livescience--2020-09-02--Visit NYC in 750 million B.C. with this epic interactive map

If New York City were built 170 million years ago , when roamed the Earth , Africa would have been a short boat ride away .
During the , the supercontinent — which formed tens of millions of years prior — would have been slowly splitting apart , the continents drifting toward their present-day positions , according to a .
The interactive map , designed by software engineer Ian Webster , visualizes how Earth 's continents evolved from about 750 million years ago to today , sweeping the user from a time when painted the planet white and an array @ @ @ @ @ @ @ emerged , to a time when humans and have become the globe 's biggest threat .
Webster built this digital globe while studying — a theory that the Earth 's outer shell is divided into pieces that move over the mantle with time , dragging continents with them .
`` I found that the data was difficult to consume and most interactive models were a bit dated or not generally accessible , '' Webster told Live Scinece .
`` Once I had the idea , I built most of the project while on @ @ @ @ @ @ @ map is built as a web application based on geological models created by geologist and paleogeography Christopher Scotese .
The site uses a software called GPlates , developed by Caltech and the University of Sydney and used by geologists to visualize plate tectonic reconstructions through time .
The user can type in the name of a city to see where that city stood on the planet millions of years ago .
For example , 600 million years ago , the land that was to become Paris was hidden underwater ; then by 200 @ @ @ @ @ @ @ to a spot near Canada .
The model also lets users jump to different timepoints of firsts for the planet , such as when the `` first '' multicellular life forms appeared or when the first flowers and hominids appeared .
`` One of my favorite parts is seeing how complex life developed relatively recently in geological terms , '' Webster said .
While the Earth formed 4.5 billion years ago , the first land plants only emerged around 430 million years ago , he added .
`` I enjoy seeing how the @ @ @ @ @ @ @ .
`` They used to be as high as the Himalayas and have eroded over the eons . ''

This is what the globe would look like 170 million years ago during the Jurassic Period.
If New York City were built 170 million years ago, when dinosaurs roamed the Earth, Africa would have been a short boat ride away.
During the Jurassic period , the supercontinent Pangaea — which formed tens of millions of years prior — would have been slowly splitting apart, the continents drifting toward their present-day positions, according to a new online interactive map .
The interactive map, designed by software engineer Ian Webster, visualizes how Earth's continents evolved from about 750 million years ago to today, sweeping the user from a time when glaciers painted the planet white and an array of single-celled organisms such as green algae emerged, to a time when humans and climate change have become the globe's biggest threat.
Related: 50 interesting facts about planet Earth
Webster built this digital globe while studying plate tectonics — a theory that the Earth's outer shell is divided into pieces that move over the mantle with time, dragging continents with them. "I found that the data was difficult to consume and most interactive models were a bit dated or not generally accessible," Webster told Live Scinece. "Once I had the idea, I built most of the project while on a long international flight."
The map is built as a web application based on geological models created by geologist and paleogeography Christopher Scotese. The site uses a software called GPlates, developed by Caltech and the University of Sydney and used by geologists to visualize plate tectonic reconstructions through time.
The user can type in the name of a city to see where that city stood on the planet millions of years ago. For example, 600 million years ago, the land that was to become Paris was hidden underwater; then by 200 million years ago, Paris had shifted to a spot near Canada. The model also lets users jump to different timepoints of firsts for the planet, such as when the "first" multicellular life forms appeared or when the first flowers and hominids appeared.
"One of my favorite parts is seeing how complex life developed relatively recently in geological terms," Webster said. While the Earth formed 4.5 billion years ago, the first land plants only emerged around 430 million years ago, he added. "I enjoy seeing how the Appalachian Mountains developed," he said. "They used to be as high as the Himalayas and have eroded over the eons."
Originally published on Live Science.


livescience--2020-09-02--Steroids are life-saving for critically ill COVID-19 patients, WHO says

There 's yet more evidence that cheap , widely available steroids can help save the lives of critically ill COVID-19 patients .
In a new analysis that included data from seven clinical trials , the drugs reduced the risk of death among patients by one-third , compared with patients given only standard care .
Based on the analysis , the World Health Organization ( WHO ) updated its , recommending that those with a severe COVID-19 infection receive the drugs for seven to 10 days as their new standard of care .
Those with mild infections should n't get because @ @ @ @ @ @ @ likely derive benefit and may derive harm '' from taking the drugs , the guidelines state .
The new analysis was published Sep. 2 in the ( JAMA ) .
Related : 20 of the worst epidemics and pandemics in history Early on , there were hints that steroids could be life-saving for COVID-19 patients .
For instance , data from China , published in March in , suggested that corticosteroids could reduce deaths among coronavirus patients with `` acute respiratory distress syndrome '' ( ARDS ) — a condition where the become @ @ @ @ @ @ @ with pus .
In June , U.K. researchers reported that a steroid called dexamethasone reduced the death rate among COVID-19 patients who required oxygen , either through ventilation or less-invasive methods , .
But that research had not yet been peer reviewed .
`` Without access to full trial details , clinicians were uncertain whether to begin using dexamethasone in patients hospitalized with COVID-19 , and if they used it , how they should implement it in practice , '' professors of medicine Hallie Prescott and Todd Rice wrote in an editorial about @ @ @ @ @ @ @ in .
That said , `` there has been widespread adoption of steroids in the care of critically ill patients with COVID-19 '' since the U.K. report came out , Dr. Nahid Bhadelia , medical director of the Special Pathogens Unit at the Boston University School of Medicine , told .
`` This is particularly true in many resource-limited countries where I work , '' she noted , given that dexamethasone is cheap and easy to get .
Related : Treatments for COVID-19 : Drugs being tested against the coronavirus Dexamethasone works by @ @ @ @ @ @ @ , and is commonly prescribed for psoriasis , , asthma and some cancers , such as leukemia , Live Science previously reported .
In the new analysis , the researchers looked at trials that tested either dexamethasone or one of two other steroids , hydrocortisone and methylprednisolone .
All the drugs similarly dampen the immune response , cause blood vessels to constrict and help to reduce fibrosis , or the development of thick scar tissue , according to the JAMA editorial .
According to the analysis , all three steroids reduced patient mortality @ @ @ @ @ @ @ authors calculated a 34 % reduction in the risk of death among critically ill patients given steroids compared with those given standard care , Stat News reported .
Overall , only 18 % of those taking steroids reported serious side effects , compared with 23 % of those given standard care ; within individual trials , these relative rates differed , but in most of the studies , steroids were n't associated with a higher risk of side effects .
The new analysis should dispel any remaining doubts about administering steroids to critical @ @ @ @ @ @ @ an associate professor of medicine and critical care physician at Vanderbilt University School of Medicine , told .
Previous studies of the SARS-CoV and MERS-CoV suggested that steroids might hobble the immune system as it attempts to fight off the pathogens , but that does n't seem to be a big concern here , according to the JAMA editorial .
The benefits of steroids outweigh the risks to critical COVID-19 patients , although `` the exact threshold at which an individual patient should be prescribed corticosteroids remains unclear , '' Prescott and Rice @ @ @ @ @ @ @ , there are different forms of acute respiratory distress syndrome , and steroids may relieve one form of ARDS more effectively than another , they noted .
Further research should reveal who exactly should be given steroids , at what dose and when in the course of their illness .

There's yet more evidence that cheap, widely available steroids can help save the lives of critically ill COVID-19 patients. In a new analysis that included data from seven clinical trials, the drugs reduced the risk of death among patients by one-third, compared with patients given only standard care.
Based on the analysis, the World Health Organization (WHO) updated its treatment guidelines for corticosteroids , recommending that those with a severe COVID-19 infection receive the drugs for seven to 10 days as their new standard of care. Those with mild infections shouldn't get steroids because "current data indicated they would not likely derive benefit and may derive harm" from taking the drugs, the guidelines state.
The new analysis was published Sep. 2 in the Journal of the American Medical Association (JAMA).
Related: 20 of the worst epidemics and pandemics in history
Early on, there were hints that steroids could be life-saving for COVID-19 patients. For instance, data from China, published in March in JAMA Internal Medicine , suggested that corticosteroids could reduce deaths among coronavirus patients with "acute respiratory distress syndrome" (ARDS) — a condition where the lungs become severely inflamed and their air sacs fill with pus.
In June, U.K. researchers reported that a steroid called dexamethasone reduced the death rate among COVID-19 patients who required oxygen, either through ventilation or less-invasive methods, Live Science previously reported . But that research had not yet been peer reviewed.
"Without access to full trial details, clinicians were uncertain whether to begin using dexamethasone in patients hospitalized with COVID-19, and if they used it, how they should implement it in practice," professors of medicine Hallie Prescott and Todd Rice wrote in an editorial about the new analysis, also published today in JAMA .
That said, "there has been widespread adoption of steroids in the care of critically ill patients with COVID-19" since the U.K. report came out, Dr. Nahid Bhadelia, medical director of the Special Pathogens Unit at the Boston University School of Medicine, told Stat News . "This is particularly true in many resource-limited countries where I work," she noted, given that dexamethasone is cheap and easy to get.
Related: Treatments for COVID-19: Drugs being tested against the coronavirus
Dexamethasone works by suppressing the immune system and reducing inflammation in the body, and is commonly prescribed for psoriasis, rheumatoid arthritis , asthma and some cancers, such as leukemia, Live Science previously reported. In the new analysis, the researchers looked at trials that tested either dexamethasone or one of two other steroids, hydrocortisone and methylprednisolone. All the drugs similarly dampen the immune response, cause blood vessels to constrict and help to reduce fibrosis, or the development of thick scar tissue, according to the JAMA editorial.
According to the analysis, all three steroids reduced patient mortality at similar rates; overall, the authors calculated a 34% reduction in the risk of death among critically ill patients given steroids compared with those given standard care, Stat News reported. Overall, only 18% of those taking steroids reported serious side effects, compared with 23% of those given standard care; within individual trials, these relative rates differed, but in most of the studies, steroids weren't associated with a higher risk of side effects.
The new analysis should dispel any remaining doubts about administering steroids to critical COVID-19 patients, Dr. Todd Rice, an associate professor of medicine and critical care physician at Vanderbilt University School of Medicine, told The New York Times . Previous studies of the coronaviruses SARS-CoV and MERS-CoV suggested that steroids might hobble the immune system as it attempts to fight off the pathogens, but that doesn't seem to be a big concern here, according to the JAMA editorial.
The benefits of steroids outweigh the risks to critical COVID-19 patients, although "the exact threshold at which an individual patient should be prescribed corticosteroids remains unclear," Prescott and Rice wrote in the editorial. For example, there are different forms of acute respiratory distress syndrome, and steroids may relieve one form of ARDS more effectively than another, they noted. Further research should reveal who exactly should be given steroids, at what dose and when in the course of their illness.
Originally published on Live Science.


livescience--2020-09-02--Largest black hole collision ever detected

Seven billion years ago , two large black holes crashed together and formed a massive new one .
It is the largest black hole collision ever detected in space , and the new black hole formed in the crash is the largest of its kind ever detected .
It 's so large , in fact , that physicists were n't sure it could exist at all .
The ripples from that collision reached the two Laser Interferometer Gravitational-Wave Observatory ( LIGO ) detectors in the U.S. and another in Italy called on May 21 , 2019 , after traveling through @ @ @ @ @ @ @ the sun has existed .
Those ripples revealed signatures of the merger of at least two black holes — one a black hole 85 times the mass of the sun and one 66 times the sun ’ s mass .
When they collided , they formed a black hole 142 times the mass of the sun .
The missing nine suns ’ worth of matter got converted into energy in the collision , shaking the universe hard enough for LIGO and Virgo to detect and interpret .
And that 's how scientists learned @ @ @ @ @ @ @ monster 142 solar mass black holes can exist at all .
“ This [ signal ] does n't look much like a chirp , which is what we typically detect , '' Nelson Christensen , a member of the Virgo collaboration , said in a statement .
`` It is more like something that goes 'bang . '
'' Related : 9 facts about black holes that will blow your mind That `` bang '' shook our region of space for only about a tenth of a second after traveling for a longer @ @ @ @ @ @ @ ever detected before .
But analyzing the shape of the wave , the researchers realized the type of black holes involved and exactly how big they were .
.
As Live Science previously reported , until now black holes have fallen into two categories : stellar-mass black holes and supermassive black holes .
Stellar-mass black holes , formed from collapsing stars , do n't get much larger than a few dozen times the mass of the sun .
These are the black holes that LIGO and Virgo have previously detected merging .
At @ @ @ @ @ @ @ supermassive black holes , with masses millions or billions of times that of our sun and the to grow whole galaxies around themselves .
The Milky Way has one , as do most other comparable galaxies .
But scientists are n't sure where they came from or how they formed ; they 've never detected a merger of such monstrous black holes .
In between the supermassives and the stellar-mass black holes is a wide `` mass gap , '' a range of masses where no black holes have ever been detected .
@ @ @ @ @ @ @ of mergers of stellar-mass black holes .
But if that is the case , then they would have to pass through this mass range .
Stellar-mass black holes would combine to form mass gap black holes , which would combine and combine until becoming supermassive .
But until now , scientists have never seen that happen .
`` One of the great mysteries in astrophysics is ‘ How do supermassive black holes form ?
’ '' study co-author Christopher Berry , a Northwestern University physicist , .
`` They are the million solar-mass @ @ @ @ @ @ @ grow from stellar-mass black holes , which are born when a star collapses , or are they born via an undiscovered means ?
Long have we searched for an intermediate-mass black hole to bridge the gap between stellar-mass and supermassive black holes .
Now , we have proof that intermediate-mass black holes do exist . ''
Related : The 12 strangest objects in the universe This discovery actually revealed that black holes can exist in two separate mass gaps .
The 85 solar mass black hole fits into the `` pair instability '' @ @ @ @ @ @ @ collapse into black holes because the outward pressure from photons and gas in their cores keeps them puffed up to large volumes , researchers believe .
But at very large masses , the energy in a star 's core converts photons into pairs of electrons and antielectrons , which together produce less pressure than photons do .
That means that when the star does collapse , the process is so fast and energetic that much of the mass gets blown away into space .
So a 130 solar-mass star can collapse and form @ @ @ @ @ @ @ `` pair instability '' gap ranges from 66 solar masses to 120 solar masses — a range where theoretical calculations suggest no black hole could directly form from a collapsing star .
The 85 solar-mass black hole detected in 2019 falls squarely in that range .
The most likely explanation is that it 's a `` second generation '' black hole , formed from two smaller progenitors .
It 's possible that the 66 solar-mass black hole was a second generation type as well , the researchers wrote in the study .
The @ @ @ @ @ @ @ a different , bigger mass gap .
A black hole that ’ s more massive than 120 suns could theoretically have formed from very large collapsing stars .
But no black hole in that range has ever been detected , and until now researchers were n't sure whether black holes of that mass could exist at all , now matter how they formed .
But this new , 142 solar-mass black hole falls squarely in that range — between the stellar masses and the supermassives .
It proves that black holes of that @ @ @ @ @ @ @ still possible , the researchers wrote , that this signal does n't reveal very large black holes as researchers assumed .
 '' What if something entirely new produced these gravitational waves ? ''
Vicky Kalogera , another Northwestern researcher , said in the Northwestern statement .
`` It 's a tantalizing prospect .
... For instance , perhaps the gravitational waves were emitted by a collapsing star in our galaxy .
The signal also could be from a cosmic string produced just after the universe inflated in its earliest moments — although @ @ @ @ @ @ @ data as well as a binary merger . ''
Gravitational wave astronomy is still so new that it 's impossible to be certain .
As LIGO , Virgo and future detectors gather more data from new events , the researchers wrote , the picture should become clearer .
And this event , with its promise of super-big black holes , might eventually become easier to explain .
A paper describing the discovery was published today ( Sept. 2 ) in the journal .
Another paper exploring its implications was also published today in @

Seven billion years ago, two large black holes crashed together and formed a massive new one. It is the largest black hole collision ever detected in space, and the new black hole formed in the crash is the largest of its kind ever detected. It's so large, in fact, that physicists weren't sure it could exist at all.
The ripples from that collision reached the two Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors in the U.S. and another in Italy called on May 21, 2019, after traveling through space for 2.5 billion years longer than the sun has existed. Those ripples revealed signatures of the merger of at least two black holes — one a black hole 85 times the mass of the sun and one 66 times the sun’s mass. When they collided, they formed a black hole 142 times the mass of the sun. The missing nine suns’ worth of matter got converted into energy in the collision, shaking the universe hard enough for LIGO and Virgo to detect and interpret. And that's how scientists learned that 85 solar mass black holes and monster 142 solar mass black holes can exist at all.
“This [signal] doesn't look much like a chirp, which is what we typically detect," Nelson Christensen, a member of the Virgo collaboration, said in a statement. "It is more like something that goes 'bang.'"
Related: 9 facts about black holes that will blow your mind
That "bang" shook our region of space for only about a tenth of a second after traveling for a longer period of time than any gravitational wave ever detected before. But analyzing the shape of the wave, the researchers realized the type of black holes involved and exactly how big they were. .
As Live Science previously reported, until now black holes have fallen into two categories: stellar-mass black holes and supermassive black holes.
Stellar-mass black holes, formed from collapsing stars, don't get much larger than a few dozen times the mass of the sun. These are the black holes that LIGO and Virgo have previously detected merging.
At the other end of the spectrum are supermassive black holes, with masses millions or billions of times that of our sun and the gravity to grow whole galaxies around themselves. The Milky Way has one, as do most other comparable galaxies. But scientists aren't sure where they came from or how they formed; they've never detected a merger of such monstrous black holes.
In between the supermassives and the stellar-mass black holes is a wide "mass gap," a range of masses where no black holes have ever been detected. One idea is that supermassives grow out of mergers of stellar-mass black holes. But if that is the case, then they would have to pass through this mass range. Stellar-mass black holes would combine to form mass gap black holes, which would combine and combine until becoming supermassive. But until now, scientists have never seen that happen.
"One of the great mysteries in astrophysics is ‘How do supermassive black holes form?’" study co-author Christopher Berry, a Northwestern University physicist, said in a statement . "They are the million solar-mass elephants in the room. Do they grow from stellar-mass black holes, which are born when a star collapses, or are they born via an undiscovered means? Long have we searched for an intermediate-mass black hole to bridge the gap between stellar-mass and supermassive black holes. Now, we have proof that intermediate-mass black holes do exist."
Related: The 12 strangest objects in the universe
This discovery actually revealed that black holes can exist in two separate mass gaps. The 85 solar mass black hole fits into the "pair instability" gap.
Lighter stars don’t collapse into black holes because the outward pressure from photons and gas in their cores keeps them puffed up to large volumes, researchers believe. But at very large masses, the energy in a star's core converts photons into pairs of electrons and antielectrons, which together produce less pressure than photons do. That means that when the star does collapse, the process is so fast and energetic that much of the mass gets blown away into space. So a 130 solar-mass star can collapse and form a 66 solar-mass black hole.
This "pair instability" gap ranges from 66 solar masses to 120 solar masses — a range where theoretical calculations suggest no black hole could directly form from a collapsing star. The 85 solar-mass black hole detected in 2019 falls squarely in that range. The most likely explanation is that it's a "second generation" black hole, formed from two smaller progenitors. It's possible that the 66 solar-mass black hole was a second generation type as well, the researchers wrote in the study.
The 142 solar mass black hole falls into a different, bigger mass gap. A black hole that’s more massive than 120 suns could theoretically have formed from very large collapsing stars. But no black hole in that range has ever been detected, and until now researchers weren't sure whether black holes of that mass could exist at all, now matter how they formed. But this new, 142 solar-mass black hole falls squarely in that range — between the stellar masses and the supermassives. It proves that black holes of that mass can exist.
And it's still possible, the researchers wrote, that this signal doesn't reveal very large black holes as researchers assumed.
"What if something entirely new produced these gravitational waves?" Vicky Kalogera, another Northwestern researcher, said in the Northwestern statement. "It's a tantalizing prospect. ... For instance, perhaps the gravitational waves were emitted by a collapsing star in our galaxy. The signal also could be from a cosmic string produced just after the universe inflated in its earliest moments — although neither of these exotic possibilities matches the data as well as a binary merger."
Gravitational wave astronomy is still so new that it's impossible to be certain. As LIGO, Virgo and future detectors gather more data from new events, the researchers wrote, the picture should become clearer. And this event, with its promise of super-big black holes, might eventually become easier to explain.
A paper describing the discovery was published today (Sept. 2) in the journal Physical Review Letters . Another paper exploring its implications was also published today in The Astrophysical Journal Letters .
Originally published on Live Science.


livescience--2020-09-02--'Spinal Tap'-size Stonehenge reveals how the ancient monument really sounded

The huge standing stones in the outer circle of acted as an amplifier and gave reverberation to enhance speech and music in ceremonies held thousands of years before modern acoustics emerged , according to new research .
The dramatic sound effects — including the repeating echo of reverberation — would have been unfamiliar to most of the people who gathered there , the researchers said , although a few might have experienced similar effects inside caves and in canyons .
The findings help explain part of a long-standing mystery of — what effect did ancient sites and buildings , such @ @ @ @ @ @ @ ancient temples , have on sounds ?
In the case of Stonehenge , which was first built around 5,000 years ago on Salisbury Plain in southwestern England , `` the amplification could have aided speech communication , and the reverberation improved musical sounds , '' wrote the researchers in a study published in the October issue of the .
Their research is based on detailed examinations of a geometrically-accurate scale model one-twelfth the size of Stonehenge , as it probably looked and sounded during its prime , about 4,200 years ago .
By @ @ @ @ @ @ @ exactly the same size as the miniature Stonehenge arch that appeared on stage in the 1984 movie `` This Is Spinal Tap . ''
Film buffs may recall that it came about after a confused member of the eponymous rock band specified the stones should be 18 inches ( 45 centimeters ) tall , instead of 18 feet ( 5.5 meters ) , which is about the height of one of the real Stonehenge arches .
Lead researcher Trevor Cox , a professor of acoustic engineering at the University of Salford near Manchester @ @ @ @ @ @ @ '' jokes whenever his research is mentioned .
`` It comes up every time , '' he said .
To make the model , Cox and his colleagues spent several months pouring plaster mixed with plastic into 3D-printed molds , to sculpt a total of 157 stones — about twice as many as remain today .
Based on laser scans of Stonehenge provided by the English Heritage Trust , which manages the historic site , the model includes the central `` horseshoe '' of the five largest stone arches and dozens of the @ @ @ @ @ @ @ life were likely , more than 140 miles ( 225 km ) away .
Crucially , the model monument also includes a complete outer circle of 30 upright sandstones and their lintels , called `` sarsens '' — from `` Saracens , '' a medieval English name for Arab Muslims that came to be used for anything thought to be pagan .
Only 17 sarsen uprights and seven lintels remain intact in the outer circle today , and recent research suggests they were .
Cox emphasized the importance of creating an accurate representation @ @ @ @ @ @ @ B.C .
so his team could learn how it sounded at that time .
They measured the sound levels at multiple locations around the model monument , both within the outer stone circle and outside it , using very high frequency sounds to compensate for its miniature scale — 12 times the frequency for structures one-twelfth of their normal size .
Such techniques have been applied since the 1930s to scale models of concert halls and opera houses , but they 've never been used before on a model of Stonehenge , Cox @ @ @ @ @ @ @ of the modern ruin of Stonehenge , which has about half as many stones as it did 4,000 years ago , and also at a complete replica of Stonehenge built as a war memorial near the town of Maryhill in southern Washington .
But the original Neolithic circle of standing stones reflected sound waves very differently than the few that remain , Cox said , and the uprights in the replica at Maryhill are simple rectangular slabs of concrete that do not have the same acoustic properties as the original hand-carved sandstones and @ @ @ @ @ @ @ Their studies showed that speech made within the outer circle was amplified by the ring of standing stones by between 10 % and 20 % , or about 5 decibels , compared with speech in the open .
They also found that the stones reverberated to mid-frequency sounds within the circle , with an average reverberation time of 0.64 seconds .
But they also found that speech or music made within the circle was much harder to hear outside it — and that suggests such activities at the center of Stonehenge were conducted @ @ @ @ @ @ @ , rather than for a large congregation .
But while Stonehenge 's effects of reverberation and amplification could be dramatic , Cox said that they did not seem to be the main reason that Stonehenge was built .
The amplification and reverberation provided by the stones was less than perfect , he said .
Yet there 's no archaeological evidence that the outer circle was ever changed from its original position .
Meanwhile , there 's evidence that ancient people often moved the bluestones to new locations within the circle .
This would @ @ @ @ @ @ @ , which are dominated by the outer circle , studies have found , according to Cox .
`` There 's no real evidence that there were big changes to the acoustics in a lot of these rearrangements , '' Cox said .
`` It does n't look like sound was driving it . ''
That suggests to him that the appearance of Stonehenge , rather than how it sounded , was the most important factor .
The technique could now be used in subterranean burial chambers , and Cox 's team hopes to @ @ @ @ @ @ @ Ring of Brodgar , standing stones on Scotland 's Orkney Islands and Neolithic stone circles in Portugal and Spain .
`` Part of the work was to say , 'Look , this is a technique that is very do-able —– it is quite laborious , but it is very do-able if you want to explore it , ' '' Cox said .
The work on his scale model has also given Cox a greater appreciation of how much work went into building the original Stonehenge .
`` Laying them all out takes a @ @ @ @ @ @ @ he explained .
`` Can you imagine the full size of these things and moving them ?
It 's just incredible . ''

The small "bluestones" at Stonehenge were moved around by ancient people over the centuries. But the changes didn't make much difference to the sound, which was dominated by the outer circle of large upright "sarsens."
The huge standing stones in the outer circle of Stonehenge acted as an amplifier and gave reverberation to enhance speech and music in ceremonies held thousands of years before modern acoustics emerged, according to new research.
The dramatic sound effects — including the repeating echo of reverberation — would have been unfamiliar to most of the people who gathered there, the researchers said, although a few might have experienced similar effects inside caves and in canyons.
The findings help explain part of a long-standing mystery of archaeology — what effect did ancient sites and buildings, such as stone circles, burial chambers and ancient temples, have on sounds?
In the case of Stonehenge, which was first built around 5,000 years ago on Salisbury Plain in southwestern England, "the amplification could have aided speech communication, and the reverberation improved musical sounds," wrote the researchers in a study published in the October issue of the Journal of Archaeological Science .
Related: In photos: A walk through Stonehenge
Their research is based on detailed examinations of a geometrically-accurate scale model one-twelfth the size of Stonehenge, as it probably looked and sounded during its prime, about 4,200 years ago.
By a curious coincidence, the model is exactly the same size as the miniature Stonehenge arch that appeared on stage in the 1984 movie "This Is Spinal Tap." Film buffs may recall that it came about after a confused member of the eponymous rock band specified the stones should be 18 inches (45 centimeters) tall, instead of 18 feet (5.5 meters), which is about the height of one of the real Stonehenge arches.
Lead researcher Trevor Cox, a professor of acoustic engineering at the University of Salford near Manchester in England, gets "Spinal Tap" jokes whenever his research is mentioned. "It comes up every time," he said.
Stonehenge reached its prime about 4,200 years ago. But what would it have sounded like to stand inside the stone circle? (Image credit: Shutterstock)
Standing stones
To make the model, Cox and his colleagues spent several months pouring plaster mixed with plastic into 3D-printed molds, to sculpt a total of 157 stones — about twice as many as remain today.
Based on laser scans of Stonehenge provided by the English Heritage Trust, which manages the historic site, the model includes the central "horseshoe" of the five largest stone arches and dozens of the smaller "bluestones" that in real life were likely dragged from ancient quarries in Wales , more than 140 miles (225 km) away.
Crucially, the model monument also includes a complete outer circle of 30 upright sandstones and their lintels, called "sarsens" — from "Saracens," a medieval English name for Arab Muslims that came to be used for anything thought to be pagan. Only 17 sarsen uprights and seven lintels remain intact in the outer circle today, and recent research suggests they were probably quarried nearby .
Related: 5 strange theories about Stonehenge
Cox emphasized the importance of creating an accurate representation of Stonehenge as it looked about 2200 B.C. so his team could learn how it sounded at that time.
They measured the sound levels at multiple locations around the model monument, both within the outer stone circle and outside it, using very high frequency sounds to compensate for its miniature scale — 12 times the frequency for structures one-twelfth of their normal size.
(Image credit: Andrew Brooks/University of Salford)
Such techniques have been applied since the 1930s to scale models of concert halls and opera houses, but they've never been used before on a model of Stonehenge, Cox said.
Acoustic studies have been made of the modern ruin of Stonehenge, which has about half as many stones as it did 4,000 years ago, and also at a complete replica of Stonehenge built as a war memorial near the town of Maryhill in southern Washington.
But the original Neolithic circle of standing stones reflected sound waves very differently than the few that remain, Cox said, and the uprights in the replica at Maryhill are simple rectangular slabs of concrete that do not have the same acoustic properties as the original hand-carved sandstones and their copies in the new model.
Creating a model of Stonehenge as it looked and sounded more than 4,000 years ago took nine months. It was built to study how the acoustics of the ancient monument affected speech and music. (Image credit: Andrew Brooks/University of Salford)
Ancient acoustics
Their studies showed that speech made within the outer circle was amplified by the ring of standing stones by between 10% and 20%, or about 5 decibels, compared with speech in the open. They also found that the stones reverberated to mid-frequency sounds within the circle, with an average reverberation time of 0.64 seconds.
But they also found that speech or music made within the circle was much harder to hear outside it — and that suggests such activities at the center of Stonehenge were conducted for the benefit of a privileged few, rather than for a large congregation.
But while Stonehenge's effects of reverberation and amplification could be dramatic, Cox said that they did not seem to be the main reason that Stonehenge was built.
Related: Stonehenge: 7 reasons the mysterious monument was built
The amplification and reverberation provided by the stones was less than perfect, he said. Yet there's no archaeological evidence that the outer circle was ever changed from its original position. Meanwhile, there's evidence that ancient people often moved the bluestones to new locations within the circle. This wouldn't have changed the overall acoustics much, which are dominated by the outer circle, studies have found, according to Cox.
"There's no real evidence that there were big changes to the acoustics in a lot of these rearrangements," Cox said. "It doesn't look like sound was driving it." That suggests to him that the appearance of Stonehenge, rather than how it sounded, was the most important factor.
The technique could now be used in subterranean burial chambers, and Cox's team hopes to look next at the acoustics of the Ring of Brodgar, standing stones on Scotland's Orkney Islands and Neolithic stone circles in Portugal and Spain.
"Part of the work was to say, 'Look, this is a technique that is very do-able —– it is quite laborious, but it is very do-able if you want to explore it,'" Cox said.
The work on his scale model has also given Cox a greater appreciation of how much work went into building the original Stonehenge.
"Laying them all out takes a few hours at one-to-12 scale," he explained. "Can you imagine the full size of these things and moving them? It's just incredible."
Originally published on Live Science.


livescience--2020-09-03--Quantum internet breakthrough could help make hacking a thing of the past

The advent of mass working from home has made many people more aware of the security risks of sending sensitive information via the internet .
The best we can do at the moment is make it difficult to intercept and hack your messages — but we ca n't make it impossible .
What we need is a new type of internet : the .
In this version of the global network , data is secure , connections are private and your worries about information being intercepted are a thing of the past .
My colleagues and I have just made @ @ @ @ @ @ @ such a quantum internet possible by scaling up the concepts behind it using existing telecommunications infrastructure .
Our current way of protecting online data is to encrypt it using that are easy to solve if you have a digital `` key '' to unlock the encryption but hard to solve without it .
However , hard does not mean impossible and , with enough time and computer power , today 's methods of encryption can be broken .
Quantum communication , on the other hand , creates keys using individual particles of light @ @ @ @ @ @ @ to the principles of quantum physics — to make an exact copy of .
Any attempt to copy these keys will unavoidably cause errors that can be detected .
This means a hacker , no matter how clever or powerful they are or what kind of supercomputer they possess , can not replicate a quantum key or read the message it encrypts .
This concept has already been demonstrated and over , and used to send secure messages between .
So why are we not already using it in everyday life ?
The @ @ @ @ @ @ @ specialized technology that means it 's not currently scalable .
were like pairs of children 's walkie talkies .
You need one pair of handsets for every pair of users that want to securely communicate .
So if three children want to talk to each other they will need three pairs of handsets ( or six walkie talkies ) and each child must have two of them .
If eight children want to talk to each other they would need 56 walkie talkies .
Obviously it 's not practical for someone to have @ @ @ @ @ @ @ website they want to communicate with over the internet .
So we figured out a way to securely connect every user with just one device each , more similar to phones than walkie talkies .
Each walkie talkie handset acts as both a transmitter and a receiver in order to share the quantum keys that make communication secure .
In our model , users only need a receiver because they get the photons to generate their keys from a central transmitter .
This is possible because of another principle of quantum physics called @ @ @ @ @ @ @ n't be exactly copied but it can be entangled with another photon so that they both behave in the same way when measured , no matter how far apart they are — what Albert Einstein called `` spooky action at a distance '' .
When two users want to communicate , our transmitter sends them an entangled pair of photons — one particle for each user .
The users ' devices then perform a series of measurements on these photons to create a shared secret quantum key .
They can then encrypt their @ @ @ @ @ @ @ securely .
By using multiplexing , a common telecommunications technique of combining or splitting signals , we can effectively send these entangled photon pairs to multiple combinations of people at once .
We can also send many signals to each user in a way that they can all be simultaneously decoded .
In this way we 've effectively replaced pairs of walkie talkies with a system more similar to a video call with multiple participants , in which you can communicate with each user privately and independently as well as all at once @ @ @ @ @ @ @ concept by connecting eight users across a single city .
We are now working to improve the speed of our network and interconnect several such networks .
Collaborators have already started using our quantum network as a test bed for several exciting applications beyond just quantum communication .
We also hope to develop even better quantum networks based on this technology with commercial partners in the next few years .
With innovations like this , I hope to witness the beginning of the quantum internet in the next ten years .
This article @ @ @ @ @ @ @ The publication contributed the article to Live Science 's Expert Voices : Op-Ed & Insights .

With a quantum internet, data is secure, connections are private and your worries about information being intercepted are a thing of the past.
The advent of mass working from home has made many people more aware of the security risks of sending sensitive information via the internet. The best we can do at the moment is make it difficult to intercept and hack your messages — but we can't make it impossible.
What we need is a new type of internet: the quantum internet . In this version of the global network, data is secure, connections are private and your worries about information being intercepted are a thing of the past.
My colleagues and I have just made a breakthrough, published in Science Advances , that will make such a quantum internet possible by scaling up the concepts behind it using existing telecommunications infrastructure.
Our current way of protecting online data is to encrypt it using mathematical problems that are easy to solve if you have a digital "key" to unlock the encryption but hard to solve without it. However, hard does not mean impossible and, with enough time and computer power, today's methods of encryption can be broken.
Quantum communication, on the other hand, creates keys using individual particles of light (photons) , which — according to the principles of quantum physics — are impossible to make an exact copy of. Any attempt to copy these keys will unavoidably cause errors that can be detected. This means a hacker, no matter how clever or powerful they are or what kind of supercomputer they possess, cannot replicate a quantum key or read the message it encrypts.
This concept has already been demonstrated in satellites and over fiber-optic cables , and used to send secure messages between different countries . So why are we not already using it in everyday life? The problem is that it requires expensive, specialized technology that means it's not currently scalable.
Previous quantum communication techniques were like pairs of children's walkie talkies. You need one pair of handsets for every pair of users that want to securely communicate. So if three children want to talk to each other they will need three pairs of handsets (or six walkie talkies) and each child must have two of them. If eight children want to talk to each other they would need 56 walkie talkies.
Obviously it's not practical for someone to have a separate device for every person or website they want to communicate with over the internet. So we figured out a way to securely connect every user with just one device each, more similar to phones than walkie talkies.
Each walkie talkie handset acts as both a transmitter and a receiver in order to share the quantum keys that make communication secure. In our model, users only need a receiver because they get the photons to generate their keys from a central transmitter.
This is possible because of another principle of quantum physics called "entanglement". A photon can't be exactly copied but it can be entangled with another photon so that they both behave in the same way when measured, no matter how far apart they are — what Albert Einstein called "spooky action at a distance".
Full network
When two users want to communicate, our transmitter sends them an entangled pair of photons — one particle for each user. The users' devices then perform a series of measurements on these photons to create a shared secret quantum key. They can then encrypt their messages with this key and transfer them securely.
By using multiplexing, a common telecommunications technique of combining or splitting signals, we can effectively send these entangled photon pairs to multiple combinations of people at once.
We can also send many signals to each user in a way that they can all be simultaneously decoded. In this way we've effectively replaced pairs of walkie talkies with a system more similar to a video call with multiple participants, in which you can communicate with each user privately and independently as well as all at once.
We've so far tested this concept by connecting eight users across a single city. We are now working to improve the speed of our network and interconnect several such networks. Collaborators have already started using our quantum network as a test bed for several exciting applications beyond just quantum communication.
We also hope to develop even better quantum networks based on this technology with commercial partners in the next few years. With innovations like this, I hope to witness the beginning of the quantum internet in the next ten years.
This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.


livescience--2020-09-03--For koalas with chlamydia, relief is finally in sight

A serious bacterial infection called is one of the leading causes of death for Australia 's .
But new research has identified an antibiotic that can manage the infection with few side effects , offering a ray of hope for these adorable , endangered marsupials .
Chlamydia , a sexually transmitted disease ( STD ) caused by the bacteria Chlamydia trachomatis , affects humans as well as koalas ; left untreated , it can cause infertility and permanent blindness in both species .
that treat chlamydia in humans also work for koalas , but their success rate varies .
And @ @ @ @ @ @ @ that can be harmful to the iconic animals , such as disrupting the gut microbes that enable digestion of eucalyptus leaves , a dietary staple for koalas .
Recently , researchers conducted the first comparative analysis of the two antibiotics that are most commonly given to koalas with chlamydia : chloramphenicol and doxycycline .
They found that not only was doxycycline a more reliable treatment for defeating infection , it also produced fewer side effects in the koalas , .
Koalas in the wild are exposed to chlamydia through sexual contact , and @ @ @ @ @ @ @ mothers .
It 's unclear exactly why koalas are so vulnerable to this disease , but their susceptibility may be linked to a virus in the same family as the human immunodeficiency virus ( HIV ) , .
Leading the new investigation was Elliot Grossman , a graduate student in the Cummings Veterinary School at Tufts University in Massachusetts .
He collaborated with veterinarian Rosie Booth , director of Australia Zoo Wildlife Hospital in Beerwah , Australia ; every year , the facility treats about 300 to 500 koalas , about 40 % @ @ @ @ @ @ @ according to the statement .
`` The wildlife hospital veterinarians had a pretty strong suspicion that chloramphenicol was causing more side effects and had potentially worse survival rates than doxycycline , '' Grossman said in the statement .
`` But there was no published research comparing the two treatments . ''
Together with Adam South , a Cummings School research assistant professor , Grossman reviewed and analyzed 311 cases of koalas with chlamydia , noting how the animals responded to the drugs they were given .
When koalas received chloramphenicol , they were @ @ @ @ @ @ @ '' — when a first course of antibiotics fails to quell the infection .
These animals were also more prone to develop , yeast infections , , dehydration and bone-marrow dysfunction , Grossman said in the statement .
By comparison , koalas given doxycycline were more likely than the chloramphenicol group to have no harmful side effects .
The scientists are currently finalizing a manuscript describing their findings , a Tufts representative told Live Science in an email .
However , the researchers ' data is already making a difference for sick koalas @ @ @ @ @ @ @ have benefited from the research that has indicated that doxycycline is currently a better antibiotic to treat koalas with chlamydiosis than the previously widely used chloramphenicol , '' Booth said in the statement .
previously received a media boost in 2018 from TV comedian John Oliver , after the Australia Zoo Wildlife Hospital announced the dedication of the John Oliver Koala Chlamydia Ward .
Oliver ( and the koalas ) might be pleased to know that thanks to this new discovery , more patients in the John Oliver ward can now look forward @ @ @ @ @

Of the 300 to 500 koalas that are brought to a rehabilitation center in eastern Australia each year, about 40% suffer from chlamydia.
A serious bacterial infection called chlamydia is one of the leading causes of death for Australia's koalas . But new research has identified an antibiotic that can manage the infection with few side effects, offering a ray of hope for these adorable, endangered marsupials.
Chlamydia, a sexually transmitted disease (STD), affects humans as well as koalas; the bacterium Chlamydia trachomatis targets humans, while koalas are sickened by Chlamydia pecorum. Left untreated, chlamydia can cause infertility and permanent blindness in both species. Antibiotics that treat chlamydia in humans also work for koalas, but their success rate varies. And some types of antibiotics produce side effects that can be harmful to the iconic animals, such as disrupting the gut microbes that enable digestion of eucalyptus leaves, a dietary staple for koalas.
Recently, researchers conducted the first comparative analysis of the two antibiotics that are most commonly given to koalas with chlamydia: chloramphenicol and doxycycline. They found that not only was doxycycline a more reliable treatment for defeating infection, it also produced fewer side effects in the koalas, according to a statement .
Related: Marsupial gallery: A pouchful of cute
Koalas in the wild are exposed to chlamydia through sexual contact, and newborns can contract the infection from their mothers. It's unclear exactly why koalas are so vulnerable to this disease, but their susceptibility may be linked to a virus in the same family as the human immunodeficiency virus (HIV), Live Science previously reported .
Leading the new investigation was Elliot Grossman, a graduate student in the Cummings Veterinary School at Tufts University in Massachusetts. He collaborated with veterinarian Rosie Booth, director of Australia Zoo Wildlife Hospital in Beerwah, Australia; every year, the facility treats about 300 to 500 koalas, about 40% of which are infected with chlamydia, according to the statement.
"The wildlife hospital veterinarians had a pretty strong suspicion that chloramphenicol was causing more side effects and had potentially worse survival rates than doxycycline," Grossman said in the statement. "But there was no published research comparing the two treatments."
Together with Adam South, a Cummings School research assistant professor, Grossman reviewed and analyzed 311 cases of koalas with chlamydia, noting how the animals responded to the drugs they were given. When koalas received chloramphenicol, they were more likely to experience "treatment failure" — when a first course of antibiotics fails to quell the infection.
These animals were also more prone to develop diarrhea , yeast infections, depression , dehydration and bone-marrow dysfunction, Grossman said in the statement. By comparison, koalas given doxycycline were more likely than the chloramphenicol group to have no harmful side effects.
The scientists are currently finalizing a manuscript describing their findings, a Tufts representative told Live Science in an email. However, the researchers' data is already making a difference for sick koalas.
"Hundreds of koalas throughout Australia have benefited from the research that has indicated that doxycycline is currently a better antibiotic to treat koalas with chlamydiosis than the previously widely used chloramphenicol," Booth said in the statement.
Chlamydia-afflicted koalas previously received a media boost in 2018 from TV comedian John Oliver, after the Australia Zoo Wildlife Hospital announced the dedication of the John Oliver Koala Chlamydia Ward. Oliver (and the koalas) might be pleased to know that thanks to this new discovery, more patients in the John Oliver ward can now look forward to a full recovery.
Editor's note: This article was updated on Sept. 3 to reflect that koalas and humans are infected by different species of chlamydia bacteria.
Originally published on Live Science.


livescience--2020-09-04--New quantum paradox throws the foundations of observed reality into question

If a tree falls in a forest and no one is there to hear it , does it make a sound ?
Perhaps not , some say .
And if someone is there to hear it ?
If you think that means it obviously did make a sound , you might need to revise that opinion .
We have found a new paradox in quantum mechanics — one of our two most fundamental scientific theories , together with Einstein 's theory of relativity — that throws doubt on some common-sense ideas about physical reality .
Take a look at these @ @ @ @ @ @ @ an event happening , it really happened .
• It is possible to make free choices , or at least , statistically random choices .
• A choice made in one place can ’ t instantly affect a distant event .
( Physicists call this “ locality ” . )
These are all intuitive ideas , and widely believed even by physicists .
But our research , , shows they can not all be true — or quantum mechanics itself must break down at some level .
This is the strongest result yet @ @ @ @ @ @ @ quantum mechanics that have upended our ideas about reality .
To understand why it 's so important , let 's look at this history .
Quantum mechanics works extremely well to describe the behavior of tiny objects , such as atoms or particles of light ( photons ) .
But that behavior is … very odd .
In many cases , quantum theory does n't give definite answers to questions such as `` where is this particle right now ? ''
Instead , it only provides probabilities for where the particle might be @ @ @ @ @ @ @ Niels Bohr , one of the founders of the theory a century ago , that 's not because we lack information , but because physical properties like `` position '' do n't actually exist until they are measured .
And what 's more , because some properties of a particle ca n't be perfectly observed simultaneously — such as position and velocity — they ca n't be real simultaneously .
No less a figure than Albert Einstein found this idea untenable .
In a with fellow theorists Boris Podolsky and Nathan Rosen , @ @ @ @ @ @ @ reality than what quantum mechanics could describe .
Read more : Einstein vs quantum mechanics ... and why he 'd be a convert today The article considered a pair of distant particles in a special state now known as an `` entangled '' state .
When the same property ( say , position or velocity ) is measured on both entangled particles , the result will be random — but there will be a correlation between the results from each particle .
For example , an observer measuring the position of the first @ @ @ @ @ @ @ measuring the position of the distant one , without even touching it .
Or the observer could choose to predict the velocity instead .
This had a natural explanation , they argued , if both properties existed before being measured , contrary to Bohr 's interpretation .
However , in 1964 Northern Irish physicist Einstein 's argument broke down if you carried out a more complicated combination of different measurements on the two particles .
Bell showed that if the two observers randomly and independently choose between measuring one or another property of @ @ @ @ @ @ @ , the average results can not be explained in any theory where both position and velocity were pre-existing local properties .
That sounds incredible , but experiments have now Bell 's correlations do occur .
For many physicists , this is evidence that Bohr was right : physical properties do n't exist until they are measured .
But that raises the crucial question : what is so special about a `` measurement '' ?
In 1961 , the Hungarian-American theoretical physicist devised a thought experiment to show what 's so tricky about the @ @ @ @ @ @ @ situation in which his friend goes into a tightly sealed lab and performs a measurement on a quantum particle — its position , say .
However , Wigner noticed that if he applied the equations of quantum mechanics to describe this situation from the outside , the result was quite different .
Instead of the friend 's measurement making the particle 's position real , from Wigner 's perspective the friend becomes entangled with the particle and infected with the uncertainty that surrounds it .
This is similar to , a thought experiment @ @ @ @ @ @ @ in a box becomes entangled with a random quantum event .
For Wigner , this was an absurd conclusion .
Instead , he believed that once the consciousness of an observer becomes involved , the entanglement would `` collapse '' to make the friend 's observation definite .
But what if Wigner was wrong ?
In our research , we built on an extended version of the Wigner 's friend paradox , by Časlav Brukner of the University of Vienna .
In this scenario , there are two physicists — call them Alice @ @ @ @ @ @ @ friends ( Charlie and Debbie ) in two distant labs .
There 's another twist : Charlie and Debbie are now measuring a pair of entangled particles , like in the Bell experiments .
As in Wigner 's argument , the equations of quantum mechanics tell us Charlie and Debbie should become entangled with their observed particles .
But because those particles were already entangled with each other , Charlie and Debbie themselves should become entangled — in theory .
But what does that imply experimentally ?
Our experiment goes like this : @ @ @ @ @ @ @ their particles .
Some time later , Alice and Bob each flip a coin .
If it 's heads , they open the door and ask their friend what they saw .
If it 's tails , they perform a different measurement .
This different measurement always gives a positive outcome for Alice if Charlie is entangled with his observed particle in the way calculated by Wigner .
Likewise for Bob and Debbie .
In any realisation of this measurement , however , any record of their friend 's observation inside the lab @ @ @ @ @ @ @ .
Charlie or Debbie will not remember having seen anything inside the lab , as if waking up from total anaesthesia .
But did it really happen , even if they do n't remember it ?
If the three intuitive ideas at the beginning of this article are correct , each friend saw a real and unique outcome for their measurement inside the lab , independent of whether or not Alice or Bob later decided to open their door .
Also , what Alice and Charlie see should not depend on how Bob @ @ @ @ @ @ @ versa .
We showed that if this were the case , there would be limits to the correlations Alice and Bob could expect to see between their results .
We also showed that quantum mechanics predicts Alice and Bob will see correlations that go beyond those limits .
Next , we did an experiment to confirm the quantum mechanical predictions using pairs of entangled photons .
The role of each friend 's measurement was played by one of two paths each photon may take in the setup , depending on a property of @ @ @ @ @ @ @ That is , the path `` measures '' the polarisation .
Our experiment is only really a proof of principle , since the `` friends '' are very small and simple .
But it opens the question whether the same results would hold with more complex observers .
We may never be able to do this experiment with real humans .
But we argue that it may one day be possible to create a conclusive demonstration if the `` friend '' is a human-level artificial intelligence running in a massive .
What does @ @ @ @ @ @ @ test may be decades away , if the quantum mechanical predictions continue to hold , this has strong implications for our understanding of reality — even more so than the Bell correlations .
For one , the correlations we discovered can not be explained just by saying that physical properties do n't exist until they are measured .
Now the absolute reality of measurement outcomes themselves is called into question .
Our results force physicists to deal with the measurement problem head on : either our experiment does n't scale up , and @ @ @ @ @ @ @ `` `` , or one of our three common-sense assumptions must be rejected .
Read more : The universe really is weird : a landmark quantum experiment has finally proved it so There are theories , like , that postulate `` action at a distance '' , in which actions can have instantaneous effects elsewhere in the universe .
However , this is in direct conflict with Einstein 's theory of relativity .
Some search for a theory that rejects freedom of choice , but they either require , or a seemingly conspiratorial @ @ @ @ @ @ @ to resolve the conflict could be to make Einstein 's theory even more relative .
For Einstein , different observers could disagree about when or where something happens — but what happens was an absolute fact .
However , in some interpretations , such as , , or the , events themselves may occur only relative to one or more observers .
A fallen tree observed by one may not be a fact for everyone else .
All of this does not imply that you can choose your own reality .
Firstly , @ @ @ @ @ @ @ , but the answers are given by the world .
And even in a relational world , when two observers communicate , their realities are entangled .
In this way a shared reality can emerge .
Which means that if we both witness the same tree falling and you say you ca n't hear it , you might just need a hearing aid .
This article was originally published at The Conversation .
The publication contributed the article to Live Science 's Expert Voices : Op-Ed & Insights .

If a tree falls in a forest and no one is there to hear it, does it make a sound? Perhaps not, some say.
And if someone is there to hear it? If you think that means it obviously did make a sound, you might need to revise that opinion.
We have found a new paradox in quantum mechanics — one of our two most fundamental scientific theories, together with Einstein's theory of relativity — that throws doubt on some common-sense ideas about physical reality.
Quantum mechanics vs. common sense
Take a look at these three statements:
When someone observes an event happening, it really happened.
It is possible to make free choices, or at least, statistically random choices.
A choice made in one place can’t instantly affect a distant event. (Physicists call this “locality”.)
These are all intuitive ideas, and widely believed even by physicists. But our research, published in Nature Physics , shows they cannot all be true — or quantum mechanics itself must break down at some level.
This is the strongest result yet in a long series of discoveries in quantum mechanics that have upended our ideas about reality. To understand why it's so important, let's look at this history.
The battle for reality
Quantum mechanics works extremely well to describe the behavior of tiny objects, such as atoms or particles of light (photons). But that behavior is … very odd.
In many cases, quantum theory doesn't give definite answers to questions such as "where is this particle right now?" Instead, it only provides probabilities for where the particle might be found when it is observed.
For Niels Bohr, one of the founders of the theory a century ago, that's not because we lack information, but because physical properties like "position" don't actually exist until they are measured.
And what's more, because some properties of a particle can't be perfectly observed simultaneously — such as position and velocity — they can't be real simultaneously.
No less a figure than Albert Einstein found this idea untenable. In a 1935 article with fellow theorists Boris Podolsky and Nathan Rosen, he argued there must be more to reality than what quantum mechanics could describe.
Read more: Einstein vs quantum mechanics ... and why he'd be a convert today
The article considered a pair of distant particles in a special state now known as an "entangled" state. When the same property (say, position or velocity) is measured on both entangled particles, the result will be random — but there will be a correlation between the results from each particle.
For example, an observer measuring the position of the first particle could perfectly predict the result of measuring the position of the distant one, without even touching it. Or the observer could choose to predict the velocity instead. This had a natural explanation, they argued, if both properties existed before being measured, contrary to Bohr's interpretation.
However, in 1964 Northern Irish physicist John Bell found Einstein's argument broke down if you carried out a more complicated combination of different measurements on the two particles.
Bell showed that if the two observers randomly and independently choose between measuring one or another property of their particles, like position or velocity, the average results cannot be explained in any theory where both position and velocity were pre-existing local properties.
That sounds incredible, but experiments have now conclusively demonstrated Bell's correlations do occur. For many physicists, this is evidence that Bohr was right: physical properties don't exist until they are measured.
But that raises the crucial question: what is so special about a "measurement"?
The observer, observed
In 1961, the Hungarian-American theoretical physicist Eugene Wigner devised a thought experiment to show what's so tricky about the idea of measurement.
He considered a situation in which his friend goes into a tightly sealed lab and performs a measurement on a quantum particle — its position, say.
However, Wigner noticed that if he applied the equations of quantum mechanics to describe this situation from the outside, the result was quite different. Instead of the friend's measurement making the particle's position real, from Wigner's perspective the friend becomes entangled with the particle and infected with the uncertainty that surrounds it.
This is similar to Schrödinger's famous cat , a thought experiment in which the fate of a cat in a box becomes entangled with a random quantum event.
Read more: Schrödinger's cat gets a reality check
For Wigner, this was an absurd conclusion. Instead, he believed that once the consciousness of an observer becomes involved, the entanglement would "collapse" to make the friend's observation definite.
But what if Wigner was wrong?
Our experiment
In our research, we built on an extended version of the Wigner's friend paradox, first proposed by Časlav Brukner of the University of Vienna. In this scenario, there are two physicists — call them Alice and Bob — each with their own friends (Charlie and Debbie) in two distant labs.
There's another twist: Charlie and Debbie are now measuring a pair of entangled particles, like in the Bell experiments.
As in Wigner's argument, the equations of quantum mechanics tell us Charlie and Debbie should become entangled with their observed particles. But because those particles were already entangled with each other, Charlie and Debbie themselves should become entangled — in theory.
But what does that imply experimentally?
Read more: Quantum physics: our study suggests objective reality doesn't exist
Our experiment goes like this: the friends enter their labs and measure their particles. Some time later, Alice and Bob each flip a coin. If it's heads, they open the door and ask their friend what they saw. If it's tails, they perform a different measurement.
This different measurement always gives a positive outcome for Alice if Charlie is entangled with his observed particle in the way calculated by Wigner. Likewise for Bob and Debbie.
In any realisation of this measurement, however, any record of their friend's observation inside the lab is blocked from reaching the external world. Charlie or Debbie will not remember having seen anything inside the lab, as if waking up from total anaesthesia.
But did it really happen, even if they don't remember it?
If the three intuitive ideas at the beginning of this article are correct, each friend saw a real and unique outcome for their measurement inside the lab, independent of whether or not Alice or Bob later decided to open their door. Also, what Alice and Charlie see should not depend on how Bob's distant coin lands, and vice versa.
We showed that if this were the case, there would be limits to the correlations Alice and Bob could expect to see between their results. We also showed that quantum mechanics predicts Alice and Bob will see correlations that go beyond those limits.
Next, we did an experiment to confirm the quantum mechanical predictions using pairs of entangled photons. The role of each friend's measurement was played by one of two paths each photon may take in the setup, depending on a property of the photon called "polarisation". That is, the path "measures" the polarisation.
Our experiment is only really a proof of principle, since the "friends" are very small and simple. But it opens the question whether the same results would hold with more complex observers.
We may never be able to do this experiment with real humans. But we argue that it may one day be possible to create a conclusive demonstration if the "friend" is a human-level artificial intelligence running in a massive quantum computer .
What does it all mean?
Although a conclusive test may be decades away, if the quantum mechanical predictions continue to hold, this has strong implications for our understanding of reality — even more so than the Bell correlations. For one, the correlations we discovered cannot be explained just by saying that physical properties don't exist until they are measured.
Now the absolute reality of measurement outcomes themselves is called into question.
Our results force physicists to deal with the measurement problem head on: either our experiment doesn't scale up, and quantum mechanics gives way to a so-called " objective collapse theory ", or one of our three common-sense assumptions must be rejected.
Read more: The universe really is weird: a landmark quantum experiment has finally proved it so
There are theories, like de Broglie-Bohm , that postulate "action at a distance", in which actions can have instantaneous effects elsewhere in the universe. However, this is in direct conflict with Einstein's theory of relativity.
Some search for a theory that rejects freedom of choice, but they either require backwards causality , or a seemingly conspiratorial form of fatalism called "superdeterminism" .
Another way to resolve the conflict could be to make Einstein's theory even more relative. For Einstein, different observers could disagree about when or where something happens — but what happens was an absolute fact.
However, in some interpretations, such as relational quantum mechanics , QBism , or the many-worlds interpretation , events themselves may occur only relative to one or more observers. A fallen tree observed by one may not be a fact for everyone else.
All of this does not imply that you can choose your own reality. Firstly, you can choose what questions you ask, but the answers are given by the world. And even in a relational world, when two observers communicate, their realities are entangled. In this way a shared reality can emerge.
Which means that if we both witness the same tree falling and you say you can't hear it, you might just need a hearing aid.
This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.


livescience--2020-09-03--The moon is rusty, and it’s likely Earth's fault

The moon is turning ever so slightly red , and it 's likely Earth 's fault .
Our planet 's atmosphere may be causing the moon to rust , new research finds .
Rust , also known as an iron oxide , is a reddish compound that forms when is exposed to water and oxygen .
Rust is the result of a common chemical reaction for nails , gates , the — and even Mars .
The Red Planet is nicknamed after its reddish hue that comes from the rust it acquired long ago when iron on its surface combined @ @ @ @ @ @ @ a statement from NASA 's Jet Propulsion Laboratory ( JPL ) in Pasadena , California .
But not all celestial environments are optimal for rusting , especially our dry , atmosphere-free moon .
`` It 's very puzzling , '' study lead author Shuai Li , an assistant researcher at the University of Hawaii at Mānoa 's Hawaii Institute of Geophysics and Planetology , said in the statement .
`` The Moon is a terrible environment for [ rust ] to form in . ''
Related : In photos : India 's Chandrayaan-2 @ @ @ @ @ @ @ data from the JPL Moon Mineralogy Mapper , which was onboard the Indian Space research Organization 's Chandrayaan-1 orbiter while it surveyed the moon in 2008 , when he realized that the poles of the moon had very different compositions than the rest of it .
During its mission , the Moon Mineralogy Mapper detected spectra , or reflected off various surfaces of the moon , to analyze its surface makeup .
When Li focused on the poles , he found that the moon 's polar surfaces had iron-rich rocks with spectral signatures @ @ @ @ @ @ @ mineral hematite , commonly found in surface , is a specific type of iron oxide , or rust , with the formula Fe2O3 .
`` At first , I totally did n't believe it .
It should n't exist based on the conditions present on the Moon , '' co-author Abigail Fraeman , a planetary geoscientist at JPL , said in the statement .
`` But since we discovered , people have been speculating that there could be a greater variety of minerals than we realize if that water had reacted with rocks @ @ @ @ @ @ @ red , it needs what 's called an oxidizer — a molecule such as oxygen that removes electrons from a material such as iron .
But the sun 's solar wind , a stream of charged particles that constantly hits the moon with , has the opposite effect .
Hydrogen is a reducer , or a molecule that donates electrons to other molecules .
Without protection from this solar wind , such as the that shields our planet from it , rust should not be able to form on the moon .
But @ @ @ @ @ @ @ be our own planet .
The moon does n't have an atmosphere of its own to provide sufficient amounts of , but it has trace amounts donated by Earth 's atmosphere , according to the statement .
This terrestrial oxygen travels to the moon along an elongated extension of the planet 's magnetic field called a `` magnetotail . ''
Earth 's magnetotail can reach all the way to the near side of the moon , where more of the hematite was found , according to the statement .
What 's more , @ @ @ @ @ @ @ blocks 99 % of solar wind from blasting the moon , drawing a temporary curtain over the lunar surface , allowing periods of time for rust to form .
But there 's still one extra ingredient that 's needed for rust to form : water .
The moon is mostly devoid of water , save for frozen water found in lunar craters on the moon 's far side — far from where most of the hematite was found .
But the researchers propose that fast-moving dust particles that bombard the moon might free @ @ @ @ @ @ @ surface layer , allowing the water to mix with the iron .
These dust particles might even be carrying water molecules themselves , and their impact might create heat that could increase the oxidation rate , the researchers said .
`` This discovery will reshape our knowledge about the Moon 's polar regions , '' Li said in a separate statement from the University of Hawaii .
`` Earth may have played an important role on the evolution of the Moon 's surface . ''
However , these are still hypotheses and more @ @ @ @ @ @ @ the moon is rusting .
Even more surprising , small amounts of hematite have been found on the far side of the moon , which should be too far for Earth 's oxygen to hitch a ride on the planet 's magnetotail , according to the statement .
The findings were published on Sept. 2 in the journal .

More of the rust was found on the near-side of the moon. The near-side of the moon is captured here by NASA's robotic Lunar Reconnaissance Orbiter spacecraft.
The moon is turning ever so slightly red, and it's likely Earth's fault. Our planet's atmosphere may be causing the moon to rust, new research finds.
Rust, also known as an iron oxide, is a reddish compound that forms when iron is exposed to water and oxygen. Rust is the result of a common chemical reaction for nails, gates, the Grand Canyon's red rocks — and even Mars. The Red Planet is nicknamed after its reddish hue that comes from the rust it acquired long ago when iron on its surface combined with oxygen and water, according to a statement from NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
But not all celestial environments are optimal for rusting, especially our dry, atmosphere-free moon.
"It's very puzzling," study lead author Shuai Li, an assistant researcher at the University of Hawaii at Mānoa's Hawaii Institute of Geophysics and Planetology, said in the statement. "The Moon is a terrible environment for [rust] to form in."
Related: In photos: India's Chandrayaan-2 mission to the moon
Li was studying data from the JPL Moon Mineralogy Mapper,which was onboard the Indian Space research Organization's Chandrayaan-1 orbiter while it surveyed the moon in 2008, when he realized that the poles of the moon had very different compositions than the rest of it.
This composite image of the moon, from the Moon Mineralogy Mapper, shows water ice on the poles. The researchers found hints of hematite when studying the spectra in those regions. (Image credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS)
During its mission, the Moon Mineralogy Mapper detected spectra, or wavelengths of light reflected off various surfaces of the moon, to analyze its surface makeup. When Li focused on the poles, he found that the moon's polar surfaces had iron-rich rocks with spectral signatures that matched that of hematite. The mineral hematite, commonly found in Earth's surface, is a specific type of iron oxide, or rust, with the formula Fe2O3.
"At first, I totally didn't believe it. It shouldn't exist based on the conditions present on the Moon," co-author Abigail Fraeman, a planetary geoscientist at JPL, said in the statement. "But since we discovered water on the Moon , people have been speculating that there could be a greater variety of minerals than we realize if that water had reacted with rocks."
This enhanced map visualizes the regions where the researchers found hints of hematite (those regions aren't actually colored red like this). (Image credit: Shuai Li)
What on Earth happened
For iron to turn rusty red, it needs what's called an oxidizer — a molecule such as oxygen that removes electrons from a material such as iron. But the sun's solar wind, a stream of charged particles that constantly hits the moon with hydrogen , has the opposite effect. Hydrogen is a reducer, or a molecule that donates electrons to other molecules. Without protection from this solar wind, such as the magnetic field that shields our planet from it, rust should not be able to form on the moon.
But it does, and the key might be our own planet.
The moon doesn't have an atmosphere of its own to provide sufficient amounts of oxygen , but it has trace amounts donated by Earth's atmosphere, according to the statement. This terrestrial oxygen travels to the moon along an elongated extension of the planet's magnetic field called a "magnetotail."
Earth's magnetotail can reach all the way to the near side of the moon, where more of the hematite was found, according to the statement. What's more, at every full moon, the magnetotail blocks 99% of solar wind from blasting the moon, drawing a temporary curtain over the lunar surface, allowing periods of time for rust to form. But there's still one extra ingredient that's needed for rust to form: water.
The moon is mostly devoid of water, save for frozen water found in lunar craters on the moon's far side — far from where most of the hematite was found. But the researchers propose that fast-moving dust particles that bombard the moon might free water molecules locked into the moon's surface layer, allowing the water to mix with the iron. These dust particles might even be carrying water molecules themselves, and their impact might create heat that could increase the oxidation rate, the researchers said.
A map showing the regions where hematite might be present on the moon (redder color indicates more hematite). (Image credit: Shuai Li)
"This discovery will reshape our knowledge about the Moon's polar regions," Li said in a separate statement from the University of Hawaii . "Earth may have played an important role on the evolution of the Moon's surface."
However, these are still hypotheses and more data is needed to understand exactly why the moon is rusting. Even more surprising, small amounts of hematite have been found on the far side of the moon, which should be too far for Earth's oxygen to hitch a ride on the planet's magnetotail, according to the statement.
The findings were published on Sept. 2 in the journal Science Advances .
Originally published on Live Science.