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Mysterious ‘Sailing Stones’ Explained

It might just be the world’s slowest game of Red Light, Green Light: Huge rocks in Death Valley National Park race across the mud flats—but only when nobody is looking. The sailing stones, as they’re called, mystified park visitors and scientists for decades. But one man believes he’s solved the puzzle.

The dry lakebed known as the Racetrack playa looks much like the rest of Death Valley—cracked and dry in the summer and frozen in winter. But nowhere else in the park will you find strange tracks trailing behind each big rock and boulder. It looks as though the stones have dragged themselves through the desert, or as though they have been dragged, by some great cosmic hand. 

All summer, the stones are still. Through autumn, they don’t budge. Then winter roars in and creeps out. By spring, the stones have moved again.

Natural and supernatural theories have abounded: Unsurprisingly, many attributed the rocks’ stealthy movements to aliens. Some said wind was the culprit; others ice; others rain; still others, mystical energy fields. Some people even steal rocks from the park, hoping to harness their magical powers. 

Scientists have set up experiments in the playa since the 1940s, trying to understand what makes the sailing stones sail. But all the results have been inconclusive, and despite frequent checks, nobody has ever been able to catch the rocks in motion.

It took a space researcher to crack the case. Planetary scientist Ralph Lorenz was working with NASA, setting up miniature weather stations in Death Valley, when he first became interested in the stones. (Conditions in the park are so severe that it’s often used as an experimental stand-in for Mars.) Although his original work was focused on summer in the desert, Lorenz realized his instruments would work just as well for monitoring the playa’s rocks in the winter. Lorenz and his team pored over images of the stones’ trails, looking for some clue.

One rock stood out. “We saw one instance where there was a rock trail and it looked like it hit another rock and bounced, but the trail didn't go all the way up to the other rock, like it was repelled somehow,” Lorenz told Smithsonian.com. “We thought if there was a collar of ice around the rock, then it might be easy to imagine why it might bounce.” 

The final breakthrough came not in the laboratory or even in the desert, but in the kitchen. Lorenz poured a little water in a plastic container, then dropped in a small rock and put the whole thing in the freezer. When he took it out, he had a rock half-sheathed in ice. That rock went into another dish, this one filled with water atop a layer of sand. He set the rock in the water, ice side up, and blew on it to give it a gentle push. The rock floated across the water, scraping a path through the sandy bottom as it went. Lorenz had found the answer. 

“Basically, a slab of ice forms around a rock, and the liquid level changes so that the rock gets floated out of the mud,” he said. “It’s a small floating ice sheet which happens to have a keel facing down that can dig a trail in the soft mud.” 

Lorenz published his findings in the American Journal of Physics in 2011. Once he knew what to look for, he was even able to catch the rocks in motion.

Not everybody is satisfied with the ice-raft explanation. Park visitors ask why it happens, but they don’t want to hear about science, park ranger Alan Van Valkenburg told Smithsonian.com. “People like a mystery—they like an unanswered question.”

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Stones, Bones, and Wrecks
3500-Year-Old Mummy Discovered in Forgotten Egyptian Tomb

As the site of the ancient city of Thebes, the modern-day Egyptian city of Luxor is filled with archaeological treasures. But until recently, two forgotten tombs—both located in the necropolis of Dra' Abu el-Naga, an important non-royal cemetery—hadn’t been fully explored. Now, National Geographic reports that experts have finally excavated these burial sites and discovered a 3500-year-old mummy, along with ornate funerary goods and colorful murals.

While excavating one of the two tombs, known as Kampp 150, experts found linen-wrapped remains that Egypt's Ministry of Antiquities believes belong to either "a person named Djehuty Mes, whose name was engraved on one of the walls ... [or] the scribe Maati, as his name and the name of his wife Mehi were inscribed on 50 funerary cones found in the tomb's rectangular chamber."

In addition to the mummy, archaeologists discovered wooden statues, masks, earthen pots, a cache of some 450 statuettes, and around 100 funerary cones—conical mud objects, which were often positioned outside a tomb's center, and could have served as identifying markers or as offerings—inside Kampp 150.

The Associated Press reported that the second tomb, known as Kampp 161, is thought to be approximately 3400 years old—about 100 years newer than its neighboring chamber—as its design is characteristic of other such structures dating back to the reigns of Amenhotep II and Thutmose IV.

Inside Kampp 161, archaeologists discovered wooden funerary masks, a decorated coffin, furniture shards, and the mural of a festival or party depicting the tomb's unknown resident and his wife receiving ceremonial offerings.

German scholar Friederike Kampp-Seyfried surveyed and numbered both tombs in the 1990s, which is how they got their names, but she did not fully excavate nor enter either one.

Officials celebrated the rediscovery of the tombs on Saturday, December 9, when they publicly announced the archaeological finds. They hope that discoveries like these will entice foreign travelers to visit Egypt, as political unrest has harmed the country's tourism industry in recent years.

“It’s truly an exceptional day,” Khaled al-Anani, Egypt's antiquities minister, said in a statement. “The 18th dynasty private tombs were already known. But it’s the first time" anyone's ever entered them.

Check out some pictures of the newly revealed relics below.

Mustafa al-Waziri, director general of Luxor's Antiquities, points at an ancient Egyptian mural found at the newly discovered 'Kampp 161' tomb at Draa Abul Naga necropolis.
Mustafa al-Waziri, director general of Luxor's Antiquities, points at an ancient Egyptian mural found at the newly discovered 'Kampp 161' tomb at Draa Abul Naga necropolis on the west Nile bank of the southern Egyptian city of Luxor, about 400 miles south of the capital Cairo, on December 9, 2017.
STRINGER/AFP/Getty Images

An Egyptian archaeological technician restores artifacts found at the newly discovered 'Kampp 161' tomb at Draa Abul Naga necropolis in Luxor, Egypt.
An Egyptian archaeological technician restores artifacts found at the newly discovered 'Kampp 161' tomb at Draa Abul Naga necropolis on the west Nile bank of the southern Egyptian city of Luxor, about 400 miles south of the capital Cairo, on December 9, 2017.
STRINGER/AFP/Getty Images

An Egyptian laborer stands next to an ancient Egyptian mural found at the newly discovered 'Kampp 161' tomb at Draa Abul Naga necropolis in Luxor, Egypt.
STRINGER/AFP/Getty Images

Ancient Egyptian wooden funerary masks and small statuettes found in and retrieved from the newly discovered 'Kampp 150' tomb at Draa Abul Naga necropolis in Luxor, Egypt.
A picture taken on December 9, 2017 shows ancient Egyptian wooden funerary masks and small statuettes found in and retrieved from the newly discovered 'Kampp 150' tomb at Draa Abul Naga necropolis on the west Nile bank of the southern Egyptian city of Luxor, about 400 miles south of the capital Cairo.
STRINGER/AFP/Getty Images

[h/t National Geographic]

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Kohske Takahashi, i-Perception (2017)
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Can You Figure Out This Newly Discovered Optical Illusion?
Kohske Takahashi, i-Perception (2017)
Kohske Takahashi, i-Perception (2017)

Ready to have your mind boggled? Take a look at the image above. What shape are the lines? Do they look like curves, or zigzags?

The image, spotted by Digg, is a new type of optical illusion published in the aptly named journal i-Perception. Discovered by Japanese psychologist Kohske Takahashi, it’s called the “curvature blindness illusion,” because—spoiler—the contrast of the lines against the gray background makes our eye see some of the lines as zigzags when, in fact, they’re all smooth curves.

The illusion relies on a few different factors, according to the three experiments Takahashi conducted. For it to work, the lines have to change contrast just at or after the peak of the curve, reversing the contrast against the background. You’ll notice that the zigzags only appear against the gray section of the background, and even against that gray background, not every line looks angled. The lines that look curvy change contrast midway between the peaks and the valleys of the line, whereas the lines that look like they contain sharp angles change contrast right at the peak and valley. The curve has to be relatively gentle, too.

Go ahead, stare at it for a while.

[h/t Digg]

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