In Carl Sagan’s 1985 sci-fi novel Contact, a radio astronomer battles naysayers and funding setbacks to persist in her audacious plan — scanning the skies for signals from aliens. Sagan had real-life inspiration for his book (and the 1997 movie of the same name): astronomer Jill Tarter, who spearheaded the search for extraterrestrial intelligence, or SETI, for decades.
In Sagan’s story, the protagonist, Ellie Arroway, detects mysterious chatter from the cosmos. Tarter had no such luck. But her story, told by journalist Sarah Scoles in Making Contact, still provides insights into what it means to be human in a vast universe potentially harboring other life. Tarter began her career as a typical radio astronomer, studying mainstream topics like stars and galaxies as a Ph.D. student. But after graduating in 1975, she began to focus on SETI, poring over data from radio telescopes, searching for unnatural blips that could be a sign of an intelligent civilization. SETI researchers typically focus on radio waves because those long wavelengths can travel through our galaxy’s dust without being absorbed. Writings about SETI are prone to dreamy romanticism, but Making Contact admirably steers clear of excessive sentimentality. As a child gaping at the stars, Tarter wondered if creatures in the heavens were looking in our direction. Of course, Scoles notes, plenty of kids have wondered the same thing. Though Tarter’s childhood musings might seem special in retrospect, they aren’t what make her stand out.
Instead, Scoles — who has clear affection for her subject — highlights Tarter’s tenacity. In the face of numerous obstacles, Tarter pushed the field forward, seemingly by force of will.
In a detailed portrait of how the science sausage gets made, the book follows Tarter as she faced numerous funding woes. The field of SETI, which has at various points in its history received money through NASA, is an easy target for funding cuts, with some politicians deriding it as a wasteful hunt for “little green men.” Tarter, like the fictional Arroway, fought with Congress for taxpayer dollars SETI received, then scrambled for cash from other sources to keep telescopes and other equipment in operation. Wealthy donors kept SETI afloat — and still do. To maximize their ability to accept funding, Tarter and other SETI pioneers founded the nonprofit SETI Institute, in Mountain View, Calif., in 1984. Throughout, Tarter somehow managed to maintain her passion for a long shot search.
Although it’s a compelling story, the book stumbles in a few places, mainly minor sloppiness with physics facts, which may bother the most astute readers. (Scoles writes, for example, “Light is the only way we can learn about the universe,” neglecting gravitational waves and neutrinos, both of which have revealed secrets of cosmic objects.)
Now retired, Tarter has lost her chance to follow in Arroway’s fictional footsteps — she will never find any alien communiqués. But even if astronomers never hear from E.T., Tarter sees benefits in the search: SETI is an opportunity to make humankind less selfish. Just the thought that other creatures might inhabit the universe can make human squabbles seem less significant.
A strange property of spider silk helps explain how the arachnids avoid twirling wildly at the end of their ropes.
Researchers from China and England harvested silk from two species of golden orb weaver spiders, Nephila edulis and Nephila pilipes, and tested it with a torsion pendulum. The device has a hanging weight that rotates clockwise or counterclockwise, twisting whatever fiber it hangs from. When a typical fiber is twisted, the weight spins back and forth around an equilibrium point, eventually returning to its original orientation. But unlike several fibers the scientists tested — copper wires, carbon fibers and even human hair — the spider silk deformed when twisted. That distortion changed the silk’s equilibrium point and cut down on the back-and-forth spinning, the scientists report in the July 3 Applied Physics Letters. Eventually, scientists might design spin-resistant ropes for mountain climbers, who, like spiders, should avoid doing the twist.
A new type of soft robot can go under the knife and make a full recovery in about a day.
Researchers fashioned a robotic hand, gripper and muscle from self-healing rubbery material. To test their robots’ resilience, the engineers sliced each with a scalpel, then put them in an oven. After cranking up the heat to 80° Celsius, baking the bots for 40 minutes, then cooling them to room temperature, the researchers found that all three bots’ cuts had completely closed up. Twenty-four hours later, the machines had regained at least 98 percent of their original strength and flexibility, the researchers report online August 16 in Science Robotics. Incisions broke bonds between two chemical ingredients that make up the material, furan and maleimide. At higher temperatures, these chemical compounds can also split up, as well as move around more easily. So as the researchers cooled the material, the compounds were able to re-bond with those on the other side of an incision. “This material could heal, in theory, an infinite number of times,” says study coauthor Bram Vanderborght, an engineer at Vrije University Brussels.
The work helps address a major limitation of squishy, flexible robots — which are better suited than their traditional, rigid counterparts for navigating rough terrain and handling fragile objects, but are vulnerable to punctures and tears. Self-healing machines could pave the way for creating more durable, reusable soft bots.
Getting rid of bodily wastes during long space flights is a problem…. A bizarre possible solution … involves whipping the wastes in with some other ingredients to produce the most unusual rocket fuel…. The four ingredients — carbon, ammonium, nitrate and aluminum — and the waste material are just blended together, and they’re ready to go…. [The material] would probably be used to help a spacecraft change position or to nudge a long-life space station occasionally to keep it up in orbit. –Science News, September 2, 1967 Update Researchers are still trying to figure out how to turn astronaut excrement into something useful. Another process proposed in 2014 would use microbes to convert the waste and other organic material into fuel. But waste might have other uses that would be especially helpful during long-term flights. Synthetic biologists at Clemson University in South Carolina are working with NASA to use algae and genetically modified yeast to turn astronaut urine into 3-D printable plastics and nutritional omega-3 fats.
Sure, students in the classroom have to remember facts, but they also have to apply them. Some research efforts to enhance learning zero in on methods to strengthen memory and recall, while others bolster students’ abilities to stay on task, think more fluidly and mentally track and juggle information.
But there’s a catch. The science behind student learning is so far based on carefully controlled studies, primarily with college students. Do the same approaches work with younger students? Will they work in a classroom of 25 or 30 kids of varying abilities? These are questions researchers are asking now, says Erin Higgins of the U.S. Department of Education’s National Center for Education Research. Moving from the lab to a classroom, with all its disruptions and distractions, is key for pinning down what works, under what conditions and for whom. In the process of tweaking some of the most promising tools and strategies for classroom use, educators hope to find ways to help low-performing students gain skills that already pay off for their more successful peers. The efforts described here draw on new, innovative training methods to boost learning in K-12 classrooms. Higgins calls them “great examples” of the work under way.
Recall with cues For college students, “free recall” is one of the most effective ways to make new knowledge stick, says psychologist Jeffrey Karpicke of Purdue University in West Lafayette, Ind. Students who read a passage and then jotted down details they remembered from the material recalled about 50 percent more information a week later than did students who just reviewed the material. The trick for younger learners, Karpicke found, is to provide cues to help recall, without making the task too easy. After studying lists of unrelated words (banana and football), fourth-graders either restudied the words or practiced retrieving them from memory before taking a free recall test. Findings, published last year in Frontiers in Psychology, show that children at all reading levels remembered at least 25 percent more words when they practiced retrieving with the help of some cues compared with just rereading the lists.
With psychologist Michael Jones of Indiana University Bloomington, Karpicke is creating a computer-based self-test to help kids hone their retrieval skills. Students might have to answer fill-in-the-blank questions or rearrange scrambled words. Teachers will be able to tailor the tests to the curriculum. Parts of the program are being tested in schools in West Lafayette this year. The program gets harder as children succeed but easier if they struggle. “It’s important that students experience success,” Karpicke says, while keeping the task challenging. Hold that thought
Working memory, which allows a person to hold on to information long enough to use it, is often a weakness in children who struggle with math, says educational psychologist Lynn Fuchs of Vanderbilt University in Nashville. Handy for remembering a phone number long enough to find a pen to write it down or for multiplying numbers in our heads, working memory can be strengthened through exercises that put progressively tougher demands on it. But general training may not be enough to help struggling math learners, according to a 2015 review of school-based programs, published in the Journal of Educational Psychology.
Fuchs has developed a routine that embeds working memory exercises within math lessons. Designed for second-graders at risk for math difficulties, the program has students focus on key words in a word problem and hold the words in mind while breaking the problem into smaller segments and choosing the right math tools to solve the problem.
Aiming to catch young learners before they fall behind, researchers are testing the program in Nashville classrooms this school year.
Sum of the parts Researchers typically test one new strategy in isolation, but in real classrooms, educators may try more than one approach at once. Jodi Davenport of WestEd, a San Francisco–based education research and development group, codirected a multi-institutional effort to revise a seventh-grade math curriculum using a handful of promising strategies. Lessons were spaced out to expose students to key concepts or procedures multiple times and were combined with frequent quizzes. Graphics accompanied examples of how to work a problem, to strengthen the connection between the visual and verbal material. Researchers trained 181 teachers at 114 schools and then tracked 2,465 students in 22 states over a full school year.
Strategies such as showing incorrect examples along with correct ones (to point out common errors) and removing distracting information were especially helpful to underperforming students, Davenport says. Students with lower pretest scores scored higher on posttests in six of eight math units when using the new curriculum versus the traditional materials, the researchers reported in March in Washington, D.C., at the Society for Research on Educational Effectiveness meeting.
Testing the program in so many schools amid teacher turnover and other real-life challenges made controlling for variance hard, so the data weren’t as robust as researchers had hoped. But there appeared to be improvements, particularly in girls, underrepresented minorities, English-language learners and special education students. The methods work by helping students focus and link related info, Davenport speculates. “Successful students have these skills,” she says. “They’ve developed strategies … to focus their attention and employ problem-solving skills as they work through a problem.” She hopes to help teachers give struggling kids those same skills.
Granting executive powers Students must learn to stay focused in the face of distraction, to direct actions toward a goal and to hold what they have just seen or heard in mind while they work with it. These abilities are part of a set of cognitive skills called executive function. There’s strong evidence that well-designed video games can improve executive function among teens and adults, says psychologist Bruce Homer of the City University of New York. “But we need more research to determine if — and how well — these skills transfer to the classroom to … improve academic performance,” he says. With psychologist Richard Mayer of the University of California, Santa Barbara, and Jan Plass of New York University’s game design center, Homer is developing a series of video games for students from middle school to college. Each game targets a specific area of executive function, such as shifting attention or avoiding distractions.
The first of three games is in testing, assigned as homework for 300 kids in Santa Barbara and New York City schools. In the game, students must quickly adapt to rule changes as aliens land on Earth and request help gathering supplies. Preliminary findings show that after eight 30-minute sessions, players of the alien game showed substantially greater improvements in ability to shift strategies in standard cognitive tests compared with students who played a different game. This fall, researchers plan to study whether gains in executive function from game play can improve actual performance in specific academic areas.
Tiny balls of melanin could someday paint the rainbow. They’re one of the key ingredients in a new way to craft a spectrum of structural colors — hues created when light interacts with special nanostructures.
Structural colors are a longer-lasting alternative to chemical pigments, which lose all pizazz when they break down. Examples of durable hues abound in nature. For instance, many bird feathers and butterfly wings get their brilliant colors in part from nanoscale texturing (SN: 6/11/16, p. 32). But finding a simple way to generate these complex structural colors — a technique that can be scaled up and used to create many different hues — has been a tricky task. In the new study, researchers made nano-sized balls of melanin aggregate into clusters called supraballs. Melanin, the pigment that darkens skin, appears black in the individual nanoparticles. But altering the spacing of the nanoparticles in the ball affects how the particles scatter light, generating a spectrum of structural colors, says study coauthor Ali Dhinojwala, a polymer scientist at the University of Akron in Ohio. So he and colleagues added a thin silica coating to the outside of the melanin nanoparticles. The coating acts like a bumper, limiting how close the particles can pack together.
Varying the diameter of the melanin core and the thickness of the silica shell creates supraballs in a range of colors, including olive, orange-red and navy blue, the researchers report September 15 in Science Advances.
This recipe is simpler than other ways of making structural colors in the lab, Dhinojwala says. The nanoparticles cluster into supraballs at room temperature in a mixture of water and an alcohol called octanol, and are easy to extract as a powder. Plus, nanoparticles with different dimensions can be mixed in one supraball to create any shade imaginable.
Nearly 1 in 5 adolescents has suffered at least one concussion, according to a survey of U.S. teens. And 5.5 percent reported two or more concussions diagnosed in their lifetimes, researchers report in the Sept. 26 JAMA.
About 13,000 eighth-, 10th- and 12th-graders participated in the 2016 Monitoring the Future survey, an annual national questionnaire of adolescent behavior and health given in schools. Among other questions, teens were asked whether they had ever had a head injury that was diagnosed as a concussion — 19.5 percent replied “yes.” Those teens were more likely than others to play competitive sports and be male, white and in a higher grade.
Previous studies have found that kids taking part in contact sports are at higher risk of suffering a concussion. These new data on actual prevalence of concussions, though self-reported, are important, say the authors, for crafting prevention efforts that protect teens from injuries.
People in the United States who wear contact lenses share an eye-opening characteristic. Roughly 85 percent report regularly taking at least one risk when wearing or cleaning their lenses. In the Aug. 18 Morbidity and Mortality Weekly Report, researchers at the U.S. Centers for Disease Control and Prevention describe results from a 2016 national survey of more than 6,000 people.
Contrary to previous studies, teens did better in some categories than adults. The no-no’s below can lead to serious eye infections, mainly by introducing microorganisms into the eye. Even water that’s safe to drink or swim in can bug up lenses.
Ripples in spacetime travel at the speed of light. That fact, confirmed by the recent detection of a pair of colliding stellar corpses, kills a whole category of theories that mess with the laws of gravity to explain why the universe is expanding as fast as it is.
On October 16, physicists announced that the Advanced Laser Interferometer Gravitational-Wave Observatory, LIGO, had detected gravitational waves from a neutron star merger (SN Online: 10/16/17). Also, the neutron stars emitted high-energy light shortly after merging. The Fermi space telescope spotted that light coming from the same region of the sky 1.7 seconds after the gravitational wave detection. That observation showed for the first time that gravitational waves, the shivers in spacetime set off when massive bodies move, travel at the speed of light to within a tenth of a trillionth of a percent. Within a day, five papers were posted at arXiv.org mourning hundreds of expanding universe theories that predicted gravitational waves should travel faster than light — an impossibility without changes to Einstein’s laws of gravity. These theories “are very, very dead,” says the coauthor of one of the papers, cosmologist Miguel Zumalacárregui of the Nordic Institute for Theoretical Physics, or NORDITA, in Stockholm. “We need to go back to our blackboards and start thinking of other alternatives.”
In the 1990s, observations of exploding stars showed that more distant explosions were dimmer than existing theories predicted. That suggested that the universe is expanding at an ever-increasing rate (SN: 10/22/11, p. 13). Cosmologists have struggled ever since to explain why.
The most popular explanation for the speedup is that spacetime is filled with a peculiar entity dubbed dark energy. “You can think of it like a mysterious fluid that pushes everything apart and counteracts gravity,” says cosmologist Jeremy Sakstein of the University of Pennsylvania, coauthor of another new paper. In the simplest version of this theory, the density of this dark energy has not changed over the history of the universe, so physicists call it a cosmological constant. This doesn’t require any changes to gravity — which is good, because gravity has been well-tested inside the solar system.
The cosmological constant idea matches observations of the wider universe, but it has some theoretical difficulties. Dark energy is about 120 orders of magnitude weaker than theorists calculate it should be (SN Online: 11/18/13), a mismatch that makes scientists uncomfortable.
Also, different methods for measuring the rate of expansion come up with slightly different numbers (SN: 8/6/16, p. 10). Measurements based on exploding stars suggest that distant galaxies are speeding away from each other at 73 kilometers per second for each megaparsec (about 3.3 million light-years) of space between them. But observations based on the cosmic microwave background, ancient light that encodes information about the conditions of the early universe, found that the expansion rate is 67 km/s per megaparsec. The disagreement suggests that either one of the measurements is wrong, or the theory behind dark energy needs a tweak.
So instead of invoking a substance to counteract gravity, theorists tried to explain the expanding universe by weakening gravity itself. Any modifications to gravity need to leave the solar system intact. “It’s quite hard to build a theory that accelerates the universe and also doesn’t mess up the solar system,” says cosmologist Tessa Baker of the University of Oxford, coauthor of still another paper.
These theories take hundreds of forms. “This field of modified gravity theories is a zoo,” says Baker. Some suggest that gravity leaks out into extra dimensions of space and time. Many others account for the universe’s speedy spreading by adding a different mysterious entity — some unknown particle perhaps — that drains gravity’s strength as the universe evolves.
But the new entity would have another crucial effect: It could slow the speed of light waves, similar to the way light travels more slowly through water than through air. That means that the best alternatives to dark energy required gravitational waves to travel faster than light — which they don’t.
Justin Khoury, a theoretical physicist at the University of Pennsylvania who has worked on several of the alternative gravity theories but was not involved in the new papers, was surprised that one gravitational-wave observation ruled out so many theories at once. He’s hardly disappointed, though.
“The fact that we’re learning something about dark energy because of this measurement is incredibly exciting,” he says.
Observing gravitational waves and light waves at the same time offers a third, independent way to measure how fast the universe is expanding. For now, that rate lies frustratingly right between the two clashing measurements scientists already had, at 70 km/s per megaparsec. But it’s still imprecise. Once LIGO and other observatories have seen 10 or 20 more neutron star collisions, researchers should be able to tell which measurement is correct and figure out whether dark energy needs an update, Zumalacárregui says.
“Gravitational waves may kill these models, but eventually they have the potential to tell us if this discrepancy is for real,” he says. “That’s something that is in itself very beautiful.”
Orangutans living in forested foothills on the Indonesian island of Sumatra represent a previously unknown species, researchers say.
Skeletal and genetic evidence puts these apes on a separate evolutionary trajectory from other orangutans in Sumatra (Pongo abelii) and Bornean orangutans (Pongo pygmaeus), says a team led by evolutionary anthropologist Michael Krützen of the University of Zurich. The researchers named the new species Pongo tapanuliensis, or the Tapanuli orangutan. Krützen’s team reports its findings online November 2 in Current Biology. The name P. tapanuliensis refers to three north Sumatran districts — North, Central and South Tapanuli — where no more than 800 of these orangutans inhabit several forested areas. Tapanuli orangutans live on the brink of extinction due to road construction, illegal forest clearing and killings by villagers and hunters, the scientists say. Estimates vary, but the World Wildlife Fund puts the total number of living orangutans at nearly 120,000.
Researchers observed Tapanuli orangutans in their hilly habitat as early as the 1930s. Yet these apes have long been overlooked in favor of Sumatran orangutans that live in swampy forests north of the Tapanuli population. Bornean orangutans also live in swampy forests.
A chance to explore Tapanuli orangutans’ biology came in 2013. Krützen’s team gained permission to study the museum-held skeleton of an adult male Tapanuli orangutan that had been killed by villagers. Comparisons with skeletons of 33 Sumatran and Bornean male orangutans revealed a range of differences in the skull and teeth of the Tapanuli ape, including a distinctively narrow palate and a relatively short jaw joint.
An analysis of DNA from 37 living orangutans, including two Tapanuli animals, indicated that Tapanuli and Sumatran orangutans diverged from a common ancestor around 3.4 million years ago. Shared gene variants pointed to interbreeding between the two species after their evolutionary split. Cross-species hookups declined sharply around 100,000 years ago and then stopped between 10,000 and 20,000 years ago, the scientists say. Sumatran and Bornean orangutans separated around 674,000 years ago, the team estimates. Only Tapanuli orangutans appear to be direct descendants of the first mainland Asian orangutan ancestors to reach Sumatra, the investigators find. Later migrations of mainland animals may have led to the evolution of Sumatran and Bornean orangutans
Scenarios in which closely related ape species interbred after evolving into distinctive biological populations probably occurred frequently, Krützen says. DNA studies suggest ancient chimpanzees and bonobos interbred, as did Homo sapiens and Neandertals (SN: 10/15/16, p. 22). Such evidence has fueled a long-standing debate over how to define the term “species” (SN: 11/11/17, p. 22).
Krützen’s team makes a good case for a third orangutan species that interbred for a long time with a closely related species, says biological anthropologist Rebecca Ackermann of the University of Cape Town in South Africa. “I’d go out on a limb and say not only that [interbreeding] played an important role in the evolution of all living apes, but that it shaped the evolution of extinct ones as well.”
