Jan 18, 2023 04:22 PM
How the periodic table survived a war to secure chemistry’s future
https://www.nature.com/articles/d41586-023-00083-4
INTRO: Hafnium isn’t a particularly remarkable element. It’s not your explosive sodium, shimmering mercury or stinky sulfur. It’s a greyish metal and is commonly used as a neutron absorber in the control rods of nuclear power plants and nuclear submarines, and as an insulator in computer chips. But hafnium’s discovery, which was reported in Nature a century ago this week, was of disproportionate importance. The element was identified by two scientists working in Copenhagen: Dutch physicist Dirk Coster and Hungarian chemist Georg von Hevesy. The find secured not only the periodic table’s legacy but also the future of chemistry. Hafnium also came to represent a hard-won victory against those determined to undermine evidence-based discovery... (MORE - details)
Ancient humans and their early depictions of the universe
https://astronomy.com/news/2023/01/ancie...e-universe
INTRO: In the Lascaux caves of southwestern France, which are famously adorned with 17,000-year-old paintings, the artist’s subject is almost always a large animal.
But hovering above the image of one bull is an unexpected addition: a cluster of small black dots that some scholars interpret as stars. Perhaps it is the eye-catching Pleiades, which Paleolithic hunter-gatherers would have seen vividly in the unpolluted sky.
Claims of prehistoric astronomy are controversial. Even if true, we frequently trace our cosmic perspective instead to Nicolaus Copernicus, who in 1543 set a steady course by proving that Earth revolves around the Sun; to Galileo Galilei and Johannes Kepler, who refined the heliocentric theory a generation later; and to all their successors, who in just a few centuries (with the considerable advantage of telescopes and other advanced technology) have produced an astonishingly detailed map of the universe.
Yet for tens of thousands of years, humans studied the heavens with just the naked eye and, eventually, crude instruments. They got plenty wrong but the stargazers of old weren’t slouches, and by a few thousand years ago they’d become surprisingly sophisticated.
“It is no exaggeration to say that astronomy has existed as an exact science for more than five millennia,” writes the late science historian John North.
Traces of those early observers, of the way they interpreted the cosmos, have reached us in the form of tantalizing artifacts. For example, dating to roughly 1600 B.C., we have what is perhaps the first portrait of the universe: the Nebra Sky Disk.
Unearthed just two decades ago in what is now eastern Germany, this 12-inch bronze circle is inlaid with gold strips in the shape of the Sun (or Full Moon), a crescent Moon, and various stars. It may have been used for religious or agricultural purposes, but its significance to those who made it is unclear.
Deeper meanings aside, experts generally agree the disk is the oldest known concrete depiction of astronomical phenomena, and that it’s more than a vague abstraction. One dense clump of stars seems to represent the Pleiades (and more accurately than the Lascaux cave painting).
If the Seven Sisters keep popping up in different times and places, it might not be coincidence — the cluster has drawn attention throughout recorded history, just by standing out from its solitary neighbors. Some cultures used it as a signal for when to plant and harvest crops.... (MORE - details)
https://www.nature.com/articles/d41586-023-00083-4
INTRO: Hafnium isn’t a particularly remarkable element. It’s not your explosive sodium, shimmering mercury or stinky sulfur. It’s a greyish metal and is commonly used as a neutron absorber in the control rods of nuclear power plants and nuclear submarines, and as an insulator in computer chips. But hafnium’s discovery, which was reported in Nature a century ago this week, was of disproportionate importance. The element was identified by two scientists working in Copenhagen: Dutch physicist Dirk Coster and Hungarian chemist Georg von Hevesy. The find secured not only the periodic table’s legacy but also the future of chemistry. Hafnium also came to represent a hard-won victory against those determined to undermine evidence-based discovery... (MORE - details)
Ancient humans and their early depictions of the universe
https://astronomy.com/news/2023/01/ancie...e-universe
INTRO: In the Lascaux caves of southwestern France, which are famously adorned with 17,000-year-old paintings, the artist’s subject is almost always a large animal.
But hovering above the image of one bull is an unexpected addition: a cluster of small black dots that some scholars interpret as stars. Perhaps it is the eye-catching Pleiades, which Paleolithic hunter-gatherers would have seen vividly in the unpolluted sky.
Claims of prehistoric astronomy are controversial. Even if true, we frequently trace our cosmic perspective instead to Nicolaus Copernicus, who in 1543 set a steady course by proving that Earth revolves around the Sun; to Galileo Galilei and Johannes Kepler, who refined the heliocentric theory a generation later; and to all their successors, who in just a few centuries (with the considerable advantage of telescopes and other advanced technology) have produced an astonishingly detailed map of the universe.
Yet for tens of thousands of years, humans studied the heavens with just the naked eye and, eventually, crude instruments. They got plenty wrong but the stargazers of old weren’t slouches, and by a few thousand years ago they’d become surprisingly sophisticated.
“It is no exaggeration to say that astronomy has existed as an exact science for more than five millennia,” writes the late science historian John North.
Traces of those early observers, of the way they interpreted the cosmos, have reached us in the form of tantalizing artifacts. For example, dating to roughly 1600 B.C., we have what is perhaps the first portrait of the universe: the Nebra Sky Disk.
Unearthed just two decades ago in what is now eastern Germany, this 12-inch bronze circle is inlaid with gold strips in the shape of the Sun (or Full Moon), a crescent Moon, and various stars. It may have been used for religious or agricultural purposes, but its significance to those who made it is unclear.
Deeper meanings aside, experts generally agree the disk is the oldest known concrete depiction of astronomical phenomena, and that it’s more than a vague abstraction. One dense clump of stars seems to represent the Pleiades (and more accurately than the Lascaux cave painting).
If the Seven Sisters keep popping up in different times and places, it might not be coincidence — the cluster has drawn attention throughout recorded history, just by standing out from its solitary neighbors. Some cultures used it as a signal for when to plant and harvest crops.... (MORE - details)