ESA’s orbiting X-ray observatory XMM-Newton has been used by a team of international astronomers to uncover part of the missing matter in the universe.
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10 years ago, scientists predicted that about half of the missing ‘ordinary’ or normal matter made of atoms exists in the form of low-density gas, filling vast spaces between galaxies.
All the matter in the universe is distributed in a web-like structure. At dense nodes of the cosmic web are clusters of galaxies, the largest objects in the universe. Astronomers suspected that the low-density gas permeates the filaments of the web.
The low density of the gas hampered many attempts to detect it in the past. With XMM-Newton’s high sensitivity, astronomers have discovered its hottest parts. The discovery will help them understand the evolution of the cosmic web.
Only about 5% of our universe is made of normal matter as we know it, consisting of protons and neutrons, or baryons, which along with electrons, form the building blocks of ordinary matter. The rest of our universe is composed of elusive dark matter (23%) and dark energy (72%).
Small as the percentage might be, half of the ordinary baryonic matter is unaccounted for. All the stars, galaxies and gas observable in the universe account for less than a half of all the baryons that should be around.
Astronomers using XMM-Newton were observing a pair of galaxy clusters, Abell 222 and Abell 223, situated at a distance of 2300 million light-years from Earth, when the images and spectra of the system revealed a bridge of hot gas connecting the clusters.
Celeste Biever and Rowan Hooper at New Scientist discuss the real world science featured in the new (Ma8, 2008) movie:
1. Superhero skin – An ‘Iron Man’ suit does not exist but portions of a wearable exoskeleton does.
2. Flying machines -SoloTrek was a flying exoskeleton that was apparently capable of travelling more than 200 kilometres. (The project shut down after a crash in 2002.) UK inventor and pilot Stuart Ross reckons his Rocketbelt packs enough power to lift him 2500 metres in the air and plans to test fly the latest model this year.
3. Friendly bots - In the movie, Stark has a friendly robot to help him build his armour. It looks too clever to be true, but in fact it is highly reminiscent of AUR. Built last year by MIT scientists, AUR is a robotic desk lamp that calculates where you are looking and moves its flexible neck to shine light on that spot.
An international team of scientists has detected that some of the glow of Earth’s aurora is polarized, an unexpected state for such emissions. Measurements of this newfound polarization in the Northern Lights may provide scientists with fresh insights into the composition of Earth’s upper atmosphere, the configuration of its magnetic field, and the energies of particles from the Sun, the researchers say.
If observed on other planets, the phenomenon might also give clues to the shape of the Sun’s magnetic field as it curls around other bodies in the solar system.
At the north and south magnetic poles, many charged particles in the solar wind —a flow of electrically charged matter from the Sun—are captured by the planet’s field and forced to plunge into the atmosphere. The particles strike atmospheric gases, causing light emissions.
Lilensten and his colleagues observed weak polarization of a red glow that radiates at an altitude of 220 kilometers. The glow results from electrons hitting oxygen atoms. The scientists had suspected that such light might be polarized because Earth’s magnetic field at high latitudes funnels the electrons, aligning the angles at which they penetrate the atmosphere.
Fluctuations in the polarization measurements can reveal the energy of the particles coming from the Sun when they enter Earth’s atmosphere, Lilensten notes. The intensity of the polarization gives clues to the composition of the upper atmosphere, particularly with regard to atomic oxygen. link
Between 1992 and 2003, scientists collected data from more than 10,000 drifting ocean buoys, which they tracked with satellites. The buoys’ movements were influenced mainly by known global currents, which are driven by wind and by differences in the temperature and salinity of seawater.
But it emerged that something else had been subtly influencing the buoys’ paths. It turned out that there were alternating strips of water running eastward or westward, a bit like parallel moving sidewalks. Niiler recalls his reaction: “My God, we’ve never seen these before.”
Satellite measurements showed that the interfaces between adjacent currents were alternately associated with slight peaks and troughs in sea level. When the team looked at this variation globally, they found that the 150-kilometre-wide bands covered pretty much every ocean.
They recorded currents flowing in opposite directions at around 40 metres per hour. The flows extend right down to the ocean floor, and the boundaries between currents are alternately associated with peaks and troughs in temperature as well as sea level. This suggests that they influence processes such as nutrient and energy flow around the oceans, but this has yet to be proven, says Niiler.
What causes the striped flows remains a puzzle. “They are a fascinating new aspect to the ocean’s circulation, but the jury is still out on the mechanisms leading to their formation,” says Geoff Vallis of the Geophysical Fluid Dynamics Laboratory at Princeton University.
He points out that similar patterns exist in atmospheric flows on other planets, for example, Jupiter. Whether similar effects are at play here is unclear, he says. link
In 1968, a sudden outbreak of startling sheep deaths in Skull Valley, Utah, was attributed to a nerve gas sprayed earlier by the Army on the nearby Dugway Proving Grounds. The investigation made by the National Communicable Disease Center was hampered by the Army's initial denial of responsibility and slowness to provide adequate gas samples for independent agencies to check. The debacle led to an overhaul of procedures concerning development of chemical weapons at Dugway. link.
Until very recently, asking what happened at or before the Big Bang was considered by physicists to be a religious question. General relativity theory just doesn’t go there – at T=0, it spews out zeros, infinities, and errors – and so the question didn’t make sense from a scientific view.
But in the past few years, a new theory called Loop Quantum Gravity (LQG) has emerged. The theory suggests the possibility of a “quantum bounce,” where our universe stems from the collapse of a previous universe. Yet what that previous universe looked like was still beyond answering.
Physicists have now developed a simplified LQG model that gives an intriguing answer: a pre-Big Bang universe might have looked a lot like ours.
“The significance of this concept is that it answers what happened to the universe before the Big Bang,” Singh told PhysOrg.com. Our study shows that the universe on the other side is very classical as ours.”
“This means that the twin universe will have the same laws of physics and, in particular, the same notion of time as in ours,” Singh said. “The laws of physics will not change because the evolution is always unitary, which is the nicest way a quantum system can evolve. In our analogy, it will look identical to its twin when seen from afar; one could not distinguish them.”
That means that our universe today, roughly 13.7 billion years after the bounce, would share many of the same properties of the pre-bounce universe at 13.7 billion years before the bounce. In a sense, our universe has a mirror image of itself, with the Big Bang (or bounce) as the line of symmetry.
Ultimately, Corichi and Singh’s model might even tell us what a future universe would look like. Depending on how fast our present universe is accelerating – which will ultimately determine its fate – there’s a possibility that a generalization of the model would predict a re-collapse of our own universe.
Human mitochondrial DNA from dried excrement recovered from Oregon's Paisley Caves is the oldest found yet in the New World -- dating to 14,300 years ago, some 1,200 years before Clovis culture.
The Paisley Caves are located in the Summer Lake basin near Paisley, about 220 miles southeast of Eugene on the eastern side of the Cascade Range. The series of eight caves are wave-cut shelters on the highest shoreline of pluvial Lake Chewaucan, which rose and fell in periods of greater precipitation during the Pleistocene.
Clovis culture began sometime between 13,200 and 12,900 years ago. Skeletal remains dating to Clovis culture have proven elusive, leaving researchers with little hard evidence beyond tell-tale cultural components such as the distinctive fluted Clovis points and other tools.
Exactly who these people living in the Oregon caves were is not known. At this point, we know they most likely came from Siberia or Eastern Asia, and we know something about what they were eating, which is something we can learn from coprolites. We're talking about human signature.
“Had the human coprolites at the Paisley Caves not been analyzed for DNA and subjected to rigorous dating methodology,” he added, "the pre-Clovis age of the artifacts recovered with the megafaunal remains could not have been conclusively proven. In other words, the pre-Clovis-aged component of this site could very well have been missed or dismissed by archaeologists.” link
