2993: Mercury Transit on Monday: The Gear You Need to Watch It Safely

SCIENCE

Mercury will pass across the face of the sun Monday (Nov. 11) in its first such “transit” since 2016.

The Mercury transit — which begins Monday at 7:35 a.m. EST (1235 GMT) and ends at 1:02 p.m. EST (1804 GMT) — is accessible to amateur astronomers, as long as they have the right equipment to view the event safely. (Warning: Never look directly at the sun without protection; serious and permanent eye damage can result.)

Here’s a brief rundown of the ways you can safely watch the transit, either first-hand or live online.

Related: Mercury Transit 2019: Where and How to See It on Nov. 11

Projecting the image

Mercury is so small that projecting the image using a simple pinhole camera, as many observers do to view solar eclipses, will not produce good results; it’s likely you won’t be able to see anything at all. Instead, you can project the image using binoculars, refractors or small Newtonian telescopes. (Schmidt-Cassegrain and Maksutov designs can’t be used for this, because of the risk of damage.)

Put a low-power eyepiece into your telescope — one that you don’t mind losing if the sun’s heat cracks it. Do not look through the eyepiece or the finder scope. Instead, align the telescope using its shadow on the ground. The more closely aligned the scope is to the sun, the darker and more circular its shadow will appear, according to the British Astronomical Association (BAA).

Take a piece of white paper and hold it about 1 foot (30 centimeters) away from the eyepiece to see the image. You may need to wiggle the telescope a bit to get a good view.

Physics lecturer Mohammad Baqir and his pet duck observed the May 9, 2016 Mercury transit using safe projection techniques.
(Image credit: Mohammad Baqir )

Binoculars or telescopes

You can also outfit your binoculars or telescope with solar filters to view the transit. The type of solar filter depends on your equipment, so check with the manufacturer to see what’s approved.

Alternatively, you can make your own filters using a sheet of Mylar or Baader AstroSolar Film. Just be sure that the homemade filter is securely over the front end of your binoculars or telescope, with no cracks.

“It is essential that the filter fixes very securely to your telescope, that it is undamaged, and that it is designed for safe use with your telescope,” the BAA officials wrote in a press release. “Only buy from reputable suppliers you trust, and thoroughly inspect your filters for damage every time you use them.”

Filters designed for eyepieces should never be used because they are “of suspect quality” and often crack when exposed to the sun’s heat, the BAA added.

A student uses his smartphone and a photographers lens with a solar filter to capture a photo of the planet Mercury transiting the sun on May 9, 2016.
(Image credit: Bill Ingalls/NASA)

Community telescopes

Many museums or amateur astronomy organizations are holding special public events for the Mercury transit. So if you don’t have your own gear, check the nearest science museum or astronomy club to see if they are going to set something up somewhere in your community.

You can find the nearest astronomy club in your area here.

Watching online

Another option is to watch the transit from wherever you happen to be that day, which is especially handy if you are stuck at work or school. Space.com will show live webcasts from Slooh and the Virtual Telescope Project.

The Slooh online observatory will begin streaming live views of the Mercury transit from telescopes around the world at 7:30 a.m. EST (1230 GMT). You can watch it live here on Space.com or directly via Slooh’s YouTube channel.

At the same time, astrophysicist Gianluca Masi of the Virtual Telescope Project in Italy will also stream live telescope views of the transit. You can watch the free webcast live here.

Meanwhile, NASA will post real-time images from its Solar Dynamics Observatory at mercurytransit.gsfc.nasa.gov/2019.

Editor’s note: Visit Space.com on Monday to see live webcast views of the rare Mercury transit from Earth and space, and for complete coverage of the celestial event. If you SAFELY capture a photo of the transit of Mercury and would like to share it with Space.com and our news partners for a story or gallery, you can send images and comments in to managing editor Tariq Malik at spacephotos@space.com.

This article was originally posted on May 6, 2016 for the previous Mercury transit and has been updated for 2019.

Follow Elizabeth Howell @howellspace. Follow Space.com on Twitter @Spacedotcom and on Facebook.

livescience
By Elizabeth Howell – Live Science Contributor
08/11/2019

 

Physicists Can Finally Peek at Schrödinger’s Cat Without Killing It Forever

SCIENCE

At last we can sneak a peek at the dead-and-alive cat.

(Image: © Shutterstock)

There may be a way of sneaking a peak at Schrödinger’s cat — the famous feline-based thought experiment that describes the mysterious behavior of subatomic particles — without permanently killing the (hypothetical) animal.

The unlucky, imaginary cat is simultaneously alive and dead inside a box, or exists in a superposition of “dead” and “alive” states, just as subatomic particles exist in a superposition of many states at once. But looking inside the box changes the state of the cat, which then becomes either alive or dead.

Now, however, a study published Oct. 1 in the New Journal of Physics describes a way to potentially peek at the cat without forcing it to live or die. In doing so, it advances scientists’ understanding of one of the most fundamental paradoxes in physics.

Related: The 18 Biggest Unsolved Mysteries in Physics

In our ordinary, large-scale world, looking at an object doesn’t seem to change it. But zoom in enough, and that’s not the case.

“We normally think the price we pay for looking is nothing,” said study lead author Holger F. Hofmann, associate professor of physics at Hiroshima University in Japan. “That’s not correct. In order to look, you have to have light, and light changes the object.” That’s because even a single photon of light transfers energy away from or to the object you’re viewing.

Hofmann and Kartik Patekar, who was a visiting undergraduate student at Hiroshima University at the time and is now at the Indian Institute of Technology Bombay, wondered if there was a way to look without “paying the price.” They landed on a mathematical framework that separates the initial interaction (looking at the cat) from the readout (knowing whether it’s alive or dead).

“Our main motivation was to look very carefully at the way that a quantum measurement happens,” Hofmann said. “And the key point is that we separate the measurement in two steps.”

By doing so, Hoffman and Patekar are able to assume that all the photons involved in the initial interaction, or peek at the cat, are captured without losing any information about the cat’s state. So before the readout, everything there is to know about the cat’s state (and about and how looking at it changed it) is still available. It’s only when we read out the information that we lose some of it.

“What is interesting is that the readout process selects one of the two types of information and completely erases the other,” said Hofmann.

Here’s how they described their work in terms of Schrödinger’s cat. Say the cat is still in the box, but rather than looking inside to determine whether the cat is alive or dead, you set up a camera outside the box that can somehow take a picture inside of it (for the sake of the thought experiment, ignore the fact that physical cameras don’t actually work like that). Once the picture is taken, the camera has two kinds of information: how the cat changed as a result of the picture being taken (what the researchers call a quantum tag) and whether the cat is alive or dead after the interaction. None of that information has been lost yet. And depending on how you choose to “develop” the image, you retrieve one or the other piece of information.

Think of a coin flip, Hofmann told Live Science. You can choose to either know if a coin was flipped or if it’s currently heads or tails. But you can’t know both. What’s more, if you know how a quantum system was changed, and if that change is reversible, then it’s possible to restore its initial state. (In the case of the coin, you would flip it back.)

“You always have to disturb the system first, but sometimes you can undo it,” Hofmann said. In terms of the cat, that would mean taking a picture, but instead of developing it to see the cat clearly, developing it in such a way as to restore the cat back to its dead-and-alive limbo state.

Crucially, the choice of readout comes with a trade-off between the resolution of the measurement and its disturbance, which are exactly equal, the paper demonstrates. The resolution refers to how much information is extracted from the quantum system, and the disturbance refers to how much the system is irreversibly changed. In other words, the more you know about the cat’s current state, the more you have irretrievably altered it.

“What I found surprising is that the ability to undo the disturbance is directly related to how much information you get about the observable,” or the physical quantity they’re measuring, Hofmann said. “The mathematics is pretty exact here.”

Though previous work has pointed to a trade-off between resolution and disturbance in a quantum measurement, this paper is the first to quantify the exact relationship, Michael Hall, a theoretical physicist at Australian National University, told Live Science in an email.

“As far as I know, no previous results have the form of an exact equality relating resolution and disturbance,” said Hall, who was not involved in the study. “This makes the approach in the paper very neat.”

Originally published on Live Science.
By Dana Najjar – Live Science Contributor
07/11/2019

 

The World’s Thickest Mountain Glacier Is Finally Melting, and Climate Change Is 100% to Blame

SCIENCE/CLIMATE CHANGE

Taku Glacier in Alaska can be seen holding strong in this satellite image captured in August 2014.
(Image: © NASA Earth Observatory)

Massive and meaty, the Taku Glacier in Alaska’s Juneau Icefield was a poster child for the frozen places holding their own against climate change. As the largest of 20 major glaciers in the region and one of the single thickest glaciers in the world (it measures 4,860 feet, or 1,480 meters, from surface to floor), Taku had been demonstrably gaining mass and spreading farther into the nearby Taku river for nearly half a century, while all of its neighboring glaciers shrank. Now, it appears those glory days are over.

In a new pair of satellite photos shared by NASA’s Earth Observatory, the slow decline of Taku Glacier has finally become apparent. Taken in August 2014 and August 2018, the photos show the icy platforms where the glacier meets the river retreating for the first time since scientists began studying Taku, in 1946.

Fragmenting ice and a retreating snow line reveals that Taku Glacier has finally succumbed to climate change in this satellite image snapped in August 2019.
(Image credit: NASA Earth Observatory)

While the shrinkage is subtle for now, the results are nonetheless shocking. According to glaciologist Mauri Pelto, who has studied the Juneau Icefield for three decades, Taku was predicted to continue advancing for the rest of the century. Not only have these signs of retreat arrived about 80 years ahead of schedule, Pelto said, but they also snuff a symbolic flicker of hope in the race to understand climate change. Of 250 mountain (or “alpine”) glaciers that Pelto has studied around the world, Taku was the only one that hadn’t clearly started to retreat.

Related: Photographic Proof of Climate Change: Time-Lapse Images of Retreating Glaciers

“This is a big deal for me because I had this one glacier I could hold on to,” Pelto, a professor at Nichols College in Massachusetts, told NASA. “But not anymore. This makes the score climate change: 250 and alpine glaciers: 0.”

Pelto discovered Taku Glacier’s retreat as part of a new study published Oct. 14 in the journal Remote Sensing. Using satellite data, Pelto looked at a region of the glacier known as the transient snow line, or the place where snow disappears and bare glacial ice begins. If a glacier loses more mass to melting than it gains from snow accumulation during a particular year, its snow line moves to higher altitudes. The relative position of this line can help researchers calculate changes in the glacier’s mass from year to year.

Historical records show that between 1946 to 1988, Taku Glacier had been gaining mass and advancing (that is, growing) by about a foot per year. After that, the advancement began to slow and the ice started to thin a bit. From 2013 to 2018, advancement stopped altogether — then, in 2018, the glacier finally started to retreat. In that year, Pelto observed the greatest mass loss and the highest snow line in Taku glacier’s history. Those changes coincided with the warmest July on record in Juneau, Pelto wrote.

While it was inevitable for even a glacier as thick as Taku to transition eventually from a period of advancement to one of retreat, those transitions generally result after decades of stability where the glacier’s edge does not move at all. Taku’s transition from growth to decay, meanwhile, seems to have lasted only a few years.

“To be able to have the transition take place so fast indicates that climate is overriding the natural cycle of advance and retreat that the glacier would normally be going through,” Pelto said.

Originally published on Live Science.
By Brandon Specktor – Senior Writer

 

Earth’s Mantle and Crust Are in a Fiery Battle to the Death … of Supercontinents

SCIENCE

(Image: © Shutterstock)

Earth’s hot, gooey center and its cold, hard outer shell are both responsible for the creeping (and sometimes catastrophic) movement of tectonic plates. But now new research reveals an intriguing balance of power — the oozing mantle creates supercontinents while the crust tears them apart.

To come to this conclusion about the process of plate tectonics, the scientists created a new computer model of Earth with the crust and mantle considered as one seamless system. Over time, about 60% of tectonic movement at the surface of this virtual planet was driven by fairly shallow forces — within the first 62 miles (100 kilometers) of the surface. The deep, churning convection of the mantle drove the rest. The mantle became particularly important when the continents got pushed together to form supercontinents, while the shallow forces dominated when supercontinents broke apart in the model.

This “virtual Earth” is the first computer model that “views” the crust and mantle as an interconnected, dynamic system, the researchers reported Oct. 30 in the journal Science Advances. Previously, researchers would make models of heat-driven convection in the mantle that matched observations of the real mantle pretty well, but didn’t mimic the crust. And models of the plate tectonics in the crust could predict real-world observations of how these plates move, but didn’t mesh well with observations of the mantle. Clearly, something was missing in the way that models put the two systems together.

Related: In Photos: Ocean Hidden Beneath Earth’s Surface

“Convection models were good for the mantle, but not plates, and plate tectonics was good for plates but not the mantle,” said Nicolas Coltice, a professor at the Ecole Normale Supérieure graduate school, part of PSL University in Paris. “And the whole story behind the evolution of the system is the feedback between the two.”

Crust plus mantle

Every grade-school model of Earth’s interior shows a thin layer of crust riding atop the hot, deformable layer of the mantle. This simplified model might give the impression that the crust is simply surfing the mantle, being moved this way and that by the inexplicable currents below.

But that isn’t quite right. Earth scientists have long known that the crust and mantle are part of the same system; they’re inescapably linked. That understanding has raised the question of whether forces at the surface — such as the subduction of one chunk of crust under another — or forces deep in the mantle are primarily driving the movement of the plates that make up the crust. The answer, Coltice and his colleagues found, is that the question is ill-posed. That’s because the two layers are so intertwined, they both make a contribution.

Over the past two decades, Coltice told Live Science, researchers have been working toward computer models that could represent the crust-mantle interactions realistically. In the early 2000s, some scientists developed models of heat-driven movement (convection) in the mantle that naturally gave rise to something that looked like plate tectonics on the surface. But those models were labor-intensive and didn’t get a lot of follow-up work, Coltice said.

Related: Earth’s 8 Biggest Mysteries

Coltice and his colleagues worked for eight years on their new version of the models. Just running the simulation alone took 9 months.

Building a model Earth

Coltice and his team had to first create a virtual Earth, complete with realistic parameters: everything from heat flow to the size of tectonic plates to the length of time it typically takes for supercontinents to form and come apart.

There are many ways in which the model isn’t a perfect mimic of Earth, Coltice said. For example, the program doesn’t keep track of previous rock deformation, so rocks that have deformed before aren’t prone to deform more easily in the future in their model, as might be the case in real life. But the model still produced a realistic-looking virtual planet, complete with subduction zones, continental drift and oceanic ridges and trenches.

Related: Earth Has a Hidden 8th Continent, Geologists Say

Beyond showing that mantle forces dominate when continents come together, the researchers found that hot columns of magma called mantle plumes are not the main reason that continents break apart. Subduction zones, where one chunk of crust is forced under another, are the drivers of continental break-up, Coltice said. Mantle plumes come into play later. Pre-existing rising plumes may reach surface rocks that have been weakened by the forces created at subduction zones. They then insinuate themselves into these weaker spots, making it more likely for the supercontinent to rift at that location.

The next step, Coltice said, is to bridge the model and the real world with observations. In the future, he said, the model could be used to explore everything from major volcanism events to how plate boundaries form to how the mantle moves around in relation to Earth’s rotation.

Originally published on Live Science.

By Stephanie Pappas – Live Science Contributor
07/11/2019

 

2976: The Curiosity Rover Just Took a Very Emo Photo of Its Rocky Martian Prison

SCIENCE

The Curiosity rover is looking for life on a bleak mountain in the middle of a crater, and it wants us all to feel its struggle.

Meanwhile, on the edge of a mountain in the middle of a crater on Mars…
(Image: © NASA/JPL-Caltech)

Mars is the only known planet in the universe inhabited solely by robots. There’s InSight, the sturdy robo-stethoscope listening for the Red Planet’s heartbeat; there’s Odyssey and the gang, a cadre of droids surveilling the planet from orbit. And then, climbing a lonely crater hundreds of miles away from its companions, there’s Curiosity, the last surviving rover on Mars.

About the size of an SUV and capable of traveling 100 feet (30 meters) per hour, Curiosity has been exploring the 3.5-billion-year-old pit called Gale Crater since landing there in 2012. Now, Curiosity is climbing the mountain, known as Mount Sharp or Aeolis Mons, at the crater’s center. In a bleak and beautiful photo taken on the 2,573rd Martian day of Curiosity’s mission (Nov. 1), the rover showed off the vast emptiness of this rocky domain.

In the new picture, posted to NASA’s Mars mission website, a debris-strewn butte curves up toward the mountain’s side while an enormous ridge of hazy rock looms in the background. That ridge is actually the rim of Gale Crater, fencing the rover in for about 50 miles (80 kilometers) in every direction.

The photo was taken from Curiosity’s back, showing the bleak horizon that the rover leaves behind as it begins its slow ascent from Mount Sharp’s base. It’s a lonely scene, to be sure, but Curiosity is looking for new friends all the time; one of the rover’s primary objectives is finding evidence that Mars could (or once did) support microbial life.

The rover hasn’t stumbled upon any native Martians (yet), but it has found plenty of evidence of past water and traces of elements like hydrogen, oxygen, phosphorus and carbon — all considered “building blocks” of life. Hopefully, the crust of sediment lining Mount Sharp will reveal more clues about how and when ancient water once flowed through the crater. In the meantime, it’s a fine place to stop and enjoy the scenery. As you can see, there’s no shortage of it.

Originally published on Live Science.
Livescience
By Brandon Specktor – Senior Writer
05/11/2019

 

2963: The Universe Might Be a Giant Loop

SCIENCE

What shape is space?

Early data from the Planck collaboration maps the cosmic microwave background across the sky.
(Image: © ESA and the Planck Collaboration)

Everything we think we know about the shape of the universe could be wrong. Instead of being flat like a bedsheet, our universe may be curved, like a massive, inflated balloon, according to a new study.

That’s the upshot of a new paper published today (Nov. 4) in the journal Nature Astronomy, which looks at data from the cosmic microwave background (CMB), the faint echo of the Big Bang. But not everyone is convinced; the new findings, based on data released in 2018, contradict both years of conventional wisdom and another recent study based on that same CMB data set.

Related: From Big Bang to Present: Snapshots of Our Universe Through Time

If the universe is curved, according to the new paper, it curves gently. That slow bending isn’t important for moving around our lives, or solar system, or even our galaxy. But travel beyond all of that, outside our galactic neighborhood, far into the deep blackness, and eventually — moving in a straight line — you’ll loop around and end up right back where you started. Cosmologists call this idea the “closed universe.” It’s been around for a while, but it doesn’t fit with existing theories of how the universe works. So it’s been largely rejected in favor of a “flat universe” that extends without boundary in every direction and doesn’t loop around on itself. Now, an anomaly in data from the best-ever measurement of the CMB offers solid (but not absolutely conclusive) evidence that the universe is closed after all, according to the authors: University of Manchester cosmologist Eleonora Di Valentino, Sapienza University of Rome cosmologist Alessandro Melchiorri and Johns Hopkins University cosmologist Joseph Silk.

The difference between a closed and open universe is a bit like the difference between a stretched flat sheet and an inflated balloon, Melchiorri told Live Science. In either case, the whole thing is expanding. When the sheet expands, every point moves away from every other point in a straight line. When the balloon is inflated, every point on its surface gets farther away from every other point, but the balloon’s curvature makes the geometry of that movement more complicated.

“This means, for example, that if you have two photons and they travel in parallel in a closed universe, they will [eventually] meet,” Melchiorri said.

In an open, flat universe, the photons, left undisturbed, would travel along their parallel courses without ever interacting.

The conventional model of the universe’s inflation, Melchiorri said, suggests that the universe should be flat. Rewind the expansion of space all the way to the beginning, to the first 0.0000000000000000000000001 seconds after the Big Bang, according to that model, and you’ll see a moment of incredible, exponential expansion as space grew out of that infinitesimal point in which it began. And the physics of that superfast expansion point to a flat universe. That’s the first reason most experts believe the universe is flat, he said. If the universe isn’t flat, you have to “fine-tune” the physics of that primordial mechanism to make it all fit together — and redo countless other calculations in the process, Melchiorri said.

But that might end up being necessary, the authors wrote in the new study.

That’s because there’s an anomaly in the CMB. The CMB is the oldest thing we see in the universe, made of ambient microwave light that suffuses all of space when you block out the stars and galaxies and other interference. It’s one of the most important sources of data on the universe’s history and behavior, because it’s so old and so spread throughout space. And it turns out, according to the latest data, that there’s significantly more “gravitational lensing” of the CMB than expected — meaning that gravity seems to be bending the microwaves of the CMB more than existing physics can explain.

The data the team is drawing upon comes from a 2018 release from the Planck experiment — a European Space Agency (ESA) experiment to map the CMB in more detail than ever before. (The new data will be published in a forthcoming issue of the journal Astronomy & Astrophysics and is available now on the ESA website. Both Di Valentino and Melchiorri were part of that effort as well.)

To explain that extra lensing, the Planck Collaboration has just tacked on an extra variable, which the scientists are calling “A_lens,” to the group’s model of the universe’s formation, “This is something that you put there by hand, trying to explain what you see. There’s no connection with physics,” Melchiorri said, meaning there’s no A_lens parameter in Einstein’s theory of relativity. “What we found is that you can explain A_lens with a positively curved universe, which is a much more physical interpretation that you can explain with general relativity.”

Melchiorri pointed out that his team’s interpretation isn’t conclusive. According to the group’s calculations, the Planck data point to a closed universe with a standard deviation of 3.5 sigma (a statistical measurement that means about 99.8% confidence that the result isn’t due to random chance). That’s well short of the 5 sigma standard physicists usually look for before calling an idea confirmed.

But some cosmologists said there were even more reasons to be skeptical.

Andrei Linde, a cosmologist at Stanford University, told Live Science that the Nature Astronomy paper failed to take into account another important paper, published to the arXiv database on Oct. 1. (That paper has not yet been published in a peer reviewed journal.)

In that paper, University of Cambridge cosmologists George Efstathiou and Steven Gratton, who both also worked on the Planck Collaboration, looked at a narrower subset of data than the Nature Astronomy paper. Their analysis also supported a curving universe, but with much less statistical confidence than Di Valentino, Melchiorri and Silk found looking at a larger segment of the Planck data. However, when Efstathiou and Graton looked at the data together with two other existing data sets from the early universe, they found that overall, the evidence pointed toward a flat universe.

Asked about the Efstathiou and Gratton paper, Melchiorri praised the careful treatment of the work. But he said the duo’s analysis relies on too small a segment of the Planck data. And he pointed out that their research is based on a modified (and, in theory, improved) version the Planck data — not the public data set that more than 600 physicists had vetted.

Linde pointed to that reanalysis as a sign that Efstathiou and Gratton’s paper was based on better methods.

Efstathiou asked not to be directly quoted, but pointed out in an email to Live Science that if the universe were curved, it would raise a number of problems — contradicting those other data sets from the early universe and making discrepancies in the  universe’s observed rate of expansion much worse. Gratton said he agreed.

Melchiorri also agreed that the closed-universe model would raise a number of problems for physics.

“I don’t want to say that I believe in a closed universe,” he said. “I’m a little bit more neutral. I’d say, let’s wait on the data and what the new data will say. What I believe is that there’s a discrepancy now, that we have to be careful and try to find what is producing this discrepancy.”

Originally published on Live Science.

Livescience
04/11/2019
By Rafi Letzter – Staff Writer

 

2943: Asteroid Impacts Might Wipe Out Alien Life Around Dwarf Stars

SCIENCE

What’s the recipe for a living planet? A new paper suggests that the right number of impacts is a key ingredient.

A NASA illustration shows an asteroid striking a planet.
(Image: © NASA/Don Davis)

What’s the recipe for a living planet? Astronomers aren’t sure — we haven’t found any other than Earth yet.

But we have some educated guesses: Life probably needs water, carbon, and enough light and heat to power a world without burning it to a crisp. The gravity shouldn’t be too high, and an atmosphere wouldn’t hurt either. But a new study proposes another essential ingredient: major asteroid and comet impacts, in just the right amounts.

When a large object strikes a planet, two things happen: The material from the object gets added to the planet’s mass, and some of the atmosphere around the impact zone gets kicked off into space, said Mark Wyatt, a University of Cambridge astronomer and lead author of the new paper. In truly giant impacts, like the one that formed Earth’s moon, some atmosphere gets booted off the far side of the planet as well, which means a bit more gets lost. But that doesn’t mean a wannabe home world should skip the impacts entirely. If a planet is to develop the conditions thought necessary for life, it’s best to belong to a middle category of planets that absorb plenty of major impacts — but not so many that they lose their atmospheres.

Related: 9 Strange, Scientific Excuses for Why Humans Haven’t Found Aliens Yet

That’s because planets almost certainly need “volatiles” in their atmospheres in order to sprout life, Wyatt told Live Science. Volatiles are chemicals, like water and carbon dioxide, that can boil at low temperatures. All life that we know of relies on water and carbon to sustain itself at a basic chemical level, and scientists believe that the properties of those chemicals make them necessary for life to arise anywhere in the universe.

But not all planets start off with the necessary concentrations of volatiles. Early in a star’s lifetime, it’s much brighter. And that extra shine is hot enough to bake all the loose dust in the region that will become the star’s habitable zone — the not-too-hot, not-too-cold area — later on. Those hot early temperatures likely strip water and other volatiles from the dust that will eventually become habitable planets. So after planets form and the star cools down, these rocky orbs need to acquire their volatiles from somewhere else in the solar system. In other words, they’ve got to smash into a bunch of big stray objects.

The researchers found that the best candidates for delivering volatiles while not stripping the planet’s atmosphere and sterilizing it are medium-size objects. Impacts from 60-foot-wide (20 meters) to 3,300-foot-wide (1 kilometer) asteroids and comets are very efficient at delivering volatiles and will tend to add more to the atmosphere than they subtract, the authors found. Bigger asteroids, between about 1 and 12 miles (2 and 20 km) across, will tend to strip more atmosphere than they add.

Giant impacts like the one that formed Earth’s moon, the authors found, don’t mess with that story as much as you might expect. Such events are pretty rare, and while they can change the composition of an atmosphere, they won’t completely remove it.

One of the important lessons from this paper is that small “M class” stars — the most common category of stars, too dim to see with the naked eye, many of them red dwarfs — are likely bad candidates for life, the authors wrote. That’s significant, because a great many potentially habitable exoplanets have turned up around those sorts of stars.

“For M stars, their low luminosity means that the habitable zone is much closer to the star than for a star like the sun,” Wyatt said.

To get enough light, an Earth-like planet circling an M-class star might have to be as close to that star as Mercury is to our sun.

And it gets worse. Right up next to a small, low-mass star, asteroids and comets fly around at much higher speeds and crash more dramatically into planets.

“Higher-velocity impacts are much more efficient at stripping an atmosphere,” Wyatt said.

That’s bad news for life on M worlds. And it’s not the only factor that makes M-world life unlikely.

“There are a number of reasons why habitable planets orbiting M dwarfs might not have an atmosphere, including stripping from stellar winds and the planets being much closer in to their host star,” said Sarah Rugheimer, an expert in exoplanet atmospheres at the University of Oxford, who was not involved in this research.

So is there any hope for life on M worlds?

“I think, ultimately, we will answer this question observationally with [the James Webb Space Telescope] soon after it launches: Do habitable planets orbiting M dwarfs have atmospheres?” Rugheimer said. “We know that slightly hotter and bigger planets orbiting M dwarfs do have thick atmospheres. But this question still remains for habitable planets: Can they retain a thin enough atmosphere, something like Earth rather than Venus?”

The authors emphasized in the paper that many of their conclusions are based on uncertainties: Where does life form? How much do other star systems out there resemble our solar system?

Edwin Bergin, an expert in planet formation and water at the University of Michigan who was not involved in this research, agreed with the authors that there are what he called “significant complications” in the calculations behind this paper.

“But the general trends they present are quite interesting and could be important,” he said.

He pointed to his own work, which has suggested that Earth started out with a thicker, nitrogen-rich atmosphere but lost much of it to impacts. The authors of this new paper suggested in their model that impacts from comets and asteroids might have shaped the atmospheres of Earth, Mars and Venus.

Down the road, the researchers said, there’s more to learn about how this work can explain our own solar system, particularly the role of giant impacts here. This paper has not yet been published in a peer-reviewed journal and is available on the preprint server arXiv.

Originally published on Live Science.
By Rafi Letzter – Staff Writer
31/10/2019

 

2929: The Black Knight Satellite: A Hodgepodge of Alien Conspiracy Theories

SCIENCE

For decades different discoveries have been linked to a single possible spacecraft of extraterrestrial origin.

An artist’s impression of the Black Knight satellite. The spacecraft has sparked a long-lived conspiracy theory.
(Image: © Future/Adrian Mann)

Sometimes the introduction of a news report will stop you in your tracks, forcing you to reread in fear you didn’t quite grasp its point the first time. That was certainly the case when Mail Online published a story on Mar. 21, 2017: “An alien satellite set up more than 12,000 years ago to spy on humans has been shot down by elite soldiers from the illuminati, UFO hunters claim.”

And with that, the conspiracy surrounding the so-called “Black Knight” satellite appeared to be very much alive.

Related: 9 Strange, Scientific Excuses for Why Humans Haven’t Found Aliens Yet

It’s been 120 years since conspiracists believed the existence of the Black Knight was recorded. Those who subscribe to the theory lay claim of an extraterrestrial spacecraft in near-polar orbit of the Earth, although they draw upon evidence so disparate that it’s not entirely clear why people link them. What they amount to, however, is an intriguing set of ingredients that, taken together, cause people to scream loud about potential cover-ups by NASA and the government. In that sense, it is a legend that refuses to go away.

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The photo evidence that isn’t evidence

A lot of the earliest discoveries that have come to be linked to the Black Knight satellite theory relate to radio signals. But a series of images from 1998 emerged that really threw the celestial cat among the pigeons. They were taken during STS-88, which was the first Space Shuttle mission to the International Space Station (ISS).

There, for all to see, were images released by NASA that showed a black object hovering above the Earth in low orbit. And it wasn’t long after the images were thrust in front of a hopeful public before people were performing some conspiratorial sums and sharing them with the wider world.

Related: The Top 10 Conspiracy Theories Explained

By way of explanation, astronaut Jerry Ross pointed out that the ISS was in the midst of being constructed when the images were taken. The U.S. team, he said, was on its way to attach the American module to the one created by the Russians and, as part of that work, they had taken four trunnion pin thermal covers with them. The task was to wrap these around four bare trunnion pins, these being rods that attached the module to the shuttle while it was being transported. This would act to prevent heat loss from the exposed metal.

The photo snapped by astronauts during Space Shuttle mission STS-88 in 1998.
(Image credit: NASA)

Unfortunately, during one of the extravehicular activities (EVA) things went a little bit wrong and one of the covers came loose from its tether, causing it to float away along with some other items. “Jerry, one of the thermal covers got away from you,” said commander Robert Cabana, and it soon became apparent that they wouldn’t be getting it back.

Subsequently captured on camera, this black object was given the object number 025570 by NASA, and a few days later the object fell from orbit and burned up. Far from being an extraterrestrial object, the black item floating in space was nothing more than a blanket.

Related: The 12 Strangest Objects in the Universe

Much of this has been placed on the record. Former NASA space engineer James Oberg, who personally knows Ross and the person who took the photos, Sergei Krikalev, has gone to great lengths to show that these supposed images of the Black Knight have less fanciful origins.

“Before leaving NASA I led the trajectory design team that produced the mission profile,” Oberg told All About Space. “Every step of the way there is consistency with what I learned as a lifelong spaceflight operations specialist: why the blankets were needed, why one of them came loose, why it floated off the way it did. The difference is, for the general public all these features are unearthly to folks who are only familiar with Earthside principles of heating, working, motion and dozens of other never-before-encountered-in-history aspects of outer space.”

Given Oberg’s debunking you’d think the matter would have drawn to a close. But no. Since the images were shared far and wide, conspiracy theories have continued.

“They are probably some of the weirdest-looking 70 mm photos to ever come out of the space shuttle program,” Oberg said. “And apparently a NASA website update made the original links inoperative, sparking concerns over a cover-up. All normal journalistic practices — determining the timeline, asking witnesses, searching for the wider context — were skipped.”

The Black Knight is likely to be debris left over from extravehicular activity (EVA).
(Image credit: Future/Adrian Mann)

Historical evidence that also isn’t evidence

By absorbing the images into a growing body of “evidence,” they were seen as definite proof that the Black Knight alien satellite really was out there. Reaching that conclusion, however, has required greats leaps of faith, and has also needed past discoveries to be forced into the overall story. Firm believers have had no problems going right back to 1899 in pursuit of such “truth” but, just like the photographic records, each piece of supposed evidence brought to the table so far has been explained away without falling back on the Black Knight myth.

So what happened in 1899? That year Nikola Tesla began to record some very odd signals, seemingly from outer space. The accomplished Serbian-American electrical engineer had a passion for wireless technology, and he was in the early throes of an experimental wireless transmission station called Wardenclyffe Tower in Shoreham, New York. While in his barn-like laboratory in Colorado Springs, he noted the unusual signals and speculated they had come from another planet, a claim greeted with disbelief and skepticism.

Related: Greetings, Earthlings! 8 Ways Aliens Could Contact Us

“The very first source of non-terrestrial radio waves was discovered in the 1930s, and that was from the centre of our galaxy, which is the most powerful radio source in the sky at many frequencies,” NASA Jet Propulsion Laboratory scientist Varoujan Gorjian explained. “It wasn’t until the 1960s that the technology evolved to detect the first pulsars. If what Tesla detected was a real signal and not an artifact of his instrument, it most likely came from Earth.”

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So why does talk of the Black Knight persist?

People continued to use Tesla’s findings to bolster claims for the Black Knight. They also took on board the work of a Norwegian engineer called Jørgen Hals, who found that radio signals he transmitted were being echoed back to him a few seconds later. We now know these as long delayed echoes, and Hals was the first person to observe them.

The fact that we don’t have a confirmed explanation of their cause, however, has been seized upon: In 1973, Duncan Lunan wrote an article in Spaceflight magazine suggesting those studying long delayed echoes had overlooked the possibility they were sent by an alien space probe.

Related: 13 Ways to Hunt Intelligent Aliens

Lunan still has faith in an extraterrestrial explanation for the recordings. “The changes in the long distance echo patterns in apparent response to changes in the outgoing signals from Earth really do look like the responses of a Bracewell probe, and there is still no satisfactory natural explanation for the phenomenon,” Lunan said. If the long distance echoes were deliberately produced by a probe, there’s a problem in that they stopped in 1975.

“If a probe was monitoring Earth, rather than trying to attract attention, perhaps it belatedly discovered from the 1973 to 1974 publicity that it had given away its presence in the 1920s and pulled out in 1975,” Lunan said. “That’s the only explanation I can see for its apparent departure.”

And yet, for all of that, Lunan said his research has nothing to do with the “Black Knight nonsense.” If there is a link between his theory and the Black Knight, it is not one that is being made by him.

live science
By David Crookes, All About Space magazine
2019-10-28T15:51:41Z

 

If There’s a Wormhole Hiding in Our Galaxy, Could We Really Find It?

SCIENCE

(Image: © Shutterstock)

Wormholes, passageways that connect one universe or time to another, are still only theoretical — but that doesn’t mean physicists aren’t looking for them. In a new study, researchers describe how to find wormholes in the folds of our galaxy.

These hypothetical passageways, created by folding a region of space like a piece of paper, are predicted by Einstein’s theory of general relativity. But they require extreme gravitational conditions, such as those around supermassive black holes.

In the new study, two researchers came up with a method to search for wormholes close to home, around the Milky Way’s central, supermassive black hole, called Sagittarius A*. If a wormhole were to exist around Sagittarius A*, the stars on one side of the passage would be influenced by the gravity of stars on the other side, the researchers said

Related: 5 Reasons We May Live in a Multiverse

If physicists can detect small changes in the expected orbits of stars, such as a star called S2 that orbits Sagittarius A*, it may indicate that a wormhole is close by, the researchers said in a statement.

Current methods aren’t sensitive enough to see the slight changes in orbit that would be caused by a star at the other end of the wormhole, but new techniques and longer observations might render it possible within the next couple of decades, study co-author Dejan Stojkovic, a cosmologist and professor of physics at the University at Buffalo College of Arts and Sciences, said in the statement.

Yet even finding these slight changes in orbit wouldn’t prove that a wormhole is nearby, he added. “When we reach the precision needed in our observations, we may be able to say that a wormhole is the most likely explanation if we detect perturbations in the orbit of S2,” Stojkovic said. “But we cannot say that, ‘Yes, this is definitely a wormhole.'” That is because other unknown celestial objects on our side of the wormhole can also be exerting a gravitational pull and causing the changes.

But not everyone’s convinced.

The star’s altered trajectory due to a wormhole is “unobservable irrespective of how accurate the measurements are,” Serguei Krasnikov, a physicist at the Central Astronomical Observatory at Pulkovo in Russia, who was not involved with the research, wrote in a commentary published in the preprint server arXiv. That’s because, even with more-precise measurements, astronomers can only measure the total acceleration of a star, not the additional acceleration caused by the gravitational influence of a star on the other end of a wormhole, he wrote.

And even if a wormhole were ever found, it might not be open for voyage.

People and spaceships probably won’t be able to pass through a wormhole, because “realistically, you would need a source of negative energy to keep the wormhole open, and we don’t know how to do that,” Stojkovic said. “To create a huge wormhole that’s stable, you need some magic.”

The paper assumes that a stable wormhole can exist, which is not supported by General Relativity, said Jolyon Bloomfield, a lecturer in the department of physics at MIT, who was also not part of the study. “I’m not convinced that the setup is valid, and hence do not trust the results that follow.”

If there is any deviation in observed acceleration of stars around Sagittarius A*, it’s “significantly more likely that a modification to General Relativity is being observed, rather than the effects of a wormhole,” he told Live Science.

The findings were published Oct. 10 in the journal Physical Review D.

Editor’s Note: This article was updated on Oct. 28 at 11:00 a.m. to include quotes from Jolyon Bloomfield. 

Originally published on Live Science.
By Yasemin Saplakoglu – Staff Writer
28/10/2019

 

US Air Force’s X-37B Space Plane Lands After Record 780-Day Mystery Mission

SCIENCE/MILITARY

What was it doing up there?

A U.S. Air Force X-37B space plane, an unpiloted miniature space shuttle, is seen after landing at NASA’s Kennedy Space Center Shuttle Landing Facility on Oct. 27, 2019 to end its record 780-day OTV-5 mission.
(Image: © U.S. Air Force)

The U.S. Air Force’s unpiloted X-37B space plane landed back on Earth Sunday (Oct. 27) after a record 780 days in orbit , racking up the fifth ultra-long mission for the military’s mini-shuttle fleet.

The X-37B’s Orbital Test Vehicle 5 (OTV-5) mission ended with a smooth autonomous touchdown at the Shuttle Landing Facility of NASA’s Kennedy Space Center in Cape Canaveral, Florida at 3:51 a.m. EDT (0751 GMT), Air Force officials said. The mission originally launched on a SpaceX Falcon 9 rocket on Sept. 7, 2017.

With the successful landing, OTV-5 broke the previous X-37B mission record of 718 days set by the OTV-4 mission in May 2017. OTV-5 is the second X-37B mission to land at NASA’s Shuttle Landing Facility (OTV-4 was the first), with previous missions landing at Vandenberg Air Force Base in California.

Related: The X-37B Space Plane: 6 Surprising Facts

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“The safe return of this spacecraft, after breaking its own endurance record, is the result of the innovative partnership between Government and Industry,” Air Force Chief of Staff Gen. David L. Goldfein said in a statement. “The sky is no longer the limit for the Air Force and, if Congress approves, the U.S. Space Force.”

The U.S. Air Force has at least two reusable X-37B spacecraft in its fleet, and both have flown multiple flights. The solar-powered space planes were built by Boeing and feature a miniature payload bay to host experiments or smaller satellites. They were originally designed to spend up to 240 days in orbit.

“The X-37B continues to demonstrate the importance of a reusable spaceplane,” said Secretary of the Air Force Barbara Barrett said in the same statement. “Each successive mission advances our nation’s space capabilities.”

Air Force officials have said that the exact nature of X-37B missions are classified, though they have dropped hints about the types of experiments OTV-5 performed in orbit. One payload was the Air Force Research Laboratory Advanced Structurally Embedded Thermal Spreader, an experiment designed to “test experimental electronics and oscillating heat pipe technologies in the long-duration space environment,” according to an Air Force statement.

OTV-5 also flew to a higher-inclination orbit than previous X-37B flights, suggesting it had new experiments or technology tests in store. In a statement today, Air Force officials confirmed OTV-5 carried multiple experiments and carried smaller satellites into orbit.

“With a successful landing today, the X-37B completed its longest flight to date and successfully completed all mission objectives,” Randy Walden, Air Force Rapid Capabilities Office director, said in the statement. “This mission successfully hosted Air Force Research Laboratory experiments, among others, as well as providing a ride for small satellites.”

Related: Mysterious X-37B Space Plane Explained: Boeing’s New Video

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The X-37B space plane was originally developed by NASA in 1999 to serve as a technology test bed for future spacecraft and looks much like a miniature version of  a space shuttle. In 2004, the military’s Defense Advanced Research Agency (DARPA) took over the project, ultimately turning it over to the U.S. Air Force’s Rapid Capabilities Office a few years later.

X-37B vehicles are 29 feet (8.8 meters) long, 9.5 feet (2.9 m) tall and have a wingspan of just under 15 feet (4.6 m). Their payload bays are about the size of a pickup truck bed, about 7 feet long and 4 feet wide (2.1 by 1.2 m).

Related: US Air Force’s Secretive X-37B Space Plane (Infographic)

Poll: What Is the US Air Force’s Mysterious X-37B Space Plane Doing in Orbit?

The first X-37B mission, OTV-1, launched in April 2010 and spend 224 days in orbit. OTV-2 launched in March 2011, marking the first flight of a second X-37B, and stayed in orbit for 468 days.

OTV-3 marked the first reflight of an X-37B (using the OTV-1 vehicle) and launched in December 2012 on a 674-day flight. The OTV-4 mission launched in May 2015 (the second flight of the OTV-2 vehicle) and spent 718 days in space. The first four OTV missions launched on Atlas V rockets, with OTV-5 marking the fleet’s first use of a SpaceX Falcon 9.

“This spacecraft is a key component of the space community. This milestone demonstrates our commitment to conducting experiments for America’s future space exploration,” said X-37B program manager Lt. Col. Jonathan Keen in the Air Force statement. “Congratulations to the X-37B team for a job well done.”

Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik. Follow us @Spacedotcom and Facebook.

By Tariq Malik – Space.com Managing Editor
26/10/2019

 

Rock Star’s Company Seeks UFOs, Finds Military Contract

SCIENCE

The arrangement with the U.S. Army will fund new technologies that could have military applications.

When not seeking UFOs, To The Stars Academy of Arts and Science will be partnering with the U.S. Army on projects involving energy propulsion, quantum physics and space-time engineering.
(Image: © Shutterstock)

A private company that researches UFOs has a new contract with the U.S. government, for developing technologies that could enhance ground vehicles in the military.

To The Stars Academy of Arts and Science (TTSA) was launched in 2017 by former Blink-182 guitarist Tom DeLonge; in December of that year, TTSA became the first company to share videos that showed U.S. Navy pilots interacting with UFOs. It was able to obtain the footage “by leveraging its team’s access” to the material, according to the company website. (The videos may not have been officially cleared for public viewing, Live Science reported in September.)

Other divisions at TTSA focus on new technology. On Oct. 17, TTSA representatives announced that the group had entered into a Cooperative Research and Development Agreement (CRADA) with the U.S. Army Combat Capabilities Development Command, according to a statement.

The five-year contract outlines a research collaboration, and the U.S. Army will provide at least $750,000 in support and resources for developing and testing TTSA technologies, Motherboard reported on Oct. 21.

Those technologies could include “inertial mass reduction, mechanical/structural meta materials, electromagnetic meta material wave guides, quantum physics, quantum communications, and beamed energy propulsion,” according to the contract.

Alongside TTSA’s technology production and theoretical research is an entertainment division that is “at the forefront of socializing the UFO conversation,” the company says. TTSA maintains a film archive of UFO sightings, and key TTSA personnel — several of whom previously held U.S. government positions — were featured in the documentary series “Unidentified: Inside America’s UFO Investigation,” which aired on the History Channel in May.

A U.S. Army representative hailed the new partnership in a statement as “an exciting, non-traditional source for novel materials and transformational technologies.”

While the U.S. Army’s interest in the project stems from its potential applications toward enhanced military performance, TTSA has other plans for the results of the collaboration, and expects to apply their findings toward “commercialization and public benefit,” Steve Justice, TTSA’s chief operations officer and Aerospace Division Director, said in the statement.

Whether that includes UFO-related applications, however, remains to be seen.

Originally published on Live Science.

By Mindy Weisberger – Senior Writer
26/10/2019

 

2901: Missing-Link Atoms Turn Up in Aftermath of Neutron-Star Collision

SCIENCE

Neutron stars are among the densest objects in the universe.
(Image: © Shutterstock)

Two neutron stars smashed together and shook the universe, triggering an epic explosion called a “kilonova” that spit lots of ultradense, ultrahot material into space. Now, astronomers have reported the most conclusive evidence yet that in the aftermath of that blast a missing-link element formed that could help explain some confusing chemistry of the universe.

When that shaking — ripples in the very fabric of space-time, called gravitational waves — reached Earth in 2017, it set off gravitational-wave detectors and became the first neutron- star collision ever detected Immediately, telescopes all over the world whirled around to study the light of the resulting kilonova. Now, data from those telescopes has revealed strong evidence of strontium whirling in the expelled matter, a heavy element with a cosmic history that was difficult to explain given everything else astronomers know about the universe.

Earth and space are littered with chemical elements of different kinds. Some are easy to explain; hydrogen, made up in its simplest form of just one proton, existed soon after the Big Bang as subatomic particles began to form. Helium, with two protons, is pretty easy to explain as well. Our sun produces it all the time, smashing together hydrogen atoms through nuclear fusion in its hot, dense belly.  But heavier elements like strontium are more difficult to explain. For a long time, physicists thought these hefty elements mostly formed during supernovas — like kilonova but on a smaller scale and resulting from the explosion of massive stars at the ends of their lives. But it’s become clear that supernovas alone can’t explain how many heavy elements are out there in the universe.

Related: The 12 Strangest Objects in the Universe

Strontium turning up in the aftermath of this first detected neutron-star collision could help confirm an alternative theory, that these collisions between much smaller, ultradense objects actually produce most of the heavy elements we find on Earth.

Physics doesn’t need supernovas or neutron-star mergers to explain every chunky atom around. Our sun is relatively young and light, so it mostly fuses hydrogen into helium. But bigger, older stars can fuse elements as heavy as iron with its 26 protons, according to NASA. However no star gets hot or dense enough before the last moments of its life to produce any elements between 27-proton cobalt and 92-proton uranium.

And yet, we find heavier elements on Earth all the time, as a pair of physicists noted in a 2018 article published in the journal Nature. Thus, the mystery.

About half of those extra-heavy elements, including strontium, are formed through a process called “rapid neutron capture,” or the “r-process” — a series of nuclear reactions that occur under extreme conditions and can form atoms with dense nuclei loaded with protons and neutrons. But scientists have yet to figure out what systems in the universe are extreme enough to produce the sheer volume of r-process elements seen in our world.

Some had suggested supernovas were the culprit. “Until recently, astrophysicists cautiously claimed that the isotopes formed in r-process events originated primarily from core collapse supernovae,” the Nature authors wrote in 2018.

Here’s how that supernova idea would work: Detonating, dying stars create temperatures and pressures beyond anything they produced in life, and spit complex materials out into the universe in brief, violent flashes. It’s part of the story Carl Sagan was telling in the 1980s, when he said that we are all made of “star stuff.”

Related: 15 Amazing Images of Stars

Recent theoretical work, according to the authors of that 2018 Nature article, has shown that supernovas might not produce enough r-process materials to explain their preponderance in the universe.

Enter neutron stars. The superdense corpses left over after some supernovas (outdone only by black holes in mass per cubic inch) are tiny in stellar terms, close in size to American cities. But they can outweigh full-size stars. When they slam together, the resulting explosions shake the fabric of space-time more intensely than any event other than colliding black holes.

And in those furious mergers, astronomers have begun to suspect, enough r-process elements could form to explain their numbers.

Early studies of the light from the 2017 collision suggested that this theory was correct. Astronomers saw evidence for gold and uranium in the way the light filtered through the material from the blast, as Live Science reported at the time, but the data was still hazy.

A new paper published yesterday (Oct. 23) in the journal Nature offers the firmest confirmation yet of those early reports.

“We actually came up with the idea that we might be seeing strontium quite quickly after the event. However, showing that this was demonstrably the case turned out to be very difficult,” study author Jonatan Selsing, an astronomer at the University of Copenhagen, said in a statement.

Astronomers weren’t sure at the time exactly what heavy elements in space would look like. But they’ve re-analyzed the 2017 data. And this time, given more time to work on the problem, they found a “strong feature” in the light that came from the kilonova that points right at strontium — a signature of the r-process and evidence that other elements likely formed there as well, they wrote in their paper.

Over time, some of the material from that kilonova will likely make its way out into the galaxy, and perhaps become part of other stars or planets, they said. Maybe, eventually, it will lead future alien physicists to look up into the sky and wonder where all this heavy stuff on their world came from.

Originally published on Live Science.
By Rafi Letzter – Staff Writer
24/10/2019

 

Humans Will Never Live on an Exoplanet, Nobel Laureate Says. Here’s Why.

SCIENCE

Image: © Shutterstock)

Here’s the reality: We’re messing up the Earth and any far-out ideas of colonizing another orb when we’re done with our own are wishful thinking. That’s according to Michel Mayor, an astrophysicist who was a co-recipient of the Nobel Prize in physics this year for discovering the first planet orbiting a sun-like star outside of our solar system.

“If we are talking about exoplanets, things should be clear: We will not migrate there,” he told Agence France-Presse (AFP). He said he felt the need to “kill all the statements that say, ‘OK, we will go to a livable planet if one day life is not possible on Earth.'”

All of the known exoplanets, or planets outside of our solar system, are too far away to feasibly travel to, he said. “Even in the very optimistic case of a livable planet that is not too far, say a few dozen light years, which is not a lot, it’s in the neighbourhood, the time to go there is considerable,” he added.

Mayor shared half of the Nobel Prize this year along with Didier Queloz for discovering the first exoplanet in October 1995. Using novel instruments at the Haute-Provence Observatory in southern France, they detected a gas giant similar to Jupiter, which they named 51 Pegasi b. (The other half of the prize was awarded to James Peebles of Princeton University for his work in dark matter and dark energy).

Since then, over 4,000 other exoplanets have been found in the Milky Way, but apparently, none of them can be feasibly reached.

Stephen Kane, a professor of planetary astrophysics at the University of California in Riverside, agrees with Mayor. “The sad reality is that, at this point in human history, all stars are effectively at a distance of infinity,” Kane told Live Science. “We struggle very hard as a species to reach the Earth’s moon.”

We might be able to send people to Mars in the next 50 years, but “I would be very surprised if humanity made it to the orbit of Jupiter within the next few centuries,” he said. Since the distance to the nearest star outside of our solar system is about 70,000 times greater than the distance to Jupiter, “all stars are effectively out of reach.”

Well, you might say, plenty of things seemed out of reach until we reached them, such as sending aircraft on intercontinental flights. But “in this case, the required physics to reach the stars, if it exists, is not known to us and it would require a fundamental change in our understanding of the relationship between mass, acceleration and energy.”

“So that’s where we stand, firmly on the Earth, and unlikely to change for a very, very long time,” he said.

Mayor told the AFP: “We must take care of our planet, it is very beautiful and still absolutely livable.”

Andrew Fraknoi, emeritus chair of the astronomy department at Foothill College in California agreed that we won’t be able to travel to these stars in the near future. But “I would never say we can never reach the stars and possible habitable planets,” he said. “Who knows how our technology will evolve after another million years of evolution.”

Originally published on Live Science.
By Yasemin Saplakoglu – Staff Writer
14/10/2019

 

2854: Underwater Volcano Creates Bubbles More Than a Quarter-Mile Across

SCIENCE

A satellite image of the Bogoslof Volcano shows volcanic clouds after a 2017 eruption.
(Image: © DigitalGlobe via Getty Images via Getty Images)

In the early 20th century, sailors near Alaska reported seeing black bubbles seeming to boil out from the sea, each one the size of the dome of the capitol building in Washington, D.C. They weren’t the only sailors who reported the bizarre phenomenon, and they weren’t mistaken, except for one thing … the bubbles were much larger.

When the mostly underwater Bogoslof volcano in the Aleutian Islands erupts, it produces giant bubbles that can reach up to 1,444 feet (440 meters) across, according to a new study. These bubbles are filled with volcanic gas, so when they burst they create volcanic clouds tens of thousands of feet in the sky, said lead author John Lyons, a research geophysicist at the Alaska Volcano Observatory of the U.S. Geological Survey.

These volcanic clouds were captured in satellite images taken after the Bogoslof volcano last erupted in 2017 — but the bubbles themselves were never photographed.

During the time of the eruption, a dull hum lingered in the air. Something was giving off low-frequency signals called infrasound — sounds below the level that humans can hear — that would last up to 10 seconds. Lyons and his team, who regularly monitor active volcanoes in Alaska, picked up on these signals in their data. But “it took us a while to figure out what they were,” Lyons told Live Science.

It was only after searching the literature that the team came up with their hypothesis that the sound was the whisper of giant gas bubbles growing within the magma of the erupting volcano. They then came up with a computer model for what was happening.

In their model, a bubble bursts out from the column of magma underwater and begins to grow. Once it reaches the sea surface, it juts out in the shape of a hemisphere and continues to grow at an even faster rate in the lower density of the atmosphere. Eventually, the pressure outside the bubble exceeds the pressure inside and the bubble begins to contract; its film becomes unstable and ruptures, causing the bubble to burst.

When it bursts, volcanic gas — water vapor, sulfur dioxide and carbon dioxide — gets released partly back into the water, where it interacts with the lava, pulling it into pieces and producing ash and volcanic clouds, Lyons said.

The team hypothesized that the low-frequency hum emanates from the growth and oscillation of each bubble and the high-frequency signal represents the burst.

“These shallow explosive submarine eruptions are so rare,” Lyons said. “There’s a lot of undersea volcanism, but the majority of it happens under lots and lots of water very deep and all that extra pressure tends to suppress how explosive eruptions are.”

But still, there are open questions and the results are limited by their methodology, which relied on a number of assumptions, he said. It’s unclear, for example, what the water is like around the bubble — if it’s like sea water or like wet cement. “It would be nice to be able to record this somewhere else, and make sure that our methodology is sound,” Lyons said.

The study was published Oct. 14 in the journal Nature Geoscience.

Originally published on Live Science.
By Yasemin Saplakoglu – Staff Writer

17/10/2019

 

2853: An Asteroid-Smashing Star Ground a Giant Rock to Bits and Covered Itself in the Remains

SCIENCE

An artist’s illustration shows an asteroid cracking to pieces.
(Image: © JPL-Caltech)

Somewhere in the galaxy, a white dwarf star suddenly started shining brightly. And now we understand the violent cataclysm that caused it: the star’s gravitational field tore the asteroid to bits, scattering its metallic bits in a shiny halo around the star.

There’s no telescope video of an asteroid shattering across space. But here’s what we do know: There’s a white dwarf star in our galaxy that, for years, emitted a consistent amount of mid-infrared (MIR) light. Then, in 2018, these emissions changed. Over the course of six months, the starlight from that point in space got about 10% more intense in the MIR spectrum — and that point is still getting brighter. The researchers think that’s because of a newly formed cloud of metallic dust between Earth and the star, likely due to the recent breakup of the asteroid.

To an outsider, it may sound counterintuitive that a cloud of dust would make a star look brighter. But Tinggui Wang, an astronomer at the University of Science and Technology of China and lead author of a paper describing the event, said the brightening makes sense if you think about how the star and the cloud interact.

“When the debris are on our line of sight to the star, it would make the star dim,” he told Live Science. “However, the [individual pieces of] debris cover only a small fraction of the sky, so the chance of being on the line of sight is small.”

However, although individual pieces of debris are small and each cover only a tiny patch of sky, the whole cloud is large — much larger than the star. Under normal conditions, only photons that fly out of the star directly at Earth reach human telescopes. But the cloud changes that. Beams of light aimed in all sorts of directions strike the cloud of the debris, heating it up and causing the bits of asteroid to emit MIR light. That light reaches Earth too, even though the beams of light that caused it normally wouldn’t have. The result is a bigger glowing region of the sky that our telescopes register as a spike in light, Wang said.

Imagine a faint flashlight in the distance on a clear night. If it’s pointed right at you, you might notice it as a thin dot of light. But if you shine the flashlight through the billowing steam of a fog machine, there’s a much bigger, bright object to catch your eye — even if the power of the light source stays the same.

Astronomers have seen clouds of debris like this before in space, said Malena Rice, an expert in the astronomy of debris disks around distant stars and doctoral student in the Yale University Department of Astronomy. And they’ve seen evidence of nonspherical objects, likely asteroids orbiting objects outside our solar system — possibly  another white dwarf. But this may be the first time astronomers have spotted an asteroid disintegrating into a debris cloud around a star.

“This process has been theorized for over a decade,” Rice, who wasn’t involved in the research, told Live Science. “But we’ve never had a chance to study the full disruption process in action until now.”

So, what could have ripped the asteroid to bits? Wang and his colleagues concluded that it was likely a gravitational effect called tidal disruption.

“A white dwarf is a very compact star,” Wang said. “As such, close to the star, the gradient of the gravitational field can be very large,” meaning gravity can change sharply over a short space.

Imagine you were floating in space, orbiting a star with your feet pointed toward it. The gravity on your feet would be greater than the gravity on your shoulders. If you’re standing on Earth right now, you’re experiencing the same effect, though the difference — the gradient — is so minimal that you don’t notice it.

In the steep gravitational fields close to white dwarfs, Wang said, gradients can become so intense that they overwhelm forces holding an object together. Large asteroids are glued together with their own gravity, but that gravity isn’t as strong as the gradients close to white dwarfs. When asteroids pass through those tidal regions, astronomers believe, they shatter, smearing across space as a cloud.

This is related to the reason some planets are surrounded by rings of dust, and not just moons, Rice said. The weaker tidal forces of large planets can keep the matter in their rings from clumping together into balls.

The astronomers are certain the debris wasn’t from a comet in this case, Wang said, because comets move so fast that the debris would quickly leave the immediate warm neighborhood around the star and cool down. It’s possible that a rocky planet blew up, he said, but the researchers believe a smaller, asteroid-sized object is more likely. (The precise distinction between a large asteroid and a small planet can be a bit vague. But when it comes to other star systems astronomers usually use “exoasteroid” to refer to smaller, jagged metal and rock objects and “exoplanet” to refer to objects large enough that their gravity has formed them into spheres.

Right now, the debris cloud is still circling the star, which goes by the name WD 0145+234. Over time, though, that cloud is likely to fall onto the stellar surface, Wang said. That infalling debris, made of metal and perhaps some warm gas, could  explain how many white dwarfs end up with evidence of significant metal pollution in their starlight.

The research has not yet been peer reviewed and was published online Oct. 10 in the preprint journal arXiv.

Originally published on Live Science.
By Rafi Letzter – Staff Writer
17/10/2019

 

Exotic ‘Fuzzy’ Dark Matter May Have Created Giant Filaments Across the Early Universe

SCIENCE

(Image: © MARK GARLICK/SCIENCE PHOTO LIBRARY)

Dark matter, the mysterious substance making up a quarter of the mass and energy of the universe, might be made from extremely tiny and light particles, new research suggests. This “fuzzy” form of dark matter—called that because these miniscule particles’ wavelengths would be smeared out over a colossally huge area—would have altered the course of cosmic history and created long and wispy filaments instead of clumpy galaxies in the early universe, according to simulations.

The findings have observational consequences — upcoming telescopes will be able to peer back to this early time period and potentially distinguish between different types of dark matter, allowing physicists to better understand its properties.

Dark matter is an unknown massive substance  found throughout the cosmos. It gives off no light — hence the name dark matter — but its gravitational effects help bind together galactic clusters and cause stars at the edges of galaxies to spin faster than they otherwise would. Many scientists believe that most dark matter is cold, meaning it moves relatively slowly. But there are entirely different ideas, such as the possibility that it’s tiny and fuzzy, meaning it would move quickly because it’s so light.

“Our simulations show that the first galaxies and stars that form look very different in a universe with fuzzy dark matter than a universe that has cold dark matter,” Lachlan Lancaster, an astrophysics graduate student at Princeton University and co-author of a new paper in the journal Physical Review Letters, told Live Science.

Lancaster explained that the most common speculations about dark matter suggest it is composed of weakly interactive massive particles (WIMPs), which would have a few tens or hundreds of times the mass of a proton. Simulations that use this type of dark matter are extremely good at re-creating the large-scale structure of the universe, including vast voids of empty space surrounded by  long, spidery filaments  of gas and dust, a formation known as the cosmic web. But on smaller scales, such models contain a number of discrepancies from what astronomers observe with their telescopes. In this standard view, dark matter should pile up in the centers of galaxies, but nobody has seen it doing so.

Fuzzy dark matter, in contrast, would be mind-bogglingly light, perhaps a billionth of a billionth of a billionth the mass of an electron, according to a statement from MIT. Quantum mechanics states that particles can also be thought of as waves, with wavelengths inversely proportional to their mass, Lancaster said. So the wavelength of such a light particle would be thousands of light-years long.

Fuzzy dark matter would therefore have a harder time clumping together than cold, WIMP dark matter. In simulations, Lancaster and his co-authors showed that a cold dark-matter universe would have galaxies that formed relatively quickly out of spherical halos.

But fuzzy dark matter would instead coalesce into long, wispy strings of material — “more giant filaments than clumpy galaxies,” Lancaster said — and galaxies would then be born larger and later. Dark matter would also have a harder time piling up in the centers of galaxies, potentially explaining why astronomers don’t observe this clumpiness when they look at galaxies.

Instruments like the Large Synoptic Survey Telescope (LSST) in Chile and 30-meter-class telescopes being built around the world will soon be able to peer back to some of the universe’s earliest days. They are expected to start taking data in the next decade, which means “we’ll either start seeing the effects of fuzzy dark matter, or start ruling them out,” Lancaster said.

Though other researchers have speculated about fuzzy dark matter, the new simulations do a more careful job of working out its cosmological effects, said Jeremiah Ostriker, an astrophysicist at Columbia University who was not involved in the work.

“This helps outline the details of what the formation of structure would be in this variant theory,” OStriker added. “And it’s one of the most interesting variant theories around.”

Lancaster said his team’s future simulations might focus on capturing more details of the fuzzy dark matter’s effects, potentially giving astronomers a better idea of what they might expect to see through their telescopes.

Originally published on Live Science.
By Adam Mann – Live Science Contributor
16/10/2019

 

2711: Nobody Knows What Made the Gargantuan Crater on the Dark Side of the Moon

SCIENCE

Scientists just debunked the most popular explanation for one of the solar system’s largest craters.

The South Pole-Aitken basin (represented by the shades of blue at the center) stretches 1,550 miles (2,500 kilometers) across and is one of the solar system’s largest craters. The dashed circle indicates the spot where researchers found a weird material beneath the basin that contains metal.
(Image: © NASA/Goddard Space Flight Center/University of Arizona)

Billions of years ago, something slammed into the dark side of the moon and carved out a very, very large hole. Stretching 1,550 miles (2,500 kilometers) wide and 8 miles (13 km) deep, the South Pole-Aitken basin, as the tremendous hole is known to Earthlings, is the oldest and deepest crater on the moon, and one of the largest craters in the entire solar system.

For decades, researchers have suspected that the gargantuan basin was created by a head-on collision with a very large, very fast meteor. Such an impact would have ripped the moon’s crust apart and scattered chunks of lunar mantle across the crater’s surface, providing a rare glimpse at what the moon is really made of. (Spoiler: It’s not cheese.) That theory gained some credence earlier this year, when China’s Yutu-2 rover, which settled into the bottom of the crater aboard the Chang’e 4 lander in January, discovered traces of minerals that seemed to originate from the moon’s mantle.

Now, however, a study published Aug. 19 in the journal Geophysical Research Letters throws those results — and the crater’s origin story — into question. After analyzing the minerals in six plots of soil at the bottom of the South Pole-Aitken basin, a team of researchers argues that the crater’s composition is all crust and no mantle, suggesting that whatever impact opened the crater billions of years ago did not hit hard enough to spray the moon’s innards onto the surface.

“We are not seeing the mantle materials at the landing site as expected,” study co-author Hao Zhang, a planetary scientist at the China University of Geosciences, said in a statement. These findings all but rule out a direct collision with a high-velocity meteor and raise the question: What, if not a head-on meteor strike, created the largest crater on the moon?

Lighting up the dark side

In their new study, the researchers used a technique called reflection spectroscopy to identify specific minerals in the lunar soil based on how individual grains reflected visible and near-infrared light.

Using equipment aboard the Yutu 2 rover, the team conducted reflectance tests on six patches of soil in the first two days following Chang’e 4’s landing, venturing about 175 feet (54 meters) away from the lander. With the help of a database that identifies lunar minerals based on a variety of factors — including size, reflectance and degradation due to solar windthe team estimated the mineral concentration in each of the plots.

Yutu 2 found a strangely colored substance in a crater on the far side of the moon.
(Image credit: China Lunar Exploration Project)

A crystalline rock called plagioclase was by far the most abundant mineral in each sample, accounting for 56% to 72% of the crater’s composition, the researchers wrote. Formed as primordial oceans of lava cool, plagioclase is extremely common in the crusts of Earth and the moon alike, but it’s less abundant in their mantles. Though the team detected other minerals in the crust that are more common in the moon’s mantle, such as olivine, these rocks made up too small a fraction of the soil samples to suggest that part of the mantle had broken through the crust.

This mineral makeup complicates the theory that a giant, high-velocity meteor created the South Pole‐Aitken basin billions of years ago, as such an impact almost certainly would have scattered chunks of mantle over the lunar surface.

So, what, then, created the crater? The researchers did not speculate in the new study. However, prior research has suggested that a renegade space rock is still the culprit, but the hit may not have been so direct. A study published in 2012 in the journal Science argued that a slightly slower-moving meteor could have struck the back of the moon at an angle of about 30 degrees and resulted in an appropriately large crater that never disturbed the moon’s mantle. However, those researchers had only simulations to go on.

If nothing else, the new research suggests that there’s a lot more exploring to do in the South Pole‐Aitken basin before an answer becomes apparent. See you on the dark side of the moon.

Originally published on Live Science.

By Brandon Specktor – Senior Writer
25/09/2019

 

2685: Where Do Black Holes Lead?

SCIENCE

Where does a black hole go?

So there you are, about to leap into a black hole. What could possibly await should — against all odds — you somehow survive? Where would you end up and what tantalizing tales would you be able to regale if you managed to clamor your way back?

The simple answer to all of these questions is, as Professor Richard Massey explains, “Who knows?” As a Royal Society research fellow at the Institute for Computational Cosmology at Durham University, Massey is fully aware that the mysteries of black holes run deep. “Falling through an event horizon is literally passing beyond the veil — once someone falls past it, nobody could ever send a message back,” he said. “They’d be ripped to pieces by the enormous gravity, so I doubt anyone falling through would get anywhere.”

If that sounds like a disappointing — and painful — answer, then it is to be expected. Ever since Albert Einstein’s general theory of relativity was considered to have predicted black holes by linking space-time with the action of gravity, it has been known that black holes result from the death of a massive star leaving behind a small, dense remnant core. Assuming this core has more than roughly three-times the mass of the sun, gravity would overwhelm to such a degree that it would fall in on itself into a single point, or singularity, understood to be the black hole’s infinitely dense core.

Related: 9 Ideas About Black Holes That Will Blow Your Mind

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The resulting uninhabitable black hole would have such a powerful gravitational pull that not even light could avoid it. So, should you then find yourself at the event horizon — the point at which light and matter can only pass inward, as proposed by the German astronomer Karl Schwarzschild — there is no escape. According to Massey, tidal forces would reduce your body into strands of atoms (or ‘spaghettification’, as it is also known) and the object would eventually end up crushed at the singularity. The idea that you could pop out somewhere — perhaps at the other side — seems utterly fantastical.

What about a wormhole?

Or is it? Over the years scientists have looked into the possibility that black holes could be wormholes to other galaxies. They may even be, as some have suggested, a path to another universe.

Such an idea has been floating around for some time: Einstein teamed up with Nathan Rosen to theorise bridges that connect two different points in space-time in 1935. But it gained some fresh ground in the 1980s when physicist Kip Thorne — one of the world’s leading experts on the astrophysical implications of Einstein’s general theory of relativity — raised a discussion about whether objects could physically travel through them.

“Reading Kip Thorne’s popular book about wormholes is what first got me excited about physics as a child,” Massey said. But it doesn’t seem likely that wormholes exist.

Indeed, Thorne, who lent his expert advice to the production team for the Hollywood movie Interstellar, wrote: “We see no objects in our universe that could become wormholes as they age,” in his book “The Science of Interstellar” (W.W. Norton and Company, 2014). Thorne told Space.com that journeys through these theoretical tunnels would most likely remain science fiction, and there is certainly no firm evidence that a black hole could allow for such a passage.

Artist’s concept of a wormhole. If wormholes exist, they might lead to another universe. But, there’s no evidence that wormholes are real or that a black hole would act like one.
(Image credit: Shutterstock)

But, the problem is that we can’t get up close to see for ourselves. Why, we can’t even take photographs of anything that takes place inside a black hole — if light cannot escape their immense gravity, then nothing can be snapped by a camera. As it stands, theory suggests that anything which goes beyond the event horizon is simply added to the black hole and, what’s more, because time distorts close to this boundary, this will appear to take place incredibly slowly, so answers won’t be quickly forthcoming.

“I think the standard story is that they lead to the end of time,” said Douglas Finkbeiner, professor of astronomy and physics at Harvard University. “An observer far away will not see their astronaut friend fall into the black hole. They’ll just get redder and fainter as they approach the event horizon [as a result of gravitational red shift]. But the friend falls right in, to a place beyond ‘forever.’ Whatever that means.”

Maybe a black hole leads to a white hole

Certainly, if black holes do lead to another part of a galaxy or another universe, there would need to be something opposite to them on the other side. Could this be a white hole — a theory put forward by Russian cosmologist Igor Novikov in 1964? Novikov proposed that a black hole links to a white hole that exists in the past. Unlike a black hole, a white hole will allow light and matter to leave, but light and matter will not be able to enter.

Scientists have continued to explore the potential connection between black and white holes. In their 2014 study published in the journal Physical Review D, physicists Carlo Rovelli and Hal M. Haggard claimed that “there is a classic metric satisfying the Einstein equations outside a finite space-time region where matter collapses into a black hole and then emerges from a while hole.” In other words, all of the material black holes have swallowed could be spewed out, and black holes may become white holes when they die.

Far from destroying the information that it absorbs, the collapse of a black hole would be halted. It would instead experience a quantum bounce, allowing information to escape. Should this be the case, it would shed some light on a proposal by former Cambridge University cosmologist and theoretical physicist Stephen Hawking who, in the 1970s, explored the possibility that black holes emit particles and radiation — thermal heat — as a result of quantum fluctuations.

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“Hawking said a black hole doesn’t last forever,” Finkbeiner said. Hawking calculated that the radiation would cause a black hole to lose energy, shrink and disappear, as described in his 1976 paper published in Physical Review D. Given his claims that the radiation emitted would be random and contain no information about what had fallen in, the black hole, upon its explosion, would erase loads of information.

This meant Hawking’s idea was at odds with quantum theory, which says information can’t be destroyed. Physics states information just becomes more difficult to find because, should it become lost, it becomes impossible to know the past or the future. Hawking’s idea led to the ‘black hole information paradox’ and it has long puzzled scientists. Some have said Hawking was simply wrong, and the man himself even declared he had made an error during a scientific conference in Dublin in 2004.

So, do we go back to the concept of black holes emitting preserved information and throwing it back out via a white hole? Maybe. In their 2013 study published in Physical Review Letters, Jorge Pullin at Louisiana State University and Rodolfo Gambini at the University of the Republic in Montevideo, Uruguay, applied loop quantum gravity to a black hole and found that gravity increased towards the core but reduced and plonked whatever was entering into another region of the universe. The results gave extra credence to the idea of black holes serving as a portal. In this study, singularity does not exist, and so it doesn’t form an impenetrable barrier that ends up crushing whatever it encounters. It also means that information doesn’t disappear.

Maybe black holes go nowhere

Yet physicists Ahmed Almheiri, Donald Marolf, Joseph Polchinski and James Sully still believed Hawking could have been on to something. They worked on a theory that became known as the AMPS firewall, or the black hole firewall hypothesis. By their calculations, quantum mechanics could feasibly turn the event horizon into a giant wall of fire and anything coming into contact would burn in an instant. In that sense, black holes lead nowhere because nothing could ever get inside.

This, however, violates Einstein’s general theory of relativity. Someone crossing the event horizon shouldn’t actually feel any great hardship because an object would be in free fall and, based on the equivalence principle, that object — or person — would not feel the extreme effects of gravity. It could follow the laws of physics present elsewhere in the universe, but even if it didn’t go against Einstein’s principle it would undermine quantum field theory or suggest information can be lost.

Related: 11 Fascinating Facts About Our Milky Way Galaxy

Artist’s impression of a tidal disruption event which occurs when a star passes too close to a supermassive black hole.
(Image credit: All About Space magazine)

A black hole of uncertainty

Step forward Hawking once more. In 2014, he published a study in which he eschewed the existence of an event horizon — meaning there is nothing there to burn — saying gravitational collapse would produce an ‘apparent horizon’ instead.

This horizon would suspend light rays trying to move away from the core of the black hole, and would persist for a “period of time.” In his rethinking, apparent horizons temporarily retain matter and energy before dissolving and releasing them later down the line. This explanation best fits with quantum theory — which says information can’t be destroyed — and, if it was ever proven, it suggests that anything could escape from a black hole.

Hawking went as far as saying black holes may not even exist. “Black holes should be redefined as metastable bound states of the gravitational field,” he wrote. There would be no singularity, and while the apparent field would move inwards due to gravity, it would never reach the center and be consolidated within a dense mass.

And yet anything which is emitted will not be in the form of the information swallowed. It would be impossible to figure out what went in by looking at what is coming out, which causes problems of its own — not least for, say, a human who found themselves in such an alarming position. They’d never feel the same again!

One thing’s for sure, this particular mystery is going to swallow up many more scientific hours for a long time to come. Rovelli and Francesca Vidotto recently suggested that a component of dark matter could be formed by remnants of evaporated black holes, and Hawking’s paper on black holes and ‘soft hair’ was released in 2018, and describes how zero-energy particles are left around the point of no return, the event horizon — an idea that suggests information is not lost but captured.

This flew in the face of the no-hair theorem which was expressed by physicist John Archibald Wheeler and worked on the basis that two black holes would be indistinguishable to an observer because none of the special particle physics pseudo-charges would be conserved. It’s an idea that has got scientists talking, but there is some way to go before it’s seen as the answer for where black holes lead. If only we could find a way to leap into one.

livescience
21/09/2019
By David Crookes – All About Space magazine

 

Something Is Killing the Universe’s Most Extreme Galaxies

And scientists are looking for the killer.

The spiral galaxy NGC 4330 is located in the Virgo Cluster. Ram-pressure stripped hot gas is shown in red, and a blue overlay shows star-forming gas.
(Image: © Fossatie et al. (2018),

In the most extreme regions of the universe, galaxies are being killed. Their star formation is being shut down and astronomers want to know why.

The first ever Canadian-led large project on one of the world’s leading telescopes is hoping to do just that. The new program, called the Virgo Environment Traced in Carbon Monoxide survey (VERTICO), is investigating, in brilliant detail, how galaxies are killed by their environment.

As VERTICO’s principal investigator, I lead a team of 30 experts that are using the Atacama Large Millimeter Array (ALMA) to map the molecular hydrogen gas, the fuel from which new stars are made, at high resolution across 51 galaxies in our nearest galaxy cluster, called the Virgo Cluster.

Commissioned in 2013 at a cost of US$1.4 billion, ALMA is an array of connected radio dishes at an altitude of 5,000 metres in the Atacama Desert of northern Chile. It is an international partnership between Europe, the United States, Canada, Japan, South Korea, Taiwan and Chile. The largest ground-based astronomical project in existence, ALMA is the most advanced millimetre wavelength telescope ever built and ideal for studying the clouds of dense cold gas from which new stars form, which cannot be seen using visible light.

Large ALMA research programs such as VERTICO are designed to address strategic scientific issues that will lead to a major advance or breakthrough in the field.

Galaxy clusters

Where galaxies live in the universe and how they interact with their surroundings (the intergalactic medium that surrounds them) and each other are major influences on their ability to form stars. But precisely how this so-called environment dictates the life and death of galaxies remains a mystery.

Galaxy clusters are the most massive and most extreme environments in the universe, containing many hundreds or even thousands of galaxies. Where you have mass, you also have gravity and the huge gravitational forces present in clusters accelerates galaxies to great speeds, often thousands of kilometres-per-second, and superheats the plasma in between galaxies to temperatures so high that it glows with X-ray light.

In the dense, inhospitable interiors of these clusters, galaxies interact strongly with their surroundings and with each other. It is these interactions that can kill off — or quench — their star formation.

Understanding which quenching mechanisms shut off star formation and how they do it is the main focus of the VERTICO collaboration’s research.

The life cycle of galaxies

As galaxies fall through clusters, the intergalactic plasma can rapidly remove their gas in a violent process called ram pressure stripping. When you remove the fuel for star formation, you effectively kill the galaxy, turning it into a dead object in which no new stars are formed.

In addition, the high temperature of clusters can stop hot gas cooling and condensing onto galaxies. In this case, the gas in the galaxy isn’t actively removed by the environment but is consumed as it forms stars. This process leads to a slow, inexorable shut down in star formation known, somewhat morbidly, as starvation or strangulation.

While these processes vary considerably, each leaves a unique, identifiable imprint on the galaxy’s star-forming gas. Piecing these imprints together to form a picture of how clusters drive changes in galaxies is a major focus of the VERTICO collaboration. Building on decades of work to provide insight into how environment drives galaxy evolution, we aim to add a critical new piece of the puzzle.

An ideal case study

The Virgo Cluster is an ideal location for such a detailed study of environment. It is our nearest massive galaxy cluster and is in the process of forming, which means that we can get a snapshot of galaxies in different stages of their life cycles. This allows us to build up a detailed picture of how star formation is shut off in cluster galaxies.

Galaxies in the Virgo cluster have been observed at almost every wavelength in the electromagnetic spectrum (for example, radio, optical and ultraviolet light), but observations of star-forming gas (made at at millimeter wavelengths) with the required sensitivity and resolution do not exist yet. As one of the largest galaxy surveys on ALMA to date, VERTICO will provide high resolution maps of molecular hydrogen gas — the raw fuel for star formation — for 51 galaxies.

With ALMA data for this large sample of galaxies, it will be possible to reveal exactly which quenching mechanisms, ram pressure stripping or starvation, are killing galaxies in extreme environments and how.

By mapping the star-forming gas in galaxies that are the smoking gun examples of environment-driven quenching, VERTICO will advance our current understanding of how galaxies evolve in the densest regions of the Universe.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

LiveScience
By Toby Brown – McMaster University
19/09/2019

 

2606: 3 Asteroids Are Zipping Past Earth Today

But don’t worry — they’re at least as far away as the moon is.

Hundreds of orbiting comets and asteroids are thought to present some risk of colliding with Earth, but the threat is typically very small.
(Image: © Shutterstock)

Three asteroids are expected to hurtle past Earth today (Sept. 9). One will pass as near as 310,000 miles (500,000 kilometers) — closer than any potential asteroid near-miss for the next three months.

Asteroid 2019 QZ3 flew by at 6:49 a.m. ET; asteroid 2019 RG2 follows at around 3:13 p.m. ET, and the third, asteroid 2019 QY4, flashes past at 9:10 p.m. ET, the International Business Times reported.

QZ3 is the biggest of the trio, with a diameter of 220 feet (67 meters), while RG2 and QY4, respectively measure approximately 66 feet (20 m) and 52 feet (16 m) in length, according to NASA’s Center for Near-Earth Object Studies (CNEOS).

Space rocks such as these, known as near-Earth objects (NEOS), are nudged by the gravity of neighboring planets into orbital paths that carry them fairly close to our cosmic address. But “close” in space is a relative term: At the closest point in their passage, all three of today’s asteroid visitors will be farther from Earth than the moon is, according to CNEOS.

RG2 is the fastest asteroid, speeding by at a velocity of nearly 50,000 miles per hour (80,000 kilometers/hour), while QY4 is moving at just over 17,000 mph (27,000 km/h). QZ3 is the slowpoke of the group, at 16,700 mph (26,800 km/h), according to IBT. Though QZ3 is the biggest asteroid, it is also the furthest from Earth, at a distance of approximately 2.3 million miles from our planet, CNEOS reported.

Another asteroid — 2006 QV89 — was previously thought to potentially follow a trajectory that could slam into Earth, with a 1-in-7,299 chance of an impact on Sept. 9. But experts announced in July that the asteroid did not appear in the area of the sky where it would have shown up if it were on a collision course with our planet, representatives with the European Southern Observatory (ESO) said in a statement.

CNEOS representatives confirmed on Aug. 15 that QV89 was no threat to Earth, and that the asteroid would instead rocket past our planet on Sept. 27 “at a comfortable distance of 4.3 million miles (6.9 million km), about 18 times the distance of the Moon.”

Currently, there are 878 NEOs that demonstrate some risk — however small it might be — of colliding with Earth, according to a list maintained by the European Space Agency (ESA). Of these, the biggest (and second on the list) is asteroid 1979 XB. Measuring about 2,300 feet (700 m) in length and traveling at more than 58,000 mph (93,300 km/h), the massive space rock is expected to come calling on Dec. 14, 2113, ESA reported.

Live Science
By Mindy Weisberger – Senior Writer
09/09/2019

 

‘Einstein’s Biggest Blunder’ May Have Finally Been Fixed

The cosmological constant has plagued physicists for more than a century.

There is a fundamental problem in physics.

A single number, called the cosmological constant, bridges the microscopic world of quantum mechanics and the macroscopic world of Einstein’s theory of general relativity. But neither theory can agree on its value.

In fact, there’s such a huge discrepancy between the observed value of  this constant and what theory predicts that it is widely considered the worst prediction in the history of physics. Resolving the discrepancy may be the most important goal of theoretical physics this century.

Lucas Lombriser, an assistant professor of theoretical physics at the University of Geneva in Switzerland, has introduced a new way of evaluating Albert Einstein’s equations of gravity to find a value for the cosmological constant that closely matches its observed value. He published his method online in the Oct. 10 issue of the journal Physics Letters B.

Related: The Biggest Unsolved Mysteries in Physics


An illustration of galaxies bending the fabric of space-time (green), and the smooth effect of dark energy (purple), which dominates the effects of gravity.(Image: © NASA/JPL-Caltech)

How Einstein’s biggest blunder became dark energy

The story of the cosmological constant began more than a century ago when Einstein presented a set of equations, now known as the Einstein field equations, that became the framework of his theory of general relativity. The equations explain how matter and energy warp the fabric of space and time to create the force of gravity. At the time, both Einstein and astronomers agreed that the universe was fixed in size and that the overall space between galaxies did not change. However, when Einstein applied general relativity to the universe as a whole, his theory predicted an unstable universe that would either expand or contract. To force the universe to be static, Einstein tacked on the cosmological constant.

Nearly a decade later, another physicist, Edwin Hubble, discovered that our universe is not static, but expanding. The light from distant galaxies showed they were all moving away from each other. This revelation persuaded Einstein to abandon the cosmological constant from his field equations as it was no longer necessary to explain an expanding universe. Physics lore has it that Einstein later confessed that his introduction of the cosmological constant was perhaps his greatest blunder.

In 1998, observations of distant supernovas showed the universe wasn’t just expanding, but the expansion was speeding up. Galaxies were accelerating away from each other as if some unknown force was overcoming gravity and shoving those galaxies apart. Physicists have named this enigmatic phenomenon dark energy, as its true nature remains a mystery.

In a twist of irony, physicists once again reintroduced the cosmological constant into Einstein’s field equations to account for dark energy. In the current standard model of cosmology, known as ΛCDM (Lambda CDM), the cosmological constant is interchangeable with dark energy. Astronomers have even estimated its value based on observations of distant supernovas and fluctuations in the cosmic microwave background. Although the value is absurdly small (on the order of 10^-52 per square meter), over the scale of the universe, it is significant enough to explain the accelerated expansion of space.

“The cosmological constant [or dark energy] currently constitutes about 70% of the energy content in our universe, which is what we can infer from the observed accelerated expansion that our universe is presently undergoing. Yet this constant is not understood,” Lombriser said. “Attempts to explain it have failed, and there seems to be something fundamental that we are missing in how we understand the cosmos. Unraveling this puzzle is one of the major research areas in modern physics. It is generally anticipated that resolving the issue may lead us to a more fundamental understanding of physics.”

Related: 8 Ways You Can See Einstein’s Theory of Relativity in Real Life

The worst theoretical prediction in the history of physics

The cosmological constant is thought to represent what physicists call “vacuum energy.” Quantum-field theory states that even in a completely empty vacuum of space, virtual particles pop in and out of existence and create energy — a seemingly absurd idea, but one that has been observed experimentally. The problem arises when physicists attempt to calculate its contribution to the cosmological constant. Their result differs from observations by a mind-boggling factor of 10^121 (that’s 10 followed by 120 zeroes), the largest discrepancy between theory and experiment in all of physics.

Such a disparity has caused some physicists to doubt Einstein’s original equations of gravity; some have even suggested alternative models of gravity. However, further evidence of gravitational waves by the Laser Interferometer Gravitational-Wave Observatory (LIGO) have only strengthened general relativity and dismissed many of these alternative theories. Which is why instead of rethinking gravity, Lombriser took a different approach to solve this cosmic puzzle.

“The mechanism I propose does not modify Einstein’s field equations,” Lombriser said. Instead, “it adds an additional equation on top of Einstein’s field equations.”

The gravitational constant, which was first used in Isaac Newton’s laws of gravity and now an essential part of Einstein’s field equations, describes the magnitude of  the gravitational force between objects. It is considered one of the fundamental constants of physics, eternally unchanged since the beginning of the universe. Lombriser has made the dramatic assumption that this constant can change.

In Lombriser’s modification of general relativity, the gravitational constant remains the same within our observable universe but may vary beyond it. He suggests a multiverse scenario where there may be patches of the universe invisible to us that have different values for the fundamental constants.

This variation of gravity gave Lombriser an additional equation that relates the cosmological constant to the average sum of matter across space-time. After he accounted for the estimated mass of all the galaxies, stars and dark matter of the universe, he could solve that new equation to obtain a new value for the cosmological constant — one that closely agrees with observations.

Using a new parameter, ΩΛ (omega lambda), that expresses the fraction of the universe made of dark matter, he found the universe is made up of about 74% dark energy. This number closely matches the value of 68.5% estimated from observations — a tremendous improvement over the huge disparity found by quantum field theory.

Although Lombriser’s framework might solve the cosmological constant problem, there’s currently no way to test it. But in the future, if experiments from other theories validate his equations,  it could mean a major leap in our understanding of dark energy and provide a tool to solve other cosmic mysteries.

Originally published on Live Science.
By Tim Childers – Live Science Contributor
06/09/2019

 

Earth’s Core Has Been Leaking for 2.5 Billion Years and Geologists Don’t Know Why

Credit: Shutterstock

Earth’s scorching core is not a loner — it has been caught mingling with other, underworldly layers. That’s according to a new study that found the innermost part of the planet leaks some of its contents into mantle plumes, some of which eventually reach Earth’s surface.

This discovery helps settle a debate that’s been raging for decades: whether the core and mantle exchange any material, the researchers said.

“Our findings suggest some core material does transfer into the base of these mantle plumes, and the core has been leaking this material for the past 2.5 billion years,” the researchers wrote in The Conversation, a website where scientists write about their research for the public. [Photos: The World’s Weirdest Geological Formations]

The finding was made possible by the metal tungsten (W), element 74 on the periodic table. If tungsten were to make a dating profile, it would note that it’s a siderophile, or “iron lover.” So, it’s no surprise that a lot of tungsten hangs out in Earth’s core, which is made primarily of iron and nickel.

On its profile, tungsten would also list that it has a few isotopes (an element with a different number of neutrons in its nucleus), including W-182 (with 108 neutrons) and W-184 (with 110 neutrons). While devising their study, the researchers realized that these isotopes could help them solve the core-leaking question.

Another element, hafnium (Hf), is a lithophile, meaning it loves rocks and can be found in Earth’s silicate-rich mantle. With a half-life of 8.9 million years, hafnium’s radioactive isotope Hf-182 decays into W-182. This means that the mantle should have more W-182 than the core does, the scientists reasoned.

“Therefore, chemical exchange between the core and the source of mantle plumes could be detectable in the 182W/184W ratio of ocean island basalts,” which come from plumes in the mantle, the researchers wrote in the study.

But this difference in tungsten would be incredibly small: The tungsten-182 composition in the mantle and core were expected to differ by only about 200 parts per million (ppm). “Fewer than five laboratories in the world can do this type of analysis,” the researchers wrote in The Conversation.

Furthermore, it’s not easy to study the core, because it begins at a depth of about 1,800 miles (2,900 kilometers) underground. To put that into perspective, the deepest hole humans have ever dug is the Kola Superdeep Borehole in Russia, which has a depth of about 7.6 miles (12.3 km).

So, the researchers studied the next best thing: rocks that oozed to Earth’s surface from the deep mantle at the Pilbara Craton in Western Australia, and the Réunion Island and Kerguelen Archipelago hotspots in the Indian Ocean.

The amount of tungsten in these rocks revealed a leak from the core. Over Earth’s lifetime, there was a big change in the W-182-to-W-184 ratio in Earth’s mantle, the researchers found. Oddly, Earth’s oldest rocks have a higher W-182-to-W-184 ratio than most modern-day rocks do, they discovered.

“The change in the 182W/184W ratio of the mantle indicates that tungsten from the core has been leaking into the mantle for a long time,” the researchers wrote in The Conversation. [Photos: Geologists Home-Brew Lava]

Earth is about 4.5 billion years old. The planet’s oldest mantle rocks, however, didn’t have any significant changes in tungsten isotopes. This suggests that from 4.3 billion to 2.7 billion years ago, there was little or no exchange of material from the core to the upper mantle, the researchers said.

But in the past 2.5 billion years, the tungsten isotope composition in the mantle has changed substantially. Why did this happen? If mantle plumes are rising from the core-mantle boundary, then perhaps, like a see-saw, material from Earth’s surface is going down into the deep mantle, the researchers said. This surface material has oxygen in it, an element that can affect tungsten, the researchers said.

Subduction, the term used for rocks from Earth’s surface descending into the mantle, takes oxygen-rich material from the surface into the deep mantle as an integral component of plate tectonics,” the researchers wrote in The Conversation. “Experiments show that [an] increase in oxygen concentration at the core-mantle boundary could cause tungsten to separate out of the core and into the mantle.”

Or, maybe as the inner core solidified after Earth formed, the oxygen concentration in the outer core increased, the researchers said. “In this case, our new results could tell us something about the evolution of the core, including the origin of Earth’s magnetic field,” they wrote in The Conversation.

The study was published online June 20 in the journal Geochemical Perspectives Letters.

Originally published on Live Science.

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