Science News

[Duke of Buckingham]

Milky Way will be hit head-on
Andromeda galaxy will smash directly into ours

By Alexandra Witze
Web edition : 4:26 pm

The monstrous Andromeda galaxy and the Milky Way are destined to hit head-on, not in a glancing blow, new observations from the Hubble Space Telescope show.

By precisely locating the same stars in Andromeda in 2002 and then again in 2010, astronomers at the Space Telescope Science Institute in Baltimore have calculated how the galaxy has moved against the background of deep space — confirming that the galaxy’s sideways motion is but a fraction of the speed at which it’s hurtling toward the Milky Way.

Andromeda is 2.5 million light-years away and closing in on the Milky Way at 250,000 miles per hour. The cosmic collision will transform the heavens into a hallucinogenic swirl 4 billion years from now. Calculations suggest that the sun will be tossed out during this galactic mash-up, to drift erratically in the eventual single, large galaxy that will coalesce from the two.

The work will appear in an upcoming Astrophysical Journal.

Four billion years from now, a collision between the Milky Way (left) and Andromeda (right) galaxies will have ripped out streams of stars, warped the galactic shapes and turned Earth’s night sky into a dramatic swirl of starlight. Credit: NASA, ESA, Z. Levay and R. van der Marel/STScI, A. Mellinger

[Duke of Buckingham]

Quantum teleportation leaps forward
Two teams improve long-distance transmission of information about particles

By Alexandra Witze
Web edition : Thursday, May 31st, 2012

Quantum information has leapt through the air about 100 kilometers or more in two new experiments, farther and with greater fidelity than ever before. The research brings truly long-distance quantum communication networks, in which satellites could beam encrypted information around the globe, closer to reality.

Both studies involve quantum teleportation, which transports the quantum state of one particle onto another. This Star Trek–like feat is possible because of a phenomenon called entanglement, in which pairs of particles become linked in such a way that measuring a certain property of one instantly determines the same property for the other, even if separated by large distances.

In teleportation, two people — physicists call them Alice and Bob — share one each of a pair of entangled particles. Alice measures a property on her particle and sends Bob a note, through regular channels, about what she did. Bob then knows how to alter his own particle to match Alice’s. Bob’s particle then possesses the information that had been contained in Alice’s, which was obliterated by her measurement. Thus the information has been “teleported” from Alice’s lab to Bob’s.

Physicists first teleported quantum information in 1997 using a single pair of entangled photons, or particles of light. Since then researchers have slowly upped the ante, teleporting with larger groups of photons, over longer distances and sometimes using atoms as the entangled particles.

In 2007 Anton Zeilinger of the University of Vienna and his colleagues set a distance record by using a pair of entangled photons to transmit a piece of quantum information over 143 kilometers, between two of the Canary Islands. In new work, posted online May 17 at arXiv.org, the team reports a cleaner and more robust version of the same experiment using multiple entangled photons.

This time around, the scientists added a phase shift into the laser beams that made the final measurement cleaner and easier to pick out from background signals. The technique, called “active feed-forward,” is “an essential ingredient in future applications such as communication between quantum computers,” Zeilinger and his colleagues wrote. Team members declined interviews because the paper is not yet published.

“Our experiment confirms the maturity and applicability of the involved technologies in real-world scenarios, and is a milestone towards future satellite-based quantum teleportation,” they wrote.

In the second experiment, Chinese researchers entangled many photons together and teleported information 97 kilometers across a lake in China. That’s two orders of magnitude farther than any other multiphoton teleportation experiment, say Jian-Wei Pan of the University of Science and Technology of China in Shanghai and his colleagues. The work appeared online May 9 on arXiv.org.

Pan’s team also developed a way to track moving teleportation signals more accurately, which again could help make the final result more robust. “Our results show that even with high-loss ground to satellite uplink channels, quantum teleportation can be realized,” the scientists wrote.

Both Zeilinger and Pan next want to teleport information to a satellite in low-earth orbit. That distance is about three times that already accomplished in the Canary Islands, but because there are fewer air molecules to interfere with the signals at higher altitudes it may be easier to do.

[Duke of Buckingham]

Plate Tectonics Cannot Explain Dynamics of Earth and Crust Formation More Than Three Billion Years Ago

ScienceDaily (June 1, 2012) — The current theory of continental drift provides a good model for understanding terrestrial processes through history. However, while plate tectonics is able to successfully shed light on processes up to 3 billion years ago, the theory isn't sufficient in explaining the dynamics of Earth and crust formation before that point and through to the earliest formation of planet, some 4.6 billion years ago. This is the conclusion of Tomas Naæraa of the Nordic Center for Earth Evolution at the Natural History Museum of Denmark, a part of the University of Copenhagen. His new doctoral dissertation has just been published by the journal Nature.

"Using radiometric dating, one can observe that Earth's oldest continents were created in geodynamic environments which were markedly different than current environments characterised by plate tectonics. Therefore, plate tectonics as we know it today is not a good model for understanding the processes at play during the earliest episodes of Earths's history, those beyond 3 billion years ago. There was another crust dynamic and crust formation that occurred under other processes," explains Tomas Næraa, who has been a PhD student at the Natural History Museum of Denmark and the Geological Survey of Denmark and Greenland -- GEUS.

Plate tectonics is a theory of continental drift and sea floor spreading. A wide range of phenomena from volcanism, earthquakes and undersea earthquakes (and pursuant tsunamis) to variations in climate and species development on Earth can be explained by the plate tectonics model, globally recognized during the 1960's. Tomas Næraa can now demonstrate that the half-century old model no longer suffices.

"Plate tectonics theory can be applied to about 3 billion years of the Earth's history. However, the Earth is older, up to 4.567 billion years old. We can now demonstrate that there has been a significant shift in the Earth's dynamics. Thus, the Earth, under the first third of its history, developed under conditions other than what can be explained using the plate tectonics model," explains Tomas Næraa. Tomas is currently employed as a project researcher at GEUS.

Central research topic for 30 years

Since 2006, the 40-year-old Tomas Næraa has conducted studies of rocks sourced in the 3.85 billion year-old bedrock of the Nuuk region in West Greenland. Using isotopes of the element hafnium (Hf), he has managed to shed light upon a research topic that has puzzled geologists around the world for 30 years. Næraa's instructor, Professor Minik Rosing of the Natural History Museum of Denmark considers Næraa's dissertation a seminal work:

"We have come to understand the context of the Earth's and continent's origins in an entirely new way. Climate and nutrient cycles which nourish all terrestrial organisms are driven by plate tectonics. So, if the Earth's crust formation was controlled and initiated by other factors, we need to find out what controlled climate and the environments in which life began and evolved 4 billion years ago. This fundamental understanding can be of great significance for the understanding of future climate change," says Minik Rosing, who adds that: "An enormous job waits ahead, and Næraas' dissertation is an epochal step."

“Plate tectonics theory can be applied to about 3 billion years of the Earth’s history. However, the Earth is older, up to 4.567 billion years old. We can now demonstrate that there has been a significant shift in the Earth’s dynamics. Thus, the Earth, under the first third of its history, developed under conditions other than what can be explained using the plate tectonics model,” explains Tomas Næraa. (Credit: Image courtesy of University of Copenhagen)

[Duke of Buckingham]

Stone Age art gets animated
Ancient cave paintings depict moving animals

By Bruce Bower
Web edition : Friday, June 1st, 2012

Welcome to Animation Domination, Stone Age style. By about 30,000 years ago, Europeans were using cartoon-like techniques to give observers the impression that lions and other wild beasts were charging across cave walls, two French investigators find.

Ancient artists created graphic stories in caves and illusions of moving animals on rotating bone disks, say archaeologist Marc Azéma of the University of Toulouse–Le Mirail in France and Florent Rivère, an independent artist based in Foix, France.

“Stone Age artists intended to give life to their images,” Azéma says. “The majority of cave drawings show animals in action.”

Flickering torches passed over painted scenes would have heightened onlookers’ sense of seeing live-action stories, the researchers suggest in the June Antiquity.

Azéma and Rivère summarize their 20 years of research on Stone Age animation techniques, much of it previously published in French, in the new paper. They also describe for the first time examples of animation at two French caves, Chauvet and La Baume Latrone.

“Movement and action are indeed represented in cave art in different manners,” remarks archaeologist Jean Clottes, a rock-art specialist who now serves as honorary conservator general of heritage for the French Ministry of Culture. Clottes led a 1998 investigation of Chauvet’s 30,000-year-old cave paintings.

A 10-meter-long Chauvet painting represents a hunting story, Azéma proposes. The story begins by showing several lions, ears back and heads lowered, stalking prey. Mammoths and other animals appear nearby. In a second section of the painting, a pride of 16 lions, some drawn smaller than the rest to appear farther away, lunge toward fleeing bison.

Stone Age artists meant to depict animal movement in such scenes, Azéma says. An eight-legged bison at Chauvet, for example, resulted from superimposing two images of the creature in different stances to create the appearance of running.

In France, 53 figures in 12 caves superimpose two or more images to represent running, head tossing and tail shaking. At the famous Lascaux Cave, 20 painted animals display multiple heads, legs or tails.

A carving on an animal bone from another Stone Age cave in France depicts three freeze-frame images of a running lion, another way to represent motion.

Ancient Europeans also invented a kind of animation toy, the researchers suggest. Sites in France and Spain have yielded stone and bone disks, typically with center holes, showing opposing images of sitting and standing animals.

In experiments conducted since 2007, Rivère has reproduced these engraved disks and looped strands of animal tendon through the center holes. By twisting these strands, the disks rotate back and forth rapidly enough to make animals appear to be sitting down and standing up.

That’s the principle behind the thaumatrope, a device invented (or perhaps reinvented) in 1825. Two strings attached to the ends of a disk or card with an image on each side — say, a vase opposite a bouquet of flowers — were twirled between the fingers, so that the rotating pictures appeared to combine into a single image, such as flowers in a vase.

Thaumatropes are considered precursors of movie cameras and animation.

Ancient artists at France's Chauvet Cave superimposed drawings of two bison to create an eight-legged beast intended to depict trotting or running, two researchers say. Credit: M. Azema, J. Clottes, Chauvet Cave scientific team

[Duke of Buckingham]

How a mosquito survives a raindrop hit
Lightweight insects can ride water droplets, as long as they separate in time

By Susan Milius
Web edition : Monday, June 4th, 2012

A raindrop hitting a mosquito in flight is like a midair collision between a human and a bus. Except that the mosquito survives.

New experiments show how the insect’s light weight works in its favor, says engineer David Hu of the Georgia Institute of Technology in Atlanta. In essence, the (relatively) huge, fast drop doesn’t transfer much of its momentum to a little wisp of an insect. Instead the falling droplet sweeps the insect along on the downward plunge. As Hu puts it, the mosquito “just rides the drop.”

The trick is breaking away from that drop before it and the insect splash into the ground. Mosquitoes that separate themselves in time easily survive a raindrop strike, Hu and his colleagues report online June 4 in the Proceedings of the National Academy of Sciences.

Such studies help reveal how animals evolved to take advantage of flight, says biologist Tyson Hedrick of the University of North Carolina at Chapel Hill. Mosquito tricks may also inspire engineers designing swarms of tiny flying robots, or interest physicists and mathematicians studying complex fluid dynamics at this scale.

Plenty of lab work has investigated how flying animals recover from disturbances, but there’s little work on raindrops because those collisions are very hard to study, Hu says. To mimic raindrop speed of about 9 meters per second, he and his colleagues tried dripping water off the third floor of a building toward ground-level mosquitoes. “It’s the worst game of darts you can imagine,” he says. “You have no hope of hitting them.”

Finally, Hu sprayed streams of water from a pump at caged lab mosquitoes and then refined the process by spraying mosquito-sized beads. His team found that mosquitoes hit with water survived using an insect version of tai chi: Move with the blow instead of resisting it. A raindrop can reach 50 times the mass of a mosquito, and after colliding, “the mosquito becomes a stowaway,” Hu says.

The wild ride comes with danger. Mosquitoes hitchhiking on water experience acceleration 100 to 300 times the force of Earth’s gravity, the researchers found. The previous champs for surviving acceleration had been jumping fleas, at a mere 130 times Earth’s gravity.

Such studies suggest insects are making tradeoffs, Hedrick says. Mosquitoes’ small mass might allow them fly through raindrops but leave them more vulnerable to other menaces, such as wind. Larger and heavier horseflies “should have no problem with wind but might be more disturbed by raindrop impacts,” he says.

Scientists who work in the field know how readily mosquitoes can survive wet weather. “I’ve worked in the field many rainy nights,” says entomologist Nathan Burkett-Cadena of the University of South Florida in Tampa, “and received zero respite from mosquitoes during even heavy rains.”

A mosquito survives being walloped by a raindrop by riding along on its descent to the ground, scientists have found. Credit: Courtesy Tim Nowack, Andrew Dickerson and David Hu/Georgia Tech


Water drops slamming into insects can knock them partly or completely off course, this laboratory video shows.

Credit: Courtesy Andrew Dickerson and David Hu/Georgia Tech

[Duke of Buckingham]

Some newfound planets are something else
Re-evaluation suggests one-third of hot giant orbs are misclassified

By Nadia Drake
Web edition : Thursday, June 7th, 2012

When the Kepler spacecraft finds a giant planet closely orbiting a star, there’s a one in three chance that it’s not really a planet at all.

At least, that’s the case according to a new study that put some of Kepler’s thousands of candidate planets to the test using a complementary method for discovering celestial objects in stellar orbits. The results, posted June 5 on arXiv.org, suggest that 35 percent of candidate giants snuggled close to bright stars are impostors, known in the planet-hunting business as false-positives.

“Estimating the Kepler false-positive rate is one of the most burning questions in this field,” says astronomer Jean-Michel Désert of the Harvard-Smithsonian Center for Astrophysics, who has performed similar calculations for smaller planets.

Estimates by Désert and others place the false-positive rate at less than 10 percent, which isn’t necessarily contradictory given the different target populations of various research efforts.

“We cannot say anything about smaller planets,” says Alexandre Santerne, a graduate student at the University of Aix-Marseille in France and coauthor of the arXiv.org paper. “It’s just for giant planets close-in.”

Kepler looks for the periodic dimming of starlight produced by planets passing between Earth and their home stars near the constellation Cygnus. But not everything that darkens a star is a planet; smaller stars, for example, might masquerade as a planet. Instead of detecting periodic twinkles, Santerne and his colleagues looked for gyrations in host stars, the wiggles produced by orbiting planets’ gravitational tugs. Since heavy, nearby planets yank more noticeably on their stars, the team focused on giant candidates with orbits of 25 days or less.

Out of more than 2,300 possible planets, only 46 fell into that category. Eleven of these were already known planets. Santerne’s team confirmed nine more.

The remaining 26 candidates included 13 unknowns, two failed brown dwarf stars, and 11 members of binary star systems. “These can mimic clearly a planetary transit event,” says Santerne. “That’s why it’s so important to distinguish these things when you want to study planets and transits from the Kepler mission.”

After distributing the unknowns according to the observed ratios of objects, the team arrived at the 35 percent false-positive rate.

That number might seem high when compared with previous estimates, but scientists don’t consider it a serious flaw for Kepler. “This false-positive percentage is very low compared to all other transit programs,” says study coauthor and astronomer Claire Moutou, also at the University of Aix-Marseille.

The authors point to a discrepancy between their result and a 2011 study done by Timothy Morton and John Johnson at Caltech, who found a false positive rate closer to 5 percent. But comparisons between the two studies might not be so simple, Morton says, noting that the two groups calculated different things. Instead of looking at impostor rates in a specific population of planets, Morton determined the probability that any candidate — plucked from the sea of twinkling candidates — was real. He also excluded data from obvious impostors.

“Everything here is sort of a game of probabilities,” Morton says, pointing to the abundance of candidates. “It will be impossible to confirm them all with observations.”

As for current estimates of billions and billions of planets in the Milky Way, Moutou says those numbers are still valid. “Short period transiting planets are exotic objects, we don’t expect them to be everywhere,” she says. “The potential billion planets are more expected to be small, long-period planets. We didn’t kill those ones, fortunately.”

[Duke of Buckingham]

Invasive mite worsens honeybee viruses
Parasite’s move into Hawaiian islands lets obscure pathogen go big and bad

By Susan Milius
Web edition : Friday, June 8th, 2012

A mite that parasitizes honeybees can turn formerly small-time, local virus strains into widespread, dominant hazards.

As the Varroa destructor mite infiltrated Hawaiian bee colonies from 2007 to 2010, viral infection strength in local bees soared a million-fold, and a once-obscure but nasty strain of deformed wing virus surged to prominence. Even when beekeepers beat back the mite, the newly prominent virus remained abundant. Mite damage plus the virus shorten the lives of bees and can destroy colonies.

So far Hawaiian beekeepers have not reported the swifter, specific malady called colony collapse disorder (SN: 7/28/2007, p. 56), but the ability of the mite — now spreading globally — to reshape viral threats is worrisome, say Stephen J. Martin of the University of Sheffield in England and his colleagues in the June 8 Science.

Honeybees in Hawaii, like the one shown on the native Hawaiian tree "Ohi'a," face worsening risks from deformed wing virus as the Varroa destructor mite spreads across the islands. Credit: Courtesy of Ethel M. Villalobos

[Duke of Buckingham]

Today at 6:30 AM Lisbon time the Mars Rover should land.

Fingers crossed.

[zombie67]

About That Overpopulation Problem

Research suggests we may actually face a declining world population in the coming years.

http://www.slate.com/articles/techno...exploding.html

[zombie67]

Not so much news, but science video...