Physicists Succeed in Making ‘Impossible’ Gamma-Ray Lens || Wired
Lenses are a part of everyday life—they help us focus words on a page, the light from stars, and the tiniest details of microorganisms. But making a lens for highly energetic light known as gamma rays had been thought impossible. Now, physicists have created such a lens, and they believe it will open up a new field of gamma-ray optics for medical imaging, detecting illicit nuclear material, and getting rid of nuclear waste….
The bending in his group’s experiment isn’t much—about a millionth of a degree, which corresponds to a refractive index of about 1.000000001. However, it could be boosted using lenses made of materials with larger nuclei such as gold, which should contain more virtual electron-positron pairs. With some refinement, gamma-ray lenses could be made to focus beams of a specific energy.
Such focused beams could detect radioactive bomb-making material, or radioactive tracers used in medical imaging. That’s because the beams would only scatter off certain radioisotopes, and stream past others unimpeded. The beams could even make new isotopes altogether, by “evaporating” off protons or neutrons from existing samples. That process could turn harmful nuclear waste into a harmless, nonradioactive byproduct.
(Source: eatsomeart, via teganneedsahobby)
How the Bow and Arrow Took Over the World || Danger Room @ Wired
The bow was the first mechanical device that could outpace projectiles thrown by hand, and it was the best weapon humans had during horse-mounted combat—all the way up until the advent of the revolving pistol. It was a pretty huge step in the scheme of weapons development.
Prehistoric cultures—amazingly, independent of one another across the globe—developed bow and arrow sets for hunting and combat. The oldest arrow points, discovered in South Africa, were made of bone and date back some 61,000 years. Pre-medieval people in Africa along with the American Indians and Eskimos had their own versions of the bow and arrow. In Japan, gigantic 8-foot-tall wooden bows were found alongside smaller models crafted from whalebone or horn, and pictures of Japan’s first emperor, Jimmu, who ruled around 660 BC, depict him holding a large bow….
[A]rchery wasn’t just for battle and food. The recreational sport dates back to the Egyptians and Greeks, and the earliest archery societies in England started popping up in the 16th Century. Early archers had to compensate for inaccurate, unsturdy wood models that sent the arrow on a circuitous trip to its target.
“If it’s not stable, the bow will zig zag after the release,” and the arrow will follow, explains Douglas Denton, the project engineer in charge of Hoyt Archery’s line of Olympic-ready bows.
And yet, for most of history, archers put up with this unruly behavior because there was nothing superior. But in the mid-20th century, bow makers found better, more stable materials like laminated wood, plastic and fiberglass. Temperature and humidity didn’t warp these materials and archery became more predictable.
Modern models borrow largely from aerospace innovations. “Limbs,” or the top and bottom fins that extend from the handle, are made of syntactic foam (think tiny, tiny glass balls) in resin that have been covered in carbon fiber—very sturdy. Super-strong bowstrings are made up of stuff like Gore fiber to prevent the instrument from snapping, which was a recurring—and painful—problem until fairly recently.
The most recent leaps in innovation have been in the bow’s geometry. In the last four years, there have been more structural changes in the bow than in the previous 30. In a nutshell, Hoyt rejiggered the way the forces operate within the instrument, so shooting arrows now requires much less effort on the bowman’s part.
[Archery was the one sport I desperately wanted to participate in during sophomore gym class. They tried to put me in driver’s ed during that unit (which made no sense — I wasn’t turning 16 until an entire year later), and I actually sobbed while trying to convince the teacher to switch me over to bows and arrows. Robin Hood and Artemis made a huge impression on me.]
by Alberto Seveso (via Colossal)
Thin Film Physics (in zero gravity)
(by Morgen Nebel; via Dark Roasted Blend)
by Martin Klimas (via butdoesitfloat)
MAGICK!!!
Like How Your Hair Hangs? Praise the Laws of Physics || New York Times
Raymond E. Goldstein, a professor of complex physical systems at the University of Cambridge in England, does not have a ponytail, but he has been pondering the physics of the hairstyle for a couple of years.
He and two other physicists have been trying to determine whether the shape of a ponytail can be deduced from the properties of a single hair. After all, a head with 100,000 strands is a complex physical system, as anyone with a copious coiffure can attest.
And it turns out that there is a simple theory. The crucial characteristics are elasticity, density and curliness, which essentially tell how springy a piece of hair is, plus the length of the ponytail. The researchers came up with a simple formula that describes the ponytail shape when the hair is bundled together.
They called it the Rapunzel number. “We couldn’t resist,” Dr. Goldstein said.
Art+Com’s Kinetic Sculpture (via Wired)
Once Hidden by Forest, Carvings in Land Attest to Amazon’s Lost World || New York Times
According to stunning archaeological discoveries here in recent years, the earthworks on Mr. Araújo’s land and hundreds like them nearby are much, much older — potentially upending the conventional understanding of the world’s largest tropical rain forest.
The deforestation that has stripped the Amazon since the 1970s has also exposed a long-hidden secret lurking underneath thick rain forest: flawlessly designed geometric shapes spanning hundreds of yards in diameter.
Alceu Ranzi, a Brazilian scholar who helped discover the squares, octagons, circles, rectangles and ovals that make up the land carvings, said these geoglyphs found on deforested land were as significant as the famous Nazca lines, the enigmatic animal symbols visible from the air in southern Peru.
“What impressed me the most about these geoglyphs was their geometric precision, and how they emerged from forest we had all been taught was untouched except by a few nomadic tribes,” said Mr. Ranzi, a paleontologist who first saw the geoglyphs in the 1970s and, years later, surveyed them by plane.
For some scholars of human history in Amazonia, the geoglyphs in the Brazilian state of Acre and other archaeological sites suggest that the forests of the western Amazon, previously considered uninhabitable for sophisticated societies partly because of the quality of their soils, may not have been as “Edenic” as some environmentalists contend.
