# The Mysterious Mathematical Principle That Links Bus Systems and Chicken Eyes

iStock

Math is everywhere—if you know where to look. Elegant equations can be observed in everything from flower petals to swirling galaxies. Universality, a phenomenon that strikes a balance between order and randomness, is one of these ubiquitous mathematical patterns that repeats itself again and again in the natural world. As Quanta Magazine lays out in the new episode of its In Theory video series, examples of universality can be seen in biology, quantum physics, and even public transportation.

In math, universality is what determines the spacing between solutions in a large matrix of random numbers. The numbers that go into the matrices may themselves be random, but when they interact, they produce a predictable outcome.

You can see the same principle at work in the world around us. Take bus routes, for instance. In 1999, a Czech physicist named Petr Šeba found the pattern in Cuernavaca, Mexico after observing how the city's bus system operated. Paid "spies" were positioned along the bus routes, and whenever a bus came, they'd let the driver know how long it had been since the last one passed through. Based on this intel, the bus driver would either slow down or speed up to maximize his passengers at the next stop. On paper, this method creates a barcode pattern of lines that appear to be placed at random but actually follow a set pattern.

That same random-looking pattern appears elsewhere, too, like in chicken eyes. While the color-sensitive cone cells in the eyes of some animals, like fish, are laid out uniformly across the retina, the cells in chickens' eyes look different. The cone cells are different sizes and look like they're scattered at random. But these cells are actually distributed according to the universality pattern—the first-ever instance of the pattern recorded in biology.

You can also see universality when you map out the energy spectrum of the uranium nucleus, the spectral measurements of sea ice, and elsewhere. To learn more about the math behind universality and how to spot it in the real world, check out the video below.

[h/t Quanta Magazine]

# It 'Rained' Spiders in Brazil Last Week—and You Can Watch It If You Dare

iStock.com/aury1979

If recent events are anything to go by, you should be less concerned about swallowing spiders in your sleep and more concerned about bird-eating spiders raining down on your head. As The Guardian reports, recent footage from the Brazilian countryside shows thousands of spiders seemingly suspended in mid-air. (Arachnophobes might want to give the video below a miss.)

In reality, they aren’t falling at all. The spiders, which likely belong to a South American species called Parawixia bistriata, are merely crawling on an ultra-fine and nearly invisible web that attaches to two objects, like trees or bushes, to form a canopy.

So why do they do it? To catch prey, naturally. They’re likely to snag a variety of insects and maybe even small birds in their communal web, which can stretch up to 13 feet wide. (And yes, they eat the birds, too.)

Brazilian biology professor Adalberto dos Santos tells The Guardian that P. bistriata are some of the rare “social” spiders that do this. They leave their webs up overnight, hide out in the nearby vegetation, and then return at dawn to feast.

While this natural phenomenon is certainly unsettling, it isn’t exactly rare. Residents of the southeast municipality of Espírito Santo do Dourado, where the video was shot, said these “spider rains” are common when the weather is hot and humid.

Here’s another video from Santo Antônio da Platina in southern Brazil in 2013.

Other species of spider have been known to jump into the wind and "surf" on strands of silk as a means of getting around. They do this to escape threats or get to food or mates in other locations, and cases of "spider flight" have been recorded all over the world. Some especially adventurous spiders have even been known to cross oceans by “ballooning” their way from one land mass to the next.

[h/t The Guardian]

# Watch a Baby Polar Bear Open Its Eyes for the Very First Time

Sometimes, after a long week, all you need is something wholesome to lift your spirits. Here to do just that is the Berlin Zoo's newest resident.

In this polar bear video spotted by Geek.com, a 5-week-old cub can be seen opening its eyes for the very first time as its mom, Tonja (pronounced like Tania), cleans and cuddles it. “While it was previously only able to explore its surroundings by groping and cuddling, the little bear can now see and hear things,” according to a translated version of the zoo’s polar bear video caption.

Like kittens and puppies, polar bears are functionally blind and deaf when they’re born. It takes polar bears several weeks longer to develop their senses compared to puppies or kittens, though—about 30 days total. Their claws come later, too.

The diminutive nature of newborn cubs may also come as a surprise. Although full-grown adults can tip the scale at more than 1300 pounds, newborns weigh just 16 to 24 ounces—about the size of a guinea pig. But they pack on the pounds quickly, and can weigh over 100 pounds by the time they’re 8 months old.

A Berlin Zoo spokesperson reportedly said the cub has a big appetite and ate a lot over the holidays (just like the rest of us, apparently). It’s now attempting to walk, but mom and baby aren’t expected to leave the cave in their enclosure before spring arrives.

According to DW Science, zoo staff don’t know the sex of the cub yet. For its protection, they plan to give mom and baby lots of alone time before they approach. Newborn polar bears are quite vulnerable—especially in the wild, where about 85 percent of the bears die before they’re 2 years old.

Meanwhile, zoo staff are keeping a watchful eye on the cub, courtesy of the infrared cameras they have set up in their den.

[h/t Geek.com]

arrow
LIVE SMARTER
arrow
LIVE SMARTER