Scientists link Neanderthal extinction to human diseases

(THIS ARTICLE IS COURTESY OF PHYSICS.ORG)

 

Scientists link Neanderthal extinction to human diseases

Stanford scientists link Neanderthal extinction to human diseases
Illustration of modern humans overcoming disease burden before Neanderthals. Credit: Vivian Chen Wong

Growing up in Israel, Gili Greenbaum would give tours of local caves once inhabited by Neanderthals and wonder along with others why our distant cousins abruptly disappeared about 40,000 years ago. Now a scientist at Stanford, Greenbaum thinks he has an answer.

In a new study published in the journal Nature Communications, Greenbaum and his colleagues propose that complex  transmission patterns can explain not only how  were able to wipe out Neanderthals in Europe and Asia in just a few thousand years but also, perhaps more puzzling, why the end didn’t come sooner.

“Our research suggests that diseases may have played a more important role in the extinction of the Neanderthals than previously thought. They may even be the main reason why modern humans are now the only human group left on the planet,” said Greenbaum, who is the first author of the study and a postdoctoral researcher in Stanford’s Department of Biology.

The slow kill

Archeological evidence suggests that the initial encounter between Eurasian Neanderthals and an upstart new human species that recently strayed out of Africa—our ancestors—occurred more than 130,000 years ago in the Eastern Mediterranean in a region known as the Levant.

Yet tens of thousands of years would pass before Neanderthals began disappearing and modern humans expanded beyond the Levant. Why did it take so long?

Employing mathematical models of disease transmission and , Greenbaum and an international team of collaborators demonstrated how the unique diseases harbored by Neanderthals and modern humans could have created an invisible disease barrier that discouraged forays into enemy territory. Within this narrow contact zone, which was centered in the Levant where first contact took place, Neanderthals and modern humans coexisted in an uneasy equilibrium that lasted tens of millennia.

Ironically, what may have broken the stalemate and ultimately allowed our ancestors to supplant Neanderthals was the coming together of our two species through interbreeding. The hybrid humans born of these unions may have carried immune-related genes from both species, which would have slowly spread through modern human and Neanderthal populations.

As these protective genes spread, the disease burden or consequences of infection within the two groups gradually lifted. Eventually, a tipping point was reached when modern humans acquired enough immunity that they could venture beyond the Levant and deeper into Neanderthal territory with few health consequences.

At this point, other advantages that modern humans may have had over Neanderthals—such as deadlier weapons or more sophisticated social structures—could have taken on greater importance. “Once a certain threshold is crossed, disease burden no longer plays a role, and other factors can kick in,” Greenbaum said.

Why us?

To understand why modern humans replaced Neanderthals and not the other way around, the researchers modeled what would happen if the suite of tropical diseases our ancestors harbored were deadlier or more numerous than those carried by Neanderthals.

“The hypothesis is that the disease burden of the tropics was larger than the disease burden in temperate regions. An asymmetry of disease burden in the contact zone might have favored modern humans, who arrived there from the tropics,” said study co-author Noah Rosenberg, the Stanford Professor of Population Genetics and Society in the School of Humanities and Sciences.

According to the models, even small differences in disease burden between the two groups at the outset would grow over time, eventually giving our ancestors the edge. “It could be that by the time modern humans were almost entirely released from the added burden of Neanderthal diseases, Neanderthals were still very much vulnerable to modern human diseases,” Greenbaum said. “Moreover, as modern humans expanded deeper into Eurasia, they would have encountered Neanderthal populations that did not receive any protective immune genes via hybridization.”

The researchers note that the scenario they are proposing is similar to what happened when Europeans arrived in the Americas in the 15th and 16th centuries and decimated indigenous populations with their more potent diseases.

If this new theory about the Neanderthals’ demise is correct, then supporting evidence might be found in the archeological record. “We predict, for example, that Neanderthal and modern  population densities in the Levant during the time period when they coexisted will be lower relative to what they were before and relative to other regions,” Greenbaum said.


Explore further

How differences in the genetic ‘instruction booklet’ between humans and Neanderthals influenced traits


More information: Gili Greenbaum et al. Disease transmission and introgression can explain the long-lasting contact zone of modern humans and Neanderthals, Nature Communications (2019). DOI: 10.1038/s41467-019-12862-7

Journal information: Nature Communications
Provided by Stanford University
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The most spectacular celestial vision you’ll never see

(THIS ARTICLE IS COURTESY OF PHYSICS.ORG)

 

The most spectacular celestial vision you’ll never see

The most spectacular celestial vision you'll never see
A simulation of HR 5183b’s brightness in the night sky as compared to Venus, one of the brightest objects visible from Earth. Credit: Teo Mocnik / UCR

Contrary to previous thought, a gigantic planet in wild orbit does not preclude the presence of an Earth-like planet in the same solar system—or life on that planet.

What’s more, the view from that Earth-like planet as its giant neighbor moves past would be unlike anything it is possible to view in our own night skies on Earth, according to new research led by Stephen Kane, associate professor of planetary astrophysics at UC Riverside.

The research was carried out on  in a planetary system called HR 5183, which is about 103 light years away in the constellation of Virgo. It was there that an eccentric giant planet was discovered earlier this year.

Normally, planets  their stars on a trajectory that is more or less circular. Astronomers believe large planets in stable, circular orbits around our sun, like Jupiter, shield us from space objects that would otherwise slam into Earth.

Sometimes, planets pass too close to each other and knock one another off course. This can result in a planet with an elliptical or “eccentric” orbit. Conventional wisdom says that a giant planet in  is like a wrecking ball for its planetary neighbors, making them unstable, upsetting weather systems, and reducing or eliminating the likelihood of life existing on them.

Questioning this assumption, Kane and Caltech astronomer Sarah Blunt tested the stability of an Earth-like planet in the HR 5183 solar system. Their modeling work is documented in a paper newly published in the Astronomical Journal.

Kane and Blunt calculated the giant planet’s  on an Earth analog as they both orbited their star. “In these simulations, the giant planet often had a catastrophic effect on the Earth twin, in many cases throwing it out of the solar system entirely,” Kane said.

“But in certain parts of the planetary system, the gravitational effect of the giant planet is remarkably small enough to allow the Earth-like planet to remain in a stable orbit.”

The team found that the smaller, terrestrial planet has the best chance of remaining stable within an area of the solar system called the —which is the territory around a star that is warm enough to allow for liquid-water oceans on a planet.

These findings not only increase the number of places where life might exist in the  described in this study—they increase the number of places in the universe that could potentially host life as we know it.

This is also an exciting development for people who simply love stargazing. HR 5813b, the eccentric giant in Kane’s most recent study, takes nearly 75 years to orbit its star. But the moment this giant finally swings past its smaller neighbor would be a breathtaking, once-in-a-lifetime event.

“When the giant is at its closest approach to the Earth-like planet, it would be fifteen times brighter than Venus—one of the brightest objects visible with the naked eye,” said Kane. “It would dominate the night sky.”

Going forward, Kane and his colleagues will continue studying planetary systems like HR 5183. They’re currently using data from NASA’s Transiting Exoplanet Survey Satellite and the Keck Observatories in Hawaii to discover new planets, and examine the diversity of conditions under which potentially habitable planets could exist and thrive.


Explore further

Newly discovered giant planet slingshots around its star


More information: Stephen R. Kane et al, In the Presence of a Wrecking Ball: Orbital Stability in the HR 5183 System, The Astronomical Journal (2019). DOI: 10.3847/1538-3881/ab4c3e

Journal information: Astronomical Journal

“Provocative” –Advanced Life in the Dark Side of Our Universe

(THIS ARTICLE IS COURTESY OF THE DAILY GALAXY)

 

“Provocative” –Advanced Life in the Dark Side of Our Universe (Weekend Feature)

 

Dark Matter Life

 

Two of the planet’s leading astrophysicists, Columbia University’s Caleb Scharf and Harvard’s Lisa Randall speculate about the possibility of the dominant dark side of our universe harboring advanced life.

“It’s a thought-provoking idea,” said Scharf, about the possibility that perhaps some advanced life five billion years ago figured out how to activate dark energy via the symmetron field, which is said to pervade space much like the Higgs field, speculates Columbia University’s Caleb Scharf in Nautil.us. Scharf’s speculative conjecture is an idea for the mechanism of an accelerating cosmic expansion called quintessence, a relative of the Higgs field that permeates the cosmos.

One of the great known unknowns of the universe is the nature of dark energy, a force field making the universe expand faster. Current theories range from end-of-the universe scenarios to dark energy as the manifestation of advanced alien life.

On March 2, 2019, The Galaxy posted “Dark Energy –“New Exotic Matter or ET Force Field?” describing a new, controversial theory that suggests that dark energy might be getting stronger and denser, leading to a future in which atoms are torn asunder and time ends.

Dark Matter –“Emerged From an Eon Before the Big Bang”

“Long, long ago, when the universe was only about 100,000 years old — a buzzing, expanding mass of particles and radiation — a strange new energy field switched on,” writes Dennis Overbye for New York Times Science. “That energy suffused space with a kind of cosmic antigravity, delivering a not-so-gentle boost to the expansion of the universe.”

Then, after another 100,000 years or so, the new field simply switched off, leaving no trace other than a sped-up universe says a team of astronomers from Johns Hopkins University led by Adam Riess, a Bloomberg Distinguished Professor and Nobel laureate. In a bold and speculative leap into the past, the team has posited the existence of this field to explain a baffling astronomical puzzle: the universe seems to be expanding faster than it should be.

Dark Energy –“New Exotic Matter or ET Force Field?”

“What we think might be the effects of mysterious forces such as dark energy and dark matter in the Universe, could actually be the influence of alien intelligence – or maybe even aliens themselves,” suggests Scharf in “Mind-Bending” –‘Hyper-Advanced ET May Be What We Perceive to Be Physics’ posted on The Galaxy on Mar 1, 2019.

“Mind-Bending” –‘Hyper-Advanced ET May Be What We Perceive to Be Physics’

“If machines continue to grow exponentially in speed and sophistication, they will one day be able to decode the staggering complexity of the living world, from its atoms and molecules all the way up to entire planetary biomes,” continues Scharf, author of The Copernicus Complex: Our Cosmic Significance in a Universe of Planets and Probabilities, in Nautil.us. “Presumably life doesn’t have to be made of atoms and molecules, but could be assembled from any set of building blocks with the requisite complexity. If so, a civilization could then transcribe itself and its entire physical realm into new forms. Indeed, perhaps our universe is one of the new forms into which some other civilization transcribed its world.”

After all, with our universe 13.5 billion years old, the cosmos may hold other life, and if some of that life has evolved beyond ours in terms of complexity and technology, adds Scharf. “We should be considering some very extreme possibilities. Today’s futurists and believers in a machine “singularity” predict that life and its technological baggage might end up so beyond our ken that we wouldn’t even realize we were staring at it. That’s quite a claim, yet it would neatly explain why we have yet to see advanced intelligence in the cosmos around us, despite the sheer number of planets it could have arisen on—the so-called Fermi Paradox.”

“Perhaps hyper-advanced life isn’t just external. Perhaps it’s already all around. It is embedded in what we perceive to be physics itself, from the root behavior of particles and fields to the phenomena of complexity and emergence,” says Scharf, a research scientist at Columbia University and director of the Columbia Astrobiology Center. “What we think might be the effects of mysterious forces such as dark energy and dark matter in the Universe, could actually be the influence of alien intelligence – or maybe even aliens themselves.”

“Dark Energy’s Known Unknown” — Could It Be the Symmetron Field That Pervades Space Much Like the Higgs Field

Once we start proposing that life could be part of the solution to cosmic mysteries, Scharf concludes, “Although dark-matter life is a pretty exotic idea, it’s still conceivable that we might recognize what it is, even capturing it in our labs one day (or being captured by it). We can take a tumble down a different rabbit hole by considering that we don’t recognize advanced life because it forms an integral and unsuspicious part of what we’ve considered to be the natural world.”

Scharf points out that Arthur C. Clarke suggested that any sufficiently advanced technology is going to be indistinguishable from magic. “If you dropped in on a bunch of Paleolithic farmers with your iPhone and a pair of sneakers,” Scharf says, “you’d undoubtedly seem pretty magical. But the contrast is only middling: The farmers would still recognize you as basically like them, and before long they’d be taking selfies. But what if life has moved so far on that it doesn’t just appear magical, but appears like physics?”

If the universe harbors other life, and if some of that life has evolved beyond our own waypoints of complexity an technology, Scharf proposes that we should be considering some very extreme positions.

Meanwhile up at Harvard, theoretical physicist Lisa Randall, speculates that an invisible civilization could be living right under your nose. In Does Dark Matter Harbor Life she observes that dark matter is the “glue” that holds together galaxies and galaxy clusters, but resides only in amorphous clouds around them. “But what.” asks Randall, “if this assumption isn’t true and it is only our prejudice—and ignorance, which is after all the root of most prejudice—that led us down this potentially misleading path?”

The Standard Model, Randall points out, contains six types of quarks, three types of charged leptons (including the electron), three species of neutrinos, all the particles responsible for forces, as well as the newly discovered Higgs boson. What if the world of dark matter, which matter interacts only negligibly with matter, harbors “a small component of dark matter would interact under forces reminiscent of those in ordinary matter. The rich and complex structure of the Standard Model’s particles and forces gives rise to many of the world’s interesting phenomena. If dark matter has an interacting component, this fraction might be influential too.”

No one had allowed, Randall asserts, for the very simple possibility that although most dark matter doesn’t interact, a small fraction of it might.

Shadow life,” exciting as that would be, won’t necessarily have any visible consequences that we would notice, making it a tantalizing possibility but one immune to observations. In fairness, dark life is a tall order. Science-fiction writers may have no problem creating it, but the universe has a lot more obstacles to overcome. Out of all possible chemistries, it’s very unclear how many could sustain life, and even among those that could, we don’t know the type of environments that would be necessary.

Nonetheless, dark life could in principle be present—even right under our noses. But without stronger interactions with the matter of our world, it can be partying or fighting or active or inert and we would never know. But the interesting thing is that if there are interactions in the dark world—whether or not they are associated with life—the effects on structure might ultimately be measured. And then we will learn a great deal more about the dark world.

Randall suggests that “if we were creatures made of dark matter, we would be very wrong to assume that the particles in our ordinary matter sector were all of the same type. Perhaps we ordinary matter people are making a similar mistake.

“Given the complexity of the Standard Model of particle physics, she observes, which describes the basic components of matter we know of, it seems very odd to assume that all of dark matter is composed of only one type of particle. Why not suppose instead that some fraction of the dark matter experiences its own forces?”

The image at the top of the page shows dark matter filaments bridge the space between galaxies in this false colour map. The locations of bright galaxies are shown by the white regions and the presence of a dark matter filament bridging the galaxies is shown in red. ( S. Epps & M. Hudson / University of Waterloo)

The Daily Galaxy via New YorkerNautil.us and New York Times

What Is the Universe Made of?

(THIS ARTICLE IS COURTESY OF LIVE SCIENCE)

 

What Is the Universe Made of?

Image of galaxy cluster Abell 2744 shows dark matter locations

In this image of galaxy cluster Abell 2744, a blue overlay shows the location of dark matter, which makes up about 75% of the cluster’s mass.
(Image: © NASA/ESA/ESO/CXC, and D. Coe (STScI)/J. Merten (Heidelberg/Bologna))

The universe is filled with billions of galaxies and trillions of stars, along with nearly uncountable numbers of planets, moons, asteroids, comets and clouds of dust and gas – all swirling in the vastness of space.

But if we zoom in, what are the building blocks of these celestial bodies, and where did they come from?

Hydrogen is the most common element found in the universe, followed by helium; together, they make up nearly all ordinary matter. But this accounts for only a tiny slice of the universe — about 5%. All the rest is made of stuff that can’t be seen and can only be detected indirectly. [From Big Bang to Present: Snapshots of Our Universe Through Time]

Mostly hydrogen

It all started with a Big Bang, about 13.8 billion years ago, when ultra-hot and densely packed matter suddenly and rapidly expanded in all directions at once. Milliseconds later, the newborn universe was a heaving mass of neutrons, protons, electrons, photons and other subatomic particles, roiling at about 100 billion degrees Kelvin, according to NASA.

Every bit of matter that makes up all the known elements in the periodic table — and every object in the universe, from black holes to massive stars to specks of space dust — was created during the Big Bang, said Neta Bahcall, a professor of astronomy in the Department of Astrophysical Sciences at Princeton University in New Jersey.

“We don’t even know the laws of physics that would have existed in such a hot, dense environment,” Bahcall told Live Science.

About 100 seconds after the Big Bang, the temperature dropped to a still-seething 1 billion degrees Kelvin. By roughly 380,000 years later, the universe had cooled enough for protons and neutrons to come together and form lithium, helium and the hydrogen isotope deuterium, while free electrons were trapped to form neutral atoms.

Because there were so many protons zipping around in the early universe, hydrogen — the lightest element, with just one proton and one neutron — became the most abundant element, making up nearly 95% percent of the universe’s atoms. Close to 5% of the universe’s atoms are helium, according to NASA. Then, about 200 million years after the Big Bang, the first stars formed and produced the rest of the elements, which make up a fraction of the remaining 1% of all ordinary matter in the universe.

Unseen particles

Something else was created during the Big Bang: dark matter. “But we can’t say what form it took, because we haven’t detected those particles,” Bahcall told Live Science.

Dark matter can’t be observed directly — yet — but its fingerprints are preserved in the universe’s first light, or the cosmic microwave background radiation (CMB), as tiny fluctuations in radiation, Bahcall said. Scientists first proposed the existence of dark matter in the 1930’s, theorizing that dark matter’s unseen pull must be what held together fast-moving galaxy clusters. Decades later, in the 1970’s, American astronomer Vera Rubin found more indirect evidence of dark matter in the faster-than-expected rotation rates of stars.

Based on Rubin’s findings, astrophysicists calculated that dark matter — even though it couldn’t be seen or measured — must make up a significant portion of the universe. But about 20 years ago, scientists discovered that the universe held something even stranger than dark matter; dark energy, which is thought to be significantly more abundant than either matter or dark matter. [Gallery: Dark Matter Throughout the Universe]

Hubble Space Telescope Image

Captured in 2014 by the Hubble Space Telescope, this picture of the evolving universe is among Hubble’s most colorful deep-space images.

(Image credit: NASA/ESA)

An irresistible force

The discovery of dark energy came about because scientists wondered if there was enough dark matter in the universe to cause expansion to sputter out or reverse direction, causing the universe to collapse inward on itself.

Lo and behold, when a team of researchers investigated this in the late 1990s, they found that not only was the universe not collapsing in on itself, it was expanding outward at an ever faster rate. The group determined that an unknown force — dubbed dark energy — was pushing against the universe in the apparent void of space and accelerating its momentum; the scientists’ findings earned physicists Adam Riess, Brian Schmidt and Saul Perlmutter the Nobel Prize in Physics in 2011.

Models of the force required to explain the universe’s accelerating expansion rate suggest that dark energy must make up between 70% and 75% of the universe. Dark matter, meanwhile, accounts for about 20% to 25%, while so-called ordinary matter — the stuff we can actually see — is estimated to make up less than 5% of the universe, Bahcall said.

Considering that dark energy makes up about three-quarters of the universe, understanding it is arguably the biggest challenge facing scientists today, astrophysicist Mario Livio, then with the Space Telescope Science Institute at Johns Hopkins University in Baltimore, Maryland, told Live Science sister site Space.com in 2018.

“While dark energy has not played a huge role in the evolution of the universe in the past, it will play the dominant role in the evolution in the future,” Livio said. “The fate of the universe depends on the nature of dark energy.”

Originally published on Live Science.

Last reversal of the Earth’s magnetic field took twice as long as previously thought

(THIS ARTICLE IS COURTESY OF PHYSICS WORLD)

 

Last reversal of the Earth’s magnetic field took twice as long as previously thought

12 Aug 2019
Geomagnetic field
(Credit: Dormy and Dion)

The last full reversal of the Earth’s geomagnetic field took at least 22,000 years to complete, researchers from the US and Japan have revealed. The finding, which was derived by combining volcanic, sedimentary and ice-core records, suggests that reversals can take several times longer than was previously thought. It also further challenges the notion that a future reversal might be completed within a human lifetime.

The geomagnetic field is produced by the motion of the Earth’s liquid outer core, which acts as a dynamo. Although superficially stable – and presently reliable enough to navigate by – the field does change with time. At present, for example, the magnetic North Pole is in the process of drifting towards Siberia, while the field strength has been decreasing steadily by around 5% for each century since human records began.

Records in the rocks

With magnetically aligned minerals in certain rocks having left us with a record of the magnetic field at the time they were formed, we know that such a weakening can be a precursor to a so-called excursion – in which the magnetic poles shift by up to around 45 degree – or a full blown reversal, in which the field flips and settles upside down. These events, products of growing instabilities in the geodynamo, appear to occur every several hundred thousands years or so.

“Reversals are generated in the deeper parts of the Earth’s interior, but the effects manifest themselves all the way through the Earth,” explains Brad Singer, a geologist at the University of Wisconsin Madison.

Exactly what impact a future reversal might have on human civilization, navigation and communications, however, is unclear. And scientists still don’t understand what causes them, how long a reversal would take, and what the warning signs of one might be.

“Unless you have complete, accurate and high-resolution record of what a field reversal really is like at the surface of the Earth, it’s difficult to even discuss what the mechanics of generating a reversal are,” Singer notes.

Better measurements

To help develop a more accurate picture, Singer and his colleagues took magnetic readings of rock samples from seven lava flows from the Canary Islands, the Caribbean, Chile, Hawaii and Tahiti. They also determined the age of the samples using a newly-enhanced method of potassium-argon radioisotope dating.

“Lava flows are ideal recorders of the magnetic field. They have a lot of iron-bearing minerals and when they cool, they lock in the direction of the field,” says Singer. “But it’s a spotty record. No volcanoes are erupting continuously. So we’re relying on careful field work to identify the right records.”

The team complemented their lava-flow records with two other sources of data on the historic orientation of the geomagnetic field. The first of these were magnetic readings taken from the sea floor, which are less precise than those taken from lava flows – due to variations in sediment rates, weaker magnetization, and biological disruption that can smear the preserved magnetic orientations – but can provide a more continuous record.

Secondly, the researchers took measurements of beryllium deposits across time, as preserved in Antarctic ice cores. Beryllium is produced when cosmos rays hit the atmosphere, which means that periods in which the magnetic field was weaker – and therefore allows more radiation to pass through it – can be identified by increased beryllium in the ice cores.

Combined together, the various records allowed the researchers to piece together the nature of the geomagnetic field over a 70,000-year period centered around the Matuyama-Brunhes reversal – the last time the field completely flipped over, around 784,000 years ago.

Longer reversal

Singer and colleagues found that the final reversal was relatively rapid by geological standards, taking less than 4000 years. However, it was preceded by two individual excursions within a period of instability lasting 18,000 years – more than twice as long as recent research had suggested reversals should take.

“I’ve been working on this problem for 25 years,” said Singer. “And now we have a richer and better-dated record of this last reversal than ever before.”

Andrew Roberts, an earth scientist from the Australian National University who was not involved in the present study, said: “I take these results to indicate that the last magnetic polarity reversal occurred during a prolonged period of time in which Earth’s magnetic field was weak and unstable.”

Roberts also notes that it is still possible that the main reversal occurred rapidly. “There have been other prolonged unstable periods, such the Blake and post-Blake events between 120 and 90 thousand years ago, during which the field has been demonstrated to have changed extremely rapidly.”

Gillian Turner, a geophysicist from the Victoria University of Wellington who also was not involved in the study, agrees: “As the accuracy and resolution of dating both volcanic rocks and sedimentary sequences continues to improve, we should expect to see excursion activity associated with successful polarity reversals more and more often.”

The research is described in the journal Science Advances.

New Hubble Data Breaks Scientists’ Understanding of the Universe

(THIS ARTICLE IS COURTESY OF THE SCIENCE NEWS SITE ‘FUTURISM’)

 

New Hubble Data Breaks Scientists’ Understanding of the Universe

A new attempt to find the universe’s age revealed troubling flaws.

Dan Robitzski 7 hours ago

There may be fundamental flaws with our understanding of the universe.

The problem came to light as scientists tried to calculate and measure a value called the Hubble Constant, which represents how rapidly the universe is expanding outward.

The value was first calculated by astronomer Edwin Hubble in the 1920s. But since then, astronomers observing and measuring the universe’s expansion have arrived at different values of the Hubble Constant, none of which seem to agree with one another. The discrepancy calls into question not only our idea of how old the universe is, but also our ability to fundamentally understand the physics that drive its behavior.

“Naturally, questions arise as to whether the discrepancy is coming from some aspect that astronomers don’t yet understand about the stars we’re measuring, or whether our cosmological model of the universe is still incomplete,” University of Chicago astronomer Wendy Freedman said in a NASA press release. “Or maybe both need to be improved upon.”

Freedman is responsible for the latest measurement of the Hubble Constant, which she calculated using a different kind of cosmic landmark from previous experiments.

Her team measured the brightness of red giant stars in distant galaxies. Because these stars reach uniform size and brightness, their distance from Earth can more readily be calculated than some other stars. Freedman’s work, which has been accepted but not yet published by The Astrophysical Journal, found that the universe is expanding at 69.8 kilometers per second per megaparsec, per the press release.

That’s a slower rate of expansion than was calculated in another recent study that focused on a different kind of star but a faster rate than was calculated in yet another study that measured light leftover from the big bang called the Cosmic Microwave Background.

Freedman originally hoped her research would serve as a tie-breaker between those other two studies — but instead it added yet another, possible value for the Hubble Constant for astronomers to reconcile.

“The Hubble constant is the cosmological parameter that sets the absolute scale, size and age of the universe; it is one of the most direct ways we have of quantifying how the universe evolves,” Freedman said in the press release. “The discrepancy that we saw before has not gone away, but this new evidence suggests that the jury is still out on whether there is an immediate and compelling reason to believe that there is something fundamentally flawed in our current model of the universe.”

Further complicating the issue, statistical analysis validates both of those two previous studies, according to a New Scientist article published last week, before Freedman’s study was announced. There’s just a one-in-3.5 million chance that their findings came from random chance.

In the middle of the next decade, NASA hopes to launch the Wide Field Infrared Survey Telescope into orbit, at which point scientists will be able to more precisely measure the distance of celestial objects, per the press release. When that happens, there’s a chance that astronomers will be able to reconcile their various Hubble Constant values.

“The Hubble constant is the biggest problem in cosmology that we have access to right now, and the hope is that this crack in our understanding is going to lead us to some even bigger cracks like dark energy and dark matter,” Duke University astronomer Daniel Scolnic told New Scientist. “We just have to chase the crack.”

READ MORE: NEW HUBBLE CONSTANT MEASUREMENT ADDS TO MYSTERY OF UNIVERSE’S EXPANSION RATE[NASA]

More on the Hubble Constant: Figuring out How Fast the Universe Is Expanding Might Require a New Type of Physics

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NASA/Victor Tangermann

Scientists are searching for a mirror universe. It could be sitting right in front of you.

(THIS ARTICLE IS COURTESY OF NBC)

 

Scientists are searching for a mirror universe. It could be sitting right in front of you.

If the “mirrorverse” exists, upcoming experiments involving subatomic particles could reveal it.
Illustration of woman holding hands up to a mirrorverse where her reflection is shining back at her.

A mirrorverse could be just as real as our own universe but almost completely cut off from it. Jackson Gibbs / for NBC News

Hubble captures elusive, irregular galaxy

(THIS ARTICLE IS COURTESY OF PHYS.ORG)

 

Hubble captures elusive, irregular galaxy

Hubble captures elusive, irregular galaxy
As an irregular galaxy, IC 10 lacks the majestic shape of spiral galaxies such as the Milky Way, or the rounded, ethereal appearance of elliptical galaxies. It is a faint object, despite its relative proximity to us of 2.2 million light-years. In fact, IC 10 only became known to humankind in 1887, when American astronomer Lewis Swift spotted it during an observing campaign. The small galaxy remains difficult to study even today, because it is located along a line-of-sight which is chock-full of cosmic dust and stars. Credit: NASA, ESA and F. Bauer

This image shows an irregular galaxy named IC 10, a member of the Local Group—a collection of over 50 galaxies in our cosmic neighborhood that includes the Milky Way.

IC 10 is a remarkable object. It is the closest-known , meaning that it is undergoing a furious bout of star formation fueled by ample supplies of cool hydrogen gas. This gas condenses into vast molecular clouds, which then form into dense knots where pressures and temperatures reach a point sufficient to ignite , thus giving rise to new generations of stars.

As an irregular galaxy, IC 10 lacks the majestic shape of spiral galaxies such as the Milky Way, or the rounded, ethereal appearance of elliptical . It is a faint object, despite its relative proximity to us of 2.2 million light-years. In fact, IC 10 only became known to humankind in 1887, when American astronomer Lewis Swift spotted it during an observing campaign. The small galaxy remains difficult to study even today, because it is located along a line-of-sight which is chock-full of cosmic dust and stars.

A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Nikolaus Sulzenauer, and went on to win 10th prize.


Explore further

Hubble takes gigantic image of the Triangulum Galaxy


“One Trillion Times Age Of The Cosmos”–Rarest Thing Ever Detected

(THIS ARTICLE IS COURTESY OF THE ‘DAILY GALAXY’)

 

“One Trillion Times Age of the Cosmos” –Rarest Thing Ever Detected

 

Cluster Abell 3827

 

“We actually saw this decay happen. It’s the longest, slowest process that has ever been directly observed, and our dark matter detector was sensitive enough to measure it,” said Ethan Brown, an assistant professor of physics at Rensselaer Polytechnic Institute. “It’s an amazing to have witnessed this process, and it says that our detector can measure the rarest thing ever recorded.”

How do you observe a process that takes more than one trillion times longer than the age of the universe? The XENON Collaboration research team did it with an instrument built to find the most elusive particle in the universe—dark matter. In a paper to be published tomorrow in the journal Nature, researchers announce that they have observed the radioactive decay of xenon-124, which has a half-life of 1.8 X 1022 years.

The XENON Collaboration runs XENON1T, a 1,300-kilogram vat of super-pure liquid xenon shielded from cosmic rays in a cryostat submerged in water deep 1,500 meters beneath the Gran Sasso mountains of Italy. The researchers search for dark matter by recording tiny flashes of light created when particles interact with xenon inside the detector. And while XENON1T was built to capture the interaction between a dark matter particle and the nucleus of a xenon atom, the detector actually picks up signals from any interactions with the xenon.

Dark Matter –“Emerged From an Eon Before the Big Bang” (Weekend Feature)

The evidence for xenon decay was produced as a proton inside the nucleus of a xenon atom converted into a neutron. In most elements subject to decay, that happens when one electron is pulled into the nucleus. But a proton in a xenon atom must absorb two electrons to convert into a neutron, an event called “double-electron capture.”

Double-electron capture only happens when two of the electrons are right next to the nucleus at just the right time, Brown said, which is “a rare thing multiplied by another rare thing, making it ultra-rare.”

When the ultra-rare happened, and a double-electron capture occurred inside the detector, instruments picked up the signal of electrons in the atom re-arranging to fill in for the two that were absorbed into the nucleus.

“Ultralight” –‘Dark Matter Exists Beyond the Standard Model’

“Electrons in double-capture are removed from the innermost shell around the nucleus, and that creates room in that shell,” said Brown. “The remaining electrons collapse to the ground state, and we saw this collapse process in our detector.”

The achievement is the first time scientists have measured the half-life of this xenon isotope based on a direct observation of its radioactive decay.

“This is a fascinating finding that advances the frontiers of knowledge about the most fundamental characteristics of matter,” said Curt Breneman, dean of the School of Science. “Dr. Brown’s work in calibrating the detector and ensuring that the xenon is scrubbed to the highest possible standard of purity was critical to making this important observation.”

Very Weird Galaxies –“The Absence of Dark Matter is Unprecedented”

The XENON Collaboration includes more than 160 scientists from Europe, the United States, and the Middle East, and, since 2002, has operated three successively more sensitive liquid xenon detectors in the Gran Sasso National Laboratory in Italy. XENON1T, the largest detector of its type ever built, acquired data from 2016 until December 2018, when it was switched off. Scientists are currently upgrading the experiment for the new XENONnT phase, which will feature an active detector mass three times larger than XENON1T. Together with a reduced background level, this will boost the detector’s sensitivity by an order of magnitude.

Three years ago researchers were excited to find that a galaxy at the heart of cluster Abell 3827 shown at the top of the page that appeared to have separated from the dark matter that surrounded it. New research suggests this is incorrect. (Nasa/ESA/Richard Massey)

The Daily Galaxy via Rensselaer Polytechnic Institute

Hubble Peers At Cosmic Blue Bauble

(THIS ARTICLE IS COURTESY OF PHYSICS.ORG AND NASA)

 

Hubble peers at cosmic blue bauble

Hubble peers at cosmic blue bauble
Messier 3: Containing an incredible half-million stars, this 8-billion-year-old cosmic bauble is one of the largest and brightest globular clusters ever discovered. Credit: ESA/Hubble & NASA, G. Piotto et al.

Globular clusters are inherently beautiful objects, but the subject of this NASA/ESA Hubble Space Telescope image, Messier 3, is commonly acknowledged to be one of the most beautiful of them all.

Containing an incredible half-million stars, this 8-billion-year-old cosmic bauble is one of the largest and brightest  ever discovered. However, what makes Messier 3 extra special is its unusually large population of variable stars—stars that fluctuate in brightness over time. New variable stars continue to be discovered in this sparkling stellar nest to this day, but so far we know of 274, the highest number found in any globular cluster by far. At least 170 of these are of a special variety called RR Lyrae variables, which pulse with a period directly related to their intrinsic brightness. If astronomers know how bright a star truly is based on its  and classification, and they know how bright it appears to be from our viewpoint here on Earth, they can thus work out its distance from us. For this reason, RR Lyrae stars are known as standard candles—objects of known luminosity whose  and position can be used to help us understand more about vast celestial distances and the scale of the cosmos.

Messier 3 also contains a relatively high number of so-called , which are shown quite clearly in this Hubble image. These are blue main sequence stars that appear to be young because they are bluer and more luminous than other stars in the . As all stars in globular clusters are believed to have formed together and thus to be roughly the same age, only a difference in mass can give these  a different color. A red, old star can appear bluer when it acquires more mass, for instance by stripping it from a nearby star. The extra mass changes it into a bluer star, which makes us think it is younger than it really is.


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