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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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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The dormant Hawaiian volcano Mauna Kea has been selected as the site of the world’s largest telescope, the much-anticipated Thirty Meter Telescope. Its enormous mirror will have nine times the light-gathering capacity as the biggest telescopes operating today, and will be able to look back to the beginnings of the universe. “It will really provide the baby pictures of the universe” [Honolulu Advertiser], says Charles Blue, a spokesman for the Thirty Meter Telescope Observatory Corporation.
The telescope’s mirror, stretching 30 meters (almost 100 feet) in diameter, will be so large that it should be able to gather light that will have spent 13 billion years traveling to earth. This means astronomers looking into the telescope will be able to see images of the first stars and galaxies forming — some 400 million years after the Big Bang [AP]. The telescope is expected to be completed by 2018, but it may not be the world’s largest for long–the European Extremely Large Telescope is scheduled for completion around the same time, and will boast a 138-foot mirror.
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Astronomers have caught sight of two stars that went kaboom only 2.5 billion years after our universe was created in the Big Bang, and say that ancient explosions are the oldest and most distant supernovas ever discovered. Researchers plan to use the new technique used to identify these supernovas to find other stars that blew up in the universe’s early days, which may aid our understanding of how the universe was seeded with heavy elements.
Only a few lightweight elements – hydrogen, helium, and lithium – are thought to have been created in the big bang; all others were forged over time in the nuclear furnaces of stars and in supernovae. Since the spectrum of light from a supernova reveals the chemical composition of the exploding star, observing many such explosions would allow astronomers to trace out a chemical history of the universe [New Scientist]. Heavier metals eventually gathered in the clouds of dust that surrounded young stars, and sometimes formed parts of rocky planets like Earth.
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The European Space Agency’s Planck observatory has reached its operating temperature of a mere tenth of a degree above the lowest temperature theoretically possible given the laws of physics, known as absolute zero. That means it’s ready for its mission: Observing the oldest light in the universe, known as the cosmic microwave background, or CMB, to create the clearest picture yet of what the young universe looked like.
Although scientists have achieved temperatures closer than this to absolute zero in the laboratory, the spacecraft is likely the coldest object in space. Such low temperatures are necessary for Planck’s detectors to study the Cosmic Microwave Background by measuring its temperature across the sky. Over the next few weeks, mission operators will fine-tune the spacecraft’s instruments. Planck will begin to survey the sky in mid-August [SPACE.com], and the first batch of data is expected to be released next year. Planck was launched May 14 and will observe the CMB from a spot more than 930,000 miles from Earth.
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The solar probe Ulysses has circled the sun for more than 18 years–almost as long as the Greek hero Odysseus, also called Ulysses, was absent from home due to the Trojan War and his prolonged journey home–but the space probe doesn’t have a homecoming in its future. Ulysses will receive its final transmission tomorrow, as researchers say the scientific findings sent home by the failing spacecraft no longer justify the mission’s costs. After shut-off, Ulysses will continue to orbit the Sun, becoming in effect a man-made ‘comet’. “Whenever any of us look up in the years to come, Ulysses will be there, silently orbiting our star, which it studied so successfully during its long and active life” [SPACE.com], says mission manager Richard Marsden.
The craft has already exceeded expectations. In February 2008, mission engineers announced with great solemnity and with heaps of praise for the orbiter that the craft would fall silent within a few months. Its power supply had grown too weak to keep the craft’s fuel lines from freezing. Not so fast: Engineers figured out that they could keep the lines warm by firing the craft’s thrusters in short bursts every couple of hours [The Christian Science Monitor]. Using that clever fix, Ulysses soldiered on for another year.
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NASA’s astronauts blasted off just yesterday on a final repair mission to the Hubble Space Telescope, but two space-based telescopes scheduled to rocket into space tomorrow may soon steal the spotlight from the Hubble. The two European Space Agency observatories, named Herschel and Planck, may revolutionize our understanding of how galaxies formed in the young universe, shortly after the Big Bang. Once the telescopes are in place, says ESA science director David Southwood, the next era of space-based astronomy will then be well and truly upon us. “They are at a pivotal point,” he says. “From now on astronomy is going to be done from deep space” [Nature News].
Both telescopes will be carried into space by the same Ariane 5 rocket, which is expected to launch tomorrow from a spaceport in French Guiana. The destination for both telescopes is a remarkable position in space known as the second Lagrangian point (L2). It is one of five gravitational “sweet-spots” around the Sun-Earth system where satellites can maintain station by making relatively few orbital corrections. L2 is some 1.5 million km from Earth on its “night side”. The observatories will circle this point [BBC News], orbiting at different distances to rule out any chance of a collision. At that stable location, the telescopes will be protected from temperature swings; a crucial point since both telescopes must be kept at frigid temperatures to study the “cold universe.”
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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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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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When the universe was young, at least one stellar factory was churning out 1,000 sun-like stars every year, according to a new study. Using an array of telescopes in the French Alps, researchers carefully scrutinised a distant galaxy whose light has taken so long to reach Earth that it appears as it was just 870 million years after the big bang [New Scientist].
The Milky Way currently forms about one sun per year, says study coauthor Chris Carilli, indicating that massive galaxies may have formed very quickly in the universe’s early days.The immense scale of the stellar factory is probably due to the fact that there was a lot more gas around in the early universe, Carilli says. Matter in the universe was indeed much denser soon after the big bang, since space itself has expanded over time [New Scientist].
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Three scientists who probed the mysteries of particle physics have been awarded the Nobel Prize in physics, the Royal Swedish Academy of Sciences announced today. The winners are Yoichiro Nambu, a Tokyo-born American citizen, and Makoto Kobayashi and Toshihide Maskawa of Japan. Nambu identified a mechanism called spontaneous broken symmetry in subatomic physics. Kobayashi and Maskawa work predicted the existence of three families of elementary particles known as quarks. According to the Standard Model of particle physics, quarks are the sub-units of protons and neutrons, which together make up the nuclei of atoms [BBC News].
“Spontaneous broken symmetry conceals nature’s order under an apparently jumbled surface,” the academy said in its citation. “Nambu’s theories permeate the standard model of elementary particle physics. The model unifies the smallest building blocks of all matter and three of nature’s four forces in one single theory.” Kobayashi and Maskawa “explained broken symmetry within the framework of the standard model but required that the model be extended to three families of quarks” [AP].
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In a bizarre finding that has disrupted the current understanding of the universe, astronomers have detected evidence of a massive gravitational force beyond the horizon of the observable universe. What’s being called a dark flow appears to be pulling vast clusters of galaxies toward a 20-degree-wide patch of sky between the constellations of Centaurus and Vela. “It does fly in the face of everything we know,” said astronomer Dale Kocevski…. “I’m sure it’s going to be controversial” [Discovery News].
When scientists talk about the observable universe, they don’t just mean as far out as the eye, or even the most powerful telescope, can see. In fact there’s a fundamental limit to how much of the universe we could ever observe, no matter how advanced our visual instruments. The universe is thought to have formed about 13.7 billion years ago. So even if light started travelling toward us immediately after the Big Bang, the farthest it could ever get is 13.7 billion light-years in distance. There may be parts of the universe that are farther away (we can’t know how big the whole universe is), but we can’t see farther than light could travel over the entire age of the universe [SPACE.com].
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Our sun, which lies 26,000 light years from the center of the the Milky Way, may have been born in a different part of the galaxy and later migrated to its current position, about halfway towards the galaxy’s outer edge. A new study defies the conventional wisdom that stars spend their entire lifespans in the same galactic region, and calls into question astronomers’ theory that galaxies have certain fixed “habitable zones” where life is more likely to evolve.
“Our view of the extent of the habitable zone is based in part on the idea that certain chemical elements necessary for life are available in some parts of a galaxy’s disk but not others,” said [lead researcher] Rok Roskar…. “If stars migrate, then that zone can’t be a stationary place” [Astrobiology Magazine].
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Ever since researchers first hypothesized the existence of a mysterious force known as dark energy in the mid-1990s, they’ve scrambled for proof that the force exists, and that it is indeed gradually causing the universe’s expansion to accelerate. Now, Hawaiian astronomers say they have found evidence of dark energy’s work by looking at microwave radiation left over from the Big Bang, and how it acts as it traverses strange regions of the universe.
The findings, which will be published in an upcoming issue of Astrophysical Journal Letters [subscription required], focus on regions of space called superclusters, which are dense with galaxies, and supervoids, which are unusually empty of galaxies. “When a microwave enters a supercluster, it gains some gravitational energy and therefore vibrates slightly faster,” [lead researcher Istvan] Szapudi said. As it leaves the supercluster, he said, “it should lose exactly the amount of energy. “But if dark energy causes the universe to stretch out at a faster rate, the supercluster flattens out in the half-billion years it takes the microwave to cross it,” Szapudi said. “Thus, the wave gets to keep some of the energy as it entered the supercluster” [Honolulu Star-Bulletin].
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For million of years after the Big Bang, the universe was a dark place filled only with wisps of hydrogen and helium, as well as the mysterious substance known as dark matter that makes up much of the universe’s mass. Now, researchers have finished running a sophisticated computer program that simulated those early cosmic conditions and replicated the production of the first primordial star, which cast the first rays of starlight out into the blackness. Researchers say that the new model shows that the first star was tiny, but rapidly grew to enormous proportions before either flaming out or collapsing.
In the early universe, researchers believe that clouds of dark matter gathered and compressed pockets of hydrogen and helium gases. According the researchers’ simulation, those areas reached a tipping point around 300 million years after the Big Bang, igniting the first nuclear reactions. Over the course of about 100,000 years, according to the model, the compressed gases reach densities roughly equivalent to that of liquid water on Earth. At that point, the gases inside the halo have formed a protostar, about one-hundredth the mass of the sun [Science News].
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