Science & TechnologyS


Truck

Geomatry: The worst shape for packing a cargo hold

Gregory Barber
Quanta Magazone
Fri, 28 Jun 2024 17:28 UTC
packing luggage car trunk
© Nico Roper for Quanta Magazine
Two mathematicians have proved a long-standing conjecture that is a step on the way toward finding the worst shape for packing the plane.

For centuries, mathematicians suspected that hexagonal tiles are the best possible way to fill space. By this they mean that if you want to subdivide a large area into tiles of equal size while minimizing the perimeter of each tile, you can't do any better than hexagons. In 1999, Thomas Hales of the University of Pittsburgh finally proved it. They're better than squares, triangles, or any other alternative.

But many shapes can't be tiled without leaving gaps. Circles, for example, obviously can't. With the best possible formation, a hexagonal-shaped circle packing, you'll fill nearly 90.69% of the plane.

In the 1920s, mathematicians began wondering: What's the worst shape to pack? In other words, what shape forces you to leave the largest gaps, even if you pack it in the best possible way? A new paper by Hales and his former graduate student Koundinya Vajjha, now an engineer at Intel, marks a major breakthrough in the search.

Comment: Further reading:

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Moon

Moon cave offers hope as exploration base

Mary Manley
Sputnik
Wed, 17 Jul 2024 00:25 UTC
moon
© AP Photo
The cave is 45 meters wide and nearly 80 meters long; an area which could be covered by about 14 tennis courts, one report revealed.

Scientists for the first time have discovered a cave on Earth's moon. The underground cave, which is accessible from the surface, could be the perfect spot to build a future lunar base. The cave lies about 492 feet below the moon's surface, and could offer shelter from the harsh surface environment, the study published in Nature on Monday said.


Comment: Perhaps not the first time. The Japanese discovered a lunar cave back in 2017.


The 147-foot wide and 262-foot long cave is located about 250 miles from where the Apollo 11, carrying astronauts Neil Armstrong and Buzz Aldrin, landed 55 years ago. The researchers note that is just one in probably hundreds of caves hidden in an "underground, undiscovered world".

Radar data collected by NASA's Lunar Reconnaissance Orbiter revealed the cave to be what is most likely an "empty lava tube".
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Rocket

SpaceX rocket mishap leaves company's Starlink satellites in the wrong orbit


NPR
Sat, 13 Jul 2024 21:01 UTC
space x starlink satellites wrong orbit
© SpaceX/APThis image from video provided by SpaceX shows the upper stage engine of a SpaceX Falcon 9 rocket, which blasted off from California on Thursday.
A SpaceX rocket has failed for the first time in nearly a decade, leaving the company's internet satellites in an orbit so low that they're doomed to fall through the atmosphere and burn up.

The Falcon 9 rocket blasted off from California on Thursday night, carrying 20 Starlink satellites. Several minutes into the flight, the upper stage engine malfunctioned. SpaceX on Friday blamed a liquid oxygen leak.

The company said flight controllers managed to make contact with half of the satellites and attempted to boost them to a higher orbit using onboard ion thrusters. But with the low end of their orbit only 84 miles (135 kilometers) above Earth — less than half what was intended — "our maximum available thrust is unlikely to be enough to successfully raise the satellites," the company said via X.
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Cassiopaea

Strange motion of neutrons proves nature is fundamentally bizarre

Michelle Starr
Science Alert
Wed, 10 Jul 2024 17:21 UTC
wave particle
© (Yuichiro Chino/Moment/Getty Images)
At the very smallest scales, our intuitive view of reality no longer applies. It's almost as if physics is fundamentally indecisive, a truth that gets harder to ignore as we zoom in on the particles that pixelate our Univerrse.

In order to better understand it, physicists had to devise an entirely new framework to place it in, one based on probability over certainty. This is quantum theory, and it describes all sorts of phenomena, from entanglement to superposition.

Yet in spite of a century of experiments showing just how useful quantum theory is at explaining what we see, it's hard to shake our 'classical' view of the Universe's building blocks as reliable fixtures in time and space. Even Einstein was forced to ask his fellow physicist, "Do you really believe the Moon is not there when you are not looking at it?"

Comment: And it seems it's even more 'bizarre' than that: (2023) Quantum breakthrough reveals reality shaped by context, measurement, system - scientists forced to rethink nature of reality

See also:

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Microscope 2

First fossil chromosomes discovered in freeze-dried mammoth skin

Giorgia Guglielmi
Nature
Thu, 11 Jul 2024 21:11 UTC
fossil chromasomes mammoth
© SciePro/SPLThe 3D structure of chromosomes (artist's impression) was thought not to survive the ravages of time, but scientists examining mammoth skin have shown otherwise.
The 3D arrangement of the DNA in the animal's cells hints at which genes were active.

On the frozen tundra of Siberia some 50,000 years ago, a woolly mammoth met its end under mysterious circumstances. In samples of the animal's skin, researchers have now discovered chromosomes preserved in their original 3D configuration1 — a feat previously thought impossible in ancient-DNA research.

The team also revealed the spatial organization of the mammoth's DNA molecules and the active genes in its skin, including one responsible for giving the animal its fuzzy appearance. The work was published today in Cell.

The study is the first to report the 3D structure of an ancient genome, says Ludovic Orlando, a molecular archaeologist at Paul Sabatier University in Toulouse, France, who didn't take part in the research. Because the spatial structure of a genome — the complete set of an organism's genetic material — holds clues to its gene activity, understanding that structure might offer deeper insights into the cell biology of the mammoth's skin than examining the DNA sequence alone, he says. "This work is simply unprecedented."
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Better Earth

Extinction and evolution: Extreme solar blasts coupled with Earth's weakening magnetic field could have dramatic impact on life

Alan Cooper, Pavle Arsenovic
The Conversation
Wed, 03 Jul 2024 18:44 UTC
aurora
© (PhotoLoader/Shutterstock)
The remarkable aurora in early May this year demonstrated the power that solar storms can emit as radiation, but occasionally the Sun does something far more destructive.

Known as "solar particle events", these blasts of protons directly from the surface of the Sun can shoot out like a searchlight into space.

Records show that around every thousand years Earth gets hit by an extreme solar particle event, which could cause severe damage to the ozone layer and increase levels of ultraviolet (UV) radiation at the surface.

We analysed what happens during such an extreme event in a paper published today. We also show that at times when Earth's magnetic field is weak, these events could have a dramatic effect on life across the planet.

Comment: History shows that these periods were also accompanied by a myriad of other phenomena, and both in the far distant past, but also as evidenced more recently with the Black Death, the civilisational collapse that occurred in various regions, and the Renaissance. And, indeed, we appear to be on the cusp of that part of the cycle once again:

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Pi

How America's fastest swimmers utilize math to win gold

Jordana Cepelewicz
Quanta Magazine
Wed, 10 Jul 2024 18:26 UTC
math analyze swim patterns competition
© Kristina Armitage/Quanta Magazine; Source: Klubovy/iStock
Number theorist Ken Ono is teaching Olympians to swim more efficiently.

In the fall of 2014, Andrew Wilson took a front-row seat in Ken Ono's number theory class at Emory University in Atlanta. Wilson was not only double majoring in applied math and physics, he was a walk-on member of Emory's swim team. Ono took an interest in Wilson's ambitions. "We thought that together, maybe we could use our interest in mathematics to help him improve as a swimmer," Ono said.

Ono, who typically studies abstract patterns in numbers and special functions called modular forms, began collecting and analyzing acceleration data from Wilson and other Emory swimmers to identify and quantify their weaknesses. "It got to the point where I could just see what an athlete was doing without actually watching them swim," he said.

Within two years, Wilson won a national collegiate championship; he would go on to earn a gold medal at the 2021 Olympics in Tokyo. By then, Ono had moved to the University of Virginia, where he worked alongside Todd DeSorbo — the head coach for both UVA swimming and the U.S. Olympic women's swim team. Ono will join the Olympic team staff in Paris later this summer as a technical consultant. "I feel like we're all in this together, trying to make something new," he said.
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Better Earth

Oldest human genome ever sequenced: 200,000-year-old Denisovan DNA shows repeated interbreeding with Neanderthals

Ann Gibbons
Science Magazine
Fri, 12 Jul 2024 21:07 UTC
Denisova špilja
Denisova Cave: The most ancient human genome yet has been sequenced — and it's a Denisovan's 200,000-year-old DNA from Siberian cave shows our elusive, extinct cousins mated repeatedly with Neanderthals
By the time population geneticist Stéphane Peyrégne gave his talk Tuesday afternoon at a meeting in Puerto Vallarta, Mexico, rumors had circulated and the auditorium was packed. He didn't disappoint: "I'm pleased to tell you about a new Denisovan genome from a 200,000-year-old male," said Peyrégne, a postdoc at the Max Planck Institute for Evolutionary Anthropology.

The genetic sequence he unveiled is the oldest high-quality human genome yet — 80,000 years older than the previous record holder: a Neanderthal that lived about 120,000 years ago. The new results come after more than a decade of effort to find fossilized bones and a second genome of a Denisovan, the mysterious archaic human discovered through its DNA 14 years ago. That first Denisovan genome came from a girl's pinkie finger bone dated between 60,000 to 80,000 years ago. The genomes of both Denisovans and the ancient Neanderthal all came from the same cold, fossil-rich site: Denisova Cave in the Altai Mountains of Siberia.

According to the analysis by Peyrégne and colleagues, the newly sequenced male comes from a distinct population of early Denisovans that interbred multiple times with a group of Neanderthals whose population had not been detected in DNA before.

Comment: See also:

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Palette

A scientist's quest to decode Vermeer's true colours

Adnan R. Khan
The Walrus
Tue, 09 Jul 2024 20:37 UTC
vermeer detail love letter
© CopyrightDetail from Johannes Vermeer's painting The Love Letter, c. 1669/70.
New techniques reveal hidden details in the Dutch master's paintings

When Frederik Vanmeert stands in front of a Johannes Vermeer painting, the temptation to go close is irresistible. In Amsterdam's Rijksmuseum, where he works as a heritage scientist, it's not hard to satisfy this craving for intimacy; patrons are free to get personal with the art. Viewers of Rembrandt's The Night Watch can approach within a metre of the canvas, while the museum's four Vermeers, hanging nearby, offer an even more intimate experience. Viewers may, if the moment moves them, lean in within centimetres, though the security guard posted nearby will likely wag a disapproving finger.

Still, even millimetres are an interminable chasm for Vanmeert. He's seen Vermeer's work in finer detail than most — at the microscopic level, down to the crystal latticework of the pigments that structure the language of the seventeenth-century Dutch painter's artistic vision. "These days, because of my work, when I look at a Vermeer, I can't help but wonder: Are we really understanding what he intended?" Vanmeert tells me, approaching The Little Street, one of only two landscapes the artist is known to have painted. "I get drawn closer to, say, this area here — the dark area of the lady's dress. It's difficult to decipher which type of fabric Vermeer meant to depict here, and I wonder if this is the original colour."
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Comet 2

The origins of dark comets


University of Michigan
Wed, 10 Jul 2024 17:54 UTC
Dark Comets
© University of Michigan
Up to 60% of near-Earth objects could be dark comets, mysterious asteroids that orbit the sun in our solar system that likely contain or previously contained ice and could have been one route for delivering water to Earth, according to a University of Michigan study.

The findings suggest that asteroids in the asteroid belt, a region of the solar system roughly between Jupiter and Mars that contains much of the system's rocky asteroids, have subsurface ice, something that has been suspected since the 1980s, according to Aster Taylor, U-M graduate student in astronomy and lead author of the study.

The study also shows a potential pathway for delivering ice into the near-Earth solar system, Taylor says. How Earth got its water is a longstanding question.

"We don't know if these dark comets delivered water to Earth. We can't say that. But we can say that there is still debate over how exactly the Earth's water got here," Taylor said. "The work we've done has shown that this is another pathway to get ice from somewhere in the rest of the solar system to the Earth's environment."

The research further suggests that one large object may come from the Jupiter-family comets, comets whose orbits take them close to the planet Jupiter. The team's results are published in the journal Icarus.
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