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Tiny pendulum may reveal gravity’s secrets

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Gravity is, at heart, a mystery. Yes, we can talk about curvature of space-time and perhaps make analogies with stretched rubber sheets. But we don’t know why mass causes space-time to curve.

To put it another way, in our theory of gravity, matter is the scenery and space-time is both cast and stage crew. But matter’s behavior is described by quantum mechanics, which takes space and time as a given. For quantum mechanics, space and time are the stage in which matter puts on the best show ever. How do we get these two theories to put on just one play?

Perhaps this is why the two theories simply do not get on—no show can have two lead actors, right? We may finally get to find out thanks to a new experimental device that may make it possible for both gravity and quantum mechanics to play lead roles.

Uniting gravity and quantum mechanics

Physicists think that it must be possible to unite gravity and quantum mechanics: a common theory from which floweth the sweet sap of quantum mechanics and the slightly mind-bending nectar of general relativity. The problem is that theories are built on data, and we have very little data about how quantum mechanics is modified by gravity (or vice versa).

Observations of quantum mechanics and gravity being simultaneously important are difficult because of scale. When the forces that govern quantum mechanics are important, gravity is incredibly weak. At the other end of the scale, gravity dominates over very long distances, while quantum effects vanish entirely at these distances. It may be that the only the event horizon of a black hole provides a natural experiment where you might observe quantum mechanics working alongside gravity. Luckily, there aren’t any nearby black holes that allow us to make detailed observations.

The alternative is to create our own hardware where we can directly observe quantum behavior being modified by gravity. Apart from the technical difficulties, this also has a downside: the gravitational effects will be Newtonian in nature and probably subject to the vagaries of the Earth’s mass distribution. It will take some top-class modeling to show that any observed deviation from predictions is due to new physics. Nevertheless, researchers are building experiments that may at least provide data.

Shh, pendulums oscillating

How do we get that data? Essentially, we need a giant and massive object that also has observable effects on a quantum system. This is exactly what the researchers are on the way to creating. It’s a pendulum, but not just any pendulum.

An ordinary pendulum—a mass on a string—will quickly slow to a stop if not given an input of further energy. Even in a vacuum, the pendulum’s string will bend and flex, dissipating its momentum. Likewise, the connections between the string and the mass, and the string and the support frame, will also bend and flex. These imperfections don’t just absorb energy from the swinging motion, they also give it back, usually at the wrong time, shifting the pendulum’s swinging motion. The result is that the pendulum’s motion is not perfectly predictable. These imperfections can be incredibly small, but they’re enough to wash out the influence of quantum mechanics.

To make a nearly perfect pendulum, the researchers welded a small silicon disc (3mm in diameter) to a fine glass fiber, which was then welded to a large glass block. The fiber drawing process and the welds were the critical steps. By paying attention to how the fiber is drawn, the researchers were able to create a 5cm long, 1µm diameter fiber that was highly uniform. The welds (as opposed to glue or clamping) provide the sort of stiff attachment that does not flex very much. To give you an idea of just how good this pendulum is, once set in motion, it was still in motion 15 hours later without any additional energy. If it had been glued and clamped, that time would be just two to three hours.

Fire up the photon cannon

The pendulum itself is not a quantum object. But it’s operating at the interface where gravity and quantum mechanics can play together. The pendulum’s natural motion is given by the laws of gravity (Newtonian gravity, in this case). But the silicon disc is an excellent mirror: it can be pushed around by light.

The basic idea is that as the mirror swings, it will also bump into photons and reflect them. That reflection gives the mirror a kick. If the mirror is moving toward the incoming light, the kick will slow it down; if the mirror is moving away from the incoming light, the kick will speed it up. This is only observable for very clean mechanical oscillators, like the one that the researchers have built.

The quantum mechanics of these interactions are very well understood, and the measurements are very precise. The oscillator’s properties are given by gravity, so any deviations may be attributable to deviations from Newtonian gravity. As I said above, though, this is going to need some mighty good modeling of both quantum and gravitational aspects of the whole system.

In the next couple of years, the researchers will build up the optical setup to allow them to drive and measure the pendulum with high-precision lasers. After that, the real fun will begin, and we may get to see the rising photon meet the falling graviton.

Physical Review Letters, 2020, DOI: 10.1103/PhysRevLett.124.221102 (About DOIs)

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COVID was the leading cause of death in Americans aged 45-54 in 2021

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Enlarge / A woman watches white flags on the National Mall on September 18, 2021 in Washington, DC. Over 660,000 white flags were installed here to honor Americans who have lost their lives to COVID-19 epidemic.

COVID-19 was the third leading cause of death in Americans between March 2020 and October 2021, accounting for one in every eight deaths.

In that time frame, COVID-19 ranked in the top five causes of death for every age group of people older than 15 years. Between January and October 2021, the pandemic disease was the leading cause of death among people 45 to 54 years old.

That’s all according to a study of national death certificate data, published Tuesday in JAMA Internal Medicine by researchers at the National Institutes of Health.

The study found COVID-19 caused roughly 700,000 deaths between March 2020 and October 2021. The pandemic disease trailed only heart disease and cancer, which caused roughly 2.15 million collectively in that time frame. The fourth and fifth deadliest afflictions in the US were accidental deaths—including car crashes, overdoses, and alcohol-related deaths—and stroke, which collectively caused around 624,000 deaths during that period.

The authors, led by Meredith Shiels, an expert in cancer epidemiology and genetics at the National Cancer Institute, broke up the time frame into two sections: the start of the pandemic in March 2020 to December 2020, and January 2021 to October 2021, the last month for which there was complete data. This revealed age-specific trends, likely driven partly by uptake of vaccines and other mitigation efforts.

In the 2020 period, COVID-19 was the second leading cause of death in people aged 85 and over, but, amid high vaccine uptake in this age group, it fell to the third leading cause of death from January to October 2021.

Younger adults saw the opposite trend. For those aged 45 to 54, COVID-19 was the fourth leading cause of death in the 2020 period but jumped to the leading cause of death in 2021. Likewise, in those aged 35 to 44, COVID-19 jumped from the fifth leading cause of death in 2020 to the second leading cause in 2021. And for those aged 15 to 24 and 25 to 34, COVID-19 wasn’t in the top five in 2020, but ranked as the fourth leading cause of death in both age groups in 2021.

For those aged 55 to 84, COVID-19 was the third leading cause of death in both time periods.

The study is limited by the potential for misclassifying deaths on death certificates. But the authors were careful to select a time cutoff that would limit provisional or incomplete data from skewing the findings. That meant, however, that the study did not include deaths from part of the delta wave or the towering omicron wave in January 2022. Since October 2021, around 300,000 additional people in the US have died from COVID-19.

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Russian astronauts use space station to promote anti-Ukraine propaganda

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Enlarge / Cosmonauts Oleg Artemyev, Denis Matveyev, and Sergey Korsakov pose with a flag of the Luhansk People’s Republic on the International Space Station.

The Russian state space corporation responsible for spaceflight activities, Roscosmos, on Monday posted images to its official Telegram channel showing three cosmonauts with the tri-color flags of the Luhansk People’s Republic and the Donetsk People’s Republic.

The photos were taken recently on board the International Space Station and show smiling cosmonauts Oleg Artemyev, Denis Matveyev, and Sergey Korsakov posing with the flags.

“This is a long-awaited day that residents of the occupied areas of the Luhansk region have been waiting for eight years,” the Roscosmos message stated. “We are confident that July 3, 2022, will forever go down in the history of the republic.”

The images and social media posting represent the most blatant use of the International Space Station—which is operated by the United States, Russia, Japan, Canada, and the European Space Agency—for Russian propaganda purposes since the invasion of Ukraine.

Luhansk and Donetsk are two breakaway “quasi-states” in the eastern region of Ukraine known as the Donbas. Ukraine and Russia have battled over the two regions since 2014, as Russia has agitated separatists in the Ukrainian territory. The United Nations does not recognize the two “republics,” and Ukraine has designated them as “temporarily occupied territories.” Fighting has heated up since the Russian invasion of Ukraine in February 2022. This past weekend, Russian forces claimed to have established control over the entire Luhansk region.

A professional relationship

NASA and Roscosmos, as well as other space agencies, have continued cooperating on the International Space Station since the invasion began. Some US officials have suggested that NASA should consider breaking ties with Russia in space due to the atrocities in Ukraine. However, the space agency’s administrator has defended the partnership on the basis that the station flies above geopolitical tensions on Earth. NASA also wants to keep flying the station, as breaking the US segment from the Russian segment would be difficult and potentially fatal to the operation of the orbital facility.

In an interview published Monday in the German publication Der Spiegel, NASA Administrator Bill Nelson reiterated this stance.

“In the midst of the Cold War, when the Soviet Union and the United States were mortal enemies and their nuclear weapons could be used at any time, a US and a Soviet spacecraft met in space in 1975,” Nelson said. “Peaceful cooperation continued even after the collapse of the Soviet Union. Our space shuttle docked with the Russian space station Mir. And then we decided to build the International Space Station together. Both countries are needed for operations, the Russians for propulsion, the Americans for power. We will continue to have a very professional relationship between cosmonauts and astronauts to keep this station alive.”

Nevertheless the provocative actions this weekend by Roscosmos, with its cosmonauts celebrating the so-called liberation of Ukrainian territory, brings the bloody conflict on Earth into space. To some observers, such as former NASA astronaut Terry Virts, Russia’s use of the space station for propaganda purposes is unacceptable.

“I am incredibly disappointed to see cosmonauts and Roscosmos using the International Space Station as a platform to promote their illegal and immoral war, where civilians are being killed every day,” said Virts, who flew side by side with Russians and commanded the space station in 2015. “The space station is supposed to be a symbol of peace and cooperation.”

Virts said NASA has largely been trying to look the other way when it comes to Russian actions, most notably when it comes to Roscosmos chief Dmitry Rogozin, who has made numerous jingoistic statements about the war. But in this case, he said, the agency really cannot afford to.

Seat swap

NASA’s cooperation with Russia may come into greater public focus in a couple of months. At present, a NASA astronaut named Frank Rubio is scheduled to fly on a Russian Soyuz spacecraft to the station in September. Around the same time, a Russian cosmonaut named Anna Kikina is due to fly on a SpaceX Crew Dragon vehicle to the station as part of the seat swap. The arrangement has not been formally agreed to by the US and Russian government.

In his German interview, Nelson defended the swap, saying, “It makes a lot of sense for us. You need both Russians and Americans to operate the space station. What happens if something is wrong with one of our spacecraft? We need the other vehicle as a back-up. And that’s why we will continue to have crew exchanges.”

Such an argument may soon ring hollow, however. Boeing’s Starliner spacecraft may make its first crewed test flight before the end of this year, and if it is successful NASA will have two US spacecraft capable of reaching the station.

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How the Yurok Tribe is bringing back the California Condor

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Enlarge / The California condor is a New World vulture, the largest North American land bird. This condor became extinct in the wild in 1987, but the species has been reintroduced in California and Arizona.

The first California condor to reach Yurok ancestral land in over a century arrived by plane and car in late March of 2022. The small plane that carried Condor 746 had a rough landing, and the bird was irritable. He rattled around in a large dog crate during the three-hour drive to the tribe’s newly built condor facility, in a remote location in Redwood National Park.

Once there, he hopped into the flight pen, a tall enclosure of wire mesh, furnished with log perches and a drinking pool. At 8 years old, Condor 746 is an adult, his naked head bright pink instead of the black found in younger birds. He’s on loan from the captive breeding program at the Peregrine Fund’s World Center for Birds of Prey in Boise, Idaho. His job is to act as the mentor for four juvenile birds who will become the founders of a reborn condor society in Yurok country.

“We have mentors because condors are so social,” says Joe Burnett, California Condor Recovery Program Manager at the Ventana Wildlife Society. Young birds in a pen with no adult will become unruly. “You get the Lord of the Flies syndrome,” says Burnett. He and his colleagues quickly learned that release programs need an adult to serve as a role model and enforce the social hierarchy that is crucial to the flock’s survival.

A few days after 746 arrived, Condor A0, age 2, entered the flight pen. The first thing she focused on was 746, lounging on a perch. Understanding that she was in a safe place, A0 checked out the food—the carcass of a stillborn calf—then flapped onto a perch and fluffed up her feathers, a sign of avian contentment. Three young male condors, tagged A1, A2, and A3, followed. The youngsters had been living together for months at other condor facilities in Boise, Idaho, and San Simeon, California, and they already felt at home with each other.

Condor, known as prey-go-neesh in the native language, is sacred to the Yurok people. The Yurok reservation lies along the Klamath River in northwest California, but much of the tribe’s ancestral land is now in the hands of government agencies or private landowners. The tribe has been working to bring back the California condor since 2003, when a group of elders identified the bird as a keystone species for both culture and ecology, and therefore the most important land-based creature in need of restoration.

Nineteen years after the Yurok made that bold decision, the condors arrived. Elders who had worked toward that pivotal moment watched as Tiana Williams-Claussen, director of the Yurok Wildlife Department, and her colleagues released each newcomer into the pen.

Williams-Claussen’s job is to understand the details of condor biology and to interpret Yurok culture for the wider world. A tribal member, she grew up on the coast near the mouth of the Klamath, and went off to Harvard University. She didn’t set out to be a condor biologist, but when she returned in 2007 with a degree in biochemical sciences, condor restoration was the work her people needed her to do. Williams-Claussen has since spent 14 years living and breathing condors, learning how to handle them, building partnerships with government agencies, and listening to what Yurok elders have to say about the great bird.

The California condor is a critically endangered species: In the 1980s, the total population dwindled to fewer than 30 individuals. Biologists concluded the species’ only chance of survival lay in capturing every living condor in order to breed the birds in captivity, safe from poisons and power lines.

Reintroducing condors to the wild proved difficult, however, and the process became a dramatic lesson for biologists on the importance of parenting and the slow pace of growing up among these long-lived, highly social birds. Scientists learned that time spent with adults was critical to the behavioral development of young condors. They also found that in a species where adults follow and protect their offspring for a year or more after the birds fledge, youngsters pioneering landscapes empty of condors require lots of human babysitting.

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