As the G7 summit and a key EU leaders' meeting draw near, a series of communication signals has emerged in China-EU economic relations, even as Brussels weighs tougher trade tools against China and some European politicians sharpen their rhetoric on the bloc's second largest trade partner.

The European Commission said on Thursday that contacts with Beijing "continue at various levels", while making clear that securing results from dialogue with the Chinese government remains its "priority", according to media outlet EFE, citing Olof Gill, deputy chief spokesperson of the commission.

Gill's remarks were made in response to a Financial Times (FT) report claiming that China had recently canceled two planned high-level diplomatic meetings with the EU in Beijing this month in protest against measures being considered by Brussels.

The same week, Chinese and German officials met in Berlin to discuss China-Germany and China-EU economic and trade relations, while Chinese Vice Premier Zhang Guoqing, addressing a France-hosted video summit, called for economic cooperation, inclusive growth and a free and open trade environment.

Analysts said the mixed signals show that dialogue is a practical need for both sides. If the EU wants results from engagement with China, they said, it should not allow new protectionist tools and negative political rhetoric to erode the trust needed for those results to emerge.

Channels remain open

In response to a question regarding the cancellations reported by FT, Chinese Foreign Ministry spokesperson Lin Jian told a press briefing on Thursday that "as we've learned, China and the EU are in communication on relevant dialogue."  

China's Vice Minister of Commerce Ling Ji, also the deputy China international trade representative, met with Ditte Juul Jorgensen, director-general of the Directorate-General for Trade and Economic Security of the European Commission on Tuesday. The two sides held in-depth and comprehensive discussions regarding the preparations for the establishment of a China-EU trade and investment consultation mechanism, according to a statement on China's Ministry of Commerce (MOFCOM) website on Wednesday.

The statement came after the Global Times learned from a source who is familiar with the situation, Ling is visiting the EU headquarters from June 9 to 14 to discuss with European officials the relevant arrangements for establishing the China-EU Trade and Investment Consultation Mechanism.

This move demonstrates China's willingness in implementing the consensus of China-EU leaders and properly handling differences and frictions through dialogue and consultation, according to the source, who declined to be named.

Ling also held talks in Berlin on Thursday with senior German officials on economic and trade issues, MOFCOM said on Friday. Ling said China has consistently advocated resolving differences through dialogue and consultation, and urged the German government to play a constructive role within the EU.

The German side said it opposes trade wars and supports China-EU dialogue and consultations to properly address each other's concerns and prevent an escalation of economic and trade frictions, while expressing willingness to strengthen communication with China on economic and trade policies.

Jian Junbo, director of the Center for China-Europe Relations at Fudan University's Institute of International Studies, told the Global Times on Friday that the recent communication signals are important because they show that both China and pragmatic voices in Europe still see dialogue as necessary, even as Brussels hardens its trade and economic-security approach toward China.

"The bloc faces internal divergence, declining industrial competitiveness and weakening growth momentum. Turning such anxieties into restrictive tools will not solve Europe's structural problems but could instead add uncertainty to China-EU cooperation," Jian said.

In an exclusive video interview with the Global Times on Thursday, Esko Aho, former Finnish prime minister and chairman of the board at the China Office of Finnish Industries, said Europe's challenges are linked to its capacity to create competitiveness and to invest in science, technology and innovation, while stressing that Europe also needs to create a better-functioning internal market, where weaknesses still remain.

Against the backdrop of Europe's internal challenges and growing global fragmentation, Aho said the EU and China share an interest in ensuring "a rules-based economic and political system," adding that challenges and risks also present opportunities.

Complexity remains

The recent pragmatic signals are unfolding at a difficult and complex moment for China-EU economic ties, as Europe ramps up pressure to impose trade restrictions, and weighs broader "economic security" tools seen as directly affecting China.

Reuters has reported that Brussels is weighing rules to cut reliance on single suppliers - notably in China - as part of a broader review of trade-defense tools.

German Chancellor Friedrich Merz said on Thursday that the EU must defend itself against unfair trade practices, signaling greater openness to recent European Commission proposals for a tougher approach to China, Politico reported. 

Without mentioning China specifically, Merz said EU leaders meeting next week in Brussels will discuss ways to better equip the bloc's trade "toolkit" as it looks to reset its trade relationship with China, according to Bloomberg.

Belgian Prime Minister Bart De Wever, described by news website Euractiv as being "at the forefront of the debate about China's impact on the European economy", has urged European leaders to develop a "serious strategy" against what he claimed was China's drive for economic domination, Euractiv reported on Tuesday.

Industry insiders warned that the EU's "economic security" toolbox targeting China is gradually moving from concept to implementation, with related policy frameworks taking shape at a faster pace, from supply-chain diversification to upgraded trade-defense measures.

Chinese authorities have repeatedly made clear their firm position on the EU's moves. After the European Commission's May 29 discussion on relations with China, MOFCOM said that "if the bloc insists on unilaterally introducing new trade tools and adopting discriminatory restrictions, China will firmly counteract them and take effective measures to safeguard its legitimate interests."

Aho said Europe has realized the need to avoid excessive dependence in critical areas, but the real challenge is where to draw the line between legitimate national interests and limits on global trade. "There are many areas where we can work together without feeling restricted," he added.

As generative artificial intelligence technology moves further into education, the annual gaokao season, China's college entrance examination period, which will kick off on Sunday, is also seeing new changes.

For some students and teachers, AI may have begun to move beyond the role of a simple answer-finding tool. In certain study scenarios, it can be used to help students review mistakes, understand knowledge points, polish essays or receive revision suggestions. But this may also raise new questions for schools during the exam preparation period.

On Friday, the Ministry of Public Security's cyber police bureau said in a WeChat post that police in Yichun, Jiangxi Province, had handled a case in which a suspect used videos of so-called "gaokao exam paper bags" to claim he had access to "leaked 2026 gaokao questions and answers." The suspect allegedly attempted to sell the fake papers for 2,000 yuan ($281) each, and the account was shut down, according to the post.

China's Ministry of Education issued a warning on June 2, reminding students and parents to be alert to false advertising such as "famous teacher predicted exam questions" and "AI predicted exam questions," the China News Agency reported.

At the same time, several AI platforms in China have announced or indicated corresponding adjustments during the gaokao period to prevent the technology from being used for exam cheating, media reports said.

The discussion around AI and the gaokao has just begun.

AI use on campus

In daily exam preparation and classroom tutoring, some teachers and students in China have already begun exploring how AI technology can be used in practice.

In Shanghai, where educational resources are highly developed, frontline teachers are beginning to test the practical boundaries of AI in language teaching, while also seeing its limitations.

Wu Xinyi, an English teacher at a high school in Shanghai, told the Global Times that AI can be used to revise essays.

"I think it is acceptable to use AI to polish an essay. You can input a specific prompt, and it can make the language sound more advanced. In fact, some teachers now also use AI to assist with essay grading," Wu told the Global Times.

"Sometimes, we deliberately compare essays written by AI tools with those written by students. You can see that it does have some very good, even impressive parts, but many parts appear rigid and formulaic," she said.

Compared with discussions in more developed regions over AI-generated text, compliance and depth of thinking, the application of such technology in less-resourced grassroots schools faces more basic thresholds.

Xiao, a teacher at a county-level high school in East China's Shandong Province, told the Global Times that AI has been included in some teaching-related tasks, and relevant departments have been actively advocating its use. But in actual grassroots teaching, implementation remains difficult.

A document Xiao showed the Global Times about an AI competition organized by local education authorities suggested that local schools are being encouraged to explore AI-related teaching practices.

"Every step is a hard threshold, from improving teachers' understanding and changing their mindset to upgrading the school's overall hardware facilities, especially for rural county-level schools with limited resources like ours," Xiao said.

Meanwhile, overreliance on AI in relation to gaokao has also drawn warnings.

China's Ministry of Education issued a warning on June 2 for the 2026 gaokao, reminding students and parents to be alert to false advertising such as "famous teacher predicted exam questions" and "AI predicted exam questions," to take the exam with integrity and strictly observe legal boundaries, the Xinhua News Agency reported.

The ministry said gaokao questions have continued to undergo reform in recent years, with directions and exam content constantly changing and innovating. Relying on AI or "experts" to predict questions in order to obtain high scores is unrealistic, the ministry said.

Fairness in the exam room
As AI is increasingly used in daily learning, how to prevent it from being used to cheat in a gaokao exam has become a matter of public concern.

Sichuan-based Red Star News recently reached out to several AI platforms in China. For instance, Doubao customer service said that Doubao could be used normally during the gaokao period, but photo-based question answering and similar functions would be unavailable, with specific arrangements subject to the actual page display during the exam.

A Tencent staff member said that, during last year's gaokao, Tencent's Yuanbao had made clear that it would not answer exam-related questions. An iFlytek staff member also said there was no definite information yet, but that large models would likely have their limits. Baidu's relevant business department said it had not yet received notice of restrictions on some Wenxin functions during the gaokao period, the report said.

According to a report by Xiaoxiang Morning Herald based in Central China's Hunan Province, in 2025, some users posted online that Tencent Yuanbao could not be used normally during the gaokao period.

After users sent image-recognition summary requests, Yuanbao replied that "this function is unavailable during gaokao hours." Other common AI tools such as Kimi, DeepSeek and Doubao also had related arrangements during the gaokao period.

The Ministry of Education reminded candidates that bringing a mobile phone, smart watch or bracelet, smart glasses and any other banned device into an exam room constitutes cheating, even if the device is switched off.

In April, the "AI + Education" action plan was issued by the Ministry of Education and other government departments, requiring in particular that AI applications be safe, trustworthy and controllable, the Beijing Youth Daily reported.

The report quoted Xie Yongjiang, director of the Institute of Internet Governance and Law at Beijing University of Posts and Telecommunications, as saying, "If there is even the smallest loophole in the organization of the exam, AI tools could magnify it infinitely and cause incalculable negative consequences. Restricting AI answering functions is meant to block the possibility of AI-assisted exam-taking and ensure absolute fairness in the exam."

From the perspective of international comparison and academic ethics, Estelle Qiu, a young scholar based in Australia, said AI is challenging intellectual property and human thinking while offering convenience.

Qiu told the Global Times that at the Australian university where she works, undergraduate students are allowed to use AI. In principle, the school allows them to first complete their own writing and then use AI for polishing, but students must clearly declare such use.

"However, there are two major pain points in AI use. First, it may undermine confidentiality to some extent. Second, when it comes to deeper academic papers, AI still cannot really get how the human mind works," she said.

The Beijing News said in a recent commentary that AI is evolving rapidly, with computing power and algorithms constantly improving and technological dividends being released. "But the faster it develops, the more necessary it is to respect rules and uphold bottom lines," the commentary said.

A viral stress-relief toy known as "Natasha" has sparked widespread controversy in China after videos showing users smashing, stomping on, piercing and otherwise "abusing" the baby-shaped toy spread across social media platforms.

According to the China Youth Daily, a growing number of primary and secondary schools across the country have issued notices banning the toy from campuses. As of Saturday, several major e-commerce platforms had removed promotional videos that marketed the product with violent content. However, some sellers were still using images of clenched fists and violence-oriented slogans to advertise the toy.

Sun Hongyan, a researcher at the China Youth & Children Research Center, a national institution specializing in youth and adolescent work research, warned that based on observational learning theory, children and adolescents could internalize behaviors by observing and imitating others. Violent ways of playing with the toy may be perceived by youth as entertaining and could normalize aggressive behaviors among young people, Sun said.

Sun noted that the toy's baby-like appearance amplifies its potential negative impact. Baby dolls symbolize vulnerable lives that deserve care and protection. As minors are still developing moral judgment, marketing messages such as "the harder you throw it, the more stress you relieve," combined with social media algorithms rewarding increasingly extreme content, may lead some young people to believe that bullying the weak is acceptable, gradually blurring their moral boundaries, according to Sun.

Yu Xukun, Executive Director of Beijing Children's Legal Aid and Research Center, also cautioned that repeated exposure to simulated violence in interaction with such toys could become psychological preparation for real-world aggression under certain circumstances.

"In cases we have handled, some children who suffered domestic violence came to believe that violence could solve problems and later directed such violence toward others, eventually facing legal consequences," Yu said.

Fang Zengquan, professor at School of Journalism and Communication at Beijing Normal University and director of the Center for Minors' Digital Literacy, criticized the marketing strategy behind the toy.

"Linking a baby-shaped toy directly to stress relief and promoting it with slogans such as 'Squeezing a baby is more stress-relieving than raising one' essentially turns the image of an infant into a gimmick," Fang said. "It encourages users, particularly adolescents, to derive pleasure from physically squeezing, pinching and deforming the toy, treating babies as objects for emotional release or entertainment."

Fang warned that repeatedly associating infant imagery with destructive behavior could weaken young people's empathy and protective instincts toward real babies and, in extreme cases, foster unconscious aggressive impulses toward living beings.

On June 1, the China Consumers Association (CCA) stated that violent and sexually suggestive marketing videos related to the toy may violate the law. According to the association, some sellers have posed the toy in sexually suggestive positions and paired it with ambiguous captions or adult-themed props, while others have used violent treatment of the toy to attract traffic and attention.

The CCA said such practices use vulgarity and violence as marketing gimmicks, run counter to core socialist values, violate the principles of common moral code, and can breach laws and regulations including the Cybersecurity Law and the Advertising Law.

The CCA urged businesses, platforms, schools and families not to allow "stress relief" to become a cover for violence or permit internet traffic to reward vulgar content.

Stress-relief toys are fundamentally products for emotional and self-oriented consumption, the CCA said, adding that all parties should work together to foster healthy and sustainable emotional-consumption environments. Online platforms should fulfill their gatekeeping responsibilities by removing and banning content involving violence, pornography and other materials that violate public morality. Manufacturers and sellers should abide by laws and regulations, ensure their products are both entertaining and safe. Meanwhile, families and schools should help minors develop healthy ways to manage stress and identify harmful online content.

The waters slated for "delimitation" by Japan and the Philippines lie east of China's Taiwan island. Their proposed so-called "delimitation negotiations" gravely infringe on China's maritime rights and interests, run counter to international law and the basic norms governing international relations, and are entirely illegal, null and void, Zhu Fenglian, a spokesperson for the State Council Taiwan Affairs Office said on Wednesday. 

Zhu noted that compatriots across the Taiwan Straits belong to the Chinese nation. They must uphold their national stance, stand for the fundamental interests of the nation, and jointly safeguard China's sovereignty and territorial integrity as well as the overall interests of the Chinese nation. 

Should the DPP authorities collude with external forces to betray national interests, they will surely be spurned by compatriots on both sides of the Straits and punished by history, the spokesperson said. 

China’s Chang’e-4 lander and rover just became the first spacecraft to land on the farside of the moon.

The lander touched down at 9:26 p.m. Eastern time on January 2, according to an announcement from the China National Space Administration. The spacecraft is part of a series of Chinese space missions named Chang’e (pronounced CHONG-uh) for the Chinese goddess of the moon.

A small rover dubbed Yutu 2, or Jade Rabbit 2, rolled off the craft several hours after landing. The rover will explore the terrain around the 186-kilometer-wide Von Kármán crater located inside the 2,500-kilometer-wide South Pole–Aitken basin. The basin, one of the largest and oldest impact features in the solar system, could contain exposed parts of the moon’s interior that might reveal details of its formation and early history (SN: 11/24/18, p. 14).
Chang’e-4 will measure some of the region’s composition, use ground-penetrating radar to probe just below the surface, and take panoramic images of a landscape that has never been seen from the ground before. It will also make measurements of charged particles and radiation, which could help support future astronaut missions, and test whether plants and insects can grow together on the moon.
Because the moon always shows the same face to Earth, it is impossible to communicate directly with spacecraft on the farside. A relay satellite named Queqiao, or Magpie Bridge, that launched in May 2018 will beam signals between Chang’e-4 and Earth (SN Online: 5/20/18).
The landing marks China’s second lunar landing, and a step towards more ambitious moon missions. The Chinese space agency is planning another mission to collect moon rock samples later in 2019.

Marathoners queuing up for a big race tend to go with the flow, surging toward the start line like a fluid.

Using footage of runners moving in groups toward the start of the Chicago Marathon, researchers developed a theory that treats the crowd like a liquid to explain its movement. The theory correctly predicted the motion of crowds of runners at marathons in two other locations, physicists report in the Jan. 4 Science.

Previous studies have devised rules for how individuals act within a crowd and used that behavior to describe crowd motion (SN: 1/10/15, p. 15). But to understand how wine swirls in a glass, you don’t need to know the behavior of each molecule. So physicists Nicolas Bain and Denis Bartolo of École Normale Supérieure de Lyon in France considered the crowd as a whole.

At the start of a marathon, runners arrange themselves into groups known as corrals, which individually advance to the starting line. Marathon staff members form a line in front of each corral, periodically holding participants back until there’s space to move forward. The researchers filmed this start-and-stop process at four marathons, including the Chicago Marathon in 2016 and 2017. The movements of the staff set off a change in crowd density and speed that traveled through the throng akin to waves produced when water is pushed, the team found. Similar effects occurred at marathons in Paris and Atlanta in 2017.

Marathon crowds are a special type in that everyone travels in the same direction. Eventually, this type of research could lead to new insight into other crowd formations, including those packed more tightly than marathon crowds, with pedestrians literally shoulder to shoulder. Such crowds sometimes result in deadly stampedes, such as the 2015 event at the hajj in Mecca, Saudi Arabia (SN: 4/7/07, p. 213). Better understanding of these crowd dynamics could help prevent similar tragedies.

Treatments for pain and other common health problems often fall short, leading to untold misery and frustration. So it’s not hard to understand the lure of a treatment that promises to be benign, natural and good for just about everything that ails you. Enter cannabidiol, or CBD.

So far, the U.S. Food and Drug Administration has approved only one drug containing the chemical: a treatment for rare and severe forms of epilepsy. But that hasn’t stopped people from trying CBD to relieve arthritis, morning sickness, pain, depression, anxiety, addiction, inflammation and acne. And it hasn’t kept companies from marketing the heck out of CBD-infused anything. It’s the sort of situation that gets us wondering: What’s the science here?
The science is skimpy at best, neuroscience writer Laura Sanders reports in this issue. Clinical trials, some of which included children, were conducted to determine safety and efficacy before the FDA approved the first CBD-based epilepsy drug in 2018. But much less research has been done on CBD with regard to other ailments.

Adding to the intrigue, CBD can be extracted from marijuana, though CBD lacks the capacity to induce a buzzy high like its sister molecule THC. So government restrictions have been tight, and scientists have had a hard time getting access to CBD for studies. That makes it less likely that we’ll get clear answers anytime soon on whether CBD is indeed a panacea, or just another triumph of hype.

The surplus of unknowns hasn’t stopped companies from marketing hundreds of CBD products as treatments, attempting to avoid scrutiny by adding disclaimers that the products “are not intended to diagnose, treat or cure or prevent any disease.” But with such large gaps in the research, people trying these products in the hope of benefit become inadvertent guinea pigs.

The process of science may be frustratingly slow, but it can get the job done. In the last decade, clinical trials on vitamin D, for example, have found that despite much excitement surrounding the “sunshine vitamin,” there’s no definitive evidence of benefits in preventing heart disease or cancer. In our recent cover story “Vitamin D supplements aren’t living up to their hype,” contributing correspondent Laura Beil described the years of effort needed to develop that data (SN: 2/2/19, p. 16).
As journalists, we see a big part of our mission as making sure that people have access to accurate, timely information about medical research, so people can make informed decisions for themselves and their families. That’s especially important when it involves products that people can self-prescribe. These two articles — by skilled journalists who put weeks of effort into reading studies, talking with researchers and investigating the business side — are great examples of how sophisticated and useful consumer science journalism can be. Most people look for health information online, but Googling a term like “CBD oil” serves up a muddle of marketing masquerading as impartial information.

CBD may end up being a worthwhile treatment for some problems beyond epilepsy; it’s too early to know. But while we wait for the evidence, it’s essential to know where the science stands right now.

A drug that treats a rare form of cystic fibrosis may have even better results if given before birth, a study in ferrets suggests.

The drug, known by the generic name ivacaftor, can restore the function of a faulty version of the CFTR protein, called CFTRG551D. The normal CFTR protein controls the flow of charged atoms in cells that make mucus, sweat, saliva, tears and digestive enzymes. People who are missing the CFTR gene and its protein, or have two copies of a damaged version of the gene, develop the lung disease cystic fibrosis, as well as diabetes, digestive problems and male infertility.
Ivacaftor can reduce lung problems in patients with the G551D protein defect, with treatment usually starting when a patient is a year old. But if the results of the new animal study carry over to humans, an even earlier start date could prove more effective in preventing damage to multiple organs.

Researchers used ferret embryos with two copies of the G551D version of the CFTR gene. Giving the drug to mothers while the ferrets were in the womb and then continuing treatment of the babies after birth prevented male infertility, pancreas problems and lung disease in the baby ferrets, called kits, researchers report March 27 in Science Translational Medicine. The drug has to be used continuously to prevent organ damage — when the drug was discontinued, the kits’ pancreases began to fail and lung disease set in.

Cystic fibrosis affects about 30,000 people in the United States and 70,000 worldwide. But only up to 5 percent of patients have the G551D defect.

Other researchers are testing combinations of three drugs, including ivacaftor, aimed at helping the roughly 90 percent of cystic fibrosis patients afflicted by another genetic mutation that causes the CFTR protein to lack an amino acid (SN: 11/24/18, p. 11). Those drug combos, if proven effective, might also work better if administered early, cystic fibrosis researcher Thomas Ferkol of Washington University School of Medicine in St. Louis writes in a commentary published with the study.

Black holes are extremely camera shy. Supermassive black holes, ensconced in the centers of galaxies, make themselves visible by spewing bright jets of charged particles or by flinging away or ripping up nearby stars. Up close, these behemoths are surrounded by glowing accretion disks of infalling material. But because a black hole’s extreme gravity prevents light from escaping, the dark hearts of these cosmic heavy hitters remain entirely invisible.

Luckily, there’s a way to “see” a black hole without peering into the abyss itself. Telescopes can look instead for the silhouette of a black hole’s event horizon — the perimeter inside which nothing can be seen or escape — against its accretion disk. That’s what the Event Horizon Telescope, or EHT, did in April 2017, collecting data that has now yielded the first image of a supermassive black hole, the one inside the galaxy M87.

“There is nothing better than having an image,” says Harvard University astrophysicist Avi Loeb. Though scientists have collected plenty of indirect evidence for black holes over the last half century, “seeing is believing.”

Creating that first-ever portrait of a black hole was tricky, though. Black holes take up a minuscule sliver of sky and, from Earth, appear very faint. The project of imaging M87’s black hole required observatories across the globe working in tandem as one virtual Earth-sized radio dish with sharper vision than any single observatory could achieve on its own.
Putting the ‘solution’ in resolution
Weighing in around 6.5 billion times the mass of our sun, the supermassive black hole inside M87 is no small fry. But viewed from 55 million light-years away on Earth, the black hole is only about 42 microarcseconds across on the sky. That’s smaller than an orange on the moon would appear to someone on Earth. Still, besides the black hole at the center of our own galaxy, Sagittarius A* or Sgr A* — the EHT’s other imaging target — M87’s black hole is the largest black hole silhouette on the sky.
Only a telescope with unprecedented resolution could pick out something so tiny. (For comparison, the Hubble Space Telescope can distinguish objects only about as small as 50,000 microarcseconds.) A telescope’s resolution depends on its diameter: The bigger the dish, the clearer the view — and getting a crisp image of a supermassive black hole would require a planet-sized radio dish.
Even for radio astronomers, who are no strangers to building big dishes (SN Online: 9/29/17), “this seems a little too ambitious,” says Loeb, who was not involved in the black hole imaging project. “The trick is that you don’t cover the entire Earth with an observatory.”
Instead, a technique called very long baseline interferometry combines radio waves seen by many telescopes at once, so that the telescopes effectively work together like one giant dish. The diameter of that virtual dish is equal to the length of the longest distance, or baseline, between two telescopes in the network. For the EHT in 2017, that was the distance from the South Pole to Spain.

Telescopes, assemble!
The EHT was not always the hotshot array that it is today, though. In 2009, a network of just four observatories — in Arizona, California and Hawaii — got the first good look at the base of one of the plasma jets spewing from the center of M87’s black hole (SN: 11/3/12, p. 10). But the small telescope cohort didn’t yet have the magnifying power to reveal the black hole itself.

Over time, the EHT recruited new radio observatories. By 2017, there were eight observing stations in North America, Hawaii, Europe, South America and the South Pole. Among the newcomers was the Atacama Large Millimeter/submillimeter Array, or ALMA, located on a high plateau in northern Chile. With a combined dish area larger than an American football field, ALMA collects far more radio waves than other observatories.

“ALMA changed everything,” says Vincent Fish, an astronomer at MIT’s Haystack Observatory in Westford, Mass. “Anything that you were just barely struggling to detect before, you get really solid detections now.”
More than the sum of their parts
EHT observing campaigns are best run within about 10 days in late March or early April, when the weather at every observatory promises to be the most cooperative. Researchers’ biggest enemy is water in the atmosphere, like rain or snow, which can muddle with the millimeter-wavelength radio waves that the EHT’s telescopes are tuned to.

But planning for weather on several continents can be a logistical headache.

“Every morning, there’s a frenetic set of phone calls and analyses of weather data and telescope readiness, and then we make a go/no-go decision for the night’s observing,” says astronomer Geoffrey Bower of the Academia Sinica Institute of Astronomy and Astrophysics in Hilo, Hawaii. Early in the campaign, researches are picky about conditions. But toward the tail end of the run, they’ll take what they can get.

When the skies are clear enough to observe, researchers steer the telescopes at each EHT observatory toward the vicinity of a supermassive black hole and begin collecting radio waves. Since M87’s black hole and Sgr A* appear on the sky one at a time — each one about to rise just as the other sets — the EHT can switch back and forth between observing its two targets over the course of a single multi-day campaign. All eight observatories can track Sgr A*, but M87 is in the northern sky and beyond the South Pole station’s sight.

On their own, the data from each observing station look like nonsense. But taken together using the very long baseline interferometry technique, these data can reveal a black hole’s appearance.

Here’s how it works. Picture a pair of radio dishes aimed at a single target, in this case the ring-shaped silhouette of a black hole. The radio waves emanating from each bit of that ring must travel slightly different paths to reach each telescope. These radio waves can interfere with each other, sometimes reinforcing one another and sometimes canceling each other out. The interference pattern seen by each telescope depends on how the radio waves from different parts of the ring are interacting when they reach that telescope’s location.
For simple targets, such as individual stars, the radio wave patterns picked up by a single pair of telescopes provide enough information for researchers to work backward and figure out what distribution of light must have produced those data. But for a source with complex structure, like a black hole, there are too many possible solutions for what the image could be. Researchers need more data to work out how a black hole’s radio waves are interacting with each other, offering more clues about what the black hole looks like.

The ideal array has as many baselines of different lengths and orientations as possible. Telescope pairs that are farther apart can see finer details, because there’s a bigger difference between the pathways that radio waves take from the black hole to each telescope. The EHT includes telescope pairs with both north-south and east-west orientations, which change relative to the black hole as Earth rotates.

Pulling it all together
In order to braid together the observations from each observatory, researchers need to record times for their data with exquisite precision. For that, they use hydrogen maser atomic clocks, which lose about one second every 100 million years.

There are a lot of data to time stamp. “In our last experiment, we recorded data at a rate of 64 gigabits per second, which is about 1,000 times [faster than] your home internet connection,” Bower says.

These data are then transferred to MIT Haystack Observatory and the Max Planck Institute for Radio Astronomy in Bonn, Germany, for processing in a special kind of supercomputer called a correlator. But each telescope station amasses hundreds of terabytes of information during a single observing campaign — far too much to send over the internet. So the researchers use the next best option: snail mail. So far, there have been no major shipping mishaps, but Bower admits that mailing the disks is always a little nerve-wracking.

Though most of the EHT data reached Haystack and Max Planck within weeks of the 2017 observing campaign, there were no flights from South Pole until November. “We didn’t get the data back from the South Pole until mid-December,” says Fish, the MIT Haystack astronomer.

Filling in the blanks
Combining the EHT data still isn’t enough to render a vivid picture of a supermassive black hole. If M87’s black hole were a song, then imaging it using only the combined EHT data would be like listening to the piece played on a piano with a bunch of broken keys. The more working keys — or telescope baseline pairs — the easier it is to get the gist of the melody. “Even if you have some broken keys, if you’re playing all the rest of them correctly, you can figure out the tune, and that’s partly because we know what music sounds like,” Fish says. “The reason we can reconstruct images, even though we don’t have 100 percent of the information, is because we know what images look like” in general.
There are mathematical rules about how much randomness any given picture can contain, how bright it should be and how likely it is that neighboring pixels will look similar. Those basic guidelines can inform how software decides which potential images, or data interpretations, make the most sense.

Before the 2017 observing campaign, the EHT researchers held a series of imaging challenges to make sure their computer algorithms weren’t biased toward creating images to match expectations of what black holes should look like. One person would use a secret image to generate faux data of what telescopes would see if they were peering at that source. Then other researchers would try to reconstruct the original image.

“Sometimes the true image was not actually a black hole image,” Fish says, “so if your algorithm was trying to find a black hole shadow … you wouldn’t do well.” The practice runs helped the researchers refine the data processing techniques used to render the M87 image.

Black holes and beyond
So, the black hole inside M87 finally got its closeup. Now what?

The EHT’s black hole observations are expected to help answer questions like how some supermassive black holes, including M87’s, launch such bright plasma jets (SN Online: 3/29/19). Understanding how gas falls into and feeds black holes could also help solve the mystery of how some black holes grew so quickly in the early universe, Loeb says (SN Online: 3/16/18).

The EHT could also be used, Loeb suggests, to find pairs of supermassive black holes orbiting one another — similar to the two stellar mass black holes whose collision created gravitational waves detected in 2015 by the Advanced Laser Interferometer Gravitational-Wave Observatory, or Advanced LIGO (SN: 3/5/16, p. 6). Getting a census of these binaries may help researchers identify targets for the Laser Interferometer Space Antenna, or LISA, which will search from space for gravitational waves kicked up by the movement of objects like black holes (SN Online: 6/20/17).
The EHT doesn’t have many viable targets other than supermassive black holes, says astrophysicist Daniel Marrone, at the University of Arizona in Tucson. There are few other things in the universe that appear as tiny but luminous as the space surrounding a supermassive black hole. “You have to be able to get enough light out of the really tiny patches of sky that we can detect,” Marrone says. “In principle, we could be reading alien license plates or something,” but they’d need to be super bright.

Too bad for alien seekers. Still, even if the EHT is a one-trick pony, spying supermassive black holes is a pretty neat trick.

Ketamine banishes depression by slowly coaxing nerve cells to sprout new connections, a study of mice suggests. The finding, published in the April 12 Science, may help explain how the hallucinogenic anesthetic can ease some people’s severe depression.

The results are timely, coming on the heels of the U.S. Food and Drug Administration’s March 5 approval of a nasal spray containing a form of ketamine called esketamine for hard-to-treat depression (SN Online: 3/21/19). But lots of questions remain about the drug.
“There is still a lot of mystery in terms of how ketamine works in the brain,” says neuroscientist Alex Kwan of Yale University. The new study adds strong evidence that newly created nerve cell connections are involved in ketamine’s antidepressant effects, he says.

While typical antidepressants can take weeks to begin working, ketamine can make people feel better in hours. Scientists led by neuroscientist Conor Liston suspected that ketamine might quickly be remodeling the brain by spurring new nerve cell connections called synapses. “As it turned out, that wasn’t true, not in the way we expected, anyway,” says Liston, of Cornell University.

Newly created synapses aren’t involved in ketamine’s immediate effects on behavior, the researchers found. But the nerve cell connections do appear to help sustain the drug’s antidepressant benefits over the longer term.

To approximate depression in people, researchers studied mice that had been stressed for weeks, either by being restrained daily in mesh tubes, or by receiving injections of the stress hormone corticosterone. These mice began showing signs of despair, such as losing their taste for sweet water and giving up a struggle when dangled by their tails.
Three hours after a dose of ketamine, the mice’s behavior righted, as the researchers expected. But the team found no effects of the drug on nerve cells’ dendritic spines — tiny signal-receiving blebs that help make new neural connections. So the creation of new synapses couldn’t be responsible for ketamine’s immediate effects on behavior, “because the behavior came first,” Liston says.

When the researchers looked over a longer time span, though, they found that these new synapses were key. About 12 hours after ketamine treatment, new dendritic spines began to pop into existence on nerve cells in part of the mice’s prefrontal cortex, the brain area responsible for complex thinking. These dendritic spines seemed to be replacing those lost during the period of stress, often along the same stretch of neuron.

To test if these newly created spines were important for the mice’s improved behavior, the researchers destroyed the spines with a laser a day after the ketamine treatment. That effectively erased ketamine’s effects, and the mice again exhibited behavior resembling depression, including struggling less when held by their tails. (The mice kept their regained sugar preference.)

Research on humans has also suggested that depressed people have diminished synapses, says Ronald S. Duman, a neuroscientist at Yale University not involved in the study. The new work adds more support to those findings by showing that destroying new synapses can block ketamine’s behavioral effects. “That’s a huge contribution and advance,” Duman says.