Excerpt from csmonitor.comThanks to a phenomenon known as gravitational lensing, the Hubble Space Telescope has captured four images of the same supernova explosion.
For the first time, a cosmic magnifying glass has allowed scientists to see the same star explosion four times, possibly offering a revealing glimpse into these explosive stellar deaths and the nature of the accelerating universe.
Astronomers using the Hubble Space Telescope have captured four images of a supernova explosion in deep space thanks to a galaxy located between Earth and the massive star explosion. You can see how Hubble saw the supernova in this NASA video. The galaxy cluster warped the fabric of space and time around it — like a bowling ball placed on a bed sheet — allowing scientists to see the supernova in four images.
"It was predicted 50 years ago that a supernova could be gravitationally lensed like this, but it's taken a long time for someone to find an example," lead study author Patrick Kelly, an astronomer at the University of California, Berkeley told Space.com. "It's fun to have been able to find the first one."
The supernova, which was discovered on Nov. 11, 2014, is located about 9.3 billion light-years away from Earth, near the edge of the observable universe. The researchers have named the distant supernova SN Refsdal in honor of the late Norwegian astrophysicist Sjur Refsdal, a pioneer of gravitational lensing studies. Due to gravitational lensing, "the supernova appears 20 times brighter than its normal brightness," study co-author Jens Hjorth, head of the Dark Cosmology Centre at the Niels Bohr Institute at the University of Copenhagen, said in a statement.
The lensing galaxy, which is about 5 billion light-years from Earth, is part of a large cluster of galaxies known MACS J1149.6+2223. In 2009, astronomers discovered that this cluster was the source of the largest known image of a spiral galaxy ever seen through a gravitational lens.
The four images of the supernova each appeared separately over the course of a few weeks. This is because light can take various paths around and through a gravitational lens, arriving at Earth at different times.
Using gravity as a lens
Gravity is created when matter warps the fabric of reality. The greater the mass of an object, the more space-time curves around that object and the stronger its gravitational pull, the discovery enshrined in Einstein's theory of general relativity, which celebrates its centennial this year.
As a result, gravity can also bend light like a lens, meaning objects see n behind powerful gravitational fields, such as those of massive galaxies, are magnified. Gravitational lensing was first discovered in 1979, and today gravitational lenses can help astronomers see features otherwise too distant and faint to detect with even the largest telescopes.
"These gravitational lenses are like a natural magnifying glass. It's like having a much bigger telescope," Kelly said in a statement. "We can get magnifications of up to 100 times by looking through these galaxy clusters."
When light is far from a gravitationally lensing mass, or if the gravitationally lensing mass is not especially large, only "weak lensing" occurs, barely distorting the light. However, when the light comes from almost exactly behind the gravitationally lensing mass, "strong lensing" can happen.
When a strongly lensed object occupies a large patch of space — for instance, if it's a galaxy — it can get smeared into an "Einstein ring" surrounding a gravitationally lensing mass. However, strong lensing of small, pointlike items — for instance, super-bright objects known as quasars — often produces multiple images surrounding the gravitationally lensing mass, resulting in a so-called "Einstein cross."
The observations of SN Refsdal mark the first time astronomers on Earth have witnessed strong lensing of a supernova, with four images of an exploding star arrayed as an Einstein cross.
An expanding universe
These new findings could help scientists measure the accelerating rate at which the universe is expanding, researchers say.
A computer model of the lensing cluster suggests the scientists missed chances to see the lensed supernova 50 and 10 years ago. However, the model also suggests more images of the explosion will repeat again within the next 10 years.
The timing of when all these images of the supernova arrive depends on the gravitational pull of the matter generating the gravitational lens. So, by measuring those times, the researchers hope to map how visible normal matter and invisible dark matter is distributed in the lensing galaxy.
Dark matter is currently one of the greatest mysteries in science, a poorly understood substance thought to make up five-sixths of all matter in the universe. A better understanding of how dark matter is behaving in this gravitationally lensing cluster might help shed light on the material's nature, Kelly said.
Analyzing when the images arrive could also help scientists pinpoint the rate at which the universe is expanding. Although there are already several ways to measure the cosmic expansion rate, "there has been a lot of heated debate between different methods, so it'd be interesting to see how this new technique might affect the area," Kelly said. "It's always nice to have completely independent measurements of the same quantity."
The scientists detailed their findings in the March 6 issue of the journal Science.
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The Future of Technology in 2015?
Excerpt from
cnet.com
The year gone by brought us more robots, worries about artificial intelligence, and difficult lessons on space travel. The big question: where's it all taking us?
Every year, we capture a little bit more of the future -- and yet the future insists on staying ever out of reach.
Consider space travel. Humans have been traveling beyond the atmosphere for more than 50 years now -- but aside from a few overnights on the moon four decades ago, we have yet to venture beyond low Earth orbit.
Or robots. They help build our cars and clean our kitchen floors, but no one would mistake a Kuka or a Roomba for the replicants in "Blade Runner." Siri, Cortana and Alexa, meanwhile, are bringing some personality to the gadgets in our pockets and our houses. Still, that's a long way from HAL or that lad David from the movie "A.I. Artificial Intelligence."
Self-driving cars? Still in low gear, and carrying some bureaucratic baggage that prevents them from ditching certain technology of yesteryear, like steering wheels.
And even when these sci-fi things arrive, will we embrace them? A Pew study earlier this year found that Americans are decidedly undecided. Among the poll respondents, 48 percent said they would like to take a ride in a driverless car, but 50 percent would not. And only 3 percent said they would like to own one.
"Despite their general optimism about the long-term impact of technological change," Aaron Smith of the Pew Research Center wrote in the report, "Americans express significant reservations about some of these potentially short-term developments" such as US airspace being opened to personal drones, robot caregivers for the elderly or wearable or implantable computing devices that would feed them information.
Let's take a look at how much of the future we grasped in 2014 and what we could gain in 2015.
Space travel: 'Space flight is hard'
In 2014, earthlings scored an unprecedented achievement in space exploration when the European Space Agency landed a spacecraft on a speeding comet, with the potential to learn more about the origins of life. No, Bruce Willis wasn't aboard. Nobody was. But when the 220-pound Philae lander, carried to its destination by the Rosetta orbiter, touched down on comet 67P/Churyumov-Gerasimenko on November 12, some 300 million miles from Earth, the celebration was well-earned.A shadow quickly fell on the jubilation, however. Philae could not stick its first landing, bouncing into a darker corner of the comet where its solar panels would not receive enough sunlight to charge the lander's batteries. After two days and just a handful of initial readings sent home, it shut down. For good? Backers have allowed for a ray of hope as the comet passes closer to the sun in 2015. "I think within the team there is no doubt that [Philae] will wake up," lead lander scientist Jean-Pierre Bibring said in December. "And the question is OK, in what shape? My suspicion is we'll be in good shape."
The trip for NASA's New Horizons spacecraft has been much longer: 3 billion miles, all the way to Pluto and the edge of the solar system. Almost nine years after it left Earth, New Horizons in early December came out of hibernation to begin its mission: to explore "a new class of planets we've never seen, in a place we've never been before," said project scientist Hal Weaver. In January, it will begin taking photos and readings of Pluto, and by mid-July, when it swoops closest to Pluto, it will have sent back detailed information about the dwarf planet and its moon, en route to even deeper space.
Also in December, NASA made a first test spaceflight of its Orion capsule on a quick morning jaunt out and back, to just over 3,600 miles above Earth (or approximately 15 times higher than the International Space Station). The distance was trivial compared to those those traveled by Rosetta and New Horizons, and crewed missions won't begin till 2021, but the ambitions are great -- in the 2030s, Orion is expected to carry humans to Mars.
In late March 2015, two humans will head to the ISS to take up residence for a full year, in what would be a record sleepover in orbit. "If a mission to Mars is going to take a three-year round trip," said NASA astronaut Scott Kelly, who will be joined in the effort by Russia's Mikhail Kornienko, "we need to know better how our body and our physiology performs over durations longer than what we've previously on the space station investigated, which is six months."
There were more sobering moments, too, in 2014. In October, Virgin Galactic's sleek, experimental SpaceShipTwo, designed to carry deep-pocketed tourists into space, crashed in the Mojave Desert during a test flight, killing one test pilot and injuring the other. Virgin founder Richard Branson had hoped his vessel would make its first commercial flight by the end of this year or in early 2015, and what comes next remains to be seen. Branson, though, expressed optimism: "Space flight is hard -- but worth it," he said in a blog post shortly after the crash, and in a press conference, he vowed "We'll learn from this, and move forward together." Virgin Galactic could begin testing its next spaceship as soon as early 2015.
The crash of SpaceShipTwo came just a few days after the explosion of an Orbital Sciences rocket lofting an unmanned spacecraft with supplies bound for the International Space Station. And in July, Elon Musk's SpaceX had suffered the loss of one of its Falcon 9 rockets during a test flight. Musk intoned, via Twitter, that "rockets are tricky..."
Still, it was on the whole a good year for SpaceX. In May, it unveiled its first manned spacecraft, the Dragon V2, intended for trips to and from the space station, and in September, it won a $2.6 billion contract from NASA to become one of the first private companies (the other being Boeing) to ferry astronauts to the ISS, beginning as early as 2017. Oh, and SpaceX also has plans to launch microsatellites to establish low-cost Internet service around the globe, saying in November to expect an announcement about that in two to three months -- that is, early in 2015.
One more thing to watch for next year: another launch of the super-secret X-37B space place to do whatever it does during its marathon trips into orbit. The third spaceflight of an X-37B -- a robotic vehicle that, at 29 feet in length, looks like a miniature space shuttle -- ended in October after an astonishing 22 months circling the Earth, conducting "on-orbit experiments."
Self-driving cars: Asleep at what wheel?
Spacecraft aren't the only vehicles capable of autonomous travel -- increasingly, cars are, too. Automakers are toiling toward self-driving cars, and Elon Musk -- whose name comes up again and again when we talk about the near horizon for sci-fi tech -- says we're less than a decade away from capturing that aspect of the future. In October, speaking in his guise as founder of Tesla Motors, Musk said: "Like maybe five or six years from now I think we'll be able to achieve true autonomous driving where you could literally get in the car, go to sleep and wake up at your destination." (He also allowed that we should tack on a few years after that before government regulators give that technology their blessing.)Google has long been working on its own robo-cars, and until this year, that meant taking existing models -- a Prius here, a Lexus there -- and buckling on extraneous gear. Then in May, the tech titan took the wraps off a completely new prototype that it had built from scratch. (In December, it showed off the first fully functional prototype.) It looked rather like a cartoon car, but the real news was that there was no steering wheel, gas pedal or brake pedal -- no need for human controls when software and sensors are there to do the work.
Or not so fast. In August, California's Department of Motor Vehicles declared that Google's test vehicles will need those manual controls after all -- for safety's sake. The company agreed to comply with the state's rules, which went into effect in September, when it began testing the cars on private roads in October.
Regardless of who's making your future robo-car, the vehicle is going to have to be not just smart, but actually thoughtful. It's not enough for the car to know how far it is from nearby cars or what the road conditions are. The machine may well have to make no-win decisions, just as human drivers sometimes do in instantaneous, life-and-death emergencies. "The car is calculating a lot of consequences of its actions," Chris Gerdes, an associate professor of mechanical engineering, said at the Web Summit conference in Dublin, Ireland, in November. "Should it hit the person without a helmet? The larger car or the smaller car?"
Robots: Legging it out
So when do the robots finally become our overlords? Probably not in 2015, but there's sure to be more hand-wringing about both the machines and the artificial intelligence that could -- someday -- make them a match for homo sapiens. At the moment, the threat seems more mundane: when do we lose our jobs to a robot?The inquisitive folks at Pew took that very topic to nearly 1,900 experts, including Vint Cerf, vice president at Google; Web guru Tim Bray; Justin Reich of Harvard University's Berkman Center for Internet & Society; and Jonathan Grudin, principal researcher at Microsoft. According to the resulting report, published in August, the group was almost evenly split -- 48 percent thought it likely that, by 2025, robots and digital agents will have displaced significant numbers of blue- and white-collar workers, perhaps even to the point of breakdowns in the social order, while 52 percent "have faith that human ingenuity will create new jobs, industries, and ways to make a living, just as it has been doing since the dawn of the Industrial Revolution."
Still, for all of the startling skills that robots have acquired so far, they're often not all there yet. Here's some of what we saw from the robot world in 2014:
Teamwork: Researchers at the École Polytechnique Fédérale De Lausanne in May showed off their "Roombots," cog-like robotic balls that can join forces to, say, help a table move across a room or change its height.
A sense of balance: We don't know if Boston Dynamics' humanoid Atlas is ready to trim bonsai trees, but it has learned this much from "The Karate Kid" (the original from the 1980s) -- it can stand on cinder blocks and hold its balance in a crane stance while moving its arms up and down.
Catlike jumps: MIT's cheetah-bot gets higher marks for locomotion. Fed a new algorithm, it can run across a lawn and bound like a cat. And quietly, too. "Our robot can be silent and as efficient as animals. The only things you hear are the feet hitting the ground," MIT's Sangbae Kim, a professor of mechanical engineering, told MIT News. "This is kind of a new paradigm where we're controlling force in a highly dynamic situation. Any legged robot should be able to do this in the future."
Sign language: Toshiba's humanoid Aiko Chihira communicated in Japanese sign language at the CEATEC show in October. Her rudimentary skills, limited for the moment to simple messages such as signed greetings, are expected to blossom by 2020 into areas such as speech synthesis and speech recognition.
Dance skills: Robotic pole dancers? Tobit Software brought a pair, controllable by an Android smartphone, to the Cebit trade show in Germany in March. More lifelike was the animatronic sculpture at a gallery in New York that same month -- but what was up with that witch mask?
Emotional ambition: Eventually, we'll all have humanoid companions -- at least, that's always been one school of thought on our robotic future. One early candidate for that honor could be Pepper, from Softbank and Aldebaran Robotics, which say the 4-foot-tall Pepper is the first robot to read emotions. This emo-bot is expected to go on sale in Japan in February.
Ray guns: Ship shape
Damn the photon torpedoes, and full speed ahead. That could be the motto for the US Navy, which in 2014 deployed a prototype laser weapon -- just one -- aboard a vessel in the Persian Gulf. Through some three months of testing, the device "locked on and destroyed the targets we designated with near-instantaneous lethality," Rear Adm. Matthew L. Klunder, chief of naval research, said in a statement. Those targets were rather modest -- small objects mounted aboard a speeding small boat, a diminutive Scan Eagle unmanned aerial vehicle, and so on -- but the point was made: the laser weapon, operated by a controller like those used for video games, held up well, even in adverse conditions.Artificial intelligence: Danger, Will Robinson?
What happens when robots and other smart machines can not only do, but also think? Will they appreciate us for all our quirky human high and low points, and learn to live with us? Or do they take a hard look at a species that's run its course and either turn us into natural resources, "Matrix"-style, or rain down destruction?Musk himself more than once in 2014 invoked the likes of the "Terminator" movies and the "scary outcomes" that make them such thrilling popcorn fare. Except that he sees a potentially scary reality evolving. In an interview with CNBC in June, he spoke of his investment in AI-minded companies like Vicarious and Deep Mind, saying: "I like to just keep an eye on what's going on with artificial intelligence. I think there is potentially a dangerous outcome."
He has put his anxieties into some particularly colorful phrases. In August, for instance, Musk tweeted that AI is "potentially more dangerous than nukes." And in October, he said this at a symposium at MIT: "With artificial intelligence, we are summoning the demon. ... You know all those stories where there's the guy with the pentagram and the holy water and he's like... yeah, he's sure he can control the demon, [but] it doesn't work out."
Musk has a kindred spirit in Stephen Hawking. The physicist allowed in May that AI could be the "biggest event in human history," and not necessarily in a good way. A month later, he was telling John Oliver, on HBO's "Last Week Tonight," that "artificial intelligence could be a real danger in the not too distant future." How so? "It could design improvements to itself and outsmart us all."
But Google's Eric Schmidt, is having none of that pessimism. At a summit on innovation in December, the executive chairman of the far-thinking tech titan -- which in October teamed up with Oxford University to speed up research on artificial intelligence -- said that while our worries may be natural, "they're also misguided."