Tag Archives: the

Science

Watch a Billion Years of Shifting Tectonic Plates in 40 Mesmerising Seconds

Leave a comment

The tectonic plates that cover Earth like a jigsaw puzzle move about as fast as our fingernails grow, but over the course of a billion years that’s enough to travel across the entire planet – as a fascinating new video shows.

 

In one of the most complete models of tectonic plate movements ever put together, scientists have condensed a billion years of movement into a 40-second video clip, so we can see how these giant slabs of rock have interacted over time.

As they move, the plates affect climate, tidal patterns, animal movements and their evolution, volcanic activity, the production of metals and more: they’re more than just a covering for the planet, they’re a life support system that affects everything that lives on the surface.

“For the first time a complete model of tectonics has been built, including all the boundaries,” geoscientist Michael Tetley, who completed his PhD at the University of Sydney, told Euronews.

“On a human timescale, things move in centimetres per year, but as we can see from the animation, the continents have been everywhere in time. A place like Antarctica that we see as a cold, icy inhospitable place today, actually was once quite a nice holiday destination at the equator.”

The moving and sliding of the plates is quite a sight if you check out the video – land masses that are near neighbours become distant cousins and vice versa, and you might be surprised at just how recently it was that the countries and continents settled into the positions that we know today.

 

Understanding these movements and patterns is crucial if scientists want to predict how habitable our planet will be in the future, and where we’re going to find the metal resources we need to ensure a clean energy future.

Plate movement is estimated through the study of the geological record – the magnetism that provides data on substrates’ historic positions in respect to Earth’s spin axis and the types of material locked in rock samples that help match the pieces of past geological plate puzzles together.

Here the team went to great lengths to choose and combine the most suitable models currently available, looking at both the movements of the continents and the interactions along plate boundaries.

“Planet Earth is incredibly dynamic, with the surface composed of plates that constantly jostle each other in a way unique among the known rocky planets,” says geoscientist Sabin Zahirovic, from the University of Sydney.

“These plates move at the speed fingernails grow, but when a billion years is condensed into 40 seconds a mesmerising dance is revealed. Oceans open and close, continents disperse and periodically recombine to form immense supercontinents.”

 

The further scientists go into the past, the more difficult it becomes to estimate how plates have moved, and in this case the Neoproterozoic to Cambrian (1,000 to 520 million years ago) eras in particular were carefully charted and brought in line to match the more modern records that we have.

Questions remain about how these plates first formed and when this formation happened, but every new data point helps us to understand the ancient history of Earth – even accounting for missing plates in some models.

The scientists admit that their work lacks some finer detail – stretched as it is across the entire planet and a billion years – but they’re hoping that it can act as a useful resource and foundation for the future study of these movements and the impact they have on everything else on the planet.

“Our team has created an entirely new model of Earth evolution over the last billion years,” says geoscientist Dietmar Müller, from the University of Sydney.

“Our planet is unique in the way that it hosts life. But this is only possible because geological processes, like plate tectonics, provide a planetary life-support system.”

The research has been published in Earth-Science Reviews.

 

Read original article here

Science

Scientists Are Inching Closer to Figuring Out How Heavy Dark Matter Really Is

Leave a comment

Scientists are finally figuring out how much dark matter – the almost imperceptible material said to tug on everything, yet emit no light – really weighs.

The new estimate helps pin down how heavy its particles could be – with implications for what the mysterious stuff actually is.

 

The research sharply narrows the potential mass of dark matter particles, from between an estimated 10^minus 24 electronvolts (eV) and 10^19 Gigaelectron volts (GeV) , to between 10^minus 3 eV and 10^7eV – a possible range of masses many trillions of trillions of times smaller than before.

The findings could help dark matter hunters focus their efforts on the indicated range of particle masses – or they might reveal a previously unknown force is at work in the universe, said Xavier Calmet, a professor of physics and astronomy at the University of Sussex in the United Kingdom.

Related: The 11 biggest unanswered questions about dark matter

Calmet, along with doctoral student Folkert Kuipers, also of the University of Sussex, described their efforts in a new study to be published in the March issue of Physical Letters B.

What is dark matter?

By some estimates, dark matter makes up about 83 percent of all the matter in the universe. It’s thought only to interact with light and ordinary matter through gravity, which means it can only be seen by the way it curves light rays.

Astronomers found the first hints of dark matter when gazing at a galactic cluster in the 1930s, and theories that galaxies are threaded with and fringed by vast halos of dark matter became mainstream after the 1970s, when astronomers realized galaxies were whirling faster than they otherwise should, given how much visible matter they contained. 

 

Related: The 12 strangest objects in the universe

Possible candidates for dark matter particles include ghostly, tiny particles known as neutrinos, theoretical dark, cold particles known as axions, and proposed weakly-interacting massive particles, or WIMPs.

The new mass bounds could help eliminate some of these candidates, depending on the details of the specific dark matter model, Calmet said.

Quantum gravity

What scientists do know is that dark matter seems to interact with light and normal matter only through gravity, and not via any of the other fundamental forces; and so the researchers used gravitational theories to arrive at their estimated range for the masses of dark matter particles.

Importantly, they used concepts from theories of quantum gravity, which resulted in a much narrower range than the previous estimates, which used only Einstein’s theory of general relativity.

“Our idea was a very simple one,” Calmet told Live Science in an email. “It is amazing that people have not thought of this before.”

Einstein’s theory of general relativity is based on classical physics; it perfectly predicts how gravity works most of the time, but it breaks down in extreme circumstances where quantum mechanical effects become significant, such as at the center of a black hole.

 

Theories of quantum gravity, on the other hand, try to explain gravity through quantum mechanics, which can already describe the other three known fundamental forces – electromagnetic force, the strong force that holds most matter together, and the weak force that causes radioactive decay.

None of the quantum gravity theories, however, as yet have strong evidence to support them.

Calmet and Kuipers estimated the lower bound for the mass of a dark matter particle using values from general relativity, and estimated the upper bound from the lifetimes of dark matter particles predicted by quantum gravity theories.

The nature of the values from general relativity also defined the nature of the upper bound, so they were able to derive a prediction that was independent of any particular model of quantum gravity, Calmet said.

The study found that while quantum gravitational effects were generally almost insignificant, they became important when a hypothetical dark matter particle took an extremely long time to decay and when the universe was about as old as it is now (roughly 13.8 billion years), he said.

 

Physicists previously estimated that dark matter particles had to be lighter than the “Planck mass” – about 1.2 x 10^19 GeV, at least a 1,000 times heavier than the largest-known particles –  yet heavier than 10^minus 24 eV to fit with observations of the smallest galaxies known to contain dark matter, he said. 

But until now, few studies had attempted to narrow the range, even though great progress had been made in understanding quantum gravity over the last 30 years, he said. “People simply did not look at the effects of quantum gravity on dark matter before.”

Unknown force

Calmet said the new bounds for the masses of dark matter particles, could also be used to test whether gravity alone interacts with dark matter, which is widely assumed, or if dark matter is influenced by an unknown force of nature.

“If we found a dark matter particle with a mass outside the range discussed our paper, we would not only have discovered dark matter, but also very strong evidence that … there is some new force beyond gravity acting on dark matter,” he said.

Related Content

From Big Bang to present: Snapshots of our universe through time

The 18 biggest unsolved mysteries in physics

The 15 weirdest galaxies in the universe

This article was originally published by Live Science. Read the original article here.

 

Read original article here

Science

Marmosets Prefer It When Another Monkey Shows an Interest in Helping Others

Leave a comment

Like humans, marmosets – tiny monkeys with Einstein-like ear tufts native to Brazil – eavesdrop on conversations between others, and prefer to approach individuals they view positively, a study in the journal Science Advances showed Wednesday.

 

While behavioral research has built up knowledge around the social lives of primates, it has tended to lack reliable ways to determine an individual’s “inside perspective,” or the inner workings of her or his mind.

Marmosets are an ideal species to study because of their close-knit social structure: They live in highly cooperative groups of around 15 family members, with the entire extended clan responsible for rearing children.

How do they decide who is reliable and who is not?

A team led by Rahel Brugger at the University of Zurich (UZH) presented 21 captive-born adult marmosets with recordings from a hidden speaker of an opposite sex adult making either food-offering calls or aggressive chatter calls in response to begging infants.

As a control, they also played the marmosets calls made by a single individual.

The scientists then pointed infrared cameras at the marmosets’ faces to record the nasal temperatures – looking for drops that indicate the monkeys were alert and engaged.

The tests found the marmosets only responded to combined and not individual calls, indicating they understood when real conversations were occurring.​

 

After playing them the recordings, the team let the marmosets enter a room filled with toys and a mirror.

Marmosets don’t recognize their own reflection, and so believed that it represented the monkey who made the recorded call.

The researchers found that overall, the marmosets preferred to approach when the recordings indicated the individual was helpful.

“This study adds to the growing evidence that many animals are not only passive observers of third-party interactions, but that they also interpret them,” said the paper’s senior author and professor of anthropology at UZH, Judith Burkart.

The team plans to use this temperature-mapping approach for future investigations, such as into the origin of morality.

© Agence France-Presse

 

Read original article here

Science

There Is One Way Humans Could ‘Safely’ Enter a Black Hole, Physicists Say

Leave a comment

To solve the mysteries of black holes, a human should just venture into one.

However, there is a rather complicated catch: A human can do this only if the respective black hole is supermassive and isolated, and if the person entering the black hole does not expect to report the findings to anyone in the entire Universe.

 

We are both physicists who study black holes, albeit from a very safe distance. Black holes are among the most abundant astrophysical objects in our Universe.

These intriguing objects appear to be an essential ingredient in the evolution of the Universe, from the Big Bang till present day. They probably had an impact on the formation of human life in our own galaxy.

A person falling into a black hole and being stretched. (Leo Rodriguez/Shanshan Rodriguez/CC BY-ND)

Two types of black holes

The Universe is littered with a vast zoo of different types of black holes.

They can vary by size and be electrically charged, the same way electrons or protons are in atoms. Some black holes actually spin. There are two types of black holes that are relevant to our discussion.

The first does not rotate, is electrically neutral – that is, not positively or negatively charged – and has the mass of our Sun. The second type is a supermassive black hole, with a mass of millions to even billions times greater than that of our Sun.

Besides the mass difference between these two types of black holes, what also differentiates them is the distance from their center to their “event horizon” – a measure called radial distance.

A person falling into a supermassive black hole would likely survive. (Leo & Shanshan Rodriguez/CC BY-ND)

The event horizon of a black hole is the point of no return. Anything that passes this point will be swallowed by the black hole and forever vanish from our known Universe.

At the event horizon, the black hole’s gravity is so powerful that no amount of mechanical force can overcome or counteract it. Even light, the fastest-moving thing in our Universe, cannot escape – hence the term “black hole”.

The radial size of the event horizon depends on the mass of the respective black hole and is key for a person to survive falling into one. For a black hole with a mass of our Sun (one solar mass), the event horizon will have a radius of just under 2 miles (3.2 kilometres).

A person approaching the event horizon of a a Sun-size black hole. (Leo and Shanshan Rodriguez/CC BY-ND)

The supermassive black hole at the center of our Milky Way galaxy, by contrast, has a mass of roughly 4 million solar masses, and it has an event horizon with a radius of 7.3 million miles or 17 solar radii.

Thus, someone falling into a stellar-size black hole will get much, much closer to the black hole’s center before passing the event horizon, as opposed to falling into a supermassive black hole.

 

This implies, due to the closeness of the black hole’s center, that the black hole’s pull on a person will differ by a factor of 1,000 billion times between head and toe, depending on which is leading the free fall.

In other words, if the person is falling feet first, as they approach the event horizon of a stellar mass black hole, the gravitational pull on their feet will be exponentially larger compared to the black hole’s tug on their head.

The person would experience spaghettification, and most likely not survive being stretched into a long, thin noodle-like shape.

Now, a person falling into a supermassive black hole would reach the event horizon much farther from the the central source of gravitational pull, which means that the difference in gravitational pull between head and toe is nearly zero.

Thus, the person would pass through the event horizon unaffected, not be stretched into a long, thin noodle, survive and float painlessly past the black hole’s horizon.

Other considerations

Most black holes that we observe in the Universe are surrounded by very hot disks of material, mostly comprising gas and dust or other objects like stars and planets that got too close to the horizon and fell into the black hole.

These disks are called accretion disks and are very hot and turbulent. They are most certainly not hospitable and would make traveling into the black hole extremely dangerous.

 

To enter one safely, you would need to find a supermassive black hole that is completely isolated and not feeding on surrounding material, gas, or even stars.

Now, if a person found an isolated supermassive black hole suitable for scientific study and decided to venture in, everything observed or measured of the black hole interior would be confined within the black hole’s event horizon.

Keeping in mind that nothing can escape the gravitational pull beyond the event horizon, the in-falling person would not be able to send any information about their findings back out beyond this horizon. Their journey and findings would be lost to the rest of the entire Universe for all time. But they would enjoy the adventure, for as long as they survived … maybe ….

Leo Rodriguez, Assistant Professor of Physics, Grinnell College and Shanshan Rodriguez, Assistant Professor of Physics, Grinnell College.

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

 

Read original article here

Science

Wombats Are The Only Animals Who Poop Cubes, And We Now Know How

Leave a comment

Patricia Yang has seen a lot of poop. In her time studying the dynamics of bodily fluids, the award-winning scientist has witnessed her share of cows dumping watery pies, rodents dropping little pellets, and elephants passing big balls of dung.

 

None of that would ultimately prepare her for what she was about to see. 

It was 2015, and Yang had just presented on a mathematical model for bowel movements. A scientist at the conference asked if her theory worked for wombats, too. Yang had never seen wombat droppings, and when she googled for pictures, she found herself looking at some of the oddest-shaped poo she’d ever seen.

The Australian mammal’s faeces are shaped like little dark cubes, the only known prismatic poops in the world. In fact, wombats are the only animals scientists have found that can produce cubes naturally, and we had no idea how they were doing it.

Yang was immediately hooked. The mystery was an old one, but no one had done any hard investigations to find out what was really going on.

A wombat on Maria Island, Australia. (Posnov/Getty Images)

She and her lab supervisor at Georgia Tech, biomechanical engineer David Hu, decided to change that. In 2018, they finally got their hands on the intestine of a bare-nosed wombat (Vombatus ursinus).

The gut, which was carefully dissected by a scientist in Tasmania and shipped to the United States, showed a clear progression from muddy matter to a hard six-sided structure with sharp corners, almost like a ‘gruesome Christmas ornament’. 

 

It looked as though these cubes were forming even before the wombat pooped them out. Further CT scans on a live adult wombat confirmed this animal does not have a square-shaped anus; it’s just as round as those of other animals, so how do wombats excrete cubes?

As it turns out, it’s all in the intestine. Using two new wombat dissections and mathematical models, Yang and her colleagues have now figured out how wombats actually poo prisms.

The first thing you need to know is that the wombat intestine is unusually long, up to nine metres in length. Compared to humans, it takes these metre-long creatures ten times longer to suck all the nutrition and water out of their food, sometimes up to two weeks.

As a result, wombat poos are nearly twice as dry as human poos, and this could be what helps them survive droughts in the Australian bush. This lengthy process probably also helps their poo form more concrete shapes. 

Just by looking at the wombat intestine, you can clearly see the gradual transition from a “yellow-green slurry of digesta”, as the authors so bluntly put it, to a dry cube with “beveled edges and flat faces”. 

Wombat intestines filled with poo hanging from top to bottom. (David Hu and Scott Carver)

Using a balloon to blow up certain parts of the intestine, researchers noticed varying levels of thickness and stiffness in some of the tissue and muscle.

Practically, this meant parts of the intestine’s circumference were contracting differently, in part due to different muscle thickness. The tight parts contracted quickly, pushing the poo harder, while the softer parts contracted more slowly, moulding corners.

 

Creating a simple model of the intestine, the authors found corners formed in less than 10 contraction cycles.

“With contractions occurring every couple of seconds over a time of five days, the faeces actually experience on the order of 100,000 contractions,” the team writes.

Enough of these contractions could plausibly form a series of cubes in the latter end of the wombat’s intestine when poo is most dried out. Dissections show cubes are formed only within the last 17 percent of the intestine. (In 2018, the team thought it was the last 8 percent).

It’s almost like baking a cake, Hu explains. The batter starts out wet and sloppy, drying out over time as it’s heated up in the oven. As it butts up against the edge of the cake tin, it begins to form corners and flat surfaces. Most of the solidifying happens right at the end.

Wombats, incidentally, squeeze out nearly 100 of these six-sided brownies every day.

Exactly why they do this is a whole other mystery. Wombats don’t have great eyesight and so they use their droppings to communicate with one another. As such, they like to poop on rocks, logs or other elevated places to make their message more visible.

The cube shape might therefore assist poo-stacking. Rounder faeces, after all, tend to roll away.

Wombat faeces in the field, stacked on rocks. (David Hu and Scott Carver)

But that’s just one idea. Another is that the six-sided structure of wombat poo allows for a greater surface area to increase the dispersal of the animal’s scent, which can convey social messages or reproductive status. 

Other scientists think we’re reading too much into it. The cube-shaped poo is probably just a result of it being dehydrated in the gut, they argue. In zoos and wildlife parks, for instance, where wombats are well hydrated, wombat poo is much less defined.

 

There’s clearly a lot we still need to know about wombat poo, but Randy Ewoldt, the mechanical engineer who first brought the mystery to Yang and Hu’s attention five years ago, told ScienceAlert he’s impressed with their progress

“The authors demonstrate heroic efforts and a collaboration covering opposite sides of the globe,” Ewoldt said in an email.

“One wonders: who else could squeeze such interdisciplinary work into this multi-faceted contribution?” 

Who indeed.

The study was published in Soft Matter. 

 

Read original article here

Science

Black Holes Could Get So Humongous, Astronomers Came Up With a New Size Category

Leave a comment

There are supermassive black holes. There are ultramassive black holes. How large can these strange objects grow? Well, there could be something even bigger than ultramassive: stupendously large black holes, according to the latest research.

 

Such hypothetical black holes – larger than 100 billion times the mass of the Sun – have been explored in a new paper which names them SLABs, an acronym that stands for “Stupendously LArge Black holeS”.

“We already know that black holes exist over a vast range of masses, with a supermassive black hole of 4 million solar masses residing at the centre of our own galaxy,” explained astronomer Bernard Carr of Queen Mary University London.

“Whilst there isn’t currently evidence for the existence of SLABs, it’s conceivable that they could exist and they might also reside outside galaxies in intergalactic space, with interesting observational consequences.”

Black holes have only a few somewhat broad mass categories. There are stellar-mass black holes; those are black holes that are around the mass of a star, up to around 100 solar masses. The next category up is intermediate mass black holes, and how large they get seems to depend on who you talk to. Some say 1,000 solar masses, some say 100,000, and others say 1 million; whatever the upper limit is, these seem to be pretty rare.

 

Supermassive black holes (SMBHs) are much, much larger, on the order of millions to billions of solar masses. These include the SMBH at the heart of the Milky Way, Sagittarius A*, at 4 million solar masses, and the most photogenic SMBH in the Universe, M87*, at 6.5 billion solar masses.

The chonkiest black holes we’ve detected are ultramassive, more than 10 billion (but less than 100 billion) solar masses. These include an absolute beast clocking in at 40 billion solar masses in the centre of a galaxy named Holmberg 15A.

“However, surprisingly, the idea of SLABs has largely been neglected until now,” Carr said.

“We’ve proposed options for how these SLABs might form, and hope that our work will begin to motivate discussions amongst the community.”

The thing is, scientists don’t quite know how really big black holes form and grow. One possibility is that they form in their host galaxy, then grow bigger and bigger by slurping up a whole lot of stars and gas and dust, and collisions with other black holes when galaxies merge.

This model has an upper limit of around 50 billion solar masses – that’s the limit at which the object’s prodigious mass would require an accretion disc so massive it would fragment under its own gravity. But there’s also a significant problem: Supermassive black holes have been found in the early Universe at masses too high to have grown by this relatively slow process in the time since the Big Bang.

 

Another possibility is something called primordial black holes, first proposed in 1966. The theory goes that the varying density of the early Universe could have produced pockets so dense, they collapsed into black holes. These would not be subject to the size constraints of black holes from collapsed stars, and could be extremely small or, well, stupendously large.

The extremely small ones, if they ever existed, would probably have evaporated due to Hawking radiation by now. But the much, much larger ones could have survived.

So, based on the primordial black hole model, the team calculated exactly how stupendously large these black holes could be, between 100 billion and 1 quintillion (that’s 18 zeroes) solar masses.

The purpose of the paper, the researchers said, was to consider the effect of such black holes on the space around them. We may not be able to see SLABs directly – black holes that aren’t accreting material are invisible, since light cannot escape their gravity – but massive invisible objects can still be detected based on the way space around them behaves.

Gravity, for instance, curves space-time, which causes the light travelling through those regions to also follow a curved path; this is called a gravitational lens, and the effect could be used to detect SLABs in intergalactic space, the team said.

The huge objects also would have implications for the detection of dark matter, the invisible mass that’s injecting way more gravity into the Universe than there should be – based on what we can actually directly detect.

One hypothetical dark matter candidate, weakly interacting massive particles (WIMPs), would accumulate in the region around a SLAB due to the immense gravity, in such concentrations that they would collide with and annihilate each other, creating a gamma-radiation halo.

And primordial black holes are themselves a dark matter candidate, too.

“SLABs themselves could not provide the dark matter,” Carr said. “But if they exist at all, it would have important implications for the early Universe and would make it plausible that lighter primordial black holes might do so.”

Also, we couldn’t resist calculating the size of a 1 quintillion solar mass black hole. The event horizon would end up over 620,000 light-years across. Uh. Stupendous.

The team’s research has been published in the Monthly Notices of the Royal Astronomical Society.

 

Read original article here

Science

This One Spot on The International Space Station Is Kept Filthy – For Science

Leave a comment

While most of us are now more fastidious about keeping our homes and workplaces clean, on board the International Space Station, cleanliness is imperative.

Of high importance is anti-bacterial measures, since bacteria tend to build up in the constantly-recycled air inside the ISS.

 

Every Saturday in space is “cleaning day” where surfaces are wiped down, and the astronauts vacuum and collect trash.

But there’s one spot on board the station where cleaning is a no-no. But don’t worry, its all for science!

The MatISS experiment, or the Microbial Aerosol Tethering on Innovative Surfaces in the International Space Station tests out five advanced materials and how well they can prevent illness-causing microorganisms from settling and growing in microgravity.

MatISS also has provided insight into how biofilms attach to surfaces in microgravity conditions.

The experiment is sponsored by the French space agency CNES and was conceived of in 2016. Three iterations of the experiment have been used on the ISS.

The first was MatISS-1, and it had four sample holders set up in for six months in three different locations in the European Columbus laboratory module.

This provided some baseline data points for researchers, as when they were returned to Earth, researchers characterized the deposits on each surface and used the control material to establish a reference for the level and type of contamination.

 

MatISS-2 had four identical sample holders containing three different types of materials, installed in a single location in Columbus. This study aimed to better understand how contamination spreads over time across the hydrophobic (water-repellant) and control surfaces.

The upgraded Matiss-2.5 was set up to study how contamination spreads – this time spatially – across the hydrophobic surfaces using patterned samples. This experiment ran for a year and recently the samples were returned to Earth and are now undergoing analysis.

The samples are made of a diverse mix of advanced materials, such as self-assembly monolayers, green polymers, ceramic polymers, and water-repellent hybrid silica.

The smart materials should stop bacteria from sticking and growing over large areas, and effectively making them easier to clean and more hygienic. The experiment hopes to figure out which materials work the best.

ESA says that “understanding the effectiveness and potential use of these materials will be essential to the design of future spacecraft, especially those carrying humans father out in space.”

Long-duration human space missions will certainly need to limit biocontamination of astronaut habitats. 

This article was originally published by Universe Today. Read the original article.

 

Read original article here

Science

Groundbreaking New Laser System Cuts Through Earth’s Atmosphere Like It’s Nothing

Leave a comment

To artists and romantics, the twinkling of stars is visual poetry; a dance of distant light as it twists and bends through a turbulent ocean of air above our heads.

Not everybody is so enamoured with our atmosphere’s distortions. To many scientists and engineers, a great deal of research and ground-to-satellite communication would be a whole lot easier if the air simply wasn’t there.

 

Losing our planet’s protective bubble of gases isn’t exactly a popular option. But Australian and French researchers have teamed up to design the next best thing – a system that guides light through the tempestuous currents of rippling air with the flick of a mirror.

The result is a laser link capable of holding its own through the atmosphere with unprecedented stability.

While astronomers have a few tricks up their sleeve to correct for the atmosphere’s distortions on incoming light, it’s been a challenge to emit a coherent beam of photons from the ground to a distant receiver so they keep together and on point.

Keeping transmissions on target and coherent – with their phases remaining neatly in line – through hundreds of kilometres of shifting air would allow us to link highly precise measurement tools and communications systems.

Satellites could probe for ores or evaluate water tables with improved precision. High-speed data transfer could require less power, and contain more information.

Lead author Ben Dix-Matthews, an electrical engineer with the International Centre for Radio Astronomy Research in Australia, explained the technology to ScienceAlert.

 

“The active terminal essentially uses a small four-pixel camera, which measures the sideways movement of the received beam,” says Dix-Matthews.

“This position measurement is then used to actively control a steerable mirror that keeps the received beam centred and removes the sideways movement caused by the atmosphere.”

In effect, the system can be used to compensate for the warping effects of the moving air in three dimensions – not just up and down, or left and right, but along the beam’s trajectory, keeping the link centred and its phases in order.

So far it’s only been tested across a relatively short distance of 265 metres (about 870 feet). About 715 metres (just under half a mile) of optical fibre cable was run underground between the transmitter and receiver to carry a beam for comparison.

The results were so stable they could be used to connect the kinds of optical atomic clocks used to test fundamental physics, such as Einstein’s theories of relativity.

With the proof of concept demonstrated, there’s no reason to think a similar technique won’t one day be aiming for the sky, and beyond. Though there are a few hurdles that need to be overcome first.

 

“During this experiment we had to do the initial alignment by hand, using a visible guide laser that was in line with the stabilised infrared beam,” Dix-Matthews told ScienceAlert.

“When making links between optical atomic clocks, it would be good to have a way of doing this coarse alignment more easily.”

Fortunately Dix-Matthews’ French collaborators are working on a device that will speed up the initial coarse alignment process, promising a second generation of laser link technology that won’t require such an involved set-up.

The team also found temperature variations in the equipment affected the phase’s stability, limiting the duration of the signal to around 100 seconds. This hurdle will also be the focus of future improvements.

We might not need to wait long. The researchers are already making headway on upgrades for their system.

“We have started using a high-power laser amplifier that should help us deal with the larger power losses expected over longer distances, such as to space,” says Dix-Matthews.

“We have also completely rebuilt our active terminal to make it more sensitive to low received powers and make it more effective at cancelling out the movement of the received beam.”

With orbiting technology rapidly becoming a major focus for many data providers, potentially filling our skies with satellites, innovations that make linking communications systems across our atmosphere will only become more sought after.

As useful as our atmosphere is for, well, keeping us all alive, there are certainly some downsides to being buried under a restless blanket of warm gas.

This research was published in Nature Communications.

 

Read original article here

Science

Scientists Think These Ridiculous Bones May Belong to New Largest-Ever Dinosaur

Leave a comment

Scientists have unearthed massive, 98-million-year-old fossils in southwest Argentina they say may have belonged to the largest dinosaur ever discovered.

Human-sized pieces of fossilized bone belonging to the giant sauropod appear to be 10-20 percent larger than those attributed to Patagotitan mayorum, the biggest dinosaur ever identified, according to a statement Wednesday from the National University of La Matanza’s CTYS scientific agency.

 

Sauropods were enormous long-necked, long-tailed, plant-eating dinosaurs – the largest terrestrial creatures to ever have lived.

Among them, Patagotitan mayorum, also from Argentina, weighed in at about 70 tonnes and was 40 meters (131 feet) long, or about the length of four school buses.

(Jose Luis Carballido/CTyS-UNLaM/AFP)

Alejandro Otero of Argentina’s Museo de La Plata is working on piecing together a likeness of the new dinosaur from two-dozen vertebrae and bits of pelvic bone uncovered so far.

He has published a paper on the unidentified dinosaur for the scientific journal Cretaceous Research, according to the university statement.

The quest for more body parts, buried deep in rock, continues. For scientists, the holy grail will be the large femur or humerus bones, which are helpful in estimating a long-extinct creature’s body mass.

The massive fossils were discovered in 2012 in the Neuquen River Valley, but excavation work only began in 2015, according to palaeontologist Jose Luis Carballido of the Museo Egidio Feruglio.

(Jose Luis Carballido/CTyS-UNLaM/AFP)

“We have more than half the tail, a lot of hip bones,” said Carballido, who also worked on the classification of Patagotitan a few years ago.

“It’s obviously still inside the rock, so we have a few more years of digging ahead of us.”

 

The massive skeleton was found in a layer of rock dated to some 98 million years ago during the Upper Cretaceous period, added geologist Alberto Garrido, director of the Museum of Natural Sciences of Zapala.

“We suspect that the specimen may be complete or almost complete,” he said.

“Everything depends on what happens with the excavations. But regardless of whether it is bigger (than Patagotitan) or not, the discovery of an intact dinosaur of such dimensions is a novelty.” 

© Agence France-Presse

 

Read original article here