For centuries, mapmakers have agonized over how to accurately display our round planet on anything other than a globe.
Now, a fundamental re-imagining of how maps can work has resulted in the most accurate flat map ever made, from a trio of map experts: J. Richard Gott, an emeritus professor of astrophysics at Princeton and creator of a logarithmic map of the universe once described as “arguably the most mind-bending map to date”; Robert Vanderbei, a professor of operations research and financial engineering who created the “Purple America” map of election results; and David Goldberg, a professor of physics at Drexel University.
Their new map is two-sided and round, like a phonograph record or vinyl LP. Like many radical developments, it seems obvious in hindsight. Why not have a two-sided map that shows both sides of the globe? It breaks away from the limits of two dimensions without losing any of the logistical convenience—storage and manufacture—of a flat map.
“This is a map you can hold in your hand,” Gott said.
Princeton professors J. Richard Gott and Robert Vanderbei worked with Drexel professor David Goldberg to create a revolutionary new map: a two-sided disk that can slip inside a textbook or be stacked neatly for storage. It provides more accurate distances than any existing flat map, while keeping visual distortions at a minimum. Credit: Video by J. Richard Gott, Robert Vanderbei and David Goldberg
In 2007, Goldberg and Gott invented a system to score existing maps, quantifying the six types of distortions that flat maps can introduce: local shapes, areas, distances, flexion (bending), skewness (lopsidedness) and boundary cuts (continuity gaps). The lower the score, the better: a globe would have a score of 0.0.
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It can be displayed with the Eastern and Western Hemispheres on the two sides, or in Gott’s preferred orientation, the Northern and Southern Hemispheres, which conveniently allows the equator to run around the edge. Either way, this is a map with no boundary cuts. To measure distances from one side to the other, you can use string or measuring tape reaching from one side of the disk to the other, he suggested.
“If you’re an ant, you can crawl from one side of this ‘phonograph record’ to the other,” Gott said. “We have continuity over the equator. African and South America are draped over the edge, like a sheet over a clothesline, but they’re continuous.”
This double-sided map has smaller distance errors than any single-sided flat map—the previous record-holder being a 2007 map by Gott with Charles Mugnolo, a 2005 Princeton alumnus. In fact, this map is remarkable in having an upper boundary on distance errors: It is impossible for distances to be off by more than ± 22.2%. By comparison, in the Mercator and Winkel Tripel projections, as well as others, distance errors become enormous approaching the poles and essentially infinite from the left to the right margins (which are far apart on the map but directly adjacent on the globe). In addition, areas at the edge are only 1.57 times larger than at the center.
Researchers at the University of Maryland have turned ordinary sheets of wood into transparent material that is nearly as clear as glass, but stronger and with better insulating properties. It could become an energy efficient building material in the future.
Wood is made of two basic ingredients: cellulose, which are tiny fibres, and lignin, which bonds those fibres together to give it strength.
Tear a paper towel in half and look closely along the edge. You will see the little cellulose fibres sticking up. Lignin is a glue-like material that bonds the fibres together, a little like the plastic resin in fibreglass or carbon fibre. The lignin also contains molecules called chromophores, which give the wood its brown colour and prevent light from passing through.
Early attempts to make transparent wood involved removing the lignin, but this involved hazardous chemicals, high temperatures and a lot of time, making the product expensive and somewhat brittle. The new technique is so cheap and easy it could literally be done in a backyard.
Starting with planks of wood a metre long and one millimetre thick, the scientists simply brushed on a solution of hydrogen peroxide using an ordinary paint brush. When left in the sun, or under a UV lamp for an hour or so, the peroxide bleached out the brown chromophores but left the lignin intact, so the wood turned white.
Researchers demonstrated after brushing a coat of hydrogen peroxide on the opaque wood material, and exposing it to one hour of sunlight, it turns transparent. (Qinqin Xia, University of Maryland/Science Advances)
Next, they infused the wood with a tough transparent epoxy designed for marine use, which filled in the spaces and pores in the wood and then hardened. This made the white wood transparent.
You can see a similar effect by taking that same piece of paper towel, dip half of it in water and place it on a patterned surface. The white paper towel will become translucent with light passing through the water and cellulose fibres without being scattered by refraction.
The epoxy in the wood does an even better job, allowing 90 per cent of visible light to pass through. The result is a long piece of what looks like glass, with the strength and flexibility of wood.
A researcher holds up a square of transparent wood material against a green leaf. (USDA Forest Service)
As window material, it would be much more resistant to accidental breakage. The clear wood is lighter than glass, with better insulating properties, which is important because windows are a major source of heat loss in buildings. It also might take less energy to manufacture clear wood because there are no high temperatures involved.
Transparent wood could become an alternative to glass in energy efficient buildings, or perhaps coverings for solar panels in harsh environments. There could be no end of uses.
Scientists around the world have noted that the Earth has been spinning on its axis faster lately—the fastest ever recorded. Several scientists have spoken to the press about the unusual phenomenon, with some pointing out that this past year saw some of the shortest days ever recorded.
For most of the history of mankind, time has been marked by the 24-hour day/night cycle (with some alterations made for convenience as the seasons change). The cycle is governed by the speed at which the planet spins on its axis. Because of that, the length of a day has become the standard by which time is marked—each day lasts approximately 86,400 seconds. The day/night cycle is remarkably consistent despite the fact that it actually varies slightly on a regular basis.
Several decades ago, the development of atomic clocks began allowing scientists to record the passage of time in incredibly small increments, in turn, allowing for measuring the length of a given day down to the millisecond. And that has led to the discovery that the spin of the planet is actually far more variable than once thought. Since such measurements began, scientists have also found that the Earth was slowing its spin very gradually (compensated by the insertion of a leap second now and then)—until this past year, when it began spinning faster—so much so that some in the field have begun to wonder if a negative leap negative second might be needed this year, an unprecedented suggestion. Scientists also noted that this past summer, on July 19, the shortest day ever was recorded—it was 1.4602 milliseconds shorter than the standard.
Planetary scientists are not concerned about the new finding; they have learned that there are many factors that have an impact on planetary spin—including the moon’s pull, snowfall levels and mountain erosion. They also have begun wondering if global warming might push the Earth to spin faster as the snow caps and high-altitude snows begin disappearing. Computer scientists, on the other hand, are somewhat concerned about the shifting spin speed—so much of modern technology is based on what they describe as “true time.” Adding a negative leap second could lead to problems, so some have suggested shifting the world’s clocks from solar time to atomic time.
Nothing keeps time like the beating heart of an atom. But even the crisp tick-tock of a vibrating nucleus is limited by uncertainties imposed by the laws of quantum mechanics.
Several years ago, researchers from MIT and the University of Belgrade in Serbia proposed that quantum entanglement could push clocks beyond this blurry boundary.
Now, we have a proof of concept in the form of an experiment. Physicists connected together a cloud of ytterbium-171 atoms with streams of photons reflected from a surrounding hall of mirrors and measured the timing of their tiny wiggles.
Their results show that entangling atoms in this way could speed up the time-measuring process of atomic nuclei clocks, making them more precise than ever. In principle, a clock based on this new approach would lose just 100 milliseconds since the dawn of time itself.
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In this case, the team found entanglement made the measurement process roughly three times faster compared with clocks acting at the SQL.
That might not seem all that dramatic, but a speed boost could be just the thing we need to study some of the more subtle influences the Universe has on time.
“As the Universe ages, does the speed of light change? Does the charge of the electron change?” says lead researcher Vladan Vuletic from MIT.
“That’s what you can probe with more precise atomic clocks.”
Plants have the same variation in body clocks as that found in humans, according to new research that explores the genes governing circadian rhythms in plants.
The research shows a single letter change in their DNA code can potentially decide whether a plant is a lark or a night owl. The findings may help farmers and crop breeders to select plants with clocks that are best suited to their location, helping to boost yield and even the ability to withstand climate change.
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To investigate the genetic basis of these local differences, the team examined varying circadian rhythms in Swedish Arabidopsis plants to identify and validate genes linked to the changing tick of the clock.
Dr. Hannah Rees, a postdoctoral researcher at the Earlham Institute and author of the paper, said: “A plant’s overall health is heavily influenced by how closely its circadian clock is synchronised to the length of each day and the passing of seasons. An accurate body clock can give it an edge over competitors, predators and pathogens.
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The team studied the genes in 191 different varieties of Arabidopsis obtained from across the whole of Sweden. They were looking for tiny differences in genes between these plants which might explain the differences in circadian function.
Their analysis revealed that a single DNA base-pair change in a specific gene—COR28—was more likely to be found in plants that flowered late and had a longer period length. COR28 is a known coordinator of flowering time, freezing tolerance and the circadian clock; all of which may influence local adaptation in Sweden.
“It’s amazing that just one base-pair change within the sequence of a single gene can influence how quickly the clock ticks,” explained Dr. Rees.
The scientists also used a pioneering delayed fluorescence imaging method to screen plants with differently-tuned circadian clocks. They showed there was over 10 hours difference between the clocks of the earliest risers and latest phased plants—akin to the plants working opposite shift patterns. Both geography and the genetic ancestry of the plant appeared to have an influence.
The shift to online science communication from conventional news platforms has been going on for a while. There is a need for credible and accurate science reporting because the miscommunication of science in the media is causing lasting damage to the public’s understanding of science.
Misinformation has consequences, as seen during the ongoing COVID-19 pandemic. Ignoring public health advice to wear masks and physically distance has cost thousands of lives and livelihoods in countries such as the United States, Brazil and Russia. Yet, resources in science journalism are dwindling. Budget cuts have slashed the number of journalists in conventional news outlets; this often affects specialized reporters like science journalists.
We need to equip scientists with science journalism skills. At Concordia University,
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This withdrawal of conventional news outlets from conducting science journalism and the increasing role of universities and scientists doing so introduce new challenges.
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Because there are fewer science journalists in conventional news outlets, the public is less able to access the scientific information they need to make informed decisions. This is further exacerbated by the flaws of the existing academic publishing model.
Currently, scientists communicate their research via private publishing groups. Due to paywalls, this research is very hard to access by the taxpayers who fund that research. Meanwhile, research funded by industry is freely accessible to the public via the publication of patents
When it comes to communicating research, there is an inherent conflict of interest between scientists and the universities that employ them.
That’s not to say that universities have sinister intentions. Universities are heavily invested in enhancing their reputations, which is closely tied to their success in raising funds through student recruitment, government grants and philanthropic endowments.
Universities view science communication as a fundraising activity, directed at funding sources, rather than the general public.
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Universities should equip scientists with the knowledge-translation skills necessary to communicate their own science critically and credibly
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Universities should also find a way to engage students in scientific communication. For example, there should be funding for internships for communications students, where those hired can manage Twitter accounts and blogs for research labs, update websites and write research publications in a more compelling, accessible and critical way
While traditional diamonds are formed over billions of years deep in the Earth where extreme pressures and temperatures provide just the right conditions to crystalize carbon, scientists are working on more expedient ways of forging the precious stones. An international team of researchers has succeeded in whittling this process down to mere minutes, demonstrating a new technique where they not only form quickly, but do so at room temperature.
This latest breakthrough was led by scientists at the Australian National University (ANU) and RMIT University, who used what’s known as a diamond anvil cell, which is a device used by researchers to generate the extreme pressures needed to create ultra-hard materials. The team applied pressure equal to 640 African elephants on the tip of a ballet shoe, doing so in a way that caused an unexpected reaction among the the carbon atoms in the device. “The twist in the story is how we apply the pressure,” says ANU Professor Jodie Bradby. “As well as very high pressures, we allow the carbon to also experience something called ‘shear’ — which is like a twisting or sliding force. We think this allows the carbon atoms to move into place and form Lonsdaleite and regular diamond.”
These regular diamonds are the type you might find in an engagement ring, while Lonsdaleite diamonds are rarer and found at meteorite impact sites. Using advanced electron microscopy, the team was able to examine the samples in detail, and found that the materials were formed within bands they liken to “rivers” of diamond. The team hopes the technique can enable them to produce meaningful quantities of these artificial diamonds, particularly Lonsdaleite, which is predicted to be 58 percent harder than regular diamonds. “Lonsdaleite has the potential to be used for cutting through ultra-solid materials on mining sites,” Bradby says. The research was published in the journal Small, while you can hear from the researchers in this video.
Airglow is the natural “glowing” of the Earth’s atmosphere. It happens all the time and across the whole globe. There are three types of airglow: dayglow, twilightglow and nightglow. Each is the result of sunlight interacting with the molecules in our atmosphere, but they have their own special way of forming.
Dayglow forms when sunlight strikes the daytime atmosphere. Some of the sunlight is absorbed by the molecules in the atmosphere, which gives them excess energy. They become excited. The molecules then release this energy as light, either at the same or slightly lower frequency (colour) as the light they absorbed. This light is much dimmer than daylight, so we can’t see it by eye.
Twilight glow is essentially the same as dayglow, but only the upper atmosphere is sunlit. The rest of the atmosphere and the observer on the ground are in darkness. So, unlike day glow, twilightglow is actually visible to us on the ground with the naked eye.
Chemiluminescence
The chemistry behind nightglow is different. There is no sunlight shining on the nighttime atmosphere. Instead, a process called “chemiluminescence” is responsible for the glowing atmosphere.
Sunlight deposits energy into the atmosphere during the day, some of which is transferred to oxygen molecules (e.g. O₂). This extra energy causes the oxygen molecules to rip apart into individual oxygen atoms. This happens particularly around 100km in altitude. However, atomic oxygen isn’t able to get rid of this excess energy easily and so acts as a “store” of energy for several hours.
Eventually the atomic oxygen does manage to “recombine”, once again forming molecular oxygen. The molecular oxygen then releases energy, again in the form of light. Several different colours are produced, including a “bright” green emission.
Airglow spotted in panoramic shot of the Very Large Telescope. Beletsky, CC BY-SA
In reality, the green nightglow isn’t particularly bright, it’s just the brightest of all nightglow emissions. Light pollution and cloudy skies will prevent sightings. If you’re lucky though, you might just be able to see it by eye or capture it on long-exposure photos.
Not to be confused with aurora
The green night glow emission is very similar to the famous green we see in the northern lights. This is unsurprising since it is produced by the same oxygen molecules as the green aurora. But the two phenomena are not related.
Aurora form when charged particles, such as electrons, bombard the Earth’s atmosphere. These charged particles, which started off at the sun and were accelerated in the Earth’s magnetosphere, collide with the atmospheric gases. They transfer energy, forcing the gases to emit light.
The aurora and airglow captured from the International Space Station.NASA
But it isn’t just the process behind them that is different. The aurora form in a ring around the magnetic poles (known as the auroral oval); whereas nightglow is emitted across the whole night sky. The aurora are very structured (due to the Earth’s magnetic field); whereas airglow is generally quite uniform. The extent of the aurora is affected by the strength of the solar wind; whereas airglow happens all the time.
Why then did we get a lot sightings from the UK recently, rather than all the time? The brightness of airglow correlates with the level of ultraviolet (UV) light being emitted from the sun – which varies over time. The time of year also seems to have an impact on the strength of airglow.
Airglow captured by Michael Darby from Cornwall, UK. The Milky Way shines through in the centre of the image. Author provided
To maximise your chances of spotting airglow, you’ll want to take a long-exposure photograph of a clear, dark, night sky. Airglow can be spotted in any direction that is free of light pollution, at about 10⁰-20⁰ above the horizon.
Emerald green, fainter than the zodiacal light and visible on dark nights everywhere on Earth, airglow pervades the night sky from equator to pole. Airglow turns up in our time exposure photographs of the night sky as ghostly ripples of aurora-like light about 10-15 degrees above the horizon. Its similarity to the aurora is no coincidence. Both form at around the same altitude of 60-65 miles (100 km) and involve excitation of atoms and molecules, in particular oxygen. But different mechanisms tease them to glow.
Earth at night from the International Space Station showing bright splashes of city lights and the airglow layer created by light-emitting oxygen atoms some 60 miles high in the atmosphere. This green cocoon of light is familiar to anyone who’s looked at photos of Earth’s night-side from orbit. Credit: NASA
Auroras get their spark from high-speed electrons and protons in the solar wind that bombard oxygen and nitrogen atoms and molecules. As excited electrons within those atoms return to their rest states, they emit photons of green and red light that create shimmering, colorful curtains of northern lights.
Green light from excited oxygen atoms dominates the light of airglow. The atoms are 56-62 miles high in the thermosphere. The weaker red light is from oxygen atoms further up. Sodium atoms, hydroxyl radicals (OH) and molecular oxygen add their own complement to the light. Credit: Les Cowley
Airglow’s subtle radiance arises from excitation of a different kind. Ultraviolet light from the daytime sun ionizes or knocks electrons off of oxygen and nitrogen atoms and molecules; at night the electrons recombine with their host atoms, releasing energy as light of different colors including green, red, yellow and blue. The brightest emission, the one responsible for creating the green streaks and bands visible from the ground and orbit, stems from excited oxygen atoms beaming light at 557.7 nanometers, smack in the middle of the yellow-green parcel of spectrum where our eyes are most sensitive.
Airglow across the eastern sky below the summertime Milky Way. Notice that unlike the vertical rays and gently curving arcs of the aurora, airglow is banded, streaky and in places almost fibrous. It’s brightest and best visible 10-15 degrees high along a line of sight through the thicker atmosphere. If you look lower, its feeble light is absorbed by denser air and dust. Looking higher, the light spreads out over a greater area and appears dimmer. Credit: Bob KingA large, faint patch of airglow below the Dippers photographed May 24. To the eye, airglow appears as colorless streaks and patches. Unlike the aurora, it’s typically too faint to excite our color vision. Time exposures show its colors well. This swatch is especially faint because it’s much higher above the horizon. Credit: Bob King
That’s not saying airglow is easy to see! For years I suspected streaks of what I thought were high clouds from my dark sky observing site even when maps and forecasts indicated pristine skies. Photography finally taught me to trust my eyes. I started noticing green streaks near the horizon in long-exposure astrophotos. At first I brushed it off as camera noise. Then I noticed how the ghostly stuff would slowly shape-shift over minutes and hours and from night to night. Gravity waves created by jet stream shear, wind flowing over mountain ranges and even thunderstorms in the lower atmosphere propagate up to the thermosphere to fashion airglow’s ever-changing contours.
An obvious airglow smear across Virgo last month. Mars is the bright object below and right of center. Light pollution from Duluth, Minn. creeps in at lower left. Credit: Bob King
Last month, on a particularly dark night, I made a dedicated sweep of the sky after my eyes had fully adapted to the darkness. A large swath of airglow spread south of the Big and Little Dipper. To the east, Pegasus and Andromeda harbored hazy spots of varying intensity, while brilliant Mars beamed through a long smear in Virgo.
To prove what I saw was real, I made the photos you see in this article and found they exactly matched my visual sightings. Except for color. Airglow is typically too faint to fire up the cone cells in our retinas responsible for color vision. The vague streaks and patches were best seen by moving your head around to pick out the contrast between them and the darker, airglow-free sky. No matter what part of the sky I looked, airglow poked its tenuous head. Indeed, if you were to travel anywhere on Earth, airglow would be your constant companion on dark nights, unlike the aurora which keeps to the polar regions. Warning – once you start seeing it, you
Excited oxygen at higher altitude creates a layer of faint red airglow. Sodium excitation forms the yellow layer at 57 miles up. Airglow is brightest during daylight hours but invisible against the sunlight sky. Credit: NASA with annotations by Alex Rivest
Airglow comes in different colors – let’s take a closer look at what causes them:
* Red – I’ve never seen it, but long-exposure photos often reveal red/pink mingled with the more common green. Excited oxygen atoms much higher up at 90-185 miles (150-300 km) radiating light at a different energy state are responsible. Excited -OH (hydroxyl) radicals give off deep red light in a process called chemoluminescencewhen they react with oxygen and nitrogen. Another chemoluminescent reaction takes place when oxygen and nitrogen molecules are busted apart by ultraviolet light high in the atmosphere and recombine to form nitric oxide (NO).
* Yellow – From sodium atoms around 57 miles (92 km) high. Sodium arrives from the breakup and vaporization of minerals in meteoroids as they burn up in the atmosphere as meteors.
* Blue – Weak emission from excited oxygen molecules approximately 59 miles (95 km) high.
Comet Lovejoy passing behind green oxygen and sodium airglow layers on December 22, 2011 seen from the space station. Credit: NASA/Dan Burbank
Airglow varies time of day and night and season, reaching peak brightness about 10 degrees, where our line of sight passes through more air compared to the zenith where the light reaches minimum brightness. Since airglow is brightest around the time of solar maximum (about now), now is an ideal time to watch for it. Even cosmic rays striking molecules in the upper atmosphere make a contribution.
https://www.youtube.com/embed/zymQQP4B21Q See lots of airglow and aurora from orbit in this video made using images taken from the space station.
If you removed the stars, the band of the Milky Way and the zodiacal light, airglow would still provide enough illumination to see your hand in front of your face at night. Through recombination and chemoluminescence, atoms and molecules creates an astounding array of colored light phenomena. We can’t escape the sun even on the darkest of nights.
In 2018, a new aurora-like discovery struck the world. From 2015 to 2016, citizen scientists reported 30 instances of a purple ribbon in the sky, with a green picket fence structure underneath. Now named STEVE, or Strong Thermal Emission Velocity Enhancement, this phenomenon is still new to scientists, who are working to understand all its details. What they do know is that STEVE is not a normal aurora—some think maybe it’s not an aurora at all—and a new finding about the formation of streaks within the structure brings scientists one step closer to solving the mystery.
“Often in physics, we build our understanding then test the extreme cases or test the cases in a different environment,” Elizabeth MacDonald, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, explains. “STEVE is different than the usual aurora, but it is made of light and it is driven by the auroral system. In finding these tiny little streaks, we may be learning something fundamentally new in how green auroral light can be produced.”
These “tiny little streaks” are extraordinarily small point-like features within the green picket fence of STEVE. In a new paper for AGU Advances, researchers share their latest findings on these points. They suggest the streaks could be moving points of light—elongated in the images due to blur from the cameras. The tip of the streak in one image will line up with the end of the tail in the next image, contributing to this speculation from the scientists. However, there are still a lot of questions to be answered—determining whether the green light is a point or indeed a line, is one extra clue to help scientists figure out what causes green light.
“I’m not entirely sure about anything with respect to this phenomenon just yet,” Joshua Semeter, a professor at Boston University and first author on the paper, said. “You have other sequences where it looks like there is a tube-shaped structure that persists from image to image and doesn’t seem to conform to a moving point source, so we’re not really sure about that yet.”
STEVE as a whole is something that scientists are still working to label. Scientists tend to classify optical features in the sky into two categories: airglow and aurora. When airglow occurs at night, atoms in the atmosphere recombine and release some of their stored energy in the form of light, creating bright swaths of color. By studying the patterns in airglow, scientists can learn more about that area of the atmosphere, the ionosphere. To be classified as an aurora, on the other hand, that release of light must be caused by electron bombardment. These features are formed differently but also look different—airglow can occur across Earth, while auroras form in a broad ring around Earth’s magnetic poles.
“STEVE in general appears to not conform well to either one of those categories,” Semeter said. “The emissions are coming from mechanisms that we don’t fully understand just yet.”
STEVE’s purple emissions are likely a result of ions moving at a supersonic speed. The green emissions seem to be related to eddies, like the ones you might see forming in a river, moving more slowly than the other water around it. The green features are also moving more slowly than the structures in the purple emissions, and scientists speculate they could be caused by turbulence in the space particles—a brew of charged particles and magnetic field, called plasma—at these altitudes.
“We know this kind of turbulence occurs. There are people who base their entire careers on studying turbulence in the ionospheric plasma formed by very rapid flows.” Semeter said. “The evidence generally comes from radar measurements. We don’t ever have an optical signature.” Semeter suggests that when it comes to the appearance of STEVE, the flows in these instances are so extreme, that we can actually see them in the atmosphere. Two different angles of distinctive green streaks below a STEVE event on Aug. 31, 2016, near Carstairs, Alberta, Canada. Recent research about the formation of these streaks is allowing scientists to learn more about this aurora-like phenomenon. Credit: Copyright Neil Zeller, used with permission
“This paper is the tip of the iceberg in this new area of these tiny little pieces of the picket fence. Something we do in physics is try to chip away to increase our understanding,” MacDonald said. “This paper establishes the altitude range and some of the techniques we can use to identify these features, then they can be better resolved in other observations.”
To establish the altitude range and identify these features, the scientists extensively used photos and videos captured by citizen scientists.
“Citizen scientists are the ones who brought the STEVE phenomenon to the scientists’ attention. Their photos are typically longer time lapse than our traditional scientific observations,” MacDonald said. “Citizen scientists don’t get into the patterns that scientists get into. They do things differently. They are free to move the camera around and take whatever exposure they want.” However, to make this new discovery of the points within STEVE, photographers actually took shorter exposure photographs to capture this movement.
To get those photographs, citizen scientists spend hours in the freezing cold, late at night, waiting for an aurora—or hopefully STEVE—to appear. While data can indicate if an aurora will show up, indicators for STEVE haven’t been identified yet. However, the aurora chasers show up and take pictures anyway.
Many hopes for a return to a semi-normal life after COVID-19 revolve around vaccines, but those injections have limits — they’re harder to deploy in low-income and rural areas where there’s no guarantee of easy distribution. Science may offer a more accessible alternative, though. Columbia University researchers have developed a nasal spray that has successfully prevented COVID-19 infections in tests with ferrets as well as a 3D model of human lungs.
The lipopeptide (that is, a lipid and peptide combination) prevents the coronavirus from fusing with a target cell’s membrane by blocking a key protein from adopting a necessary shape. It should work immediately and last for at least 24 hours. It’s also affordable, lasts a long time, and doesn’t need refrigeration.
A spray like this is still some ways from reaching the public. There would need to be human clinical trials, not to mention large-scale production to provide enough access. Scientists are planning to “rapidly advance” to further testing, Columbia said.
The move could bring protection to many parts of the world where mass COVID-19 vaccinations would be difficult. It might also serve as a “complement” even in places where vaccines are readily available, key researchers Anne Moscona and Matteo Porotto said. People who can’t take vaccines, or those for whom vaccinations don’t work, could spray themselves daily knowing they’d be safe. That, in turn, could further limit the spread of the virus and hasten the end to the pandemic.
Scientists have found evidence that frozen methane deposits in the Arctic Ocean – known as the “sleeping giants of the carbon cycle” – have started to be released over a large area of the continental slope off the East Siberian coast, the Guardian can reveal.
High levels of the potent greenhouse gas have been detected down to a depth of 350 metres in the Laptev Sea near Russia, prompting concern among researchers that a new climate feedback loop may have been triggered that could accelerate the pace of global heating.
The slope sediments in the Arctic contain a huge quantity of frozen methane and other gases – known as hydrates. Methane has a warming effect 80 times stronger than carbon dioxide over 20 years. The United States Geological Survey has previously listed Arctic hydrate destabilisation as one of four most serious scenarios for abrupt climate change.
The international team onboard the Russian research ship R/V Akademik Keldysh said most of the bubbles were currently dissolving in the water but methane levels at the surface were four to eight times what would normally be expected and this was venting into the atmosphere.
“At this moment, there is unlikely to be any major impact on global warming, but the point is that this process has now been triggered. This East Siberian slope methane hydrate system has been perturbed and the process will be ongoing,” said the Swedish scientist Örjan Gustafsson, of Stockholm University, in a satellite call from the vessel.
MIT researchers have now found that people who are asymptomatic may differ from healthy individuals in the way that they cough. These differences are not decipherable to the human ear. But it turns out that they can be picked up by artificial intelligence.
In a paper published recently in the IEEE Journal of Engineering in Medicine and Biology, the team reports on an AI model that distinguishes asymptomatic people from healthy individuals through forced-cough recordings, which people voluntarily submitted through web browsers and devices such as cellphones and laptops.
The researchers trained the model on tens of thousands of samples of coughs, as well as spoken words. When they fed the model new cough recordings, it accurately identified 98.5 percent of coughs from people who were confirmed to have Covid-19, including 100 percent of coughs from asymptomatics — who reported they did not have symptoms but had tested positive for the virus.
The team is working on incorporating the model into a user-friendly app, which if FDA-approved and adopted on a large scale could potentially be a free, convenient, noninvasive prescreening tool to identify people who are likely to be asymptomatic for Covid-19. A user could log in daily, cough into their phone, and instantly get information on whether they might be infected and therefore should confirm with a formal test.
“The effective implementation of this group diagnostic tool could diminish the spread of the pandemic if everyone uses it before going to a classroom, a factory, or a restaurant,” says co-author Brian Subirana, a research scientist in MIT’s Auto-ID Laboratory.
Subirana’s co-authors are Jordi Laguarta and Ferran Hueto, of MIT’s Auto-ID Laboratory.
Prior to the pandemic’s onset, research groups already had been training algorithms on cellphone recordings of coughs to accurately diagnose conditions such as pneumonia and asthma. In similar fashion, the MIT team was developing AI models to analyze forced-cough recordings to see if they could detect signs of Alzheimer’s, a disease associated with not only memory decline but also neuromuscular degradation such as weakened vocal cords.
They first trained a general machine-learning algorithm, or neural network, known as ResNet50, to discriminate sounds associated with different degrees of vocal cord strength. Studies have shown that the quality of the sound “mmmm” can be an indication of how weak or strong a person’s vocal cords are. Subirana trained the neural network on an audiobook dataset with more than 1,000 hours of speech, to pick out the word “them” from other words like “the” and “then.”
The team trained a second neural network to distinguish emotional states evident in speech, because Alzheimer’s patients — and people with neurological decline more generally — have been shown to display certain sentiments such as frustration, or having a flat affect, more frequently than they express happiness or calm. The researchers developed a sentiment speech classifier model by training it on a large dataset of actors intonating emotional states, such as neutral, calm, happy, and sad.
The researchers then trained a third neural network on a database of coughs in order to discern changes in lung and respiratory performance.
Finally, the team combined all three models, and overlaid an algorithm to detect muscular degradation. The algorithm does so by essentially simulating an audio mask, or layer of noise, and distinguishing strong coughs — those that can be heard over the noise — over weaker ones.
With their new AI framework, the team fed in audio recordings, including of Alzheimer’s patients, and found it could identify the Alzheimer’s samples better than existing models. The results showed that, together, vocal cord strength, sentiment, lung and respiratory performance, and muscular degradation were effective biomarkers for diagnosing the disease.
[…]
Surprisingly, as the researchers write in their paper, their efforts have revealed “a striking similarity between Alzheimer’s and Covid discrimination.”
A team of physicists led by Professor Patrick Windpassinger at Johannes Gutenberg University Mainz (JGU) has successfully transported light stored in a quantum memory over a distance of 1.2 millimeters. They have demonstrated that the controlled transport process and its dynamics has only little impact on the properties of the stored light. The researchers used ultra-cold rubidium-87 atoms as a storage medium for the light as to achieve a high level of storage efficiency and a long lifetime.
“We stored the light by putting it in a suitcase so to speak, only that in our case the suitcase was made of a cloud of cold atoms. We moved this suitcase over a short distance and then took the light out again. This is very interesting not only for physics in general, but also for quantum communication, because light is not very easy to ‘capture’, and if you want to transport it elsewhere in a controlled manner, it usually ends up being lost,” said Professor Patrick Windpassinger, explaining the complicated process.
In the chart here we see global transport emissions in 2018. This data is sourced from the International Energy Agency (IEA).
Road travel accounts for three-quarters of transport emissions. Most of this comes from passenger vehicles – cars and buses – which contribute 45.1%. The other 29.4% comes from trucks carrying freight.
Since the entire transport sector accounts for 21% of total emissions, and road transport accounts for three-quarters of transport emissions, road transport accounts for 15% of total CO2 emissions.
Aviation – while it often gets the most attention in discussions on action against climate change – accounts for only 11.6% of transport emissions. It emits just under one billion tonnes of CO2 each year – around 2.5% of total global emissions [we look at the role that air travel plays in climate change in more detail in an upcoming article]. International shipping contributes a similar amount, at 10.6%.
Rail travel and freight emits very little – only 1% of transport emissions. Other transport – which is mainly the movement of materials such as water, oil, and gas via pipelines – is responsible for 2.2%.
A team of US astrophysicists has produced one of the most precise measurements ever made of the total amount of matter in the Universe, a longtime mystery of the cosmos.
The answer, published in The Astrophysical Journal on Monday, is that matter consists of 31.5 percent—give or take 1.3 percent—of the total amount of matter and energy that make up the Universe.
The remaining 68.5 percent is dark energy, a mysterious force that is causing the expansion of the Universe to accelerate over time, and was first inferred by observations of distant supernovae in the late 1990s.
Put another way, this means the total amount of matter in the observable Universe is equivalent to 66 billion trillion times the mass of our Sun, Mohamed Abdullah, a University of California, Riverside astrophysicist and the paper’s lead author told AFP.
Most of this matter—80 percent—is called dark matter. Its nature is not yet known but it may consist of some as-yet-undiscovered subatomic particle.
[…]
So how exactly do you weigh the Universe?
The team honed a 90-year-old technique that involves observing how galaxies orbit inside galaxy clusters—massive systems that contain thousands of galaxies.
These observations told them how strong each galaxy cluster‘s gravitational pull was, from which its total mass could then be calculated.
Fate of the Universe
In fact, explained Wilson, their technique was originally developed by the pioneering astronomer Fritz Zwicky, who was the first person to suspect the existence of dark matter in galaxy clusters, in the 1930s.
He noticed that the combined gravitational mass of the galaxies he observed in the nearby Coma galaxy cluster was insufficient to prevent those galaxies from flying away from one another, and realized there must be some other invisible matter at play.
The UCR team refined Zwicky’s technique, developing a tool they called GalWeight that determines more accurately which galaxies belong to a given cluster and which do not.
They applied their tool to the Sloan Digital Sky Survey, the most detailed three-dimensional maps of the Universe currently available, measuring the mass of 1,800 galaxy clusters and creating a catalog.
Finally, they compared the number of clusters observed per unit volume in their catalog against a series of computer simulations, each of which was fed a different value for the total matter of the Universe.
Simulations with too little matter had too few clusters, while those with too much matter had too many clusters.
The “Goldilocks” value they found fit the simulations just right.
Public health crises have spawned conspiracy theories as far back as when the Black Death ravaged Europe in the 1300s, as people desperately try to make sense of the chaotic forces disrupting their lives. While modern science offers a better understanding of how diseases infect people and how to contain them, COVID-19 conspiracy theories are spreading rapidly via social media, unreliable news outlets and from our own political leaders, including U.S. President Donald Trump. The result: many Americans now believe pandemic-related conspiracy theories—and, alarmingly, those same people are less likely to take steps to prevent the virus from spreading.
In a University of Pennsylvania Annenberg Public Policy Center study published Monday in Social Science & Medicine, researchers surveyed a group of 840 U.S. adults—first in late March, and then again in mid-July—to determine how Americans’ beliefs and actions regarding the pandemic changed over time. Overall, they found that COVID-19 conspiracy theories are not only commonplace, they’re gaining traction. Back in March, 28% of people believed a debunked rumor that the Chinese government created the coronavirus as a bioweapon; that number rose to 37% by July. About 24% believed that the U.S. Centers for Disease Control and Prevention exaggerated the virus’ danger to hurt Trump politically despite a lack of evidence; by July, that figure rose to 32%. And in March, about 15% of respondents said they believed that the pharmaceutical industry created the virus to boost drug and vaccine sales—another unfounded theory—compared to 17% in July.
Whether or not someone thinks NASA hired Stanley Kubrick to fake the moon landing has little bearing on the world beyond that person. But in the case of a pandemic—which requires people to follow public health guidance in order to keep one another safe—conspiratorial thinking can have disturbing consequences. Indeed, the Annenberg study found that only 62% of people who were most likely to believe the coronavirus conspiracies said they wear a mask every day when they’re around other people away from home, compared to 95% of non-believers. Furthermore, people who believe COVID-19 conspiracy theories were 2.2 times less likely to say they wanted to receive a vaccine in March; by July, they were 3.5 times less likely to want to be vaccinated.
“Belief in pandemic conspiracy theories appears to be an obstacle to minimizing the spread of COVID-19,” said Dan Romer, Annenberg Public Policy Center research director and a study co-author, in a statement.
Where are people picking up COVID-19 conspiracy theories? Believers were more likely to be heavy users of social media and viewers of conservative media like Fox News, the study found. Meanwhile, people who watch other television news channels were more likely to follow public health guidance and to desire vaccination.
While the researchers say they understand how pandemic conspiracy theories are spreading, they say it’s still a challenge to get believers to reconsider once they’re sucked in. Other research suggests that simply correcting false information doesn’t usually work—and can even cause some people to believe conspiracies even more deeply.
“Conspiracy theories are difficult to displace because they provide explanations for events that are not fully understood, such as the current pandemic, play on people’s distrust of government and other powerful actors, and involve accusations that cannot be easily fact-checked,” said Kathleen Hall Jamieson, Annenberg Public Policy Center director and study co-author, in a statement.
For the first time, climate scientists have compiled a continuous, high-fidelity record of variations in Earth’s climate extending 66 million years into the past. The record reveals four distinctive climate states, which the researchers dubbed Hothouse, Warmhouse, Coolhouse, and Icehouse.
These major climate states persisted for millions and sometimes tens of millions of years, and within each one the climate shows rhythmic variations corresponding to changes in Earth’s orbit around the sun. But each climate state has a distinctive response to orbital variations, which drive relatively small changes in global temperatures compared with the dramatic shifts between different climate states.
[…]
“We’ve known for a long time that the glacial-interglacial cycles are paced by changes in Earth’s orbit, which alter the amount of solar energy reaching Earth’s surface, and astronomers have been computing these orbital variations back in time,” explained coauthor James Zachos, distinguished professor of Earth and planetary sciences and Ida Benson Lynn Professor of Ocean Health at UC Santa Cruz.
“As we reconstructed past climates, we could see long-term coarse changes quite well. We also knew there should be finer-scale rhythmic variability due to orbital variations, but for a long time it was considered impossible to recover that signal,” Zachos said. “Now that we have succeeded in capturing the natural climate variability, we can see that the projected anthropogenic warming will be much greater than that.”
For the past 3 million years, Earth’s climate has been in an Icehouse state characterized by alternating glacial and interglacial periods. Modern humans evolved during this time, but greenhouse gas emissions and other human activities are now driving the planet toward the Warmhouse and Hothouse climate states not seen since the Eocene epoch, which ended about 34 million years ago. During the early Eocene, there were no polar ice caps, and average global temperatures were 9 to 14 degrees Celsius higher than today.
[…]
Critical to compiling the new climate record was getting high-quality sediment cores from deep ocean basins through the international Ocean Drilling Program (ODP, later the Integrated Ocean Drilling Program, IODP, succeeded in 2013 by the International Ocean Discovery Program). Signatures of past climates are recorded in the shells of microscopic plankton (called foraminifera) preserved in the seafloor sediments. After analyzing the sediment cores, researchers then had to develop an “astrochronology” by matching the climate variations recorded in sediment layers with variations in Earth’s orbit (known as Milankovitch cycles).
“The community figured out how to extend this strategy to older time intervals in the mid-1990s,” said Zachos, who led a study published in 2001 in Science that showed the climate response to orbital variations for a 5-million-year period covering the transition from the Oligocene epoch to the Miocene, about 25 million years ago.
“That changed everything, because if we could do that, we knew we could go all the way back to maybe 66 million years ago and put these transient events and major transitions in Earth’s climate in the context of orbital-scale variations,” he said.
[…]
Now that they have compiled a continuous, astronomically dated climate record of the past 66 million years, the researchers can see that the climate’s response to orbital variations depends on factors such as greenhouse gas levels and the extent of polar ice sheets.
“In an extreme greenhouse world with no ice, there won’t be any feedbacks involving the ice sheets, and that changes the dynamics of the climate,” Zachos explained.
Most of the major climate transitions in the past 66 million years have been associated with changes in greenhouse gas levels.
[…]
The new climate record provides a valuable framework for many areas of research, he added. It is not only useful for testing climate models, but also for geophysicists studying different aspects of Earth dynamics and paleontologists studying how changing environments drive the evolution of species.
A surprising number of hillstream loaches—a family of Asian fish—are capable of walking on land using all four limbs, according to a new study. It’s a discovery that could explain how some of the earliest animals managed to stroll on solid ground.
South Asian hillstream loaches are a family of small fish that can often be found clinging to rocks in fast-moving waters. New research published in the Journal of Morphology suggests at least 11 species of hillstream loaches can also walk on land, as evidenced by their peculiar anatomies. At least one species, a blind cavefish known as Cryptotora thamicola, has actually been caught in the act, but the new research suggests other hillstream loaches can do it as well.
Brooke Flammang, a biologist at the New Jersey Institute of Technology and the study’s lead principal investigator, along with her colleagues, analyzed 29 hillstream loach specimens. Using micro-CT scans, the team studied and compared the various specimens, looking at their distinctive shapes, muscle groups, and skeletal structures.
Cryptotora thamicola as seen in multiple perspectives.
Image: Zach Randall, Florida Museum of Natural History, and BE Flammang, NJIT
This international team of researchers, which included scientists from the Florida Museum of Natural History, Louisiana State University, and Thailand’s Maejo University, also conducted some genetic work, sampling the DNA of 72 loaches in order to reconstruct their evolutionary family tree.
Together, the physical and genetic analysis revealed the fishes’ unusual land-walking capabilities.
“In most fishes, there is no bony connection between the backbone and the pelvic fins. These fish are different because they have hips,” explained Flammang in an email. “The hip bone is a sacral rib, and within the fishes we studied, we found three morphological variants ranging from very thin and not well-connected to robust and having a sturdy connection. We expect that those with the largest, most robust ‘hip’-bones have the best walking ability.”
Cryptotora thamicola in the wild.
Image: Florida Museum
Of the fish studied, 11 were found to have these robust hips, or pelvic girdles. Interestingly, the resulting gait is reminiscent of the way salamanders walk on land. As noted, the only documented example of a walking hillstream loach is Cryptotora thamicola, also known as the cave angel fish. These blind fish, in addition to walking on land, have been seen climbing up waterfalls, which they do using all four limbs.
[…]
Flammang said these fish don’t represent an intermediate species, that is, some kind of missing link between fully aquatic animals and those capable of living on land.
“But we know that throughout evolution, organisms have repeatedly converged on similar morphologies as a result of facing similar pressures of natural selection,” she said. “And we also know that physics does not change with time. Therefore, we can learn from the mechanics of how this fish walks and use it to better understand how extinct early animals may have walked.”
Researchers at McMaster University have developed a new technique to tease ancient DNA from soil, pulling the genomes of hundreds of animals and thousands of plants—many of them long extinct—from less than a gram of sediment.
The DNA extraction method, outlined in the journal Quarternary Research, allows scientists to reconstruct the most advanced picture ever of environments that existed thousands of years ago.
The researchers analyzed permafrost samples from four sites in the Yukon, each representing different points in the Pleistocene-Halocene transition, which occurred approximately 11,000 years ago.
This transition featured the extinction of a large number of animal species such as mammoths, mastodons and ground sloths, and the new process has yielded some surprising new information about the way events unfolded, say the researchers. They suggest, for example, that the woolly mammoth survived far longer than originally believed.
In the Yukon samples, they found the genetic remnants of a vast array of animals, including mammoths, horses, bison, reindeer and thousands of varieties of plants, all from as little as 0.2 grams of sediment.
The scientists determined that woolly mammoths and horses were likely still present in the Yukon’s Klondike region as recently as 9,700 years ago, thousands of years later than previous research using fossilized remains had suggested.
[…]
The technique resolves a longstanding problem for scientists, who must separate DNA from other substances mixed in with sediment. The process has typically required harsh treatments that actually destroyed much of the usable DNA they were looking for. But by using the new combination of extraction strategies, the McMaster researchers have demonstrated it is possible to preserve much more DNA than ever.
in a paper published on Aug. 17, in Nature Nanotechnology, Stanford scientists demonstrate a new approach to slow light significantly, much like an echo chamber holds onto sound, and to direct it at will. Researchers in the lab of Jennifer Dionne, associate professor of materials science and engineering at Stanford, structured ultrathin silicon chips into nanoscale bars to resonantly trap light and then release or redirect it later. These “high-quality-factor” or “high-Q” resonators could lead to novel ways of manipulating and using light, including new applications for quantum computing, virtual reality and augmented reality; light-based WiFi; and even the detection of viruses like SARS-CoV-2.
“We’re essentially trying to trap light in a tiny box that still allows the light to come and go from many different directions,” said postdoctoral fellow Mark Lawrence, who is also lead author of the paper. “It’s easy to trap light in a box with many sides, but not so easy if the sides are transparent—as is the case with many Silicon-based applications.”
Nearly 60 years ago, the Nobel prize–winning physicist Eugene Wigner captured one of the many oddities of quantum mechanics in a thought experiment. He imagined a friend of his, sealed in a lab, measuring a particle such as an atom while Wigner stood outside. Quantum mechanics famously allows particles to occupy many locations at once—a so-called superposition—but the friend’s observation “collapses” the particle to just one spot. Yet for Wigner, the superposition remains: The collapse occurs only when he makes a measurement sometime later. Worse, Wigner also sees the friend in a superposition. Their experiences directly conflict.
Now, researchers in Australia and Taiwan offer perhaps the sharpest demonstration that Wigner’s paradox is real. In a study published this week in Nature Physics, they transform the thought experiment into a mathematical theorem that confirms the irreconcilable contradiction at the heart of the scenario. The team also tests the theorem with an experiment, using photons as proxies for the humans. Whereas Wigner believed resolving the paradox requires quantum mechanics to break down for large systems such as human observers, some of the new study’s authors believe something just as fundamental is on thin ice: objectivity. It could mean there is no such thing as an absolute fact, one that is as true for me as it is for you.
[…]
in 2018, Richard Healey, a philosopher of physics at the University of Arizona, pointed out a loophole in Brukner’s thought experiment, which Tischer and her colleagues have now closed. In their new scenario they make four assumptions. One is that the results the friends obtain are real: They can be combined with other measurements to form a shared corpus of knowledge. They also assume quantum mechanics is universal, and as valid for observers as for particles; that the choices the observers make are free of peculiar biases induced by a godlike superdeterminism; and that physics is local, free of all but the most limited form of “spooky action” at a distance.
Yet their analysis shows the contradictions of Wigner’s paradox persist. The team’s tabletop experiment, in which they created entangled photons, also backs up the paradox. Optical elements steered each photon onto a path that depended on its polarization: the equivalent of the friends’ observations. The photon then entered a second set of elements and detectors that played the role of the Wigners. The team found, again, an irreconcilable mismatch between the friends and the Wigners. What is more, they varied exactly how entangled the particles were and showed that the mismatch occurs for different conditions than in Brukner’s scenario. “That shows that we really have something new here,” Tischler says.
It also indicates that one of the four assumptions has to give. Few physicists believe superdeterminism could be to blame. Some see locality as the weak point, but its failure would be stark: One observer’s actions would affect another’s results even across great distances—a stronger kind of nonlocality than the type quantum theorists often consider. So some are questioning the tenet that observers can pool their measurements empirically. “There are facts for one observer, and facts for another; they need not mesh,” suggests study co-author and Griffith physicist Howard Wiseman. It is a radical relativism, still jarring to many. “From a classical perspective, what everyone sees is considered objective, independent of what anyone else sees,” says Olimpia Lombardi, a philosopher of physics at the University of Buenos Aires.
And then there is Wigner’s conclusion that quantum mechanics itself breaks down. Of the assumptions, it is the most directly testable, by experiments that are probing quantum mechanics on ever larger scales.
In 1969, British physicist Roger Penrose suggested that energy could be generated by lowering an object into the black hole’s ergosphere—the outer layer of the black hole’s event horizon, where an object would have to move faster than the speed of light in order to remain still.
Penrose predicted that the object would acquire a negative energy in this unusual area of space. By dropping the object and splitting it in two so that one half falls into the black hole while the other is recovered, the recoil action would measure a loss of negative energy—effectively, the recovered half would gain energy extracted from the black hole’s rotation. The scale of the engineering challenge the process would require is so great, however, that Penrose suggested only a very advanced, perhaps alien, civilisation would be equal to the task.
Two years later, another physicist named Yakov Zel’dovich suggested the theory could be tested with a more practical, earthbound experiment. He proposed that “twisted” light waves, hitting the surface of a rotating metal cylinder turning at just the right speed, would end up being reflected with additional energy extracted from the cylinder’s rotation thanks to a quirk of the rotational doppler effect.
But Zel’dovich’s idea has remained solely in the realm of theory since 1971 because, for the experiment to work, his proposed metal cylinder would need to rotate at least a billion times a second—another insurmountable challenge for the current limits of human engineering.
Now, researchers from the University of Glasgow’s School of Physics and Astronomy have finally found a way to experimentally demonstrate the effect that Penrose and Zel’dovich proposed by twisting sound instead of light—a much lower frequency source, and thus much more practical to demonstrate in the lab.
[…]
Marion Cromb, a Ph.D. student in the University’s School of Physics and Astronomy, is the paper’s lead author. Marion said: “The linear version of the doppler effect is familiar to most people as the phenomenon that occurs as the pitch of an ambulance siren appears to rise as it approaches the listener but drops as it heads away. It appears to rise because the sound waves are reaching the listener more frequently as the ambulance nears, then less frequently as it passes.
“The rotational doppler effect is similar, but the effect is confined to a circular space. The twisted sound waves change their pitch when measured from the point of view of the rotating surface. If the surface rotates fast enough then the sound frequency can do something very strange—it can go from a positive frequency to a negative one, and in doing so steal some energy from the rotation of the surface.”
As the speed of the spinning disc increases during the researchers’ experiment, the pitch of the sound from the speakers drops until it becomes too low to hear. Then, the pitch rises back up again until it reaches its previous pitch—but louder, with amplitude of up to 30% greater than the original sound coming from the speakers.
Marion added: “What we heard during our experiment was extraordinary. What’s happening is that the frequency of the sound waves is being doppler-shifted to zero as the spin speed increases. When the sound starts back up again, it’s because the waves have been shifted from a positive frequency to a negative frequency. Those negative-frequency waves are capable of taking some of the energy from the spinning foam disc, becoming louder in the process—just as Zel’dovich proposed in 1971.”
Professor Daniele Faccio, also of the University of Glasgow’s School of Physics and Astronomy, is a co-author on the paper. Prof Faccio added: “We’re thrilled to have been able to experimentally verify some extremely odd physics a half-century after the theory was first proposed. It’s strange to think that we’ve been able to confirm a half-century-old theory with cosmic origins here in our lab in the west of Scotland, but we think it will open up a lot of new avenues of scientific exploration. We’re keen to see how we can investigate the effect on different sources such as electromagnetic waves in the near future.”
The research team’s paper, titled “Amplification of waves from a rotating body,” is published in Nature Physics.
Researchers used a computer simulation to show how a flushing toilet can create a cloud of virus-containing aerosol droplets that is large and widespread and lasts long enough that the droplets could be breathed in by others.
With recent studies showing the novel coronavirus that causes COVID-19 can survive in the human digestive tract and show up in feces of the infected, this raises the possibility the disease could be transmitted with the use of toilets.
Toilet flushing creates a great deal of turbulence, and qualitative evidence suggests this can spread both bacteria and viruses. The public, however, remains largely unaware of this infection pathway, since few quantitative studies have been carried out to investigate this possible mechanism.
In the journal Physics of Fluids, precise computer models were used to simulate water and air flows in a flushing toilet and the resulting droplet cloud. The investigators used a standard set of fluid dynamic formulas, known as the Navier-Stokes equations, to simulate flushing in two types of toilet—one with a single inlet for flushing water, and another with two inlets to create a rotating flow.
The investigators also used a discrete phase model to simulate movement of the numerous tiny droplets likely to be ejected from the toilet bowl into the air. A similar model was used recently to simulate the movement of aerosol droplets ejected during a human cough.
The results of the simulations were striking.
As water pours into the toilet bowl from one side, it strikes the opposite side, creating vortices. These vortices continue upward into the air above the bowl, carrying droplets to a height of nearly 3 feet, where they might be inhaled or settle onto surfaces. These droplets are so small they float in the air for over a minute. A toilet with two inlet ports for water generates an even greater velocity of upward flowing aerosol particles.
“One can foresee that the velocity will be even higher when a toilet is used frequently, such as in the case of a family toilet during a busy time or a public toilet serving a densely populated area,” said co-author Ji-Xiang Wang, of Yangzhou University.
The simulations show that nearly 60% of the ejected particles rise high above the seat for a toilet with two inlet ports. A solution to this deadly problem is to simply close the lid before flushing, since this should decrease aerosol spread.
However, in many countries, including the United States, toilets in public restrooms are often without lids. This poses a serious hazard. The investigators also suggest a better toilet design would include a lid that closes automatically before flushing.
Astronomers have finally found hard-to-detect visible matter scattered across space, left over from the Big Bang, after searching for nearly thirty years, according to a study published in Nature.
“We know from measurements of the Big Bang how much matter there was in the beginning of the Universe,” said Jean-Pierre Macquart, lead author of the paper and an associate professor at Curtin University, Australia, this week. “But when we looked out into the present universe, we couldn’t find half of what should be there. It was a bit of an embarrassment.”
Macquart isn’t referring to dark energy or dark matter. Instead, the study deals with baryonic matter, which is normal stuff made of protons and neutrons. The computer or device you’re using right now to read this is made up of it. This matter should also be out there in space, too, lingering between the galaxies and stars, but it’s missing, or rather, boffins couldn’t find it. The material is spread incredibly thinly across the void, making it difficult to detect.
But now scientists have managed to find some of that missing matter by inspecting fast radio bursts, which are powerful radio waves that are emitted for a few milliseconds. By following the line-of-sight of each blast, they were able to determine the electron column density, and count every baryon ionized by the electromagnetic wave.
“The radiation from fast radio bursts gets spread out by the missing matter in the same way that you see the colours of sunlight being separated in a prism,” Macquart said. “We’ve now been able to measure the distances to enough fast radio bursts to determine the density of the universe. We only needed six to find this missing matter.”
The density of missing matter they found was tiny; it’s equivalent to about “about one or two atoms in a room the size of an average office.” The measurement allows the academics to estimate the amount of missing matter in the universe.
The fast radio bursts were observed using the Australian Square Kilometre Array Pathfinder (ASKAP) telescope array at the Murchison Radio-astronomy Observatory located in Western Australia. “ASKAP both has a wide field of view, about 60 times the size of the full Moon, and can image in high resolution,” said Ryan Shannon, co-author of the paper and an associate professor at Swinburne University of Technology.
“This enables the precision to determine the location of the fast radio burst to the width of a human hair held 200m away,” he concluded.
A team of University of Rhode Island scientists and statisticians conducted a sophisticated quantitative analysis of a mass extinction that occurred 215 million years ago and found that the cause of the extinction was not an asteroid or climate change, as had previously been believed. Instead, the scientists concluded that the extinction did not occur suddenly or simultaneously, suggesting that the disappearance of a wide variety of species was not linked to any single catastrophic event.
Their research, based on paleontological field work carried out in sediments 227 to 205 million years old in Petrified Forest National Park, Arizona, was published in April in the journal Geology.
According to David Fastovsky, the URI professor of geosciences whose graduate student, Reilly Hayes, led the study, the global extinction of ancient Late Triassic vertebrates—the disappearance of which scientists call the Adamanian/Revueltian turnover—had never previously been reconstructed satisfactorily. Some researchers believed the extinction was triggered by the Manicouagan Impact, an asteroid impact that occurred in Quebec 215.5 million years ago, leaving a distinctive 750-square-mile lake. Others speculated that the extinction was linked to a hotter and drier climate that occurred at about the same time.
“Previous hypotheses seemed very nebulous, because nobody had ever approached this problem—or any ancient mass extinction problem—in the quantitative way that we did,” Fastovsky said. “In the end, we concluded that neither the asteroid impact nor the climate change had anything to do with the extinction, and that the extinction was certainly not as it had been described—abrupt and synchronous. In fact, it was diachronous and drawn-out.”
The Adamanian/Revueltian turnover was the perfect candidate for applying the quantitative methods employed by the research team, Fastovsky said. Because the fossil-rich layers at Petrified Forest National Park preserve a diversity of vertebrates from the period, including crocodile-like phytosaurs, armored aetosaurs, early dinosaurs, large crocodile-like amphibians, and other land-dwelling vertebrates, Hayes relocated the sites where known fossils were discovered and precisely determined their age by their position in the rock sequence. He was assisted by URI geosciences majors Amanda Bednarick and Catherine Tiley.
Hayes and URI Statistics Professor Gavino Puggioni then applied several Bayesian statistical algorithms to create “a probabilistic estimate” of when the animals most likely went extinct. This method allowed for an unusually precise assessment of the likelihood that the Adamanian vertebrates in the ancient ecosystem went extinct dramatically and synchronously, as would be expected with an asteroid impact.
Previous research concluded that the asteroid impact occurred 215.5 million years ago and the climate change some 3 to 5 million years later. The URI researchers demonstrated that the extinctions happened over an extended period between 222 million years ago and 212 million years ago. Some species of armored archosaurs Typothorax and Paratypothorax, for instance, went extinct about 6 million years before the impact and 10 million years before the climate change, while those of Acaenasuchus, Trilophosaurus and Calyptosuchus went extinct 2 to 3 million years before the impact. Desmatosuchus and Smilosuchus species, on the other hand, went extinct 2 to 3 million years after the impact and during the very early stages of the climate change.
“It was a long-lasting suite of extinctions that didn’t really occur at the same time as the impact or the climate change or anything else,” Fastovsky said. “No known instantaneous event occurred at the same time as the extinctions and thus might have caused them.”
The URI professor believes it will be difficult to apply these quantitative methods to calculate other mass extinctions because equally rich fossil data and precise radiometric dates for them aren’t available at other sites and for other time periods.
“This was like a test case, a perfect system for applying these techniques because you had to have enough fossils and sufficiently numerous and precise dates for them,” he said. “Other extinctions could potentially be studied in a similar way, but logistically it’s a tall mountain to climb. It’s possible there could be other ways to get at it, but it’s very time consuming and difficult.”
