Baby planets marinate in a life-giving cyanide ‘soup,’ analysis reveals

Published on October 16, 2021Written by livescience.com

The universe may be teeming with the molecules needed for life, a new study finds.

The results come from the most comprehensive maps ever made of the types and locations of chemicals in the gas and dust surrounding newborn stars.
Stars spring from enormous clouds of gas and dust, which collapse under their own weight into disk-like structures. The centers of these disks heat up through friction and increased pressure until they ignite into fusion-powered stars, while the surrounding matter slowly clumps together into ever-larger chunks.

“We have known for some time that planets form in disks around young stars and that these disks contain molecules of interest for predicting the future compositions of planets,” Karin Öberg, an astrochemist at Harvard University in Cambridge, Massachusetts, told Live Science.
A few years ago, Öberg and her colleagues decided to use the Atacama Large Millimeter/submillimeter Array (ALMA), a telescope in Chile that sees in the radio part of the electromagnetic spectrum, as a part of the Molecules with ALMA at Planet-forming Scales (MAPS) program. Because of their shapes and the bonds inside them, different chemicals vibrate in unique ways, producing telltale signatures that ALMA can capture, according to ALMA scientists.
The team looked at five protoplanetary disks, all between 1 million and 10 million years old, within a few hundred light-years of Earth. “That means they are in an actively planet-forming epoch,” Öberg said.
MAPS determines not only the specific molecules in protoplanetary disks but also their locations. “Planets can form at many different distances from the star,” Öberg said, so it’s important to know what chemicals are available in each location to build these future planets.
An astounding 20 papers from this extensive mapping project are being published in a special future issue of The Astrophysical Journal Supplement Series; the first of these papers was made available on the preprint server arXiv on Sept. 15.
“What’s so awesome is that there are several pieces rather than one big answer,” Öberg said. “I think all 20 papers provide some different piece of the puzzle.”
One of the most exciting findings for her was the abundance and distribution of a class of molecules known as cyanides. The simplest member of this family, hydrogen cyanide, is typically considered a poison, though many theories for the origin of life include a major role for this chemical class, she said.
“Seeing them in large abundance means planets are forming in the kind of soup we’d like to see” in order to fuel the emergence of life, Öberg added.
Cyanides also tended to be concentrated toward the inner parts and midplanes of the disks studied by MAPS — exactly where planets are expected to arise, she said.
Such molecules could form only in a low-oxygen environment with lots of carbon, Öberg added. This suggests that planets will be born with carbon-rich atmospheres, another point in favor of living things, since carbon is the basis of organic chemistry.
The results show that at least some of the organic building blocks of life are probably available in other stellar systems, but that doesn’t necessarily make it more likely for humanity to find living organisms elsewhere.
“It’s promising from an origin-of-life point of view,” Öberg said. “But there’s still a lot of work to do.”
Living creatures would have needed a certain subset of chemicals in specific amounts in order to arise spontaneously, and scientists have yet to agree on what that recipe for life was.
There has been a lot of past effort into understanding the chemistry in the clouds that give rise to stars, as well as into analyzing the molecules in asteroids and comets, which can contain information about later periods of planetary formation, said Kathrin Altwegg, a planetary scientist at the University of Bern in Switzerland who was not involved in the new work.
“But there was one stage missing,” Altwegg told Live Science — the stage that determined the chemistry in protoplanetary disks, and the results from this project are now helping to fill in unexplored details.
The findings also imply that a great deal of complex chemical formation already takes place prior to the birth of stars and planets, suggesting that these molecules come from interstellar clouds and are, therefore, widespread in space, she added.
See more here: livescience.com
Header image: Astronomy Magazine
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What if the universe had no beginning?

Published on October 16, 2021Written by livescience.com

In the beginning, there was … well, maybe there was no beginning. Perhaps our universe has always existed — and a new theory of quantum gravity reveals how that could work.

“Reality has so many things that most people would associate with sci-fi or even fantasy,” said Bruno Bento, a physicist who studies the nature of time at the University of Liverpool in the U.K.

In his work, he employed a new theory of quantum gravity, called causal set theory, in which space and time are broken down into discrete chunks of space-time. At some level, there’s a fundamental unit of space-time, according to this theory.
Bento and his collaborators used this causal-set approach to explore the beginning of the universe. They found that it’s possible that the universe had no beginning — that it has always existed into the infinite past and only recently evolved into what we call the Big Bang.
A quantum of gravity
Quantum gravity is perhaps the most frustrating problem facing modern physics. We have two extraordinarily effective theories of the universe: quantum physics and general relativity. Quantum physics has produced a successful description of three of the four fundamental forces of nature (electromagnetism, the weak force and the strong force) down to microscopic scales. General relativity, on the other hand, is the most powerful and complete description of gravity ever devised.
But for all its strengths, general relativity is incomplete. In at least two specific places in the universe, the math of general relativity simply breaks down, failing to produce reliable results: in the centers of black holes and at the beginning of the universe. These regions are called “singularities,” which are spots in space-time where our current laws of physics crumble, and they are mathematical warning signs that the theory of general relativity is tripping over itself. Within both of these singularities, gravity becomes incredibly strong at very tiny length scales.
As such, to solve the mysteries of the singularities, physicists need a microscopic description of strong gravity, also called a quantum theory of gravity. There are lots of contenders out there, including string theory and loop quantum gravity.
And there’s another approach that completely rewrites our understanding of space and time.
Causal set theory
In all current theories of physics, space and time are continuous. They form a smooth fabric that underlies all of reality. In such a continuous space-time, two points can be as close to each other in space as possible, and two events can occur as close in time to each other as possible.
But another approach, called causal set theory, reimagines space-time as a series of discrete chunks, or space-time “atoms.” This theory would place strict limits on how close events can be in space and time, since they can’t be any closer than the size of the “atom.”
For instance, if you’re looking at your screen reading this, everything seems smooth and continuous. But if you were to look at the same screen through a magnifying glass, you might see the pixels that divide up the space, and you’d find that it’s impossible to bring two images on your screen closer than a single pixel.
This theory of physics excited Bento. “I was thrilled to find this theory, which not only tries to go as fundamental as possible — being an approach to quantum gravity and actually rethinking the notion of space-time itself — but which also gives a central role to time and what it physically means for time to pass, how physical your past really is and whether the future exists already or not,” Bento told Live Science.
Beginning of time
Causal set theory has important implications for the nature of time.
“A huge part of the causal set philosophy is that the passage of time is something physical, that it should not be attributed to some emergent sort of illusion or to something that happens inside our brains that makes us think time passes; this passing is, in itself, a manifestation of the physical theory,” Bento said. “So, in causal set theory, a causal set will grow one ‘atom’ at a time and get bigger and bigger.”
The causal set approach neatly removes the problem of the Big Bang singularity because, in the theory, singularities can’t exist. It’s impossible for matter to compress down to infinitely tiny points — they can get no smaller than the size of a space-time atom.
So without a Big Bang singularity, what does the beginning of our universe look like? That’s where Bento and his collaborator, Stav Zalel, a graduate student at Imperial College London, picked up the thread, exploring what causal set theory has to say about the initial moments of the universe. Their work appears in a paper published Sept. 24 to the preprint database arXiv. (The paper has yet to be published in a peer-reviewed scientific journal.)
The paper examined “whether a beginning must exist in the causal set approach,” Bento said. “In the original causal set formulation and dynamics, classically speaking, a causal set grows from nothing into the universe we see today. In our work instead, there would be no Big Bang as a beginning, as the causal set would be infinite to the past, and so there’s always something before.”
Their work implies that the universe may have had no beginning — that it has simply always existed. What we perceive as the Big Bang may have been just a particular moment in the evolution of this always-existing causal set, not a true beginning.
There’s still a lot of work to be done, however. It’s not clear yet if this no-beginning causal approach can allow for physical theories that we can work with to describe the complex evolution of the universe during the Big Bang.
“One can still ask whether this [causal set approach] can be interpreted in a ‘reasonable’ way, or what such dynamics physically means in a broader sense, but we showed that a framework is indeed possible,” Bento said. “So at least mathematically, this can be done.”
In other words, it’s … a beginning.
See more here: livescience.com
Header image: Science News
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New Study: Melting ‘glue’ Explains World’s Largest Iceberg Doom

Published on October 8, 2021Written by livescience.com

The thinning of an icy “glue” that holds fractured ice together may drive ice shelf collapse in Antarctica, according to a new study.

Ice shelves are massive stretches of ice that build up over many thousands of years, Live Science previously reported. But warming air and rising ocean temperatures have been driving ice shelves to disintegrate. Many of Antarctica’s ice shelves have fractured or collapsed in the past couple of decades, according to the new study, but exactly what’s accelerating the ice loss has been unclear.

To figure this out, a group of glaciologists zoomed in on rifts on Antarctica’s Larsen C Ice Shelf, which calved a Delaware-size iceberg called A68 in July 2017.
The split of A68, an iceberg approximately 2,240 square miles (5,800 square kilometers) in area, reduced the size of Larsen C by 12 percent, Live Science previously reported. Larsen C is the third ice shelf on Antarctica’s western peninsula to undergo massive ice loss in the past two decades.
The prevailing theory was that these splits were happening due to a process known as hydrofracturing, in which pools of melted ice on the surface of ice shelves seep through the cracks and expand once they freeze again, co-author Eric Rignot, a professor of Earth system science at the University of California, Irving, said in a statement. “But that theory fails to explain how iceberg A68 could break from the Larsen C ice shelf in the dead of the Antarctic winter when no melt pools were present.”
Rignot and his colleagues analyzed hundreds of rifts, or fractures, in the Larsen C Ice Shelf, using a model of ice sheets and sea level changes developed by NASA, as well as data from satellites and research aircraft. They zoomed in on 11 cracks and modeled three melting scenarios.
Two out of the three scenarios focused on the role of “melange,” a mix of windblown snow, frozen seawater and ice shelf fragments that exists inside and around rifts and typically works to seal the fractures, according to the statement.
In the first scenario, the glaciologists modeled what would happen if the ice shelf thinned due to melting; in the second, they modeled what would happen if the ice melange thinned; and in the third, they modeled what would happen if both the ice shelf and the melange thinned. Their simulations showed that the thinning of the melange controlled the rate at which the rift opened.
If the ice shelf thinned but the melange remained just as thick, the rift widening slowed down with time. In other words, the melange acted as a “healing” glue, fusing parts of the cracks. If both the ice shelf and the melange thinned, rift widening also slowed but not as much as it did in the first scenario. If the ice shelf remained the same but the melange thinned, as in the third scenario, the average annual rate of the rift widening increased from 249 to 367 feet (76 to 112 meters).
Just like sea ice, melange is vulnerable to the effects of warming oceans and rising air temperatures. “The melange is thinner than ice to begin with,” lead author Eric Larour, NASA Jet Propulsion Laboratory research scientist said in the statement.
Just 32 to 66 feet (10 to 20 m) of melange thinning is enough to reactivate a rift, or start to unzip it and trigger a major calving event, the authors wrote in the study. Reactivating a rift can trigger ice shelves to retreat decades before water ponding would cause hydrofractures on the ice sheet surface, they wrote.
“The thinning of the ice melange that glues together large segments of floating ice shelves is another way climate change can cause rapid retreat of Antarctica’s ice shelves,” Rignot said. “With this in mind, we may need to rethink our estimates about the timing and extent of sea level rise from polar ice loss — i.e., it could come sooner and with a bigger bang than expected.”
The findings were published online Sept. 27 in the journal Proceedings of the National Academy of Sciences.
See more here: livescience.com
Header image: Beck / NASA Operation IceBridge
Bold emphasis added
Editor’s note: I get the impression we are now supposed to believe ‘climate change’ is the ONLY cause of iceberg calving.
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Cave Sealed By Sand one of last Neanderthal refuges?

Published on October 7, 2021Written by livescience.com

A cave chamber sealed off by sand for some 40,000 years has been discovered in Vanguard Cave in Gibraltar — a finding that could reveal more about the Neanderthals who lived in the area around that time.

“Given that the sand sealing the chamber was [40,000] years old, and that the chamber was therefore older, it must have been Neanderthals,” who lived in Eurasia from about 200,000 to 40,000 years ago and were likely using the cave, Clive Finlayson, director of the Gibraltar National Museum, told Live Science in an email.
While Finlayson’s team was studying the cave last month, they discovered the hollow area.
After climbing through it, they found it is 43 feet (13 meters) in length, with stalactites hanging like eerie icicles from the chamber ceiling.
Along the surface of the cave chamber, the researchers found the remains of lynx, hyenas and griffon vultures, as well as a large whelk, a type of sea snail that was likely carried into the chamber by a Neanderthal, the archaeologists said in a statement.
The researchers are eager to see what they will find once they start excavating.
One possibility is that the team will discover Neanderthal burials, Finlayson said.
“We found the milk tooth of a 4-year-old Neanderthal close to the chamber four years ago,” he said. The tooth “was associated with hyenas, and we suspect the hyenas brought the child [who was likely dead] into the cave.”
Researchers have discovered plenty of evidence of Neanderthals’ presence in the cave system, called the Gorham’s Cave Complex, including a carving that may have been early Neanderthal artwork.
In addition, findings have suggested that, at this cave system, our closest extinct relatives butchered seals, plucked feathers off birds of prey to wear as ornaments and used tools, Live Science previously reported.
Scientists have speculated that this cave system may have been one of the last places Neanderthals lived before they went extinct around 40,000 years ago.
See more here: livescience.com
Header image: Gibraltar National Museum
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