Subtle cosmic vibrations kicked up by swirling black holes have captured the public imagination — and the minds of the physics Nobel Prize committee members, too.

Three scientists who laid the groundwork for the first direct detection of gravitational waves have won the Nobel Prize in physics. Rainer Weiss of MIT, and Kip Thorne and Barry Barish, both of Caltech, will share the 9-million-Swedish-kronor (about $1.1 million) prize, with half going to Weiss and the remainder split between Thorne and Barish.
Though researchers often wait decades for Nobel recognition, the observation of gravitational waves was so monumental that the scientists were honored less than two years after the discovery’s announcement.

“These detections were so compelling and earth shattering…. Why wait?” says Clifford Will of the University of Florida in Gainesville, who was not directly involved with the discovery. “It’s fabulous. Absolutely fabulous.”

Weiss, Thorne and Barish are pioneers of the Laser Interferometer Gravitational Wave Observatory, or LIGO. On February 11, 2016, LIGO scientists announced they had spotted gravitational waves produced by a pair of merging black holes. This first-ever detection generated a frenzy of excitement among physicists and garnered front-page headlines around the world.

LIGO’s observation of gravitational waves directly confirmed a 100-year-old prediction of Einstein’s general theory of relativity — that rapidly accelerating massive objects stretch and squeeze spacetime, producing ripples that travel outward from the source (SN: 3/5/16, p. 22).
“If Einstein was still alive, it would be absolutely wonderful to go to him and tell him about the discovery. He would be very pleased, I’m sure of it,” Weiss said during a news conference at MIT a few hours after he got word of the win. “But then to tell him what the discovery was, that it was a black hole, he would have been absolutely flabbergasted because he didn’t believe in them.”

As enthusiastic team members clad in LIGO-themed T-shirts celebrated the discovery, Weiss stressed that the discovery was a group effort. “I’m a symbol of that. It’s not all on my shoulders, this thing,” he said, citing the large collaboration of scientists whose work led up to LIGO’s detection.

Physicists anticipate that LIGO will spark an entirely new field of astronomy, in which scientists survey the universe by feeling for its tremors. “It will allow us to see the parts of the universe that were not revealed to us before,” says LIGO team member Carlos Lousto of the Rochester Institute of Technology in New York.

LIGO’s first incarnation, which officially began collecting data in 2002 and ran intermittently until 2010, yielded no hints of gravitational waves. After years of upgrades, the souped-up detectors, known as Advanced LIGO, began searching for spacetime ripples in 2015. Almost as soon as the detectors were turned on — even before scientific data-taking had formally begun — scientists detected the minuscule undulations of their first black hole collision. Those ripples, spotted on September 14, 2015, journeyed to Earth from 1.3 billion light-years away, where they were produced by two colossal black holes that spiraled inward and merged into one (SN: 3/5/16, p. 6).

Quivers from those converging black holes, when converted into an audio signal, made a tell-tale sound called a “chirp,” reminiscent of a bird’s cry. The particulars of that signature reveal details of the collision. “The beauty of the symphony is in what you can extract from the tiny wiggles, or the wiggles on tops of wiggles, in that signal,” Thorne said at an Oct. 3 news conference at Caltech.
Since that first detection, scientists have observed three more black hole collisions. And additional gravitational ripples may already be in the bag: It’s rumored that LIGO scientists have also detected a smashup of neutron stars (SN Online: 8/25/17). In fact, Weiss teased an announcement to come on October 16.

An astounding feat of engineering, LIGO consists of two enormous L-shaped detectors that stretch across the wooded landscape of Livingston, La., and the desert of Hanford, Wash. Each detector boasts two 4-kilometer-long arms through which laser light bounces back and forth between mirrors.

Gravitational waves passing through a detector stretch one arm while shortening the other. LIGO compares the arms’ sizes using the laser light to measure length differences a tiny fraction of the size of a proton. Gravitational waves should produce signals in the two distant detectors nearly simultaneously, helping scientists to rule out spurious signals that can be caused by events as mundane as a truck bouncing along nearby.

“LIGO is probably one of the best and most amazing instruments ever built by mankind,” Barish said at the Caltech news conference. But building it was a risky endeavor: No one had previously attempted anything like it, and no one could say for sure whether the effort would succeed. “What’s fundamental is you have to be willing to take risks to do great things,” Barish said.

In August, LIGO’s two detectors teamed up with the similarly designed Virgo detector near Pisa, Italy (SN Online: 8/1/17). The latest gravitational wave sighting, made on August 14, showed up in all three detectors almost simultaneously, which allowed scientists to pinpoint the region of space in which the black holes resided more precisely than ever before (SN Online: 9/27/17).

Weiss spent decades on the project, beginning with nascent scribbles on scraps of paper and early prototypes. In the 1960s, Weiss came up with the idea for a laser gravitational wave detector while teaching a class on general relativity. (Other researchers had independently proposed the technique as well.) He refined that idea and built a small, prototype detector, establishing the basic blueprint that would eventually evolve into LIGO.
Inspired by a conversation with Weiss, Thorne, who had been studying theoretical aspects of gravitational waves, assembled a team to work on the technique at Caltech in the ’70s. (Thorne was a 1958 semifinalist in the Science Talent Search, a program of the Society for Science & the Public, which publishes Science News.)

Another LIGO founder, Ronald Drever, died in March. Drever, who had been working on gravitational wave detectors at the University of Glasgow, joined Thorne at Caltech in 1979. Weiss and Drever each worked individually on prototypes, before Weiss officially teamed up with Thorne and Drever in 1984 to create LIGO (SN: 3/5/16, p. 24). Drever did live to hear of the first detection, Will says, but “it’s sad that he didn’t live to see it all.”

Barish joined the project later, becoming director of LIGO in 1994. He stayed in that role for more than 10 years, elevating LIGO from scientists’ daydreams into reality. Barish oversaw construction and commissioning of the detectors, as well as initial gravitational wave searches. “He entered the experiment in a crucial moment, when it was necessary to bring the experiment to a different level, make it a big collaboration,” says Alessandra Buonanno of the Max Planck Institute for Gravitational Physics in Potsdam, Germany.

Speculation that LIGO would nab a Nobel began as soon as the discovery was announced. So the collaboration was not surprised by the honor. “We were certainly expecting this to happen,” says LIGO team member Manuela Campanelli of the Rochester Institute of Technology. Still, the lack of surprise didn’t dampen the mood of festivity. “I feel in a dream,” says Buonanno.

LIGO and Virgo are currently in a shutdown period while scientists tinker with the detectors to improve their sensitivity. The gravitational wave hunt will resume next year. Besides black hole mergers and neutron star smashups, in the future, scientists might also spot waves from an exploding star, known as a supernova. Upcoming detectors might sense trembles generated in the Big Bang, providing a glimpse of the universe’s beginnings.

And scientists may even find new phenomena that they haven’t predicted. “I await expectantly some huge surprises in the coming years,” Thorne said.

Some scientific anniversaries celebrate events so momentous that they capture the attention of many nonscientists as well — or even the entire world.

One such anniversary is upon us. December 2 marks the semisesquicentennial (75th anniversary) of the first controlled and sustained nuclear fission chain reaction. Only four years after German scientists discovered nuclear fission, scientists in America took the first step toward harnessing it. Many of those scientists were not Americans, though, but immigrants appalled by Hitler and horrified at the prospect that he might acquire a nuclear fission weapon.

Among the immigrants who initiated the American fission effort was Albert Einstein. His letter to President Franklin Roosevelt, composed at the request and with the aid of immigrant Leo Szilard from Hungary, warned of nuclear fission’s explosive potential. Presented with Einstein’s letter in October 1939, Roosevelt launched what soon became the Manhattan Project, which eventually produced the atomic bomb. It was another immigrant, Enrico Fermi from Italy, who led the initial efforts to show that building an atomic bomb was possible.

Fermi had arrived in the United States in January 1939, shortly after receiving the Nobel Prize in physics for his work on creating artificial elements heavier than uranium. Except that he hadn’t actually done so — his “new elements” were actually familiar elements produced by the splitting of the uranium nucleus. But nobody knew that fission was possible, so Fermi had misinterpreted his results. Chemists Otto Hahn and Fritz Strassmann, working in Germany, conducted experiments in 1938 that produced the element barium by bombarding uranium with neutrons. So Hahn and Strassmann got the credit for discovering fission, although they didn’t really know what they had done either. It was Lise Meitner, a former collaborator of Hahn’s who had recently left Germany to avoid Nazi anti-Semitism, who figured out that they had split the uranium nucleus.
Meitner’s nephew Otto Frisch revealed her insight to Niels Bohr, the world’s leading atomic physicist, just as he stepped aboard a ship for a visit to America. Upon arriving in the United States, Bohr informed Fermi and Princeton University physicist John Archibald Wheeler of Hahn’s experiment and Meitner’s explanation. Fermi immediately began further experimental work at Columbia University to investigate fission, as did Szilard, also at Columbia (and others in Europe); Bohr and Wheeler tackled the issue from the theoretical side.

Fermi and Szilard quickly succeeded in showing that a fission “chain reaction” was in principle possible: Neutrons emitted from fissioning uranium nuclei could induce more fission. By September, Bohr and Wheeler had produced a thorough theoretical analysis, explaining the physics underlying the fission process and identifying which isotope of uranium fissioned most readily. It was clear that the initial speculations about fission’s potential power had not been exaggerated.

“Almost immediately it occurred to many people around the world that this could be used to make power and that it could be used for nuclear explosives,” another immigrant who worked on the Manhattan Project, the German physicist Hans Bethe, told me during an interview in 1997. “Lots of people verified that indeed when uranium is bombarded by neutrons, slow neutrons in particular, a process occurs which releases tremendous amounts of energy.”
Bethe, working at Cornell University, did not immediately join the fission project — he thought building a bomb would take too long to matter for World War II. “I thought this had nothing to do with the war,” he said. “So I instead went into radar.”

Fermi, despite being an immigrant, was put in charge of constructing an “atomic pile” (nowadays nuclear reactor) to verify the chain reaction theory. He was, after all, widely acknowledged as the world’s leading nuclear experimentalist (and was no slouch as a theorist either); colleagues referred to him as “The Pope” because of his supposed infallibility. Construction of the pile began on a squash court under the stands of the University of Chicago’s football stadium. The goal was to demonstrate the ability to generate a chain reaction, in which any one fissioning nucleus would emit enough neutrons to trigger even more nuclei to fission.

“It became clear to Fermi almost immediately that in order to do this with natural uranium you had to slow down the neutrons,” Bethe said.

Fermi decided that the best material for slowing neutrons was graphite, the form of carbon commonly used as pencil lead. But in preliminary tests the graphite did not do the job as Fermi had anticipated. He reasoned that the graphite contained too many impurities to work effectively. So Szilard began searching for a company that could produce ultrapure graphite. He found one, Bethe recalled, that happily agreed to meet Fermi’s purity requirements — for double the usual graphite price.
Ultimately Fermi’s atomic pile succeeded, producing a sustained chain reaction on December 2, 1942. That success led to the establishment of the secret laboratory in Los Alamos, N.M., where physicists built the bombs that brought World War II to an end in 1945.

By then, Bethe had been persuaded to join the project. He arrived at Los Alamos in April 1943 and witnessed the first nuclear explosion, at Alamogordo, N.M., on July 16, 1945.

“I was among the people who looked at it from a 20-mile distance,” he said. “It was impressive.”

Historians frequently cite the report of J. Robert Oppenheimer, director of the Los Alamos project, who said that the explosion reminded him of a line from the Hindu Bhagavad Gita: “Now I am become Death, the destroyer of worlds.”

Bethe recalled a different response, from one of the military officials on the scene.

“One of the officers at the explosion said, ‘My god. Those longhairs have let it get away from them.’”

PHILADELPHIA — Protein-manufacturing factories within cells are picky about which widgets they construct, new research suggests. These ribosomes may not build all kinds of proteins, instead opting to craft only specialty products.

Some of that specialization may influence the course of embryo development, developmental biologist and geneticist Maria Barna of Stanford University School of Medicine and colleagues discovered. Barna reported the findings December 5 at the joint meeting of the American Society for Cell Biology and European Molecular Biology Organization.
Ribosomes, which are themselves made up of many proteins and RNAs, read genetic instructions copied from DNA into messenger RNAs. The ribosomes then translate those instructions into other proteins that build cells and carry out cellular functions. A typical mammalian cell may carry 10 million ribosomes. “The textbook view of ribosomes is that they are all the same,” Barna said. Even many cell biologists have paid little attention to the structures, viewing them as “backstage players in controlling the genetic code.”

But that view may soon change. Ribosomes actually come in many varieties, incorporating different proteins, Barna and colleagues found. Each variety of ribosome may be responsible for reading a subset of messenger RNAs, recent studies suggest. For instance, ribosomes containing the ribosomal protein RPS25 build all of the proteins involved in processing vitamin B12, Barna and colleagues reported July 6 in Molecular Cell. Vitamin B12 helps red blood cells and nerves work properly, among other functions. Perhaps other biological processes are also controlled, in part, by having specific types of ribosomes build particular proteins, Barna said.

In unpublished work presented at the meeting, Barna and colleagues also found that certain ribosome varieties may be important at different stages of embryonic development. The researchers coaxed embryonic stem cells growing in lab dishes to develop into many types of cells. The team then examined the ribosomal proteins found in each type of cell. Of the 80 ribosomal proteins examined, 31 changed protein levels in at least one cell type, Barna said. The finding may indicate that specialized ribosomes help set a cell’s identity.

Although Barna’s idea of diverse ribosomes goes against the classical textbook view, “the concept is not heretical at all,” says Vassie Ware, a molecular cell biologist at Lehigh University in Bethlehem, Pa., not involved in the work.
These findings may help explain why some people with mutations in certain ribosomal protein genes develop conditions such as Diamond-Blackfan anemia — a blood disorder in which the bone marrow doesn’t make enough red blood cells — but don’t have problems in other body tissues, Ware says.

That disease is caused by mutations in the RPL5 and RPL11 genes, which encode ribosomal building blocks. If all ribosomes were alike, people with mutations in ribosomal components should have malfunctions all over their bodies, or might not ever be born. RPL5 and RPL11 proteins may be part of specialized ribosomes that are important in the bone marrow but not elsewhere in the body.

Despite their name, pelican spiders aren’t massive, fish-eating monstrosities. In fact, the shy spiders in the family Archaeidae are as long as a grain of rice and are a threat only to other spiders.

Discovering a new species of these tiny Madagascar spiders is tough, but Hannah Wood has done just that — 18 times over.

Wood, an arachnologist at the Smithsonian National Museum of Natural History in Washington D.C., analyzed the genes and anatomy of live and museum pelican spider specimens to find these new species. She describes them in a paper published online January 11 in ZooKeys.
Like other pelican spiders, the new species have an elongated “neck” and beaklike pincers, or chelicerae. The way they use those long chelicerae to strike from a distance, earned them another name: assassin spiders. Once impaled, the helpless prey dangles from these meat hooks until the venom does its work (SN: 3/22/14, p. 4).

Probing the spiders’ tiny anatomy under a microscope, Wood looked for hints to distinguish one species from another. Arachnologists often look to spiders’ genitals: Males and females from the same species typically evolved specially shaped organs to mate. If the “lock” doesn’t fit the “key,” the spiders are likely of a different species.

Thanks to Wood, 18 more species of pelican spiders — some of which were previously misclassified — now have names. Eriauchenius rafohy honors an ancient Madagascar queen, and E. wunderlichi, an eminent arachanologist. Wood, one of the foremost experts on pelican spiders, says she expects there are still more species to find. Perhaps an E. woodi?

A teenage girl climbed into an underground cave around 13,000 years ago. Edging through the ink-dark chamber, she accidentally plunged to her death at the bottom of a deep pit.

Rising seas eventually inundated the cave, located on Central America’s Yucatán Peninsula. But that didn’t stop scuba divers from finding and retrieving much of the girl’s skeleton in 2007.

“First Face of America,” a new NOVA documentary airing February 7 on PBS, provides a closeup look at two dangerous underwater expeditions that resulted in the discovery and salvaging of bones from one of the earliest known New World residents, dubbed Naia.
The program describes how studies of Naia’s bones (SN: 6/14/14, p. 6) and of genes from an 11,500-year-old infant recently excavated in Alaska have generated fresh insights into how people populated the Americas. Viewers watch anthropologist and forensic consultant James Chatters, who directed scientific studies of Naia’s remains, as he reconstructs the ancient teen’s face and charts the lower-body injuries that testify to what must have been a rough life.
In one suspenseful scene, cameras record Chatters talking with scuba divers shortly before the divers descend into the submerged cave to collect Naia’s bones. The scientist describes how thousands of years of soaking in seawater have rendered the precious remains fragile. He uses a plaster cast of a human jaw to demonstrate for scuba diver Susan Bird how to handle Naia’s skull so that it stays intact while being placed in a padded box. Bird’s worried expression speaks volumes.

“On the day of the dive, there was so much tension, so many people on the verge of freaking out,” Bird recalls in the show. When the divers return from their successful mission, collective joy breaks out.
The scene then shifts to a lab where Chatters painstakingly re-creates what Naia looked like. Asian-looking facial features raise questions about how the ancient youth ended up in Central America. That’s where University of Alaska Fairbanks anthropologist Ben Potter enters the story. In 2013, Potter and colleagues excavated the remains of two infant girls at an Alaskan site dating nearly to Naia’s time. Analysis of DNA recovered from one of the infants , described in the Jan. 11 Nature , supports a scenario in which a single founding Native American population reached a land bridge that connected northeast Asia to North America around 35,000 years ago. As early as 20,000 years ago, those people had moved into their new continent, North America. Naia’s face reflects her ancestors’ Asian roots.
In tracing back how people ended up in the Americas, NOVA presents an outdated model of ancient humans moving out of Africa along a single path through the Middle East around 80,000 years ago. Evidence increasingly indicates that people started leaving Africa 100,000 years ago or more via multiple paths (SN: 12/24/16, p. 25). That’s a topic for another show, though. In this one, Naia reveals secrets about the peopling of the Americas with a lot of help from intrepid scuba divers and state-of-the-art analyses. It’s fitting that a slight smile creases her reconstructed face.

Bedbugs leave a lasting legacy.

Their poop contains a chemical called histamine, part of the suite of pheromones that the insects excrete to attract others of their kind. Human exposure to histamine can trigger allergy symptoms like itchiness and asthma. (Our bodies also naturally release histamine when confronted with an allergen.) Histamine stays behind long after the bedbugs disappear, scientists report February 12 in PLOS ONE.

Researchers from North Carolina State University in Raleigh collected dust from apartments in a building with a chronic bedbug infestation. After a pest control company treated the apartments by raising the temperature to a toasty 50° Celsius, the researchers sampled the dust again. They compared those two sample groups with a third, from area homes that hadn’t had bedbugs for at least three years.

Dust from the infested apartments had levels of histamine chemical that were 22 times as much as the low amount found in bedbug-free houses, the researchers found. And while the heat treatment got rid of the tiny bloodsuckers, it didn’t lower the histamine levels.

Future pest control treatments might need to account for bedbugs’ long-term effects.

AUSTIN, Texas — An analysis of the metals in dozens of Picasso’s bronze sculptures has traced the birthplace of a handful of the works of art to the outskirts of German-occupied Paris during World War II.

This is the first time that the raw materials of Picasso’s sculptures have been scrutinized in detail, conservation scientist Francesca Casadio of the Art Institute of Chicago said February 17 at the annual meeting of the American Association for the Advancement of Science. And the elemental “fingerprints” help solve a mystery surrounding the sculptures’ origins.
“In collaboration with curators, we can write a richer history of art that is enriched by scientific findings,” Casadio said.

Casadio and colleagues from the Art Institute of Chicago and Northwestern University in Evanston, Ill., studied 39 bronzes in the collection of the Picasso Museum in Paris. The team used a portable X-ray fluorescence spectrometer to record the amount of copper, tin, zinc and lead at several points on each sculpture.
Based on the percentage of tin versus zinc in the bronze, “we found that there are compositional groups that relate to a specific foundry,” Casadio said. Seventeen sculptures had a foundry mark on them, so the researchers could relate metal mixes to specific foundries.
But seven sculptures lack foundry marks. Based on their composition, researchers pegged five to a specific foundry — that of Émile Robecchi, a craftsman whose workshop sat in the southern outskirts of Paris. Original invoices from the foundry surfaced two years ago and revealed when some of the pieces were cast. For instance, the description, weight and size written on one invoice confirmed that the bronze of Tête de femme de profil (Marie­Thérèse) — a portrait of one of Picasso’s mistresses originally sculpted in plaster in 1931 — was cast at the foundry in February 1941.
At that time, the war had been under way for years and the Germans had just occupied Paris. Picasso worried that his fragile plaster sculptures could be easily destroyed and sought to have them cast in bronze.

The team’s analysis also found two distinct mixtures of bronze that came out of the Robbechi foundry. That difference makes sense in the context of 1940s occupied Paris, when the Germans instituted laws requiring that people turn in certain metals to go toward war efforts, Casadio said.

“A lot of [foundries’] archives are incomplete or nonexistent,” Casadio said. The new analysis “reinforces why it’s really important to collaborate and how science adds the missing piece of the puzzle.”

Chile’s Atacama Desert is so dry that some spots see rain only once a decade. Salt turns the sandy soil inhospitable, and ultraviolet radiation scorches the surface. So little can survive there that scientists have wondered whether snippets of DNA found in the soil are just part of the desiccated skeletons of long-dead microbes or traces of hunkered-down but still living colonies.

A rare deluge has solved that mystery. Storms that dumped a few centimeters of rain on the Atacama in March 2015 — a decade’s worth in one day — sparked a microbial superbloom, researchers report February 26 in Proceedings of the National Academy of Sciences.
That storm initially threw a wrench into plans for scientists to get a snapshot of microbial life under normal, hyperarid conditions in the Atacama. “But in the end, it came back as a lucky stroke,” says study coauthor Dirk Schulze-Makuch, an astrobiologist at the Technische Universität Berlin. He and his colleagues drove mining vehicles into the desert to collect soil samples just a few weeks after the storm, and then returned again in 2016 and 2017 to track changes as the moisture dissipated.

The team found microbes — a mix of extremophile archaea, bacteria and fungi — that were tolerant of desiccation, salinity and UV radiation. The kinds of species were fairly consistent across sampling sites, which suggests there’s something of a native microbial community that can survive in this salty sand by going dormant between periods of moisture, says Schulze-Makuch.

Schulze-Makuch and his colleagues also found evidence for enzymes that are by-products of cellular metabolism. And traces of ATP, the molecule that cells use for energy, lingered inside cells. Those markers of life were the most bountiful at the first sampling time, and then declined as the soil dried out again.

Collectively, it’s evidence that microbes aren’t just dying and leaving their DNA behind in the Atacama — they’re laying low to live another day. That’s encouraging to Schulze-Makuch: He’s interested in the Atacama as a proxy for conditions on Mars.
Armando Azua-Bustos, an astrobiologist at the Centro de Astrobiología in Madrid who was not part of this study, agrees. “If we’re finding that, on Earth, truly dry places are still inhabited,” he says. “That opens the door to finding life elsewhere in the universe.”

Honeybees and bumblebees have a way to resist toxic compounds in some widely used insecticides.

These bees make enzymes that help the insects break down a type of neonicotinoid called thiacloprid, scientists report March 22 in Current Biology. Neonicotinoids have been linked to negative effects on bee health, such as difficulty reproducing in honeybees (SN: 7/26/16, p 16). But bees respond to different types of the insecticides in various ways. This finding could help scientists design versions of neonicotinoids that are less harmful to bees, the researchers say.
Such work could have broad ramifications, says study coauthor Chris Bass, an applied entomologist at the University of Exeter in England. “Bees are hugely important to the pollination of crops and wild flowers and biodiversity in general.”

Neonicotinoids are typically coated on seeds such as corn and sometimes sprayed on crops to protect the plants from insect pests. The chemicals are effective, but their use has been suspected to be involved in worrisome declines in numbers of wild pollinators (SN Online: 4/5/12).

Maj Rundlöf of Lund University in Sweden helped raise the alarm about the insecticides. In 2015, she reported that neonicotinoid-treated crops reduced the populations of bees that fed from the plants. Rundlöf, who was not involved with the new study, says the new research is important because it clarifies differences between the insecticides. “All neonicotinoids are not the same,” she says. “It’s a bit unrealistic to damn a whole group of pesticides.”

Bass and his colleagues, which include scientists from Bayer, one of the main producers of neonicotinoids, investigated resistance to thiacloprid by looking at bees’ defense systems. The team focused on enzymes known as P450s, which can metabolize toxic chemicals, breaking them down before they affect the bee nervous system. The researchers used drugs to inhibit groups of P450 enzymes. When the family enzymes called CYP9Q was inhibited, bees became 170 times as sensitive to thiacloprid, dying from a much smaller dose, the researchers found. Discovering the enzymes’ protective power could lead to more effective ways to simultaneously avoid harming bees and help crops.
“We live in an era that uses pesticides,” Rundlöf says. “We need to figure out the ones that are safest.”

Mass: About 60 billion suns’ worth.

Location: The galaxy NGC1052–DF2, about 65 million light-years from Earth.

An unusual galaxy is surprisingly lacking in dark matter, scientists report March 28 in Nature.

In typical galaxies, normal matter is swamped by dark matter, an unidentified invisible substance that makes up most of the matter in the universe. The existence of dark matter explains the unexpectedly fast speeds at which stars swirl around galaxies, and how galaxies move within clusters.
But one galaxy, NGC1052–DF2, appears to have less dark matter than normal matter, or potentially none at all. Given its mass — it holds stars with about 200 million times the mass of the sun — it would be expected to have about 300 times as much dark matter as normal matter. That adds up to about 60 billion times the sun’s mass in missing dark matter.

Using observations from several telescopes, Yale University astronomer Pieter van Dokkum and colleagues studied 10 bright clumps of stars within the galaxy, known as globular clusters, and measured their velocities. The more mass there is in the galaxy, the faster the clusters should move around it. So if dark matter were present, the clusters should cruise at a relatively rapid clip. Instead, the clusters were moving slowly, indicating a dark matter–free zone.
In most galaxies, stars move faster than naïvely expected, which suggests dark matter lurks within them, providing an extra source of mass. Most physicists believe dark matter is an undetected type of particle. But some think that the hint of extra matter might be a mirage, caused by an incomplete understanding of the workings of gravity. These researchers favor a theory known as modified Newtonian dynamics, or MOND (SN: 3/31/07, p. 206), which adjusts the rules of gravity to make sense of stars’ motions, without requiring any new, elusive particles.

The new study, says van Dokkum, bolsters the idea that dark matter is real, instead of an illusion. “Until now, whenever we saw a galaxy, we also saw dark matter,” says van Dokkum. “We didn’t know for sure whether dark matter and galaxies were two separable things.”

Because MOND proposes tweaking the laws of physics, then — if correct — its effects should be felt in every galaxy across the cosmos. That makes it hard for MOND to explain the unusually slow speeds of the star clusters in NGC1052–DF2.

“It’s intriguing, but it’s not something I’m going to lose sleep over,” says Stacy McGaugh, an astrophysicist at Case Western Reserve University in Cleveland. He studies MOND and thinks the theory might still be able to explain this galaxy. That’s because NGC1052–DF2 is nestled close to another galaxy. That other galaxy could alter MOND’s predictions, perhaps explaining why the star clusters move slowly. The effect of that proximity needs to be taken into account to determine if MOND can explain the observations, he says.

Still, McGaugh acknowledges that NGC1052–DF2 is problematic for MOND. But it is also problematic for the standard dark matter picture, he says, as it’s not clear how such a galaxy could form in the first place. Most galaxies are thought to form around clumps of dark matter, so a galaxy devoid of the stuff is hard to explain.

NGC1052–DF2 is unusual in other ways. It’s a faint, ghostly blob known as an ultradiffuse galaxy. Although about the same volume as the Milky Way, NGC1052–DF2 contains many fewer stars. Scientists are struggling to understand why such galaxies look so different from most others (SN: 12/10/16, p. 18). Finding an ultradiffuse galaxy without dark matter further complicates the puzzle.

If scientists can explain how the galaxy formed, it might improve understanding of the properties of dark matter. “In physics we always want to find really extreme laboratories to test theories and ideas,” says astrophysicist James Bullock of the University of California, Irvine. This galaxy is extreme indeed.