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Solar Wind Is Strangely Drawn to Earth's North Pole, And Scientists Don't Know Why - ScienceAlert
Likely the most well-known result of the Earth's magnetic field are the Aurora Borealis and Australis (Northern and Southern Lights). When charged particles from the solar wind run into the Earth's magnetic field, they can occasionally elicit sp
Likely the most well-known result of the Earth's magnetic field are the Aurora Borealis and Australis (Northern and Southern Lights). When charged particles from the solar wind run into the Earth's magnetic field, they can occasionally elicit spectacular light displays. For years now, scientists have thought that the charged particles that cause those displays were sent in equal numbers toward the North and South Pole. However, recent research from a team led by scientists from the University of Alberta, have shown that there are actually more charged particles heading north rather than south. The question now is why? The data the scientists used was collected by the Swarm satellite constellation a set of 3 satellites that have been observing the Earth's magnetic field since 2013. One thing it noticed in that time is that the Earth's magnetic south pole is "further away from the Earth's spin axis than the magnetic north pole" says Ivan Pakhotin, the paper's lead author. This leads to differences in reflection of a type of electromagnetic waves known as Alfvén waves, which eventually cause differences in how the North and South Poles interact with the solar wind. This measured asymmetry could mean any number of things. For one, the chemistry taking place in the upper atmosphere could vary dramatically between the North and South Poles, which could have significant climate impacts down on the ground. But also, it could mean a discrepancy between the two Auroras. So far the impacts of the asymmetry are unclear, and as with almost all good science, it warrants further study. Swarm will continue its mission to collect data that will be relevant to solving the mystery. In the meantime, those of us lucky enough to get to experience the Auroras themselves can continue to stare upward in wonder, no matter how dissimilar they might be. This article was originally published by Universe Today. Read the original article.
Physicists Observe Fleeting 'Polaron' Quasiparticles For The First Time - ScienceAlert
Polarons are important nanoscale phenomena: a transient configuration between electrons and atoms (known as quasiparticles) that exist for only trillionths of a second.
Polarons are important nanoscale phenomena: a transient configuration between electrons and atoms (known as quasiparticles) that exist for only trillionths of a second. These configurations have unique characteristics that can help us understand some of the mysterious behaviours of the materials they form within and scientists have just observed them for the first time. Polarons were measured in lead hybrid perovskites, next-gen solar cell materials that promise to boost conversion rates beyond the silicon panels that are primarily used today. Scientists are hoping that polaron observations will go some way to telling us exactly how perovskites turn sunlight into electricity so well. To find the polarons, scientists trained light on single crystals of lead hybrid perovskites, watching with a giant X-ray free-electron laser called the Linac Coherent Light Source (LCLS) capable of imaging materials at the smallest scales over the shortest times, down to trillionths of a second (or picoseconds). (Greg Stewart/SLAC National Accelerator Laboratory) Above: Illustration of polarons in lead hybrid perovskite. "When you put a charge into a material by hitting it with light, like what happens in a solar cell, electrons are liberated, and those free electrons start to move around the material," says physicist Burak Guzelturk from the Argonne National Laboratory, run by the US Department of Energy. "Soon they are surrounded and engulfed by a kind of bubble of local distortion the polaron that travels along with them. Some people have argued that this bubble protects electrons from scattering off defects in the material, and helps explain why they travel so efficiently to the solar cell's contact to flow out as electricity." As promising as perovskites are as a solar panel material, it's not entirely clear why: they have lots of defects that should limit how well current can flow through them, and they're notoriously fragile and unstable. Polarons might offer up some answers. These polarons are essentially brief travelling distortions of the material's atomic lattice structure, and were shown to shift around 10 layers of atoms outwards. The distortion increased the spacing of the surrounding atoms by about 50 times to 5 billionths of a metre over tens of picoseconds. The minute distortions or bubbles were larger than scientists were expecting, allowed to move by the flexible and soft atomic lattice structure of the hybrid perovskite. The material is in some ways behaving as a solid and a liquid at the same time. "These materials have taken the field of solar energy research by storm because of their high efficiencies and low cost, but people still argue about why they work," says materials scientist Aaron Lindenberg from Stanford University. "The idea that polarons may be involved has been around for a number of years, but our experiments are the first to directly observe the formation of these local distortions, including their size, shape, and how they evolve." While perovskites are already being used in solar energy production, often in combination with silicon, they're not without their challenges while we've seen major efficiency gains from these materials, they're hypothesised to be capable of even more. As the years go by, scientists continue to overcome hurdles that have kept solar panel efficiencies lower than they should be, and with our reliance on solar farms rising, improvements of even just a few percentage points can make a big difference. However, the researchers behind the polaron discovery are keen to emphasise that they haven't answered all the questions around these quasiparticles yet and there's lots more to learn about their impacts on perovskites and other materials. "While this experiment shows as directly as possible that these objects really do exist, it doesn't show how they contribute to the efficiency of a solar cell," says Lindenberg. "There's still further work to be done to understand how these processes affect the properties of these materials." The research has been published in Nature Materials.
Scientists Just Discovered 3 New Kinds of Carnivorous Sponge in The Deep Ocean - ScienceAlert
Even though we know the deep sea is weird, 'carnivorous sea sponges' still sound like something from a sci-fi movie. And yet, researchers just announced the discovery of three new such species off the coast of Australia.
Even though we know the deep sea is weird, 'carnivorous sea sponges' still sound like something from a sci-fi movie. And yet, researchers just announced the discovery of three new such species off the coast of Australia. Go a few hundred metres deep into the ocean, and it starts to look like you're in a whole new world: From a creature that looks like a sea star crossed with an octopus, to shark-devouring fish, to carnivorous sponges we've never seen before. "It just goes to show how much of our deep oceans are yet to be explored these particular sponges are quite unique in that they are only found in this particular region of The Great Australian Bight a region that was slated for deep sea oil exploration," said one of the researchers, Queensland Museum Sessile Marine Invertebrates Collection manager Merrick Ekins. Typically, sea sponges are multicellular filter feeders - they have holey tissues for flowing water, from which their cells extract oxygen and food. They're pretty simple creatures, with no nervous, digestive, or circulatory system, but have existed in some form for over 500 million years. Scanning electron microscope image of Abyssocladia oxyasters. (Ekins et al., Zootaxa, 2020) But carnivorous sponges are a bit different. Some carnivorous sponges still use the water flow system, while others (like the three newly discovered species) have lost this ability altogether, and nab small crustaceans and other prey using filaments or hooks. The researchers in this study found three new species of carnivorous sponges - Nullarbora heptaxia, Abyssocladia oxyasters and Lycopodina hystrix, which are also all new genera, as well as a closely related species of sponge that isn't carnivorous, Guitarra davidconryi. All these species were found at depths of between 163 and over 3,000 metres (535 to 9,842 feet) deep. "Here we report on an additional four new species of sponges discovered from the Great Australian Bight, South Australia. This area has recently been surveyed, using a Smith-McIntyre Grab and a Remotely Operated Vehicle (ROV) to photograph and harvest the marine biota," the researchers write in their new paper. "These new species are the first recorded carnivorous species from South Australia and increase the number of species recorded from around Australia to 25." The sponges are also prettier than you would imagine, looking a little like flowers with their spiky protrusions, but not a lot like sponges. Close up of A. oxyaster. (Ekins et al., Zootaxa, 2020) Carnivorous sponges are having a bit of a moment. We've known about them since 1995, but many more have recently been discovered around the world. "Over the past two decades, our knowledge of carnivorous sponge diversity has almost doubled," the same team explains in an earlier paper, where they described their discovery of 17 new species of carnivorous sponges. "[This is] due in part to rapid advances in deep sea technology including ROVs and submersibles able to photograph and harvest carnivorous sponges intact, and also to the herculean efforts of a number of contemporary taxonomists redescribing many of the older species described in the 19th and 20th centuries." Nearly every species of carnivorous sponge found in Australia was discovered during a CSIRO RV Investigator Voyage in 2017, showing just how important these deep-sea investigations are. With the bottom of the ocean still mostly unexplored, we imagine we'll see plenty more species of carnivorous sponges, and other weird and wonderful sea creatures. The research has been published in Zootaxa.
Traces of a Mysterious Particle Predicted Decades Ago May Have Been Detected - ScienceAlert
Evidence of a long-sought hypothetical particle could have been hiding in plain (X-ray) sight all this time.
Evidence of a long-sought hypothetical particle could have been hiding in plain (X-ray) sight all this time. The X-ray emission coming off a collection of neutron stars known as the Magnificent Seven is so excessive that it could be coming from axions, a long-predicted kind of particle, forged in the dense cores of these dead objects, scientists have demonstrated. If their findings are confirmed, this discovery could help unravel some of the mysteries of the physical Universe including the nature of the mysterious dark matter that holds it all together. "Finding axions has been one of the major efforts in high-energy particle physics, both in theory and in experiments," said astronomer Raymond Co of the University of Minnesota. "We think axions could exist, but we haven't discovered them yet. You can think of axions as ghost particles. They can be anywhere in the Universe, but they don't interact strongly with us so we don't have any observations of them yet." Axions are hypothetical ultra-low-mass particles, first theorised in the 1970s to resolve the question of why strong atomic forces follow something called charge-parity symmetry, when most models say they don't need to. Axions are predicted by many models of string theory a proposed solution to the tension between general relativity and quantum mechanics and axions of a specific mass are also a strong dark matter candidate. So scientists have a number of really good reasons to go looking for them. If they exist, axions are expected to be produced inside stars. These stellar axions are not the same as dark matter axions, but their existence would imply the existence of other kinds of axions. One way to search for axions is by looking for excess radiation. Axions are expected to decay into pairs of photons in the presence of a magnetic field so if more electromagnetic radiation than there should be is detected in a region where this decay is expected to take place, that could constitute evidence of axions. In this case, excess hard X-radiation is exactly what astronomers have found when looking at the Magnificent Seven. These neutron stars the collapsed cores of dead massive stars that died in a supernova are not clustered in a group, but share a number of traits in common. They are all isolated neutron stars of around middle-age, a few hundred thousand years since stellar death. They are all cooling, emitting low-energy (soft) X-rays as they do so. They all have strong magnetic fields, trillions of times stronger than Earth's, powerful enough to trigger axion decay. And they are all relatively nearby, within 1,500 light-years from Earth. This makes them an excellent laboratory for looking for axions, and when a team of researchers led by senior author and physicist Benjamin Safdi of the Lawrence Berkeley National Laboratory studied the Magnificent Seven with multiple telescopes, they identified high-energy (hard) X-ray emission not expected for neutron stars of that type. In space, however, there are many processes that can produce radiation, so the team had to carefully examine other potential sources of the emission. Pulsars, for instance, emit hard X-radiation; but the other kinds of radiation emitted by pulsars, such as radio waves, are not present in the Magnificent Seven. Another possibility is that unresolved sources near the neutron stars could be producing the hard X-ray emission. But the datasets the team used, from two different space X-ray observatories XMM-Newton and Chandra indicated that the emission is coming from the neutron stars. Nor, the team found, is the signal likely to be the result of a pile-up of soft X-ray emission. "We are pretty confident this excess exists, and very confident there's something new among this excess," Safdi said. "If we were 100 percent sure that what we are seeing is a new particle, that would be huge. That would be revolutionary in physics." That's not to say that the excess is a new particle. It could be a previously unknown astrophysical process. Or it could be something as simple as an artefact from the telescopes or data processing. "We're not claiming that we've made the discovery of the axion yet, but we're saying that the extra X-ray photons can be explained by axions," Co said. "It is an exciting discovery of the excess in the X-ray photons, and it's an exciting possibility that's already consistent with our interpretation of axions." The next step will be to try to verify the finding. If the excess is produced by axions, then most of the radiation should be emitted at higher energies than XMM-Newton and Chandra are capable of detecting. The team hopes to use a newer telescope, NASA's NuSTAR, to observe the Magnificent Seven across a wider range of wavelengths. Magnetised white dwarf stars could be another place to look for axion emission. Like the Magnificent Seven, these objects have strong magnetic fields and are not expected to produce hard X-ray emission. "This starts to be pretty compelling that this is something beyond the Standard Model if we see an X-ray excess there, too," Safdi said. The research has been published in Physical Review Letters.
For The First Time, Electric Eels Have Been Seen Hunting And Zapping Prey as a Group - ScienceAlert
Electric eels appear to not be the loners we thought they were.
Electric eels appear to not be the loners we thought they were. In a small lake deep in the Amazon River basin in Brazil, scientists have for the first time recorded the fish not just living together, but actively working together to forage, and to bring down their prey. There's even evidence that the strategy is working. Of the plentiful Volta's electric eels (Electrophorus voltai, not a true eel but a type of knifefish) found living in the lake, many were over 1.2 metres (4 feet) in length and thriving. "This is an extraordinary discovery," said ichthyologist Carlos David de Santana of the Smithsonian Institution's National Museum of Natural History. "Nothing like this has ever been documented in electric eels." Not much is known about Volta's electric eel. The fish was only recently discovered in a lake along the Iriri river, and officially described and recognised as a distinct species last year. But it packs a punch, able to discharge a single shock in excess of 860 volts more powerful than any other electric eel on record. De Santana and his team first observed the electric eels hunting in a group in 2012. Over 100 individuals seemed to work together to herd and kill prey so that the entire shoal could feed. But one observation wasn't enough to classify the hunt as normal behaviour. In 2014, the team returned and found even more Volta's electric eels, so they got to work observing and recording the animals. Over 72 hours of continuous observation, they saw the electric eels engage in five more hunts. Not only was this enough to classify the behaviour as normal, it allowed the researchers to observe and record exactly how these "social predation events" occur. During the day and night, the electric eels mostly rested. At dusk and dawn, the twilight hours, the electric eels stirred themselves to hunt. This, the team noted in their paper, is unusual: Typically, Volta's electric eels are only observed foraging at night and solo. The difference here is striking. On each occasion, over 100 individual electric eels aggregated and started swimming in circles, effectively herding groups of smaller fish, mostly characins, into a "prey ball" that they gradually chivvied into shallower waters. Then, once the prey ball was tightly corralled with nowhere to go, up to 10 of the electric eels moved forward and launched a powerful joint strike, stunning the prey which would jump out of the water before falling back down, senseless. "If you think about it, an individual of this species can produce a discharge of up to 860 volts so in theory if 10 of them discharged at the same time, they could be producing up to 8,600 volts of electricity," de Santana said. "That's around the same voltage needed to power 100 light bulbs." Once the prey was stunned, the shoal could move in and feed at leisure. Each hunt, the team found, took around an hour and involved five to seven electrical strikes. "Hunting in groups is pretty common among mammals, but it's actually quite rare in fishes," de Santana said. "There are only nine other species of fishes known to do this, which makes this finding really special." Nevertheless, while the hunts may be normal, the team still believes they could be pretty rare. In their interviews with locals, the electric eels' congregation and hunting behaviour wasn't mentioned. So, whether the electric eels gather to hunt or go solo could be dependent on the right conditions, such as high prey abundance, and specific locations with lots of shelter for large numbers of these fish. While a lot is still unknown, the team believes the electric eels likely return to the lake on an annual basis. They have launched a citizen science project called Projeto Poraquê, where locals can log observations; those data could prove invaluable. And the team is planning to return to the location in the hope of observing the animals again. "In addition to trying to locate additional populations of eels involved on group foraging, our future field- and laboratory-based studies will investigate social predation in electric eels focusing on the link between population, social structures, genomics, and electrogenesis," they wrote in their paper. "In short, this case offers a unique perspective for future studies on the evolutionary interplay between predatory and escape tactics among vertebrates." The research has been published in Ecology & Evolution.
Our Forests Are on Track to Hit a Crucial Climate Tipping Point by 2050, Scientists Warn - ScienceAlert
Forests and other land ecosystems today absorb 30 percent of humanity's CO2 pollution, but rapid global warming could transform these natural 'sinks' into carbon 'sources' within a few decades, opening another daunting front in the fight against clim
Forests and other land ecosystems today absorb 30 percent of humanity's CO2 pollution, but rapid global warming could transform these natural 'sinks' into carbon 'sources' within a few decades, opening another daunting front in the fight against climate change, alarmed researchers have said. Climate skeptics often describe CO2 as "plant food", suggesting that increased greenhouse gas emissions will be offset by a massive upsurge in plant growth. But the new study shows that beyond a certain temperature threshold - which varies according to region and species - the capacity of plants to absorb CO2 declines. Under current greenhouse gas emission trends, plants across half the globe's terrestrial ecosystem could start to release carbon into the atmosphere faster than they sequester it by the end of the century, researchers reported this week in Science Advances. Ecosystems that store the most CO2 - especially tropical and boreal forests - could lose more than 45 percent of their capacity as carbon sponges by mid-century, a team led by Katharyn Duffy from Northern Arizona University found. "Anticipated higher temperatures associated with elevated CO2 could degrade land carbon uptake," said the study, based not on modelling but data collected over a period of 25 years. Failure to take this into account leads to a "gross overestimation" of the role Earth's vegetation might play in reducing global warming, the researchers warned. "The temperature tipping point of the terrestrial biosphere lies not at the end of the century or beyond, but within the next 20 to 30 years." Key to understanding how this could happen is the difference between photosynthesis and respiration, two chemical processes essential to plant life that respond differently to rising temperatures. Drawing energy from sunlight, plants absorb carbon dioxide through their leaves and water from the soil, producing sugar to boost growth and oxygen, which is released into the air. This is photosynthesis, which can only happen when there is daylight. By contrast, the transfer of energy to cells through respiration - with CO2 excreted as a waste product - happens around the clock. To find out if there is a temperature beyond which land-based ecosystems would start to absorb less CO2, Duffy and her team analysed records from a global observation network, called FLUXNET, spanning 1991 to 2015. FLUXNET essentially tracks the movement of CO2 between ecosystems and the atmosphere. They found that global photosynthesis peaks at certain temperatures, depending on the type of plant, and then declines thereafter. Respirations rates, however, increase across all types of ecosystems without appearing to reach a maximum threshold. "At higher temperatures, respiration rates continue to rise in contrast to sharply declining rates of photosynthesis," the study found. If carbon pollution continue unabated, this divergence will could see the CO2 absorption drop by half as early as 2040. "We are rapidly entering temperature regimes where biosphere productivity will precipitously decline, calling into question the future viability of the land sink," the researchers concluded. The findings also call into question the integrity of many national commitments under the Paris Agreement - known as nationally determined contributions, or NDCs - to reduce greenhouse gases. "These rely heavily on land uptake of carbon to meet pledges," the authors point out. The study notes that capping global warming under two degrees Celsius above pre-industrial levels, the cornerstone target of the 2015 Paris climate treaty, "allows for near-current levels of biosphere productivity, preserving the majority of land carbon uptakes." Earth has warmed at least 1.1C so far, and is currently on track to heat up another two to three degrees by century's end unless emissions are rapidly and drastically reduced. In 2019, a football pitch of primary, old-growth trees was destroyed in the tropics every six seconds - about 38,000 square kilometres (14,500 square miles) in all, according to satellite data. © Agence France-Presse
Calculations Show It'll Be Impossible to Control a Super-Intelligent AI - ScienceAlert
The idea of artificial intelligence overthrowing humankind has been talked about for many decades, and scientists have just delivered their verdict on whether we'd be able to control a high-level computer super-intelligence. The answer? Almost defini
The idea of artificial intelligence overthrowing humankind has been talked about for many decades, and scientists have just delivered their verdict on whether we'd be able to control a high-level computer super-intelligence. The answer? Almost definitely not. The catch is that controlling a super-intelligence far beyond human comprehension would require a simulation of that super-intelligence which we can analyse. But if we're unable to comprehend it, it's impossible to create such a simulation. Rules such as 'cause no harm to humans' can't be set if we don't understand the kind of scenarios that an AI is going to come up with, suggest the authors of the new paper. Once a computer system is working on a level above the scope of our programmers, we can no longer set limits. "A super-intelligence poses a fundamentally different problem than those typically studied under the banner of 'robot ethics'," write the researchers. "This is because a superintelligence is multi-faceted, and therefore potentially capable of mobilising a diversity of resources in order to achieve objectives that are potentially incomprehensible to humans, let alone controllable." Part of the team's reasoning comes from the halting problem put forward by Alan Turing in 1936. The problem centres on knowing whether or not a computer program will reach a conclusion and answer (so it halts), or simply loop forever trying to find one. As Turing proved through some smart math, while we can know that for some specific programs, it's logically impossible to find a way that will allow us to know that for every potential program that could ever be written. That brings us back to AI, which in a super-intelligent state could feasibly hold every possible computer program in its memory at once. Any program written to stop AI harming humans and destroying the world, for example, may reach a conclusion (and halt) or not it's mathematically impossible for us to be absolutely sure either way, which means it's not containable. "In effect, this makes the containment algorithm unusable," says computer scientist Iyad Rahwan, from the Max-Planck Institute for Human Development in Germany. The alternative to teaching AI some ethics and telling it not to destroy the world something which no algorithm can be absolutely certain of doing, the researchers say is to limit the capabilities of the super-intelligence. It could be cut off from parts of the internet or from certain networks, for example. The new study rejects this idea too, suggesting that it would limit the reach of the artificial intelligence the argument goes that if we're not going to use it to solve problems beyond the scope of humans, then why create it at all? If we are going to push ahead with artificial intelligence, we might not even know when a super-intelligence beyond our control arrives, such is its incomprehensibility. That means we need to start asking some serious questions about the directions we're going in. "A super-intelligent machine that controls the world sounds like science fiction," says computer scientist Manuel Cebrian, from the Max-Planck Institute for Human Development. "But there are already machines that perform certain important tasks independently without programmers fully understanding how they learned it." "The question therefore arises whether this could at some point become uncontrollable and dangerous for humanity." The research has been published in the Journal of Artificial Intelligence Research.
A Distant Galaxy Is Flaring With Strange Regularity, And Scientists Have Figured Out Why - ScienceAlert
Roughly every 114 days, almost like clockwork, a galaxy 570 million light-years away lights up like a firework. Since at least 2014, our observatories have recorded this strange behaviour; now, astronomers have put the pieces together to figure out w
Roughly every 114 days, almost like clockwork, a galaxy 570 million light-years away lights up like a firework. Since at least 2014, our observatories have recorded this strange behaviour; now, astronomers have put the pieces together to figure out why. In the centre of the spiral galaxy, named ESO 253-G003, a supermassive black hole is being orbited by a star that, every 114 days, swings close enough for some of its material to be slurped up, causing a brilliant flare of light across multiple wavelengths. Then, it moves away, surviving to be slurped again on its next close approach. Because of the regularity of the flares, astronomers have nicknamed the galaxy "Old Faithful", like the geyser in Yellowstone National Park. "These are the most predictable and frequent recurring multiwavelength flares we've seen from a galaxy's core, and they give us a unique opportunity to study this extragalactic Old Faithful in detail," said first author of the study, astronomer Anna Payne of the University of Hawai'i at Mnoa. "We think a supermassive black hole at the galaxy's center creates the bursts as it partially consumes an orbiting giant star." The flares were first detected in November of 2014, picked up by the All-Sky Automated Survey for Supernovae (ASAS-SN). At the time, astronomers thought that the brightening was a supernova occurring in ESO 253-G003. But in 2020, when Payne was looking over the ASAS-SN data on ESO 253-G003, she found another flare from the same location. And another. And another. In total, she identified 17 flares, spaced roughly 114 days apart. She and her team then predicted that the galaxy would flare again on 17 May, 7 September and 26 December of 2020 - and they were right. They named the repeated flaring ASASSN-14ko, and those accurate predictions meant they were able to take new, more detailed observations of the May flare with NASA's powerful TESS telescope. Previous observations from other instruments also provided data across a range of wavelengths. "TESS provided a very thorough picture of that particular flare, but because of the way the mission images the sky, it can't observe all of them," said astronomer Patrick Vallely of Ohio State University. "ASAS-SN collects less detail on individual outbursts, but provides a longer baseline, which was crucial in this case. The two surveys complement one another." But a supernova flares just once, then fades, since such an event destroys the originating star; so whatever was causing the eruptions of light in optical, ultraviolet and X-ray wavelengths had to be something else. A supermassive black hole emitting regular flares as it snacks on an orbiting star isn't unheard of - one was identified last year, on a nine-hour flaring schedule - but the case wasn't as simple with ESO 253-G003. That's because ESO 253-G003 is actually two galaxies in the final stages of merging, which means there should be two supermassive black holes in its centre. Recent research has shown that two interacting supermassive black holes can cause repeated flaring, but the objects in the centre of ESO 253-G003 are thought to be too far apart to interact in this way. Another possibility raised was a star crashing through an accretion disc of material swirling around and feeding into one of the black holes. This had to be ruled out too. As the star crashed through the disc at different locations and angles, the shapes of its flares should have been different - but the observations showed that the flares from ESO 253-G003 were too closely matched. The third possibility was repeated partial tidal disruption, where a larger massive object repeatedly strips material from a smaller orbiting one. If a star was on an eccentric 114-day orbit around the black hole, its close approach, or periastron, could see it veering close enough to have material stripped before it hurtles away again. When this material collides with the accretion disc, it causes a flare. And this is what seems to be happening. With this scenario in mind, the team analysed the observations. They analysed the light curve of every flare, and also compared them to other known black hole tidal disruption events. And they determined that the star was likely orbiting a supermassive black hole clocking in at 78 million solar masses. At every closest approach, the star losing around 0.3 percent of the mass of the Sun - about three Jupiters - to the black hole would be sufficient to cause the observed flares while allowing the star to live on. "If a giant star with a puffy envelope wanders close, but not too close, on a very elongated orbit, then the black hole can steal some of the outer material without ripping apart the entire star." said astronomer Benjamin Shappee of the University of Hawaii Institute for Astronomy. "In that case, the giant star will just keep returning again and again until the star is exhausted." It's not clear how long the star and the black hole have been maintaining this dance, which makes it hard to calculate how long the star has left. But the team has predicted when the next two flares are due to occur - in April and August of this year - and have plans to take even more observations. It represents an extremely rare opportunity to understand supermassive black hole mass accretion. "In general, we really want to understand the properties of these black holes and how they grow," said astronomer Kris Stanek of Ohio State University. "The ability to exactly predict the timing of the next episode allows us to take data that we could not otherwise take, and we are taking such data already." The research has been presented at the 237th meeting of the American Astronomical Society. It will also be submitted to The Astrophysical Journal, and is available on arXiv.
Physicists Detect Tantalising Hints of a "Fundamentally New Form of Quantum Matter" - ScienceAlert
Metals and insulators are the yin and yang of physics, their respective material properties strictly dictated by their electrons' mobility - metals should conduct electrons freely, while insulators keep them in place.
Metals and insulators are the yin and yang of physics, their respective material properties strictly dictated by their electrons' mobility - metals should conduct electrons freely, while insulators keep them in place. So when physicists from Princeton University in the US found a quantum quirk of metals bouncing around inside an insulating compound, they were lost for an explanation. We'll need to wait on further studies to find out exactly what's going on. But one tantalising possibility is that a previously unseen particle is at work, one that represents neutral ground in electron behaviour. They're calling it a 'neutral fermion'. "This came as a complete surprise," says physicist Sanfeng Wu from Princeton University in the US. "We asked ourselves, 'What's going on here?' We don't fully understand it yet." The phenomenon at the centre of the discovery is quantum oscillation. As the term implies, it involves the swinging back-and-forth of freely moving particles under certain experimental conditions. To get a little more technical, the oscillations occur when a material is cooled to levels where quantum behaviours more easily dominate and a magnetic field is applied and varied. Cranking the magnetic field up and down causes untethered charged particles, such as electrons, to slip between energy bands referred to as Landau levels. It's a technique commonly used to study the atomic landscape occupied by electrons across a material, specifically in those with metallic properties. Insulators are thought to be a whole other kettle of fish. With their electrons following strict stay-at-home orders, quantum oscillations aren't a thing. At least, they shouldn't be. The team looked at tungsten ditelluride, which is a strange semimetal that takes on properties of an insulator when bathed in a magnetic field - and were surprised to see quantum oscillations happening. Despite the shock, they have some thoughts on what could be going on. While a flowing charge would make this insulator a conductor (which is a paradox), having neutral particles 'flow' would fit the bill of insulator and quantum oscillator, which makes more sense. "Our experimental results conflict with all existing theories based on charged fermions, but could be explained in the presence of charge-neutral fermions," adds colleague Pengjie Wang. The only problem is that truly neutral fermions shouldn't exist, according to the Standard Model of Particle Physics. Fermions are particles that are sort of like the 'Lego blocks' of matter, while the other type of fundamental particles are bosons - charge-carrying particles. A truly neutral particle is also its own antiparticle - and this is something we've seen in bosons, but never fermions. So finding a truly neutral fermion would probably rewrite our understanding of physics, but that isn't what the researchers think is happening here - instead they think what they've detected is more of a neutral quasiparticle, which is a quantum type of hybrid particle. To understand what a quasiparticle is, imagine particle physics as a study of music. Fundamental particles like quarks and electrons are individual instruments. They form the basis of a variety of bigger particles, from three-piece rock bands like protons or symphonies like whole atoms. Bands playing in sync on opposing stages can even be viewed as a single event a quasiparticle that for all purposes are playing as one. Quantum weirdness can smear the properties of electrons in ways that make fractions of their charge across spaces. In other words, some electron quasiparticles will carry some bits of the electron, like its spin, but not its charge, effectively creating a neutral version of itself. Exactly what flavour of quasiparticle is operating here (if any) is yet to be worked out, but the researchers are describing it as completely new territory not just in experimentation, but in theory. "If our interpretations are correct, we are seeing a fundamentally new form of quantum matter," says Wu. "We are now imagining a wholly new quantum world hidden in insulators. It's possible that we simply missed identifying them over the last several decades." Neutral fermions have a potential role in improving the stability of quantum devices, so finding evidence of one here would be more than an academic curiosity, with promising practical applications. It's still early days. But so many discoveries in science have emerged from those timeless words, 'What's going on here?' This research was published in Nature.
This Breathtaking Close-Up of Mars' 'Grand Canyon' Is Giving Us Goosebumps - ScienceAlert
Tithonium Chasma is one big canyon. At a staggering 810 kilometres (503 miles) long, it's a large part of Valles Marineris - the biggest canyon system we know of in the whole Solar System.
Tithonium Chasma is one big canyon. At a staggering 810 kilometres (503 miles) long, it's a large part of Valles Marineris - the biggest canyon system we know of in the whole Solar System. This close-up image of the chasma was taken back in 2013 by the High Resolution Imaging Science Experiment (HiRISE) camera on board the Mars Reconnaissance Orbiter, and was just featured as the HiRISE Picture of the Day. The image shows around a kilometre (0.6 miles) of Mars terrain with torturous hills and valleys, but as you can see in the other images, when you start to zoom out, this is just one small section of a gigantic whole. (NASA/JPL/UArizona) But how did it get there? The Grand Canyon on Earth which is five times shallower and 10 times shorter than the Valles Marineris was carved by the Colorado River. But scientists aren't sure what would have formed the 8- to 10-kilometre (5 to 6.2 miles) deep canyon of Valles Marineris and Tithonium Chasma, so they've been taking photos to try and find out. We know that the tilt of Mars's axis (called the obliquity) is not as stable as Earth's, ranging widely from over 60 degrees to under 10 in the ancient past. An uncropped, uncoloured version of the picture above. (NASA/JPL/UArizona) "It is possible, though unproven, that higher obliquity triggered partial melting of some of Mars' water ice," HiRISE spokesperson Edwin Kite wrote back in 2014. "Our best chance at understanding this is to find piles of ice, dust, silt or sand that accumulated over many cycles of obliquity change." The image of Tithonium Chasma above shows these findings. The sediment layers - those dark and light stripes running diagonally down the middle of the image - are relatively uniform, possibly showing the gradual buildup of sediments over many long cycles of this axial tilt change. A map showing the location on the Valles Marineris. (NASA/JPL/UArizona) Even seven years after this photo was taken, we're still not sure what created the Valles Marineris. Some researchers suspect a large tectonic "crack" may have split Mars' surface, to be later enhanced by lava flow, or potentially water if the planet's axial tilt was just right. But really, although these images are scientifically interesting to astronomers, they're also just gorgeous. The staggering scale of these otherwordly peaks and troughs, captured by a spacecraft 264 kilometres (163.8 miles) from the planet's surface, really can't be understated. You can see even more pictures of the Valles Marineris here.
A Tiny, 'Cold' Star Has Released One of The Most Powerful Superflares Ever Seen - ScienceAlert
As far as stars go, SDSSJ013333 resembles the quiet kid in school nobody remembers. Small, dim, and unremarkable, it does little to gain attention. That is until it throws a whopping big tantrum.
As far as stars go, SDSSJ013333 resembles the quiet kid in school nobody remembers. Small, dim, and unremarkable, it does little to gain attention. That is until it throws a whopping big tantrum. Days before 2018 drew to a close, the Ground-based Wide Angle Camera (GWAC) at Xinglong Observatory in Beijing alerted researchers to a burst of light worth paying attention to. After hitting its peak in just under a minute, the entire event a solar flare dubbed GWAC 181229A lasted a matter of a few hours. But given where it came from, it would be one worth considering for the record books. A flick through star catalogues quickly revealed SDSSJ013333 sulking on its own roughly 490 light-years away, so dark and distant the astronomers had a hard time pinning down exactly how far away it truly was. Not a star you'd expect to blast out something so bright. SDSSJ013333 belongs to a category of stellar objects called ultra-cool dwarfs. Typically around a third of the mass of our own Sun, they have an effective temperature that's only half as hot, and a slow-burning furnace that can last hundreds of billions of years. But although ultra-cool dwarfs might take things slow, every now and then their magnetic fields snap and reconnect in ways that see them erupt with tremendous bursts of radiation and plasma. We're not talking a tiny roasting either. Thanks to the brilliance of many such emissions, these flares can only be described as super. Usually, superflares are the work of youngsters, especially the slightly warmer red dwarfs. One from a red dwarf was caught by a Japanese research team last year, measuring roughly 20 times as powerful as anything seen coming out of our Sun. But the flare put out by ultra-cool SDSSJ013333 let one rip that would put most to shame. Typically measured in a unit of energy called an erg (from an old Greek word for work, ergon), a typical flare might put out around 10^30 ergs. Superflares can reach up as high as around 10^36 ergs. Astronomers estimated SDSSJ013333 released just over 10^34 ergs of energy; an insane effort for such a cold-hearted star, and possibly among the largest ever recorded for one in its particular class. To put it another way, the flare briefly made the star 10,000 times brighter, taking its magnitude from just over 24 down to a more dazzling 15. Not something we'd see with the naked eye, but bright enough for a good telescope to capture. The researchers have made their results available on the pre-publish arXiv database for public perusal, where we can read their take on it while it awaits peer review. As remarkable as the event is, it's only in context of other flares that we can learn how ultra-cool dwarfs which make up around 15 percent of all stellar objects in our corner of the galaxy form and develop. "Thanks to the large eld of view and the high survey cadence, GWAC is well-suited for the detection of white-light ares. Actually, we have hitherto detected more than 130 white-light ares with an amplitude more than 0.8 mag," the team reports. "More GWAC units are planned to work in the next two years, aiming to increase the detection rate of high-amplitude stellar flares by monitoring more than 5,000 square degrees simultaneously." That's a lot of space. But we'll need to cast a wide net to see what else is lurking out in our galaxy. Having solid evidence of what these stars are capable of ejecting can help astronomers better understand the physics churning away beneath their surface. It also has implications for the possibility of life around these stars. One ultra-cool dwarf turned celebrity in recent years is TRAPPIST-1. Found to be surrounded by an extensive family of exoplanets some of which are in a zone that could make them damp with liquid water it was once speculated as a hot spot for future alien hunters. That was all until astronomers did the sums on how often TRAPPIST-1 might bake its brood of tiny worlds in a sterilising tsunami of high energy solar wind. Similarly, if SDSSJ013333 was home to an alien paradise before, chances are slim we'd find much standing there now. This research was published on arXiv.org.
Birds Have a Mysterious 'Quantum Sense'. For The First Time, Scientists Saw It in Action - ScienceAlert
Seeing our world through the eyes of a migratory bird would be a rather spooky experience. Something about their visual system allows them to 'see' our planet's magnetic field, a clever trick of quantum physics and biochemistry that helps them naviga
Seeing our world through the eyes of a migratory bird would be a rather spooky experience. Something about their visual system allows them to 'see' our planet's magnetic field, a clever trick of quantum physics and biochemistry that helps them navigate vast distances. Now, for the first time ever, scientists from the University of Tokyo have directly observed a key reaction hypothesised to be behind birds', and many other creatures', talents for sensing the direction of the planet's poles. Importantly, this is evidence of quantum physics directly affecting a biochemical reaction in a cell - something we've long hypothesised but haven't seen in action before. Using a tailor-made microscope sensitive to faint flashes of light, the team watched a culture of human cells containing a special light-sensitive material respond dynamically to changes in a magnetic field. A cell's fluorescence dimming as a magnetic field passes over it. (Ikeya and Woodward, CC BY) The change the researchers observed in the lab match just what would be expected if a quirky quantum effect was responsible for the illuminating reaction. "We've not modified or added anything to these cells," says biophysicist Jonathan Woodward. "We think we have extremely strong evidence that we've observed a purely quantum mechanical process affecting chemical activity at the cellular level." So how are cells, particularly human cells, capable of responding to magnetic fields? While there are several hypotheses out there, many researchers think the ability is due to a unique quantum reaction involving photoreceptors called cryptochromes. Cyrptochromes are found in the cells of many species and are involved in regulating circadian rhythms. In species of migratory birds, dogs, and other species, they're linked to the mysterious ability to sense magnetic fields. In fact, while most of us can't see magnetic fields, our own cells definitely contain cryptochromes. And there's evidence that even though it's not conscious, humans are actually still capable of detecting Earth's magnetism. To see the reaction within cyrptochromes in action, the researchers bathed a culture of human cells containing cryptochromes in blue light caused them to fluoresce weakly. As they glowed, the team swept magnetic fields of various frequencies repeatedly over the cells. They found that, each time the magnetic filed passed over the cells, their fluorescent dipped around 3.5 percent - enough to show a direct reaction. So how can a magnetic field affect a photoreceptor? It all comes down to something called spin - a innate property of electrons. We already know that spin is significantly affected by magnetic fields. Arrange electrons in the right way around an atom, and collect enough of them together in one place, and the resulting mass of material can be made to move using nothing more than a weak magnetic field like the one that surrounds our planet. This is all well and good if you want to make a needle for a navigational compass. But with no obvious signs of magnetically-sensitive chunks of material inside pigeon skulls, physicists have had to think smaller. In 1975, a Max Planck Institute researcher named Klaus Schulten developed a theory on how magnetic fields could influence chemical reactions. It involved something called a radical pair. A garden-variety radical is an electron in the outer shell of an atom that isn't partnered with a second electron. Sometimes these bachelor electrons can adopt a wingman in another atom to form a radical pair. The two stay unpaired but thanks to a shared history are considered entangled, which in quantum terms means their spins will eerily correspond no matter how far apart they are. Since this correlation can't be explained by ongoing physical connections, it's purely a quantum activity, something even Albert Einstein considered 'spooky'. In the hustle-bustle of a living cell, their entanglement will be fleeting. But even these briefly correlating spins should last just long enough to make a subtle difference in the way their respective parent atoms behave. In this experiment, as the magnetic field passed over the cells, the corresponding dip in fluorescence suggests that the generation of radical pairs had been affected. An interesting consequence of the research could be in how even weak magnetic fields could indirectly affect other biological processes. While evidence of magnetism affecting human health is weak, similar experiments as this could prove to be another avenue for investigation. "The joyous thing about this research is to see that the relationship between the spins of two individual electrons can have a major effect on biology," says Woodward Of course birds aren't the only animal to rely on our magnetosphere for direction. Species of fish, worms, insects, and even some mammals have a knack for it. We humans might even be cognitively affected by Earth's faint magnetic field. Evolution of this ability could have delivered a number of vastly different actions based on different physics. Having evidence that at least one of them connects the weirdness of the quantum world with the behaviour of a living thing is enough to force us to wonder what other bits of biology arise from the spooky depths of fundamental physics. This research was published in PNAS.