Talk about a long trip. An exploding star’s burst of light traveled 13 billion years, from the early days of the universe to the present day, before being detected by astronomers here on Earth. Researchers say this exploding star is the most distant blast ever seen.
The light from the distant explosion, called a gamma-ray burst, first reached Earth on April 23 and was detected by NASA’s Swift satellite. Gamma-ray bursts are thought to be associated with the formation of star-sized black holes as massive stars collapse. Within hours, telescopes around the world were turned on the burst — the most violent explosions in the universe — observing its fading afterglow to glean clues about its source and location [SPACE.com].
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At the University of Cambridge it’s out with black holes, in with tiny vibrating strings of energy. The prestigious professorship that was most recently held by Stephen Hawking, the physicist whose great contributions to the field include new models of black holes, has been given to the string theory luminary Michael Green.
The Lucasian Professorship was established in 1663 and previous holders have included Isaac Newton [BBC News]; it’s considered one of the most prestigious academic posts in the world. Hawking held the job for 30 years, but stepped down in September following his 67th birthday, in accordance with a university rule.
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In a lab in Nanjing, China, two researchers are mucking about with what could be called the world’s first artificial black hole–but there’s no reason for alarm. The researchers, Qiang Cheng and Tie Jun Cui, haven’t created a doomsday device, but rather a nifty experiment that harnesses the strange properties of metamaterials. Physicists have already learned how to steer light around an object within a metamaterial to create an invisibility cloak…. Now Qiang and Tie have created a metamaterial that distorts space so severely that light entering it (in this case microwaves) cannot escape [Technology Review].
The lab experiment simulates a cosmological black hole, where the intense gravity curves space-time, sucking in any matter or radiation that gets too close. Not even light can escape a black hole (hence the name). The researchers couldn’t duplicate the intense gravity, but they could build a metamaterial with a physical structure that would make light curve into its central core, never to return. The device they built works only with microwaves so far, but the researchers say a visible light black hole is the next step.
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Physicists in Washington State and Louisiana recently spent two years hunting for the mysterious gravitational waves first predicted by Einstein, but detected nothing: zilch, zero, nada, nary a ripple. But that “null result” is itself of great value, researchers say, because it tells them where to look for the waves next. The findings are a nice reminder that scientific progress isn’t always about the dramatic discovery; it’s often a long, careful process of testing hypotheses, analyzing results, and heading back to the drawing board.
Einstein’s theory of general relativity states that every time mass accelerates — even when you rise up out of your chair — the curvature of space-time changes, and ripples are produced. However, the gravitational waves produced by one person are so small as to be negligible. The waves produced by large masses, though, such as the collision of two black holes or a large supernova explosion, could be large enough to be detected [SPACE.com].
Beyond those large disturbances, the universe is thought to be filled with small disturbances left over from the rapid period of expansion that followed the Big Bang, in a phenomenon known as the stochastic (meaning randomly distributed) gravitational wave background. If the expansion of the newborn universe had produced strong gravity waves, the physicists working at the two Laser Interferometer Gravitational-wave Observatory (LIGO) centers would have detected them. Since they found nothing, researchers have determined that smaller waves were produced, which they’ll need more sensitive instruments to detect. Says study coauthor Vuk Mandic: “We now know a bit more about parameters that describe the evolution of the universe when it was less than one minute old” [Sky & Telescope].
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Stephen Hawking, the world’s leading theoretical physicist, was among a group of 16 to receive the Presidential Medal of Freedom, the highest civilian award. The medal honors those who have significantly contributed to world peace, U.S. security or other endeavors.
Pres. Barack Obama presented the award, lauding Hawking’s immense contributions in spite of his physical disability due to a neurological disorder. “From his wheelchair, he has led us on a journey to the farthest and strangest reaches of the cosmos. In so doing, he has stirred our imagination and showed us the power of the human spirit,” [Sky News], Obama said of Hawking as he placed the medal around his neck. Besides his contributions to the field of physics through his research on topics like black holes and cosmology, Hawking, 67, is also the author of the best-selling science book A Brief History of Time.
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Astronomers believe they’ve found something never before detected in the universe: a black hole of intermediate size. And while that may not sound thrilling to the layman, researchers are thrilled by the discovery of the so-called “Hyper-Luminous X-ray Source 1,” which is poised at the edge of galaxy ESO 243-49. Astronomers are excited because they’ve seen plenty of small black holes and large black holes, but experts had questioned whether a medium-sized variety could exist. These middleweights, at about 500 times the mass of the sun, could represent a missing link between common stellar black holes, created by the death of a single star, and the supermassive variety that can pack the mass of millions or even billions of suns [SPACE.com].
Astronomers explain that small black holes, between three and 20 times the mass of the sun, are created when big stars collapse and leave behind a gravitational pull strong enough to block nearby light rays. Researchers have speculated that super-massive black holes result from the successive fusion of many smaller black holes. But without finding evidence of a medium-size hole, it was a tough theory to prove [Wired.com]. Supermassive black holes are of particular interest because they lurk at the hearts of most galaxies, and may play an important role in galaxy formation.
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In several labs around the world, sound waves are doing things they’ve never done before. Teams working in England and the Ukraine have made a sonic laser, or “saser,” which operates in the terahertz range, with sound waves oscillating more than a trillion times per second. Meanwhile, in an Israeli lab, researchers say they’ve created the first ever sonic black hole that traps sound waves and won’t let them escape.
The saser uses packets of sonic vibrations called “phonons” much like a regular laser uses photons. Specifically, the acoustic laser device consists of a sonic beam traveling through a “superlattice” constructed of 50 sheets of material each only atoms thick that are alternately made of gallium arsenide and aluminium arsenide, two materials found in semiconductor [CNET]. The phonons bounce back and forth inside the lattice, which causes more phonons to be released and amplifies the overall signal. The result is the formation of an intense series of synchronised phonons inside the stack, which leaves the device as a narrow saser beam of high-frequency ultrasound [New Scientist].
At the moment the terahertz saser, described in a paper published in the journal Physical Review B, is mainly a neat trick, but it may find practical applications down the line, says lead researcher Tony Kent. “Fifty years ago many eminent scientists said that light amplification by the stimulated emission of radiation [lasers] was no more than a scientific curiosity,” says Kent, but lasers are now used for everything from digital storage and cancer treatment to weaponry [New Scientist]. Kent says the new saser technology could lead to breakthroughs in imaging for tiny, nanoscale objects.
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Researchers have recalculated the mass of a gigantic black hole at the core of the M87 galaxy, and found that it’s about two times as massive as previously estimated: The new study says that M87’s black hole weighs the same as 6.4 billion suns. Researchers say the findings may indicate that many black holes have been underestimated, and also say that the results from this “local” galaxy only 50 million light-years away may solve a mystery regarding the extremely distant black holes known as quasars.
Astronomers had previously estimated M87’s total mass, calculating how much of that mass came from both the galaxy’s stars and its central black hole. But previous models didn’t have the supercomputing power to estimate the mass contributed by the galaxy’s “dark halo.” The dark halo is a spherical region surrounding the galaxy that extends beyond its main visible structure. It contains “dark matter”, an as yet unidentified material that cannot be directly detected by telescopes but which astronomers know is there from its gravitational interaction with everything else that can be seen [BBC News].
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When the universe was young, it somehow produced a giant space blob that has astronomers completely puzzled. Researchers have caught sight of an enormous patch of hot hydrogen gas officially known as a Lyman-alpha blob, named for a particular wavelength of light released when an electron loses energy in a hydrogen atom. It spans some 55,000 light years, about half the width of the Milky Way, and it sits some 12.9 billion light years from Earth. That means we are seeing it as it was 12.9 billion years ago, when the universe was just 800 million years old [New Scientist].
The blob poses a cosmological conundrum because astronomers didn’t think such a big cloud could form so early in the history of the universe. Current models hold that between 200 million and one billion years after the Big Bang, the first colossal stars formed, emitting radiation that stripped light elements of their electrons and turned the Universe into a soup of charged particles. Only after this “re-ionisation epoch” did matter as we now know it really start to clump together [BBC News]. Astronomers thought that objects as big as the newly discovered blob would take a great deal of time to gradually grow from the mergers of smaller chunks of matter.
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After yesterday’s alarming news that world-renowned physicist Stephen Hawking had been hospitalized and was “very ill” with a respiratory infection, reports from the hospital today come as a relief. According to Cambridge University, Hawking is now on the road to recovery. “He is comfortable and his family is looking forward to him making a full recovery,” the university, where Hawking is a professor of mathematics, said in a short statement [CNN].
Hawking’s ex-wife, Jane Hawking, also reassured the public. “I have been to see him and he’s fine – he’s doing well. I don’t think his condition is life-threatening” [Telegraph], she said. Others expressed their admiration for the man who hasn’t let his paralysis from Lou Gehrig’s disease slow him down. “He is amazingly resilient,” said Andrew Fabian, the head of the Royal Astronomical Society and a professor of astronomy at Cambridge. “He goes around the world — he does more traveling than most of us. … And he just seems unstoppable. It’s truly amazing” [AP].
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Image: NASA
Stephen Hawking, the world-renowned physicist and author, is reportedly “very ill” and being treated at the hospital. Says University of Cambridge spokesman Greg Hayman: “Professor Hawking is very ill…. He has been suffering from a chest infection for a number of weeks which has meant he has had to cancel a number of appointments.” Hawking was flown back to the U.K. from the U.S. at the weekend, Hayman said. He was taken to hospital at lunch time today [Bloomberg].
Hawking has remained active despite being diagnosed at 21 with ALS, (amyotrophic lateral sclerosis), an incurable degenerative disorder also known as Lou Gehrig’s disease. For some years, Hawking has been almost entirely paralyzed, and he communicates through an electronic voice synthesizer activated by his fingers [AP].
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The sound of scientific discovery isn’t the clichéd “Eureka!” It’s much more like this recent exclamation from NASA astrophysicist Alan Kogut: “What the heck is this?” Dr. Kogut remembered exclaiming when he first saw the data. “This shouldn’t be here” [The New York Times].
Kogut was looking at a measurement of cosmic radio signals detected by sensitive antennas borne aloft in a balloon, which floated 21 miles above Texas for several hours. While scanning the sky, the instruments found a booming, uniformly distributed radio noise six times louder than anyone had predicted…. The researchers calculate that the radio noise is much too large to be accounted for by the combined emissions of all the galaxies in the universe that emit radio waves [Science News].
When researchers started to contemplate where that signal may have come from, things began to get interesting. It’s possible, says Kogut, that the radio waves may have been emitted during the death of the universe’s first stars. Those stellar pioneers were brutish monsters, so the story believed by most astronomers goes, lumbering clouds of hydrogen and helium hundreds of times more massive than the Sun. They lived fast and bright and died hard, exploding or collapsing into massive black holes less than a billion years after the Big Bang, never to be seen again [The New York Times]. When they collapsed into black holes, they may have spewed forth jets of charged particles that emitted these radio waves.
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Astronomers know that at the heart of every supermassive galaxy is a giant black hole. But new data suggests that the two did not necessarily form in tandem. Instead, black holes may have formed earlier, or at least much more quickly, than their surrounding galaxies. Previous studies had revealed a striking link between black holes and the amount of gas and stars contained in [their] galaxies’ bulges — the regions that lie within a few thousand light-years of the galaxies’ cores. Regardless of their size, the bulges always turned out to be 700 times as massive as the giant black holes at the galaxies’ hubs [Science News]. New measurements of much more distant galaxies, which appear much younger, defy the expected mass ratio. In these younger pairings, the relative mass of the black holes is much greater, hinting that the black holes came first.
Researchers used the Very Large Array radio telescope in New Mexico and the Plateau de Bure Interferometer in France to measure the mass of four distant galaxies as they appeared less than two billions years after the Big Bang. From the motions of the molecular gas, which concentrates in the central part of the galaxies, the team calculated the total amount of mass in the bulges and compared that number to the mass of the central black holes [Science News]. The galactic bulges were only about 30 times more massive than their central black holes. At the American Astronomical Society’s meeting, where the work was presented, astronomer Chris Carilli said, “The simplest conclusion is that the black holes come first and they somehow grow the galaxy around them” [Wired News].
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In the violent heart of our Milky Way galaxy lies a supermassive black hole with a mass equivalent to four million suns. But although the gravitational maw gobbles up anything that gets too close, it can also set up conditions that allow for the birth of new stars just a few light years away, according to a new study. Lead researcher Elizabeth Humphreys says the results, which uncovered what appear to be two young stars as close as seven light-years from the galactic center, were surprising, as that is “one of the last places … you would expect to find stars forming” [Scientific American].
Gas clouds that approach a black hole are usually ripped apart by the intense gravitational forces, but the new finding suggests that the molecular gas at the center of the Milky Way from which the stars form is denser than previously thought. The higher density gas makes it easier for the self-gravity of the condensing cloud to overcome the strong pull of the black hole and to collapse to form new stars [SPACE.com].
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In a galaxy far, far away—11.1 billion light-years away, to be exact—researchers have discovered the telltale signature of water. The water molecules seem to be located in the galaxy’s center, where a supermassive black hole called a quasar is spewing out tons of radiation as material falls into it. The water molecules lie in clouds of dust and gas that feed the black hole, and appear to be amplifying radio waves at a specific frequency, forming what’s called a maser, or the radio equivalent of a laser [Wired News].
The quasar, called MG J0414+0534, is so far away that the light researchers are observing originated when the universe was only 2.5 billion years old. “We now know water is out there,” says Violette Impellizzeri from the Max Planck Institute (MPI) for Radio Astronomy in Bonn, Germany. “Because water masers arise close to the cores of galaxies, our result opens new interesting possibilities for studying supermassive black holes [at the galactic cores] at a time when galaxies were forming” [New Scientist].
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