JERUSALEM: Israeli President Shimon Peres tasked Prime Minister Benjamin Netanyahu on Saturday with forming a new government after two days of intense talks with the parties recently elected to the new parliament.
"I have decided to charge Benjamin Netanyahu with forming the government," Peres said at a press conference at his official residence in Jerusalem, after 82 of the 120 members of the Knesset had declared in favour of the premier.
- AFP/de
Evelyn Husband-Thompson, widow of Columbia Commander Rick Husband, remembers the fallen crew and the devastating impact of the 2003 disaster in a ceremony Friday at the Space Mirror Memorial honoring fallen astronauts.
In an emotional memorial service, the widow of the shuttle Columbia's commander recalled their last meeting the day before launch and the devastation the families felt when they learned their loved ones had perished during re-entry 10 years ago Friday.
Speaking in front of the Space Mirror Memorial to fallen astronauts at the Kennedy Space Center's visitor complex, Evelyn Husband-Thompson shared memories of Columbia commander Rick Husband and his six crewmates, saying how proud the families were of the crew's accomplishments during their 16-day science mission.
The night before landing, the families "shared a meal together at a local restaurant," she said. "I went to bed with the NASA (television) channel left on quietly in the background and I fell asleep, thanking God for the great mission, and I was so excited for the reunion with my husband."
Instead, the families listened in disbelief at the shuttle's 3-mile-long runway the next morning as it became clear Columbia had suffered a catastrophic failure during re-entry.
"February 1, 2003, became a traumatic, shocking day," Husband-Thompson said. "Anticipating a joyful homecoming of our crew, we were jolted in the viewing area into a nightmarish stroll of fear, uncertainty, and horror that led to a crushing announcement that the crew had perished during re-entry.
"Words of sorrow, efforts to comfort, even fathoming the magnitude of loss was overwhelming that day. Looks of disbelief from one family member to another brought little comfort. The shock was so intense that even tears were not freely able to fall. They would come in the weeks, months, and years to follow, in waves and in buckets."
And in the months and years that followed, she said, "the human spirit, created by God, began to minister to my family."
"Friends and family cared for us, and countless thousands of others prayed for us. To all of you, I want to say thank you.... God bless the families of STS-107. May our broken hearts continue to heal and may beauty continue to replace the ashes. God bless you."
In an interview before the ceremony, Husband-Thompson said she remains a strong supporter of NASA and the manned space program.
"NASA's an amazing group of folks and they have been hugely supportive of us," she said. "It was Rick's dream since he was 4 years old, and obviously what happened was devastating. But it doesn't stop the cause of space exploration. I totally support it. It's contributed so much to our world."
Several hundred space managers, engineers, and acquaintances gathered to mark the 10th anniversary of the Columbia disaster, the 27th anniversary of Challenger's loss on Jan. 28, 1986, and the 46th anniversary of a launch pad fire on Jan. 27, 1967, that killed three Apollo astronauts.
Husband-Thompson chats with friends before a memorial service marking the 10th anniversary of the Columbia disaster.
Their names are carved in the Space Mirror Memorial, along with others who lost their lives in the pursuit of spaceflight.
Columbia was destroyed during re-entry when hot gas penetrated the shuttle's left wing through a hole in a leading edge heat shield panel. The hole was caused by the impact of foam insulation that fell from the ship's external tank during launch 16 days earlier.
As a postaccident investigation would show, NASA had a long history of problems with "foam shedding," but continued to launch shuttles without a thorough understanding of the implications.
"In looking back, there was no malicious intent by any engineer or manager in the decisions they made that led to the loss of Columbia and her crew," said Kennedy Space Center Director Robert Cabana, a veteran shuttle commander. "They were doing their very best to be successful. But we are human and oftentimes, when lacking sufficient data, we make poor decisions. And that results in events like Apollo 1, Challenger, and Columbia."
Cabana said NASA had learned from its mistakes "and we are going on to even greater accomplishments."
"But we must never forget the hard lessons that we learned in the past," he told the crowd. "It's important that we pause to remember and reflect. We must do our very best to prevent something like that from ever happening again. Too much is at stake."
William Gerstenmaier, director of manned space operations at NASA Headquarters in Washington, echoed Cabana's sentiments, saying the Columbia accident "wasn't caused by a single event or a single person, but by a series of technical and cultural missteps stemming all the way back to the first shuttle launch in 1981 when ice and foam first struck the (orbiter)."
"This was a first indication we had a design problem," he said. "But we continued to fly without fully investigating the consequences of foam hitting the orbiter. We continued to lose foam on many missions and this reinforced the idea that all was well. We did not stay hungry, and we didn't deeply analyze the implications of foam being released at precisely the wrong moment."
He cautioned engineers to stay vigilant, to "recognize even the smallest potential flaw can become a big problem."
"In honor of the Columbia crew, it is our job to be aware of the technical subtleties and be creative about understanding them and the underlying problems," he said. "Even small problems can surface as major failures."
At the conclusion of the memorial ceremony, three NASA T-38 jets roared overhead in a "missing man" formation. Gospel singer BeBe Winans performed his song "Ultimate Sacrifice," and Husband-Thompson, assisted by Gerstenmaier, Cabana, and Eileen Collins, commander of the first post-Columbia shuttle mission, placed a wreath at the base of the Space Mirror.
Photograph by Dieu Nalio Chery, AP
The magnitude 7 earthquake that struck near Port au Prince, Haiti, in January 2010 so devastated the country that recovery efforts are still ongoing.
Professional dancer Georges Exantus, one of the many casualties of that day, was trapped in his flattened apartment for three days, according to news reports. After friends dug him out, doctors amputated his right leg below the knee. With the help of a prosthetic leg, Exantus is able to dance again. (Read about his comeback.)
Why We Love It
"This is an intimate photo, taken in the subject's most personal space as he lies asleep and vulnerable, perhaps unaware of the photographer. The dancer's prosthetic leg lies in the foreground as an unavoidable reminder of the hardships he faced in the 2010 earthquake. This image makes me want to hear more of Georges' story."—Ben Fitch, associate photo editor
"This image uses aesthetics and the beauty of suggestion to tell a story. We are not given all the details in the image, but it is enough to make us question and wonder."—Janna Dotschkal, associate photo editor
Published February 1, 2013
(Official White House Photo by Pete Souza)
After a week of speculation over the authenticity of claims by President Obama that he regularly participated in skeet shooting at Camp David, the White House released a photograph today showing him firing a shotgun.
The photo shows Obama targeting clay pigeons at the presidential retreat last August, according to the White House. In an interview published Sunday the president said he shoots skeet “all the time” during stays at the compound. The comment was a response to a question of whether he had ever held a gun.
“Not the girls, but oftentimes guests of mine go up there. And I have a profound respect for the traditions of hunting that trace back in this country for generations. And I think those who dismiss that out of hand make a big mistake,” he said.
READ: Skeet-Shooter Obama Has ‘Respect’ for Hunters
But amid a White House-backed push for stronger gun-control in the U.S., some questioned whether the claim was an embellishment or even true. Politicians who regularly use firearms often advertise the fact to gun owners, but ABC News has not found a quote from Obama referencing his own use before the statement on Sunday.
“If he is a skeet shooter, why have we not heard of this?” asked Rep. Marsha Blackburn, R-Tenn. “Why have we not seen photos? Why has he not referenced it at any point in time as we have had this gun debate that is ongoing?”
PHOTOS: From 2009 to Now: Obama Since His First Inauguration
Appearing on CNN this week, the congresswoman challenged Obama to a skeet shooting contest.
The Associated Press reported in 2010 a second-hand reference to the activity. After a visit with the Texas Christian University rifle team, a student reportedly told the AP that Obama told her he’d practiced shooting with the Secret Service.
This the only known image of Obama holding a gun.
Asked Monday about the president’s interview, Press Secretary Jay Carney responded to reporters about how often the president participates in shooting.
“I would refer you simply to his comments,” he said. “I don’t know how often. He does go to Camp David with some regularity, but I’m not sure how often he’s done that.”"
On Wednesday, Carney addressed the issue again, telling press that when the president travels to “Camp David, he goes to spend time with his family and friends and relax, not to produce photographs.”
White House officials and some Obama supporters have compared skeet-doubters to “skeeters” or “birthers,” the label fixed to those who deny Obama was born on U.S. soil in his home state of Hawaii, and therefore is ineligible for the Oval Office.
“Attn skeet birthers. Make our day — let the photoshop conspiracies begin!” senior adviser David Plouffe wrote on Twitter this morning, referencing the popular photo-editing software.
In January, Obama signed several executive orders strengthening gun regulation and revealed proposals that, if enacted, would include bans on assault weapons and high capacity magazines. The move began in response to the December mass-shooting of 20 first graders and six adults at a Newtown, Conn., elementary school.
INFOGRAPHIC: Guns in America: By The Numbers
A recent ABC News/Washington Post poll found 53 percent of Americans viewed Obama’s gun control plan favorably, 41 percent unfavorably.
The photo’s release comes two days before Obama travels to Minneapolis for a speech continuing his push for tougher gun control, where he is expected to appear alongside local law enforcement officials.
Astrophile is our weekly column on curious cosmic objects, from the solar system to the far reaches of the multiverse
Object: Titanium oxide snow
Location: The hot-Jupiter planet HD 209458b
There is something magical about waking up to discover it has snowed during the night. But there's no powdery white blanket when it snows on exoplanet HD 209458b. Snow there is black, smoky and hot as hell – resembling a forest fire more than a winter wonderland. Put it this way: you won't be needing mittens.
HD 209458b belongs to a family called hot Jupiters, gas-giant planets that are constantly being roasted due to their closeness to their sun. By contrast, the gas giants in our immediate neighbourhood, including Jupiter, are frigid, lying at the solar system's far reaches.
HD 209458b is also noteworthy because it is tidally locked, so one side is permanently facing towards its star while the other is in perpetual night. On the face of it, these conditions wouldn't seem to invite snow: temperatures on the day side come close to 2000° C, while the night side is comparatively chilly at around 500° C.
Snow made of water is, of course, impossible on this scorched world, but the drastic temperature differential sets up atmospheric currents that swirl material from the day side to night and vice versa. That means that any substances with the right combination of properties might be gaseous on the day side and then condense into a solid on the night side, and fall as precipitation. Say hello to titanium oxide snow.
Although oxides of titanium make up only a small component of a hot Jupiter's atmosphere, these compounds have the right properties to fall as snow. But there was a snag that could have put a stop to any blizzards. Older computer models of hot Jupiters suggested that titanium oxides condensing in the air on the night side would snow – and remain on the relatively cool surface forever. "Imagine on Earth if you had no mechanism to evaporate water, it would never rain," says Vivien Parmentier of the Côte d'Azur Observatory in Nice, France.
Now he and colleagues have created a more detailed 3D computer model that shows that the snow can become a gas again as it falls and the temperature and pressure increase. Strong updraughts can then blow the titanium oxides back to the upper atmosphere. "The gas can come back on the top layers and snow again and again," says Parmentier.
Snowfall on HD 209458b would be like none you've ever seen. Though titanium dioxide is white and shiny, for example, the snowflakes would also contain silica oxides from the atmosphere, making them black. Since the atmosphere is also dark, snowstorms on the planet would be a smoky affair, the opposite of the white-outs we get on Earth. "It would be like being in the middle of a forest fire," says Parmentier.
Although the team studied a particular hot Jupiter, their model should apply equally to other planets of this type, suggesting hot snow is a common occurrence. Parmentier says we may have already spotted snow clouds on another hot Jupiter, HD 189733b, as spectral analysis of the planet suggests the presence of microscopic particles in its atmosphere
David Sing of the University of Exeter, UK, who helped identify such particles on HD 189733b, says the team's new model goes a long way to explaining how titanium oxides behave on hot Jupiters. "We're pretty used to water condensing on Earth; there it is titanium because the temperatures are so much hotter."
Hot, black snow – now that would be something to wake up to.
Reference: http://arxiv.org/abs/1301.4522
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SANTIAGO: Rafael Nadal admits that he could find things tough on his return to competitive tennis next week after seven months on the sidelines.
The Spaniard arrived in Santiago on Friday amid great expectation and was received by Chilean president Sebastian Pinera at his residence, La Moneda Palace.
Nadal, an 11-time Grand Slam winner, is preparing to take part in the ATP event in Vina del Mar, 120 kilometres to the west, next week.
He will team up with Juan Monaco in the doubles on Tuesday, before his singles return on Wednesday.
Nadal is a wildcard entry into the singles event, and sought to play down talk of a winning comeback after such a long time on the sidelines.
"Undoubtedly the clay surface is a little less aggressive on my knee," he said, explaining why he chose to return in the first clay-court tournament of the calendar year.
"My aim is to compete courageously and hopefully the knee will stand up to it.
"There is always the possibility that I will lose in the first round after so many months without competing."
World number five Nadal won the last of his 11 Grand Slam titles to date at last year's French Open but has not played a competitive match since losing to Czech outsider Lukas Rosol in the second round at Wimbledon last June.
"Of course I still feel pain in the knee that sometimes stops me from playing, but you have to start sometime and I am here to try and give my best and hope that my knee comes through it," he added.
"The injury looks much better. There is no risk that I will suffer any setbacks here."
- AFP/jc
The release of the BlackBerry Z10 smartphone will be remembered as either a breath of new life for the company or a last gasp as it fell into irrelevance. By all accounts, the Z10 is a tremendous step forward in design and hardware over previous BlackBerrys, but it's coming at a time when the smartphone market is crowded with established contenders with massive app stores already in place.
CNET contributor Ben Parr says that the Z10 and its keyboard-wielding buddy Q10 face a major deficit on the app front. He argues that iOS and
Android have an insurmountable lead in the app race, meaning the Z10 will never attract the new customers BlackBerry needs to grow and survive.
Others suggest the smaller app store and lack of popular apps like Instagram don't matter for a company that specializes in the enterprise market. Some expect the BlackBerry app store to catch up over time.
No matter how you look at it, the Z10 faces fierce competition. Its security and management features make it an attractive buy for businesses, but some have already deserted the BlackBerry platform. CNET reader loose_screw writes, "My company, and many others that I know of, have already switched from BB to iPhone/Android. I don't think a new BB phone is going to make us switch back to BB."
The Z10 and its modern design has been a long time coming, but we'll have to wait and see if it and the Q10 can pull BlackBerry back from tottering on the brink. Is the Z10 the smartphone savior BlackBerry needs to save the company? Vote in our poll and talk it out in the comments.
A mile beneath the ocean's waves waits a buried cache beyond any treasure hunter's wildest dreams: gold, copper, zinc, and other valuable minerals.
Scientists have known about the bounty for decades, but only recently has rising demand for such commodities sparked interest in actually surfacing it. The treasure doesn't lie in the holds of sunken ships, but in natural mineral deposits that a handful of companies are poised to begin mining sometime in the next one to five years.
The deposits aren't too hard to find—they're in seams spread along the sea floor, where natural hydrothermal vents eject rich concentrations of metals and minerals.
These underwater geysers spit out fluids with temperatures exceeding 600ºC. And when those fluids hit the icy seawater, minerals precipitate out, falling to the ocean floor.
The deposits can yield as much as ten times the desirable minerals as a seam that's mined on land.
While different vent systems contain varying concentrations of precious minerals, the deep sea contains enough mineable gold that there's nine pounds (four kilograms) of it for every person on Earth, according to the National Oceanic and Atmospheric Administration's (NOAA) National Ocean Service.
At today's gold prices, that's a volume worth more than $150 trillion.
Can an Industry Be Born?
But a fledgling deep-sea mining industry faces a host of challenges before it can claim the precious minerals, from the need for new mining technology and serious capital to the concerns of conservationists, fishers, and coastal residents.
The roadblocks are coming into view in the coastal waters of Papua New Guinea, where the seafloor contains copper, zinc, and gold deposits worth hundreds of millions of dollars and where one company, Nautilus Minerals, hopes to launch the world's first deep-sea mining operation.
Last year, the Papua New Guinean government granted the Canadian firm a 20-year license to mine a site 19 miles (30 kilometers) off their coast, in the Bismarck Sea in the southwestern Pacific Ocean. The company plans to mine the site, known as Solwara 1, by marrying existing technologies from the offshore oil and gas industry with new underwater robotic technologies to extract an estimated 1.3 million tons of minerals per year.
Samantha Smith, Nautilus's vice president for corporate social responsibility, says that ocean floor mining is safer, cleaner, and more environmentally friendly than its terrestrial counterpart.
"There are no mountains that need to be removed to get to the ore body," she says. "There's a potential to have a lot less waste ... No people need to be displaced. Shouldn't we as a society consider such an option?"
But mining a mile below the sea's surface, where pressure is 160 times greater than on land and where temperatures swing from below freezing to hundreds of degrees above boiling, is trickier and more expensive than mining on terra firma.
Nautilus says it will employ three remote-controlled construction tools that resemble giant underwater lawn mowers to cut the hard mineral ore from the seafloor and pump it a mile up to a surface vessel.
That vessel would be equipped with machinery that removes excess water and rock and returns it to the mining site via pipeline, an effort aimed at avoiding contaminating surface waters with residual mineral particles. The company would then ship the rock to a concentrator facility to remove the mineral from the ore.
An Unknown Impact
At least that's the plan.
But the ocean floor is still a mysterious place, seldom visited by humans, compounding the known difficulties of working at sea.
Scientists weren't even able to prove the existence of underwater hydrothermal vents until 1977.
That year, an expedition of geologists, geochemists, and geophysicists from the Woods Hole Oceanographic Institute, Oregon State University, the Massachusetts Institute of Technology, Stanford University, and the U.S. Geological Survey proved their existence in the Galapagos rift with cameras and a manned dive in the submersible Alvin.
The animal-rich landscape and huge temperature shifts came as a surprise.
"When the first people went down there, and saw these things, they had no idea," says Mike Coffin, a geophysicist and executive director of the Institute for Marine and Antarctic Studies at the University of Tasmania in Australia. "The submersible had windows that could melt at temperatures lower than what was coming out of the vent."
And, in contrast to the desert-like landscape that the scientists expected, it turns out that hydrothermal vents are home to lots of life: snails the size of tennis balls, seven-foot-long (two-meter-long) tubeworms, purple octopi, and all-white crabs and skates.
It turns out that, far from the sun's life-giving light, the same minerals now eyed by the mining industry support lively communities.
Now some researchers fear that deep-sea mining could jeopardize those communities by altering their habitats before the systems have been fully explored and explained.
"We're still just grappling with this reality of commercialization of the deep sea," says Cindy Van Dover, director of Duke University's Marine Lab. "And scrambling to figure out what we need to know."
Van Dover was aboard the first manned biological exploration of the hydrothermal vents in 1982 and was the only woman to pilot the submersible Alvin. Despite the strides that have been made in understanding the deep sea, she says, it's still a young science.
When it comes to the impacts of mining on any deep-sea life, "there's a particular type of research that needs to be done," she says. "We haven't yet studied the ecosystem services and functions of the deep sea to understand what we'd lose.
"We don't yet know what we need to know," Van Dover says.
Conservationists also say they want to know more about the vent ecosystems and how they will be mined.
"The whole world is new to the concept of deep-sea mining," says Helen Rosenbaum, coordinator of the Deep Sea Mining Campaign, a small activist group in Australia that campaigns against mining the Solwara 1 site.
"This is going to be the world's first exploitation of these kinds of deep resources. The impacts are not known, and we need to apply precautionary principles," she says. "If we knew what the impacts were going to be, we could engage in a broad-based debate."
Rosenbaum says some communities in Papua New Guinea are raising concerns about the sustainability of local livelihoods in the face of mining and say they aren't receiving the information they need.
The Deep Sea Mining Campaign is especially concerned about the impacts of toxic heavy metals from the mining activities on local communities and fish. The group claims that the Environmental Impact Statement for the Solwara 1 mine hasn't effectively modeled the chemistry of the metals that would be stirred up by the mining process or the ocean currents that could transport them closer to land.
"The Solwara 1 project is scheduled to be a three-year project," Rosenbaum says. "The mining company thinks they'll be out of there before there are problems with heavy metal uptake. We might not see the effects for several years."
A report released in November 2012 by the Deep Sea Mining Campaign ties exploratory pre-mining activities and equipment testing by Nautilus to "cloudy water, dead tuna, and a lack of response of sharks to the age-old tradition of shark calling."
Shark calling is a religious ritual in which Papau New Guineans lure sharks from the deep and catch them by hand.
Another concern for Deep Sea Mining Campaign: Papua New Guinea's government has a 30 percent equity share in the minerals as part of a seabed lease agreement with Nautilus.
The company and government are currently involved in a lawsuit over these finances, but the Deep Sea Mining Campaign says government investment could compromise its regulatory efforts.
Mining for Dollars
Nautilus' Smith insists that the company has taken a careful and transparent approach. "The biggest challenge the company faces," she says, "is funding."
Fluctuations in commodity pricing, the high cost of working underwater, and financial disagreements with the Papua New Guinean government have been setbacks for Nautilus.
Last November, the company announced that it had suspended construction of its mining equipment in order to preserve its financial position. Smith says that Nautilus is still committed to finding a solution for its work in Papua New Guinea, and that the company could still extract minerals as early as 2014.
Other companies around the world are also exploring the possibility of mining throughout the South Pacific.
The International Seabed Authority, which regulates use of the seafloor in international waters in accordance with the United National Convention on the Law of the Sea, has granted 12 exploratory permits to various governments—including India, France, Japan, Russia, China, Korea, and Germany—in roughly the last decade.
And as long as the promise of riches await, more firms and governments will be looking to join the fray.
"It's economics that drive things," says the University of Tasmania's Coffin. "Tech boundaries are being pushed, and science just comes along behind it and tries to understand what the consequences are. Ideally, it should be the other way around."
The retired Alabama trucker who shot a school bus driver and is now holding a kindergarten student in an underground bunker was scheduled to be in court Wednesday to answer for allegedly shooting at his neighbors in a dispute over a damaged speed bump.
Jimmy Lee Dykes, 65, has been holed up in a 6 by 8 foot bunker 4 feet underground with a 5-year-old autistic boy named Ethan since Tuesday, when he boarded a school bus and asked for two 6 to 8 year old boys. School bus driver Charles Albert Poland Jr., 66, was shot several times by Dykes, and died trying to protect the children.
Police said that they do not think that Dykes had any connection to Ethan, and that SWAT teams and police are negotiating with Dykes.
"I could tell you that negotiators continue to communicate with the suspect and that there's no reason to believe the child has been harmed," Sheriff Wally Olson said late Thursday.
PHOTOS: Worst Hostage Situations
Dykes' neighbor Claudia Davis told The Associated Press that he had yelled at her and fired his gun at her, her son James Davis, Jr. and her baby grandson after he claimed their truck caused damage to a speed bump in the dirt road near his property. No one was hurt, but Davis, Jr. told the AP that he believes the shooting and kidnapping are connected to the scheduled court hearing.
"I believe he thought I was going to be in court and he was going to get more charges than the menacing, which he deserved, and he had a bunch of stuff to hide and that's why he did it," he said.
This was not Dykes' only run-in with people in the neighborhood, where he had come to be known as a menacing figure. Neighbor Ronda Wilbur told the AP that Dykes beat her 120-pound dog with a lead pipe when it entered the side of the dirt rode his trailer sits on. Wilbur said her dog died a week later.
Early last year, two pit bulls belonging to neighbors Mike and Patricia Smith escaped and got into his yard. Patricia Smith said that Dykes threatened to shoot her children when they went to retrieve them.
Neighbor Ronda Wilbur said that Dykes would be seen on his property at all hours of the day.
"It could be 2 o'clock in the morning, it could be midnight. He was out there either digging or moving dirt," she said.
As the underground standoff moved into its fourth day, tensions grow in this small community near Midland City, Ala., which is now enveloped by SWAT teams and police.
"That's an innocent kid. Let him go back to his parents, he's crying for his parents and his grandparents and he does not know what's going on," Midland City Mayor Virgil Skipper told ABC News. "Let this kid go."
Neighbor Jimmy Davis said that he has seen the bunker where Dykes has been known to hunker down for up to eight days.
"He's got steps made out of cinder blocks going down to it, Davis said. "It's lined with those red bricks all in it."
Police say he may have enough supplies to last him weeks.
Former FBI profiler and ABC News consultant Brad Garrett said there's a distinct reason why authorities are keeping details about Dykes under wraps.
"One of reasons they are keeping negations closed and not releasing his picture, is to try to insulate the situation, so they don't have a situation where they don't have to deal with his anger and rage," he said.
Meanwhile, children are trying to understand why this happened to their friend
"He always comes up to my house to play," 10-year-old Trisha Beaty told ABC News. "I miss him. I miss him a lot."
Birds of a feather flock together and now so do brainless, inanimate blobs. Made of microscopic particles, the artificial swarms could shed light on the mysterious mechanisms behind the natural swarming seen in fish and birds. They might also lead to materials with novel properties like self-healing.
Animals such as birds, fish and even humans that move together in swarms have individual intelligence, but Jérémie Palacci of New York University and colleagues wondered whether inanimate objects could also swarm. "From a physicist's point of view, if many different systems behave in the same way there must be an underlying physical rule," he says.
To explore this idea, the team created microscopic plastic spheres, each one with a cubic patch of haematite, an iron oxide, on its surface. When submerged in hydrogen peroxide, the spheres spread out in a disordered fashion. The team then shone blue light on the particles, causing the haematite cubes to catalyse the breakdown of any nearby hydrogen peroxide into water and oxygen. As hydrogen peroxide concentration dropped temporarily in these regions due to the reaction, osmotic forces cause more hydrogen peroxide to flow into them, and that in turn buffets the spheres. The whole process then repeats.
When two spheres come close enough to each other, the balance of chemical forces shifts so that the two spheres are attracted. If there are enough spheres in the same place they will cluster together to form shapes of symmetrically arranged particles, which the team call crystals (see video, above). These crystals continue to be buffeted by the movement caused by the breakdown of hydrogen peroxide – but now they move together as one object, replicating a life-like swarm. Switch off the light, however, and the reaction stops, causing the crystal to lose the forces that hold it together, and the particle distribution becomes disordered once again.
"This system shows that even though the particles have no social interaction or intelligence, you can exhibit collective behaviour with no biology involved," says Palacci. Since the haematite is magnetic, it is even possible to steer the crystals in one direction by applying a magnetic field. Such control might be useful if the artificial swarms are to be harnessed for applications.
As the particles automatically fill any gaps that form in the crystal, again thanks to the chemical dynamics of the system, they could be used to create a self-assembling, self-healing material. The work is published in the journal Science today.
Iain Couzin of Princeton University says these kinds of systems are very useful for studying biological collective behaviour because researchers have complete control over their interactions – unlike natural systems.
His team has its own swarming experiment published in the same issue of Science, based on schools of fish that prefer to stay in shade. Their paper shows that shining a light on some of the fish in the school causes them to speed up, to get away from the light. But as a result, non-illuminated fish also speed up, even though, if acting purely as individuals, they would have had no reason to do so. "We show just by using simple interactions that schools can have a sense of responsiveness to the environment that individuals do not have," he says.
Couzin sees no reason why such behaviour should be limited to natural systems. "In future it may be possible to create systems of particles that can make collective decisions – something we often think of as only possible in biological systems," he says.
Journal references: Living crystals: Science, DOI: 10.1126/science.1230020; Fish: Science, DOI: 10.1126/science.1225883
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