Hurricane” Hawkins participates in the 2019 Senior Games,
All images copyright NSGA

Here she is, as the Scorpions would say, rocking the 50-meter dash like a hurricane. On Monday, 103-year-old Baton Rouge native Julia "Hurricane" Hawkins set a new world record in her division—the women's 100-plus—by completing the 50-meter dash at the Senior Games in Albuquerque, New Mexico, in just 46.07 seconds.

Amazingly, this isn't the only world record Hawkins holds: In 2017, the former teacher set her first world record (which she still holds) by finishing the 100-meter race in less than 40 seconds. "I thought it’d be neat to run at 100, and do the 100-yard dash,” Hawkins told KRQE. Although family members say she has always been active, she only started running fairly recently—lacing up her sneakers for the first time at the age of 101.

Hawkins, who credits the sport with keeping her mind and body sharp, says she has no plans of slowing down any time soon. Her preferred method of training? Walking around her garden. "I have an acre of land and I have 50 kinds of trees, and I’m working on them all the time,” Hawkins said.

While the "Hurricane" nickname is certainly befitting, the world-class athlete has a better suggestion: "I like the flower lady better."

Aside from maintaining her personal health, Hawkins has a more noble goal each time she picks up the pace. "I hope I’m inspiring [other people] to be healthy,” she said, "and to realize you can still be doing it at this kind of an age.”

[h/t KRQE]

4 Reasons Why Climbing Everest Is Deadlier Than Ever

Prakash Mathema/Getty Images
Prakash Mathema/Getty Images

On April 18, 2014, an avalanche killed 16 Sherpas on Mount Everest, making it the deadliest day in the mountain’s history. But one year later, a 7.8-magnitude earthquake triggered another fatal avalanche that killed more than 20 climbers and shut the mountain down for the 2015 season. During this year's season, at least 11 climbers have died on Everest experts say.

At 29,029 feet, Everest is known for its dangers; that's part of the allure. But in recent years, tragedies have spiked, and frozen bodies scattered across the mountain are an eerie reminder of the growing hazards. So why is the world’s tallest mountain claiming more lives than ever before?

1. Climate change makes Mount Everest unpredictable.

Everest tragedies are nothing new; since 1990, at least one climber has died in pursuit of the summit every year. But each climbing season, Everest is getting more unstable. Kent Clement, a professor of outdoor studies at Colorado Mountain College, argues that climate change is possibly the most imminent risk for climbers.

“As temperatures rise, Everest’s thousands of feet of ice and water are becoming unstable, making the mountain even more volatile,” Clement said.

Collapsing seracs—50- to 100-foot columns of ice formed by intersecting glacier crevasses—are a growing threat. Seracs can stand perfectly still for decades, then spontaneously fall over, killing those nearby and, in some cases, triggering avalanches further down the mountain. Case in point: The deadly 2014 avalanche that killed 16 Sherpas was caused by a serac collapse in the Khumbu Icefall, the most dangerous section of the route up Everest's southeastern face.

As you’d expect, climate-related risks are the new norm. A study in the journal The Cryosphere [PDF] predicts that Mount Everest’s glaciers could shrink by 70 percent this century, making currently unstable sections of the routes even more so.

2. Human biology is at odds with high altitudes on Mount Everest.

Climbers ascending the Khumbu Icefall on Mount Everest
Prakash Mathema/Getty Images

In addition to natural disasters, Everest climbers face a number of life-threatening health risks.

In high-altitude settings, there is less oxygen in the atmosphere, and oxygen doesn’t diffuse into a climber’s blood as well as it would at sea level. That can lead to serious medical problems. The two most common illnesses on Everest are high-altitude pulmonary edema (HAPE), in which constricted blood vessels cause fluid to leak into the lungs' air sacs; and high-altitude cerebral edema (HACE), in which fluid leaks from blood vessels in the brain, causing headaches, neurologic dysfunction, coma, and eventually death if not treated (and in some cases, even when treated).

“Altitude illness impacts people in different ways, and we don’t really know who is susceptible until they have altitude illness,” Christopher Van Tilburg, an expert in travel medicine and a physician Oregon's Providence Hood River Memorial Hospital, told Mental Floss. “High-altitude pulmonary edemas can hit people suddenly—even highly trained, fit mountaineers.”

3. Neurological and psychological factors can impair Everest climbers' judgment.

Another health risk that affects a climber’s cognition is hypoxia, which is simply when the brain doesn’t get enough oxygen. According to Clement, hypoxia can drastically impair judgment, making it one of the most dangerous Everest risks.

“The higher you climb, the more your judgment gets impaired,” Clement said. “It’s amazing how hard it is for smart people to do simple math and memory problems at high altitudes.”

In addition to causing treacherous missteps, hypoxia can drive climbers to push harder and go farther than they normally would—but not in a good way. These “cognitive traps” often happen when a climber gets closer to the top and replace logic and safety with stubborn determination, putting everything at risk to reach their goal. Another word for it? Summit fever.

According to Clement, the cure is setting a strict turnaround time: an ironclad moment when a climber promises to turn around and forego the summit to save their life. Turnaround times are decided before setting foot on Everest, and should be agreed upon between climbers, guides, and expedition leaders. But hypoxia, exposure, and inexperience can encourage climbers to ignore the protocol.

“Every time you ignore your turnaround time, you’re putting yourself at risk,” Clement said. “Professional guides are also supposed to follow these rules, but they get stuck in cognitive traps, too, because the more clients they get to the top, the more clients they’ll have next season.”

4. Medicine can reduce—but not eliminate—Mount Everest's dangers.

Any climb above 19,000 feet—the altitude known as “the death zone”—will have associated health risks, but there are treatments that can help climbers survive. Medicines include acetazolamide (sold under the brand name Diamox), a diuretic that helps prevent a mild edema, and dexamethasone (brand name Decadron), a steroid used to treat a brain edema and reverse the symptoms of acute mountain sickness. The only true fix for acute mountain sickness is immediate descent.

The best way to stay alive on Everest is proper training, fitness, and organization, but even those steps can't guarantee safety.

“Training doesn’t really offset objective hazards like rock falls, ice falls, avalanches, and earthquakes,” said Van Tilburg. “And while we have medicine for altitude illness to help people acclimatize, we don’t have medicines for the myriad other risks on Everest.”

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