Einstein’s general relativity theory is questioned but still stands ‘for now,’ team reports

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Photo of artist rendering of SO-2 star.

A star known as S0-2 (the blue and green object in this artist’s rendering) made its closest approach to the supermassive black hole at the center of the Milky Way in 2018. Artist’s rendering by Nicolle Fuller/National Science Foundation.

More than 100 years after Albert Einstein published his iconic theory of general relativity, it is beginning to fray at the edges, said Andrea Ghez, UCLA professor of physics and astronomy. Now, in the most comprehensive test of general relativity near the monstrous black hole at the center of our galaxy, Ghez and her research team report July 25 in the journal Science that Einstein’s theory of general relativity holds up.

“Einstein’s right, at least for now,” said Ghez, a co-lead author of the research. “We can absolutely rule out Newton’s law of gravity. Our observations are consistent with Einstein’s theory of general relativity. However, his theory is definitely showing vulnerability. It cannot fully explain gravity inside a black hole, and at some point we will need to move beyond Einstein’s theory to a more comprehensive theory of gravity that explains what a black hole is.”

Einstein’s 1915 theory of general relativity holds that what we perceive as the force of gravity arises from the curvature of space and time. The scientist proposed that objects such as the sun and the Earth change this geometry. Einstein’s theory is the best description of how gravity works, said Ghez, whose UCLA-led team of astronomers has made direct measurements of the phenomenon near a supermassive black hole — research Ghez describes as “extreme astrophysics.”

The laws of physics, including gravity, should be valid everywhere in the universe, said Ghez, who added that her research team is one of only two groups in the world to watch a star known as S0-2 make a complete orbit in three dimensions around the supermassive black hole at the center of the Milky Way. The full orbit takes 16 years, and the black hole’s mass is about 4 million times that of the sun.

The researchers say their work is the most detailed study ever conducted into the supermassive black hole and Einstein’s theory of general relativity.

The key data in the research were spectra that Ghez’s team analyzed last April, May and September as her “favorite star” made its closest approach to the enormous black hole. Spectra, which Ghez described as the “rainbow of light” from stars, show the intensity of light and offer important information about the star from which the light travels. Spectra also show the composition of the star. These data were combined with measurements Ghez and her team have made over the last 24 years.

Spectra — collected at the W.M. Keck Observatory in Hawaii using a spectrograph built at UCLA by a team led by colleague James Larkin — provide the third dimension, revealing the star’s motion at a level of precision not previously attained. (Images of the star the researchers took at the Keck Observatory provide the two other dimensions.) Larkin’s instrument takes light from a star and disperses it, similar to the way raindrops disperse light from the sun to create a rainbow, Ghez said.

“What’s so special about S0-2 is we have its complete orbit in three dimensions,” said Ghez, who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics. “That’s what gives us the entry ticket into the tests of general relativity. We asked how gravity behaves near a supermassive black hole and whether Einstein’s theory is telling us the full story. Seeing stars go through their complete orbit provides the first opportunity to test fundamental physics using the motions of these stars.”

Ghez’s research team was able to see the co-mingling of space and time near the supermassive black hole. “In Newton’s version of gravity, space and time are separate, and do not co-mingle; under Einstein, they get completely co-mingled near a black hole,” she said.

“Making a measurement of such fundamental importance has required years of patient observing, enabled by state-of-the-art technology,” said Richard Green, director of the National Science Foundation’s division of astronomical sciences. For more than two decades, the division has supported Ghez, along with several of the technical elements critical to the research team’s discovery. “Through their rigorous efforts, Ghez and her collaborators have produced a high-significance validation of Einstein’s idea about strong gravity.”

Keck Observatory Director Hilton Lewis called Ghez “one of our most passionate and tenacious Keck users.” “Her latest groundbreaking research,” he said, “is the culmination of unwavering commitment over the past two decades to unlock the mysteries of the supermassive black hole at the center of our Milky Way galaxy.”

The researchers studied photons — particles of light — as they traveled from S0-2 to Earth. S0-2 moves around the black hole at blistering speeds of more than 16 million miles per hour at its closest approach. Einstein had reported that in this region close to the black hole, photons have to do extra work. Their wavelength as they leave the star depends not only on how fast the star is moving, but also on how much energy the photons expend to escape the black hole’s powerful gravitational field. Near a black hole, gravity is much stronger than on Earth.

Ghez was given the opportunity to present partial data last summer, but chose not to so that her team could thoroughly analyze the data first. “We’re learning how gravity works. It’s one of four fundamental forces and the one we have tested the least,” she said. “There are many regions where we just haven’t asked, how does gravity work here? It’s easy to be overconfident and there are many ways to misinterpret the data, many ways that small errors can accumulate into significant mistakes, which is why we did not rush our analysis.”

Ghez, a 2008 recipient of the MacArthur “Genius” Fellowship, studies more than 3,000 stars that orbit the supermassive black hole. Hundreds of them are young, she said, in a region where astronomers did not expect to see them.

It takes 26,000 years for the photons from S0-2 to reach Earth. “We’re so excited, and have been preparing for years to make these measurements,” said Ghez, who directs the UCLA Galactic Center Group. “For us, it’s visceral, it’s now — but it actually happened 26,000 years ago!”

This is the first of many tests of general relativity Ghez’s research team will conduct on stars near the supermassive black hole. Among the stars that most interest her is S0-102, which has the shortest orbit, taking 11 1/2 years to complete a full orbit around the black hole. Most of the stars Ghez studies have orbits of much longer than a human lifespan.

Ghez’s team took measurements about every four nights during crucial periods in 2018 using the Keck Observatory — which sits atop Hawaii’s dormant Mauna Kea volcano and houses one of the world’s largest and premier optical and infrared telescopes. Measurements are also taken with an optical-infrared telescope at Gemini Observatory and Subaru Telescope, also in Hawaii. She and her team have used these telescopes both on site in Hawaii and remotely from an observation room in UCLA’s department of physics and astronomy.

Black holes have such high density that nothing can escape their gravitational pull, not even light. (They cannot be seen directly, but their influence on nearby stars is visible and provides a signature. Once something crosses the “event horizon” of a black hole, it will not be able to escape. However, the star S0-2 is still rather far from the event horizon, even at its closest approach, so its photons do not get pulled in.)

Photo of telescope pointing to the sky.

Lasers from the two Keck telescopes point in the direction of the center of our galaxy. Each laser creates an “artificial star” that astronomers can use to correct for the blurring caused by the Earth’s atmosphere. Photo: Ethan Tweedie

Ghez’s co-authors include Tuan Do, lead author of the Science paper, a UCLA research scientist and deputy director of the UCLA Galactic Center Group; Aurelien Hees, a former UCLA postdoctoral scholar, now a researcher at the Paris Observatory; Mark Morris, UCLA professor of physics and astronomy; Eric Becklin, UCLA professor emeritus of physics and astronomy; Smadar Naoz, UCLA assistant professor of physics and astronomy; Jessica Lu, a former UCLA graduate student who is now a UC Berkeley assistant professor of astronomy; UCLA graduate student Devin Chu; Greg Martinez, UCLA project scientist; Shoko Sakai, a UCLA research scientist; Shogo Nishiyama, associate professor with Japan’s Miyagi University of Education; and Rainer Schoedel, a researcher with Spain’s Instituto de Astrofısica de Andalucıa.

The National Science Foundation has funded Ghez’s research for the last 25 years. More recently, her research has also been supported by the W.M. Keck Foundation, the Gordon and Betty Moore Foundation and the Heising-Simons Foundation; as well as Lauren Leichtman and Arthur Levine, and Howard and Astrid Preston.

In 1998, Ghez answered one of astronomy’s most important questions, helping to show that a supermassive black hole resides at the center of our Milky Way galaxy. The question had been a subject of much debate among astronomers for more than a quarter of a century.

A powerful technology that Ghez helped to pioneer, called adaptive optics, corrects the distorting effects of the Earth’s atmosphere in real time. With adaptive optics at Keck Observatory, Ghez and her colleagues have revealed many surprises about the environments surrounding supermassive black holes. For example, they discovered young stars where none was expected to be seen and a lack of old stars where many were anticipated. It’s unclear whether S0-2 is young or just masquerading as a young star, Ghez said.

In 2000, she and colleagues reported that for the first time, astronomers had seen stars accelerate around the supermassive black hole. In 2003, Ghez reported that the case for the Milky Way’s black hole had been strengthened substantially and that all of the proposed alternatives could be excluded.

In 2005, Ghez and her colleagues took the first clear picture of the center of the Milky Way, including the area surrounding the black hole, at Keck Observatory. And in 2017, Ghez’s research team reported that S0-2 does not have a companion star, solving another mystery.

This article originally appeared in the UCLA Newsroom.

Study finds cultural differences in attitudes toward infidelity, jealousy

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Photo of father and small son.

The 11 societies studied included the Namibian community of the Himba, where this father and child live. Photo credit: Brooke Scelza.

In cultures where fathers are highly invested in the care of their children, both men and women respond more negatively to the idea of infidelity, a cross-cultural study led by UCLA professor of anthropology Brooke Scelza found.

Jealousy is a well-examined human phenomenon that women and men often experience differently, but the study published this week in Nature Human Behavior also examined cultural differences in the experience of jealousy, by surveying 1,048 men and women from 11 societies on five continents.

Scelza wanted to use established evolutionary science to go beyond the idea that a phenomenon of human behavior is either universal or variable.

“In studying jealousy we find evidence for both,” she said. “Almost everywhere men tend to be more upset than women by sexual infidelity,” she said. “At the same time, cultural factors lead to population-level differences in how infidelity is viewed.”

For example, in places where men are not expected to be as involved in day-to-day care of children, people were less prone to jealousy. And in cultures that are more accepting of what Scelza describes as “concurrent” sexual relationships, responses to questions about jealousy were more muted.

The study harnessed expertise from a dozen researchers who have worked extensively in the populations surveyed. Eight were small-scale societies, including the Himba, a pastoral community in Namibia, and the Tismane, indigenous people of Bolivia. Three populations of respondents were from urban settings, such as Los Angeles, India and Okinawa, Japan.

Researchers used a five-point scale to determine attitudes about infidelity and jealousy.

“Very few people of either sex said that either sexual or emotional infidelity was ‘very good’ but responses of ‘OK’ and ‘good’ were not uncommon,” Scelza said. “What is most interesting is that we were able to not just show that cross-cultural variation in jealous response exists, which by itself is not very surprising, but we were able to explain some of that variation using principles from evolutionary theory about the relative costs and benefits of infidelity, including how common extramarital sex is, and whether men are very involved in child-rearing.”

Another surprising finding of the study was that in the majority of populations studied, both men and women found sexual infidelity more upsetting than emotional infidelity. In only four of the populations, including Los Angeles and Okinawa, a majority of women responded that emotional infidelity was more upsetting. These responses echoed what women surveyed in smaller communities like the Himba and Tsimane reported to researchers — that sexual infidelity leads to fears of loss of paternal support and resources for children.

“Typically, we tend to think that emotional infidelity is more likely to lead to loss of resources, which is why it is thought to be more upsetting to women, but we found the opposite,” Scelza said.

This study is part of a growing body of work over the last decade from social scientists who seek to be more inclusive and not just focus their research on western, educated, industrial, rich and democratic — also known as WEIRD — societies, Scelza said.

“For a long time in psychology there was a tendency to use student samples from U.S. and European universities, and if they found a consistent result, extrapolate that as something that could be a ‘human universal,’” she said. “But there are many reasons to believe that people from WEIRD populations are unlikely to be representative of humanity more generally.”

For example, Scelza’s idea for the study was sparked by her ongoing work with Himba pastoralists living in rural Namibia. In her work on marital and family dynamics she found that both women and men frequently had multiple concurrent sexual partners but still experienced happy marriages.

“Over and over I was told that one could love both their husband and another man, and that in fact, many people would be uninterested in having a spouse who could not attract other partners,” she said. “It made me wonder whether or not people in this culture experienced jealousy at all. It turns out they do, but those findings inspired me to take a broader look at how jealousy is treated around the world, and try to understand where and why people view it differently.”

This article originally appeared in the UCLA Newsroom.

Photo of smoggy Los Angeles skyline

Air quality app influences behavior by linking environment to health

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Photo of smoggy Los Angeles skyline

An air quality app prompted a majority of its users to take measures to reduce air pollution’s effects on their health.

Nine out of 10 people worldwide breathe polluted air and 7 million die every year from air pollution, according to the World Health Organization. Air quality mobile applications could mitigate these health risks by educating people and promoting preventive behavioral changes, a UCLA study found.

“I think information can be very powerful to change your behavior,” said the study’s lead author, Magali Delmas, a professor of management at the UCLA Institute of the Environment and Sustainability and the Anderson School of Management.

To test the effectiveness of an air quality app, a team of UCLA researchers created AirForU. Similar to a weather app, AirForU gave users information such as hourly air quality updates, next-day air quality forecasts and seven-day historical averages. Data was taken from the Environmental Protection Agency’s AirNow website.

Sixty-nine percent of the app’s 2,740 users said the app prompted them to take measures to reduce air pollution’s effects on their health, and 58% said they learned new information about the health impacts of air pollution.The researchers tracked how often users checked the app and surveyed them to find out how often they shared air quality information with others.

Engagement was found to be highest among health-conscious users, including those who exercised frequently or had preexisting conditions — such as asthma or heart disease — that can be aggravated by air pollution. These users opened the app one to two more times a week than other users.

Additional motivations such as emails and in-app notifications increased engagement, generating two to three more app visits a week. However, the paper’s authors noted that too many notifications could backfire, annoying users.

As part of an end-of-study feedback survey, researchers measured behavioral changes. The most common actions users took to protect their health were not exercising outdoors when air pollution levels were high (21.7%) and closing windows (20.2%). Their knowledge of air quality rose as well, from 10% in the intake survey to 70% in the exit survey.

The study ran from 2015 to 2017, but it was cut short. “[A] company used lawyers to try to influence the type of information we provided in the app,” the study stated, after “one app user contacted a facility about their toxic releases.” The letter was written by attorneys representing an unidentified company. Though all of the app’s information was publicly available through government sources, UCLA Health decided to remove the app from the store. By that time, the information needed for the study had already been collected.

The researchers suggested increasing transparency about data sourcing and potentially including attorneys in development teams for similar apps.

Maintaining long-term engagement was another challenge. App engagement dropped 90 percent about three months after signup. The paper’s authors suggest it could indicate that users learned enough during that time, or that additional strategies are needed to engage them further.

While users can no longer download AirForU, Delmas and Kohli see potential for future apps to go beyond educating users and promote behavioral change — informing public advocacy to address air pollution through policies and responsible business practices.

“I hope others will learn from what we did to build something that is even more effective,” Delmas said.

This article originally appeared in the UCLA Newsroom.

Physical Sciences Dean Miguel García-Garibay has been elected a 2019 Fellow of the American Chemical Society

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Photo of Miguel García-Garibay

Miguel García-Garibay, Dean of the UCLA College Division of Physical Sciences.

Miguel García-Garibay, dean of the UCLA Division of Physical Sciences and professor of chemistry and biochemistry, has been elected a 2019 fellow of the American Chemical Society, the ACS announced.

García-Garibay is a pioneer in research on molecular motion in crystals, molecular machines and green chemistry.

He has earned worldwide recognition in the fields of organic photochemistry, solid-state organic chemistry and physical organic chemistry. García-Garibay studies the interaction of light and molecules in crystals. Light can have enough energy to break and make bonds in molecules, and his research team has shown that crystals offer an opportunity to control the outcome of these chemical reactions. He is interested in the basic science of molecules in crystals.

His research has applications for green chemistry that may lead to the production of specialty chemicals that would be very difficult to produce by traditional methods due to their complex structures, as well as applications for molecular electronics and miniaturized devices. His research group has made advances in the field of artificial molecular machines and amphidynamic crystals, a term García-Garibay invented, referring to crystals built with molecules that have a combination of static and mobile components. His research is funded by the National Science Foundation, among other funding sources.

“I can get a precise picture of the molecules in the crystals, the precise arrangement of atoms, with almost no uncertainty,” García-Garibay said. “This provides a large level of control, which enables us to learn the different principles governing molecular functions at the nanoscale.”

He has won many honors for his research, including selection as a fellow of the American Association for the Advancement of Science, as well as numerous honors from the National Science Foundation and the American Chemical Society. He is a member of the California NanoSystems Institute and the Society for Advancement of Chicanos/Hispanics and Native Americans in Science, among other scholarly organizations.

ACS fellows are nominated by their peers and selected for their outstanding accomplishments in scientific research, education and public service. The 2019 fellows will be honored at a ceremony during the ACS national meeting in San Diego on Aug. 26.

This story originally appeared here.

Mathematician named a Great Immigrant by Carnegie Corporation

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Photo of Terence Tao

Terence Tao. Photo Credit: Reed Hutchinson

 

Terence Tao, professor of mathematics, who holds the James and Carol Collins Chair in the UCLA College, has been named by Carnegie Corporation of New York on its 2019 annual list of Great Immigrants — a salute to 38 naturalized citizens who “strengthen America’s economy, enrich our culture and communities, and invigorate our democracy through their lives, their work, and their examples.”

Tao became the first mathematics professor in UCLA history to be awarded the Fields Medal in 2006, often described as the “Nobel Prize in mathematics.” He has earned many other honors, including the National Science Foundation’s Alan T. Waterman Award, the Breakthrough Prize in Mathematics, Royal Society’s 2014 Royal Medal for physical sciences and the Royal Swedish Academy of Sciences’ Crafoord Prize. National Geographic magazine featured him in its “What makes a genius?” May 2017 issue.

Every Fourth of July since 2006, the Carnegie Corporation of New York has sponsored the public awareness initiative to commemorate the legacy of its founder, Scottish immigrant Andrew Carnegie, who believed strongly in both immigration and citizenship.

“As we celebrate these 38 extraordinary individuals, we are reminded of the legacy of our founder, Andrew Carnegie, who showed the country how immigrants contribute to the great, unfinished story that is America,” said Vartan Gregorian, president of Carnegie Corporation of New York.

This article originally appeared in the UCLA Newsroom.

Professor’s latest book examines the history of cities

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Photo of Monica Smith

Monica Smith. Photo credit: Paul Connor

The only thing a person really needs to be an archaeologist is a good sense of observation, UCLA professor of anthropology Monica Smith proclaims in her most recent book, “Cities: The First 6,000 Years.”

Advanced degrees and research experience are useful of course, but successful fieldwork is rooted in “noticing,” she said.

Archaeologists are always looking down noticing traces of what’s been left behind, and the stories detritus can tell, she said. These days at UCLA that might mean traces of glitter bombs launched by graduates during the last several weeks.

“We walk along and there’s all this glitter on the ground, and even though it gets cleaned away, you can never get it all so then you start to see little traces of glitter everywhere, because people are tracking it on their shoes all around campus,” Smith said. “We’re not only walking through an archaeological site, we’re making one.”

Smith is amused at the thought of future archaeologists encountering and interpreting the meaning behind those trace elements of shimmer in the dust around this particular area in one of Earth’s largest cities.

In vivid style, Smith’s latest book examines ways in which human civilization has organized itself into city life during the last 6,000 years, a relatively short time span in the grand scheme of human existence. Today, more than half of the world’s population resides in cities, and that number will continue to grow. But that wasn’t always so.

In “Cities,” Smith tracks the ways metropolitan hubs in different parts of the world emerged unrelated to one another, but in eerily similar forms, revealing the inherent similarities of humans’ needs regardless of what part of the world their civilization evolved.

“I started asking myself, ‘Why do these places all look the same even though they’re different times, different areas, different cultures and different languages?’” she said. “What is it about our human cognitive capacity that leads us to have the same form over and over and over again?”

She imagines how the first Spanish warriors to arrive in Cuzco in Peru, or Tenochtitlan in present day Mexico City, encountered the layout of ancient Inca and A

ztec cities, with shops and open squares and marketplaces resembling what they would see at home — despite the cultures never having had contact before.

“The similarities suggest that humans developed cities because it was the only way for a large number of people to live together in a single place where they could all get something new they wanted, whether that was a job, entertainment, medical care or education,” Smith said.

For the purposes of her analysis, Smith defines a city as a place with a dense population of multiple ethnicities; a diverse economy with an abundant variety of readily available goods; buildings and spaces of religion or ritual; a vertical building landscape that encompasses residential homes, courts, schools and government offices; formal entertainment venues; open grounds and multipurpose spaces; broad avenues and thoroughfares for movement.

Before cities, the human population was scattered across larger agrarian swaths, with families having everything they needed to survive in their own homes. People would come together for trading festivals or sacred ceremonies. These most likely began to last longer and longer, Smith said, creating a permanent collective settlement around places conducive to providing food, water, shelter and entertainment. Humans essentially took the bold step of living away from their immediate food supply to live in cities among larger groups of other humans.

Takeout food vendors have been a staple of cities stretching about as far back as you can get, with evidence of takeout food in ancient cities like Pompeii and Angkor, Smith notes in her book.

And cities allowed for the evolution of all kinds of new jobs and enterprises — bookkeeping, the service industry and managers — constituting a newly emergent middle class that found new opportunities to thrive in dense populations.

Some aspects of city life accelerated long-standing tendencies. Humans are a unique species in the animal kingdom due to our deep dependence on objects, a fact that aids archeologists in their work of noticing. Ancient cities also struggled with some of the same things we do in modern times — trash for example, Smith said.

“We think of ourselves as bad modern people because we have all this trash,” Smith said. “But everyone everywhere has trash. Ancient cities are full of trash. Modern cities are full of trash because people want more stuff.”

Archaeologists are obsessed with trash, Smith said. They learn much and encounter new questions from what was considered disposable to our ancestors.

Smith’s book also offers a descriptive window into day-to-day life on an archaeological dig, sharing challenges and the excitement of new technologies that help identify potential dig sites. People working to excavate subway tunnels and building foundations in modern Athens, Rome, Mexico City, Istanbul, Paris and other places are constantly finding new evidence of these metropolises’ earliest incarnations.

Much like current generations of young adults and children who cannot imagine a world without the internet, cities are here to stay, Smith said.

“From this point forward, there is no way that humans can live without urbanism, there is no ‘going back to the land,’” she said. “We can take a sort of comfort in the fact that the challenges we face like infrastructure, transportation, water sourcing, pollution and trash have essentially been a part of city life from the very beginning.”

Smith said one of the goals of her writing is to inspire people to think of cities as dynamic and adaptable.

“We can work to make cities not only more efficient, but more equitable, in the sense of social justice and greater opportunities for larger numbers of people, along with greater diversity,” she said. “Cities are not just inherited configurations, but are places with potential for growing into the better societies that we wish for ourselves and others.”

This article originally appeared in the UCLA Newsroom.

4d graphic rendering of iron-platinum nanoparticle

Atomic motion is captured in 4D for the first time

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4d graphic rendering of iron-platinum nanoparticle

The image shows 4D atomic motion captured in an iron-platinum nanoparticle at three different times.
Credit: Alexander Tokarev

Results of UCLA-led study contradict a long-held classical theory

Everyday transitions from one state of matter to another — such as freezing, melting or evaporation — start with a process called “nucleation,” in which tiny clusters of atoms or molecules (called “nuclei”) begin to coalesce. Nucleation plays a critical role in circumstances as diverse as the formation of clouds and the onset of neurodegenerative disease.

A UCLA-led team has gained a never-before-seen view of nucleation — capturing how the atoms rearrange at 4D atomic resolution (that is, in three dimensions of space and across time). The findings, published in the journal Nature, differ from predictions based on the classical theory of nucleation that has long appeared in textbooks.

“This is truly a groundbreaking experiment — we not only locate and identify individual atoms with high precision, but also monitor their motion in 4D for the first time,” said senior author Jianwei “John” Miao, a UCLA professor of physics and astronomy, who is the deputy director of the STROBE National Science Foundation Science and Technology Center and a member of the California NanoSystems Institute at UCLA.

Research by the team, which includes collaborators from Lawrence Berkeley National Laboratory, University of Colorado at Boulder, University of Buffalo and the University of Nevada, Reno, builds upon a powerful imaging techniquepreviously developed by Miao’s research group. That method, called “atomic electron tomography,” uses a state-of-the-art electron microscope located at Berkeley Lab’s Molecular Foundry, which images a sample using electrons. The sample is rotated, and in much the same way a CAT scan generates a three-dimensional X-ray of the human body, atomic electron tomography creates stunning 3D images of atoms within a material.

Miao and his colleagues examined an iron-platinum alloy formed into nanoparticles so small that it takes more than 10,000 laid side by side to span the width of a human hair. To investigate nucleation, the scientists heated the nanoparticles to 520 degrees Celsius, or 968 degrees Fahrenheit, and took images after 9 minutes, 16 minutes and 26 minutes. At that temperature, the alloy undergoes a transition between two different solid phases.

Although the alloy looks the same to the naked eye in both phases, closer inspection shows that the 3D atomic arrangements are different from one another. After heating, the structure changes from a jumbled chemical state to a more ordered one, with alternating layers of iron and platinum atoms. The change in the alloy can be compared to solving a Rubik’s Cube — the jumbled phase has all the colors randomly mixed, while the ordered phase has all the colors aligned.

In a painstaking process led by co-first authors and UCLA postdoctoral scholars Jihan Zhou and Yongsoo Yang, the team tracked the same 33 nuclei — some as small as 13 atoms — within one nanoparticle.

“People think it’s difficult to find a needle in a haystack,” Miao said. “How difficult would it be to find the same atom in more than a trillion atoms at three different times?”

The results were surprising, as they contradict the classical theory of nucleation. That theory holds that nuclei are perfectly round. In the study, by contrast, nuclei formed irregular shapes. The theory also suggests that nuclei have a sharp boundary. Instead, the researchers observed that each nucleus contained a core of atoms that had changed to the new, ordered phase, but that the arrangement became more and more jumbled closer to the surface of the nucleus.

Classical nucleation theory also states that once a nucleus reaches a specific size, it only grows larger from there. But the process seems to be far more complicated than that: In addition to growing, nuclei in the study shrunk, divided and merged; some dissolved completely.

“Nucleation is basically an unsolved problem in many fields,” said co-author Peter Ercius, a staff scientist at the Molecular Foundry, a nanoscience facility that offers users leading-edge instrumentation and expertise for collaborative research. “Once you can image something, you can start to think about how to control it.”

The findings offer direct evidence that classical nucleation theory does not accurately describe phenomena at the atomic level. The discoveries about nucleation may influence research in a wide range of areas, including physics, chemistry, materials science, environmental science and neuroscience.

“By capturing atomic motion over time, this study opens new avenues for studying a broad range of material, chemical and biological phenomena,” said National Science Foundation program officer Charles Ying, who oversees funding for the STROBE center. “This transformative result required groundbreaking advances in experimentation, data analysis and modeling, an outcome that demanded the broad expertise of the center’s researchers and their collaborators.”

Other authors were Yao Yang, Dennis Kim, Andrew Yuan and Xuezeng Tian, all of UCLA; Colin Ophus and Andreas Schmid of Berkeley Lab; Fan Sun and Hao Zeng of the University at Buffalo in New York; Michael Nathanson and Hendrik Heinz of the University of Colorado at Boulder; and Qi An of the University of Nevada, Reno.

The research was primarily supported by the STROBE National Science Foundation Science and Technology Center, and also supported by the U.S. Department of Energy.

This story originally appeared in the UCLA Newsroom.

Photo of baby laughing

Babies Know the Difference between the Laughter of Friends and Strangers

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Five-month-olds may use chuckles to identify information about social interactions

Photograph of baby laughing

Credit: Aarti Kalyani Getty Images

Most people can share a laugh with a total stranger. But there are subtle—and detectable—differences in our guffaws with friends.

Greg Bryant, a cognitive scientist at the University of California, Los Angeles, and his colleagues previously found that adults from 24 societies around the world can distinguish simultaneous “co-laughter” between friends from that between strangers. The findings suggested that this ability may be universally used to help read social interactions. So the researchers wondered: Can babies distinguish such laughter, too?

Bryant and his fellow researcher Athena Vouloumanos, a developmental psychologist at New York University, played recordings of co-laughter between pairs of either friends or strangers to 24 five-month-old infants in New York City. The babies listened longer to the laughs shared between buddies—suggesting they could tell the two types apart, according to a study published in March in Scientific Reports.

The researchers then showed the babies short videos of two people acting either like friends or strangers and paired those with the audio recordings. The babies stared for longer at clips paired with a mismatched recording—for example, if they saw friends interacting but heard strangers laughing.

“There’s something about co-laughter that is giving information to even a five-month-old about the social relationship between the individuals,” Bryant says. Exactly what components of laughter the infants are detecting remains to be seen, but prior work by Bryant’s team provides hints. Laughs between friends tend to include greater fluctuations in pitch and intensity, for example.

Such characteristics also distinguish spontaneous laughs from fake ones. Many scientists think unprompted laughter most likely evolved from play vocalizations, which are also produced by nonhuman primates, rodents and other mammals. Fake laughter probably emerged later in humans, along with the ability to produce a wide range of speech sounds. The researchers suggest that we may be sensitive to spontaneous laughter during development because of its long evolutionary history.

“It’s really cool to see how early infants are distinguishing between different forms of laughter,” says Adrienne Wood, a psychologist at the University of Virginia, who was not involved in the study. “Almost every waking moment is a social interaction for [babies], so it makes sense that they are becoming very attuned to their social worlds.”

This story originally appeared in the Scientific American.

Andrea Ghez, Lauren B. Leichtman & Arthur E. Levine Chair in Astrophysics at UCLA, receiving an honorary doctorate from Oxford University on June 26, 2019. Ghez is with her sons.

UCLA astronomer receives honorary degree from Oxford

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By Lisa Garibay

Andrea Ghez, Lauren B. Leichtman & Arthur E. Levine Chair in Astrophysics at UCLA, receiving an honorary doctorate from Oxford University on June 26, 2019. Ghez is with her sons.

UCLA’s Andrea Ghez with her sons at Oxford University.

Andrea Ghez, distinguished professor of physics and astronomy and director of UCLA’s Galactic Center Group, was awarded an honorary degree today from Oxford University during its annual Encaenia ceremony.

Ghez demonstrated the existence of a supermassive black hole at the center of our galaxy, with a mass 4 million times that of our sun. Her work provided the best evidence yet that these exotic objects really do exist, providing an opportunity to study the fundamental laws of physics in the extreme environment near a black hole, and learn what role this black hole has played in the formation and evolution of our galaxy.

She joins an eclectic group including cellist Yo-Yo Ma, Nobel laureate Daniel Kahneman, and UC Berkeley professor Jennifer Doudna, who developed the CRISPR-Cas9 technology for gene editing.

Ghez, who is the Lauren B. Leichtman & Arthur E. Levine Chair in Astrophysics, earned her bachelor’s degree in physics from MIT in 1987 and her doctorate from Caltech in 1992, and has been on the faculty at UCLA since 1994.

This article was originally published on the UCLA Newsroom.

New simulations suggest that carbon (C) routinely bonded with iron (Fe), silicon (Si) and oxygen (O) deep within the magma ocean that covered Earth when it was young.

New insights about carbon and ice could clarify inner workings of Earth, other planets

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New simulations suggest that carbon (C) routinely bonded with iron (Fe), silicon (Si) and oxygen (O) deep within the magma ocean that covered Earth when it was young.

New simulations suggest that carbon (C) routinely bonded with iron (Fe), silicon (Si) and oxygen (O) deep within the magma ocean that covered Earth when it was young.

 

Most people behave differently when under extreme pressure. Carbon and ice are no different.

Two new studies show how these key planetary ingredients take on exotic forms that could help researchers better understand the composition of Earth’s core as well as the cores of planets across the galaxy. Craig Manning, a UCLA professor of geology and geochemistry, is a co-senior author of one of the papers, which was published today in the journal Nature, and senior author of the other, which was published in Nature Communications in February.

The Nature Communications paper revealed that high pressure deep inside the young Earth may have driven vast stores of carbon into the planet’s core while also setting the stage for diamonds to form. In the Nature report, researchers found that water ice undergoes a complex crystalline metamorphosis as the pressure slowly ratchets up.

Scientists have long understood that the amount of carbon sequestered in present-day Earth’s rocks, oceans and atmosphere is always in flux because the planet shuffles the element around in a vast cycle that helps regulate climate. But researchers don’t know whether the Earth locked away even more carbon deep in its interior during its formative years — information that could reveal a little more about how our planet and others like it are built.

To pursue an answer to that question, Manning and colleagues calculated how carbon might have interacted with other atoms under conditions similar to those that prevailed roughly 4.5 billion years ago, when much of Earth was still molten. Using supercomputers, the team created simulations to explore what would happen to carbon at temperatures above 3,000 degrees Celsius (more than 5,400 degrees Fahrenheit) and at pressures more than 100,000 times of those on Earth’s surface today.

The experiment revealed that under those conditions, carbon tends to link up with iron, which implies that there might be considerable quantities of carbon sealed in Earth’s iron core today. Researchers had already suspected that in the young planet’s magma ocean, iron atoms hooked up with one another and then dropped to the planet’s center. But the new research suggests that this molten iron rain may have also dragged carbon down with it. Until now, researchers weren’t even sure whether carbon exists down there.

The team also found that as the pressure ramps up, carbon increasingly bonds with itself, forming long chains of carbon atoms with oxygen atoms sticking out.

“These complex chains are a form of carbon bonding that we really hadn’t anticipated at these conditions,” Manning said.

Such molecules could be a precursor to diamonds, which consist of many carbon atoms linked together.

Solving an icy enigma

The machinations of carbon under pressure provide clues as to how Earth-like planets are built. Frozen planets and moons in other solar systems, however, may also have to contend with water ice. In a separate paper, Manning and another team of scientists looked at how the molecular structure of extremely cold ice changes when put under intense pressure.

Under everyday conditions, water ice is made up of molecules laid out in honeycomb-like mosaics of hexagons. But when ice is exposed to crushing pressure or very low temperature — in labs or possibly deep inside remote worlds — the molecules can assume a bewildering variety of patterns.

One of those patterns, known as amorphous ice, is an enigma. In amorphous ice, the water molecules eschew rigid crystalline order and take on a free-form arrangement. Manning and colleagues set out to try and understand how amorphous ice forms.

First, they chilled normal ice to about 170 degrees below zero Celsius (about 274 degrees below zero Fahrenheit). Then, they locked the ice in the jaws of a high-tech vice grip inside a cryogenic vacuum chamber. Finally, over the span of several hours, they slowly stepped up the pressure in the chamber to about 15,000 times atmospheric pressure. They stopped raising the pressure periodically to fire neutrons through the ice so that they could see the arrangement of the water molecules.

Surprisingly to the researchers, the amorphous ice never formed. Instead, the molecules went through a series of previously known crystalline arrangements.

However, when the researchers conducted the same experiment but raised the pressure much more rapidly — this time in just 30 minutes — amorphous ice formed as expected. The results suggest that time is the secret ingredient: When pressure increases slowly, tiny seeds of crystalline ice have time to form and take over the sample. Otherwise, those seeds never get a chance to grow.

The findings, published May 23 in the journal Nature, could be useful to researchers who study worlds orbiting other suns and are curious about what conditions might be like deep inside frozen planets.

“It’s entirely likely that there are planets dominated by ice in other solar systems that could obtain these pressures and temperatures with ease,” Manning said. “We have to have this right if we’re going to have a baseline for understanding the interiors of cold worlds that may not be like Earth.”

Both papers were funded in part by the Deep Carbon Observatory, a 10-year program started in 2009 to investigate the quantities, movements, forms and origins of deep carbon inside Earth. The Nature Communications paper was also funded by the European Research Council and was co-authored by researchers at the Ecole Normale Supérieure de Lyon in France, one of whom — Natalia Solomatova — completed her undergraduate studies at UCLA. The Nature paper was co-authored by UCLA geologist Adam Makhluf and researchers from Oak Ridge National Laboratory and the National Research Council of Canada.

This article originally appeared on the UCLA Newsroom.