‘Earth-like’ Exoplanet Could Have a Comet’s Tail

Posted: 03 Sep 2010 01:13 PM PDT

When the super-Earth COROT-7b was discovered in 2009, it was heralded as the rockiest, most truly Earth-like exoplanet yet. But a new study suggests it's more like a comet.

In a paper to be published in the journal Icarus, an international team of astronomers led by Alessandro Mura of the Italian Institute for Interplanetary Space Physics in Rome argue that, given the planet's likely composition and distance from its star, COROT-7b probably loses its surface elements to space in a long, comet-like tail of charged particles.

COROT-7b is less than twice the size of Earth and about five times Earth's mass, and orbits a sun-like star about 390 light-years away. Because COROT-7b's density is similar to Earth's, astronomers hailed it as the first rocky exoplanet discovered and one of the best candidates for hosting extraterrestrial life.

But the rocky world also sits almost 100 times closer to its star than the Earth is to the sun, and it orbits its star once every 0.85 Earth days. The temperature on the daylight side of the planet is a scorching 4000 degrees Fahrenheit, hot enough for minerals on the rocky surface to break down and release charged particles into space, where they would be picked up and blown away by the stellar wind.

"We expect that the stellar radiation pressure and the plasma environment will cause the build-up of an elongated comet-like exosphere," the authors write. Depending on what the planet is made of, and whether it was once the rocky core of a "super-Neptune" as some have suggested, the tail could be composed of elements like sodium, oxygen, magnesium or silicon oxide.

The researchers compare this vision of COROT-7b with Mercury, which has a similarly antagonistic relationship with the sun and also leaks charged particles in a long tail.

"The planet appears to be more like a 'super-Mercury' under much extremer environmental conditions," the researchers write.

The team suggests that a tail composed of sodium or calcium could theoretically be detected on COROT-7b from ground-based telescopes. Although detecting such a tail would probably eliminate COROT-7b as a candidate habitable world, "this project would be the very first attempt to learn something of the mineralogy of a rocky planet orbiting another star."

Image: 1) Artist's impression of COROT-7b, ESO/L. Calcada. 2) Model of COROT-7b's proposed sodium tail, assuming the planet is 4000 degrees Fahrenheit at its surface. A. Mura et al, Icarus 2010. doi:10.1016/j.icarus.2010.08.015

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Glint of Starlight Could Reveal Liquid Oceans on Exoplanets

Posted: 03 Sep 2010 11:54 AM PDT

The sparkle of starlight off water could be the clincher for finding oceans on extrasolar planets. And it could be observable with the tech that will be deployed in the next generation of space telescopes.

"A glinting planet looks different from a non-glinting planet, and it's detectable with current technology," said Tyler Robinson, a graduate student at the University of Washington and lead author of a new paper in Astrophysical Journal Letters. "This is one step toward proving there's liquid water at the surface of an extrasolar planet."

The proposed technique for finding wet worlds takes advantage of the same effect that makes sunsets on the Pacific coast so spectacular. The idea was suggested by Carl Sagan in 1993, and has been used to confirm the presence of liquid lakes on Saturn's moon Titan.

"The oceans do a really good job of reflecting light like a mirror," Robinson said. "Especially when you have the sun really low on the horizon, most of the sunlight comes reflected off of the water towards you. The same thing happens on the scale of a planet."

Robinson and his colleagues showed that when a planet appears crescent-shaped to an Earthly observer, starlight reflecting off oceans can make the planet appear up to twice as bright as a planet with no oceans. They also showed that the sparkle of starlight off oceans looks different from light scattered through clouds.

Most other proposed techniques for finding water on an extrasolar planet rely on taking its spectrum, or detailed measurements of the planet's atmosphere, and looking for the chemical fingerprint of two hydrogen atoms and one oxygen. But this strategy would show only that the planet hosts water vapor, not liquid oceans, and the technology is still a long way off.

"To get a good spectrum would require a big telescope that is still 10 or 20 years away from being designed or launched," said exoplanet expert Darren Williams of Penn State University, who has also studied ways to search for exo-oceans but was not involved in the new work. "That's really becoming a long-range, futuristic sort of thing."

Robinson and his colleagues proved that the glint effect could be observable with the telescope touted as the successor to Hubble: the James Webb Space Telescope, slated to launch in 2014. If the telescope is accompanied by a shield to block starlight, as suggested in the New Worlds Observer mission concept, it will be sensitive to the light glinting off extrasolar oceans.

To test whether the glint would be visible to the new space telescope, Robinson imagined he was an alien observer looking back at Earth. He used data from weather satellites and NASA's EPOXI mission to build a computer model of what Earth would look like to a distant observer, including weather patterns, seasonal changes and wind speeds over the oceans that would influence the height of waves.

The model "does explain what we can observe on our own planet from other spacecraft in the solar system, so you can trust the model that they're using to do these calculations," Williams said.

Unfortunately, even the James Webb Space Telescope won't be able to take sharp enough images of exoplanets to tell whether the planet is in a crescent phase, much less directly see a glint. The telescope will just see a dot of light getting brighter and dimmer as it circles its star.

"We have to look for evidence of this glint when we just have this pale, tiny speck of light on our camera," Robinson said.

So Robinson and colleagues added up all the light reflected by the model Earth to see if the glint would light up the whole planet enough to be seen from space. They found that Earth in the crescent phase would be twice as bright with a glint as without it. "That's significant," Robinson said. "A factor of two is a really big deal."

The researchers also found that the glint effect is strongest in the near infrared part of the electromagnetic spectrum, just beyond what the human eye can see. These wavelengths of light are not as badly scattered as they pass through a planet's atmosphere. Conveniently, they are also the wavelengths that the new space telescope will be most attuned to.

"The James Webb Space Telescope is really well suited to do this," Robinson said.

Looking for the glint would not be the first line of investigation, however. Rather, Robinson imagines the technique could confirm that a good exo-Earth candidate, a plant that is about Earth's size planet and lies the right distance from its star to support liquid water, actually does have oceans at its surface.

"We would first worry about whether the planet is even remotely Earthlike before looking for the glint," he said.

"What's nice about this result here is that we have a chance of doing interesting things with Earthlike planets with the James Webb Space Telescope, which is basically sitting on the hangar waiting to be launched into space," commented Williams. "We can do that in our research lifetimes. That's the most exciting thing about this."

Image: 1) Astrophysical Journal Letters/Tyler Robinson. Left: NASA Astrobiology Institute's Virtual Planetary Laboratory. Right: Earth and Moon Viewer. 2) NASA

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NASA Flies First Drone Over Hurricane

Posted: 03 Sep 2010 10:22 AM PDT

Hurricane Earl is waning as it moves northward up the east coast of the United States. Some of the first researchers to notice the weakening had front row seats, watching the eye of the hurricane via drone flights.

In addition to the usual cadre of satellites, NASA is using a small fleet of unmanned aircraft into, over and around the hurricane as it tracks north from the Caribbean. While flying into a hurricane is nothing new, Earl is the first hurricane that NASA has observed using their unmanned Global Hawk observation aircraft (pictured above).

The aircraft are giving researchers a 3-D view of the temperature, waver vapor and cloud liquid water in the hurricane. Using a High-Altitude Monolithic Microwave Integrated Circuit Sounding Radiometer, or HAMSR in official NASA acronymese, the Global Hawk is able to look down into the eye of the storm to the sea surface and compare different layers in relatively high resolution and in real time.

The unmanned aircraft left the Dryden Flight Research Center in California earlier in the week and spent all day Thursday flying over Earl at an altitude of about 63,000 feet. Along with HAMSR, the Global Hawk also carries an HD camera, giving hurricane scientists new capabilities to watch the storm strengthen or degrade in real time.

In addition to the Global Hawk which flew over the top of the hurricane, a NASA DC-8 is flying researchers through the eye of the hurricane and the high flying WB-57 is also participating in the research flights. NASA used images taken by astronauts aboard the International Space Station as their orbit took them over the storm as well.

Temperatures across the eye of hurricane Earl using HAMSR aboard the unmanned Global Hawk (pink crosses mark lightning)

The observations and measurements are part of the Genesis and Rapid Intensification Process experiment NASA is conducting during the 2010 hurricane season. New instruments such as HAMSR, as well as a weather radar aboard the DC-8 capable of creating 3-D images of precipitation from inside the hurricane are helping researchers gain a better understanding of the rapidly changing nature of hurricanes.

Hurricane Earl from the International Space Station taken the morning of Sept. 3

High resolution maps and images isn't the only information available to the public. Hurricane researchers inside the DC-8 were also sending out tweets as they flew into and out of the hurricane. One of the tweets sent out Thursday mentioned the degradation of the eye wall at the center of Earl, an early sign of a weakening hurricane.

NASA plans to continue using the aircraft through the end of the month as more hurricanes line up in the Atlantic.

Images: NASA

Baby Lion Cub Live Webcam Launched

Posted: 03 Sep 2010 09:57 AM PDT

The Smithsonian National Zoo has just launched a live webcam of the zoo's four new baby African lion cubs and their mother. The cubs were born during the late night and early morning of Aug. 30 and 31 and will remain indoors until late fall.

The litter is the first for 5-year-old mother lion Shera, and the first surviving litter for 4-year-old male Luke. The new batch of cubs is part of an effort to develop a lion pride at the zoo, which has involved many years of planning.

Luke, Shera and her 6-year-old sister Nababiep started spending almost all their time in the yard together as a group six months ago. Shera and Luke bred in the second week of May. Over the past few weeks, the keepers started separating Shera to give her privacy and emulate the natural process.

In the wild, lions may wait up to six weeks before introducing their cubs to the rest of the pride.

Nababiep gave birth to a single cub in May, but it died when a straw seed got lodged in the lung, causing pneumonia.

"Since the unfortunate death of Naba's cub, we've investigated various alternative bedding options," lion-and-tiger-keeper Rebecca Stites said in a press release Sept. 3. "The use of bedding is imperative as it protects the cubs from trauma during the first fragile weeks of their lives. We've provided Shera and her cubs with shavings and soft hay with as few seed as possible."

Keepers suspect that Nababiep is pregnant again.

The formation of prides makes lions unique among the great cats, many of which are solitary animals. In the wild, African lions are threatened by hunting, disease and habitat loss.

Image: Smithsonian National Zoo

Posted: 02 Sep 2010 01:57 PM PDT

Unlike infectious diseases and news, behavior change spreads faster through online networks that have many close connections instead of many distant ties. Redundancy is key, as people are more likely to engage in a behavior if they see many others doing it.

"There has been a lot of theory about the difference between information and behavior spreading," said economic sociologist Damon Centola of the Massachusetts Institute of Technology, author of the study published Sept. 3 in Science. "We've assumed that they are the same, but you can imagine that behavior is not really like that, that you need to be convinced."

The research has important implications for people designing online communities intended to change or maintain a behavior, like weight watchers or online health communities, Centola said.

To do the experiment, he created an internet-based health community and invited people already participating in other online health forums to join. Over 1,500 people signed up to participate, and they were placed anonymously in one of two different kinds of networks: a random network with many distant ties (above left), or a clustered network with many overlapping connections (above right).

Users in both networks had the same number of assigned "health buddies." They couldn't contact their buddies directly, but they could see how their buddies rated content on the site, and could receive e-mails informing them of their buddies activities. Centola said he deliberately didn't pay the volunteers, so they would participate out of legitimate interest in the site's content.

In six different trials over a period a few weeks, Centola seeded the site with information about an online health forum and tracked people as they signed up and participated.

In the clustered network, 54 percent of the people signed up for the forum, compared to 38 percent in the random network, and almost four times as fast. Not surprisingly, Centola also found the more friends people had that also signed up, the more likely they were to return to the forum to participate.

"I feel that the greatest contribution of this study has to do with the very unusual social experiment that it relies on," said economist Tomas Barrios of Stanford University, who wasn't involved in the study. "Usually experimental data for social experiments comes from hard-to-swallow lab settings, or if not, very low tension, low risk social situations that can be ethically intervened by experimenters."

Barrios also said many researchers have made mathematical models to understand the spread of behavior, but that the models have have little application in predicting what will actually happen in the real world.

These studies cannot be done yet using data from Facebook or Twitter, Centola says, because the network is constantly changing and too gigantic to download all at once.

Image: Damon Centola

Posted: 02 Sep 2010 01:13 PM PDT

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Cones Formed by Hot Lava Running over Water or Ice

A new batch of sharp Martian close-ups from NASA's HiRISE camera were released on Sept. 1. HiRISE (High Resolution Imaging Science Experiment) has been circling Mars on the Mars Reconnaissance Orbiter for four years now, taking dramatic photos of the red planet with a telephoto lens to make any paparazzi jealous. The camera can focus on objects the size of a beach ball from more than 180 miles away.

The 236 new images, taken between July 8 and July 31, cover the planet practically from pole to pole. They zoom in on terrain ranging from volcanic cones to cratered planes, from wind-swept dunes to crusts of ice. The images even capture evidence of ongoing geological processes on Mars today, like fresh craters that may have formed between January and June of this year.

These are some of our favorites from the new set. But since January, the HiRISE team has been letting the public point the camera. You can suggest new terrain to explore using their "HiWish" feature.

Above: These volcanic cones were formed by hot lava running over water or ice. The heat from the lava boiled the water underneath, and the water burst upwards in an exploding bubble of lava. The explosion threw chunks of molten and solid lava into the air to gather into the cones. These cones are similar in size and shape to cones found in Iceland.

Image: NASA/JPL/University of Arizona

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Posted: 02 Sep 2010 01:03 PM PDT

By Alasdair Wilkins, io9

The atmosphere of a young exoplanet didn't fit any of our existing models for what gas giants should look like. But when astronomers added huge dust clouds, it was a perfect fit, perhaps revealing a larger truth about gas giants.

The planet in question is HR 8799 b, a gas giant about seven times the mass of Jupiter. It's one of three gas giants revolving around the star HR 8799, located about 1,300 light-years away. The system was first discovered in 2008, and now astronomers have been able to perform spectroscopic analysis of the planets. These analyses are extraordinarily powerful, giving us close approximations of the planet's chemical composition, cloud properties, and even temperature.

We can figure out the temperature of an exoplanet by measuring the amount of methane in its atmosphere. According to the almost nonexistent methane levels on HR 8799, its temperature couldn't be any cooler than about 1,700 degrees Fahrenheit. But other metrics, such as the planet's apparent youthful age and the amount of energy it's sending out, suggest it should be about 250 degrees cooler than that, assuming our current models are right.

As it turns out, our models are wrong, or at least they didn't take into account the possibility of massive dust clouds on HR 8799 b. When those clouds are added into the equation, the data fits together perfectly and explains the 250 degree swing. Because this particular gas giant is one of the youngest we've ever observed and analyzed, it's quite possible that this extreme dustiness is just a natural part of a gas giant's infancy, which tells us something about the beginnings of our own solar system's four gas giants.

Images: 1) NASA, ESA, G. Bacon (STSci). 2) NASA.

Posted: 02 Sep 2010 12:22 PM PDT

Just north of a truck stop along Interstate 80 in Battle Mountain, Nevada, lies evidence that the Earth's magnetic field once went haywire.

Magnetic minerals in 15-million-year-old rocks appear to preserve a moment when the magnetic north pole was rapidly on its way to becoming the south pole, and vice versa. Such "geomagnetic field reversals" occur every couple hundred thousand years, normally taking about 4,000 years to make the change. The Nevada rocks suggest that this particular switch happened at a remarkably fast clip.

Anyone carrying a compass would have seen its measurements skew by about a degree a week — a flash in geologic time. A paper describing the discovery is slated to appear in Geophysical Research Letters.

It is only the second report of such a speedy change in geomagnetic direction. The first, described in 1995 based on rocks at Steens Mountain, Oregon, has never gained widespread acceptance in the paleomagnetism community. A second example could bolster the theory that reversals really can happen quickly, over the course of years or centuries instead of millennia.

"We're trying to make the case that [the new work] is another record of a superfast magnetic change," says lead author Scott Bogue, a geologist at Occidental College in Los Angeles.

Researchers aren't sure why the geomagnetic field reverses itself. Many think it must have something to do with what creates the field in the first place — convective motions of liquid iron in the planet's spinning outer core.

Bogue and his colleague, Jonathan Glen of the U.S. Geological Survey in Menlo Park, California, went to Nevada to study a series of well-preserved lava flows. As each flow cooled, it preserved the orientation of the magnetic field at the time, frozen like a tiny compass needle in the rock's magnetic crystals.

One particular flow caught the scientists' attention because it seemed to carry a complex magnetic history. This lava, Bogue says, initially started to cool and then was heated again within a year as a fresh lava flow buried it. The fresh lava re-magnetized the crystals within the rock below, causing them to reorient themselves a whopping 53 degrees. At the rate the lava would have cooled, says Bogue, that would mean the magnetic field was changing direction at approximately 1 degree per week.

The Steens Mountain rocks have been reported to preserve a change of 6 degrees per day. That rate was so high — imagine trying to navigate when a compass changes by multiple degrees per day — that many scientists challenged the report. One line of argument held that the liquid outer core simply can't generate magnetic field changes that rapidly. Another held that, even if the changes were happening, they wouldn't be observable at the surface because the Earth's internal electrical conductivity would screen the signals out.

The Nevada rocks bolster the idea that such changes could be happening, says Bogue — even if scientists still can't explain why.

Not all experts are convinced by the new paper. Dennis Kent, a paleomagnetist at Rutgers University in Piscataway, New Jersey, says it would be "a curious coincidence" to have two brief lava flows just happen to cool and capture a 53-degree change in direction, when reversals happen only a few times per million years.

The last stable reversal occurred 780,000 years ago. Some geologists argue the Earth is overdue for a reversal and might even be entering one now, as the geomagnetic field has been getting weaker over the past 150 years or more.

But apocalyptic SyFy channel movies to the contrary, nobody should worry about waking up one morning to geomagnetic havoc, says Bogue. "To geologists a polarity reversal is a nearly instantaneous thing that changes a global feature of the Earth — it's really a spectacular phenomenon," he says. "But if you were alive when it was happening, it probably wouldn't be that big a deal."

Image: Scott Bogue

Posted: 02 Sep 2010 12:03 PM PDT

A reinterpretation of the fossil record suggests a new answer to one of evolution's existential questions: whether global mass extinctions are just short-term diversions in life's preordained course, or send life careening down wholly new paths.

Some scientists have suggested the former. Rates of species diversification — the speed at which groups adapt and fill open ecological niches — seemed to predict what's flourished in the aftermath of past planetary cataclysms. But according to the calculations of Macquarie University paleobiologist John Alroy, that's just not the case.

"Mass extinction fundamentally changes the dynamics. It changes the composition of the biosphere forever. You can't simply predict the winners and losers from what groups have done before," he said.

Alroy was once a student of paleontologist Jack Sepkoski, who in the 1980s formalized the notion that Earth has experienced five mass extinctions in the 550 million years since life became durable enough to leave a fossil record. Graphs of taxonomic abundance depict lines rising steadily as life diversifies, plunging precipitously during each extinction, and rising again as life proliferates anew.

As the fossil record is patchy and long-term evolutionary principles still debated, paleobiologists have historically disagreed about what these extinctions mean. Some held that, in the absence of extinctions, species would diversify endlessly. The Tree of Life could sprout new branches forever. Others argued that each taxonomic group had limits; once it reached a certain size, each branch would stop growing.

Sepkoski's calculations put him on the limits side of this argument. He also proposed that, by looking at the rate at which each group produced new species, one could predict the winners and losers of each mass extinction's aftermath. Groups that diversified rapidly would flourish. Their destiny was already established.

"It's a clockmaker vision of evolution. Each group has fixed dynamics, and if there's an extinction, it just messes it up a bit," said Alroy. "That's what I'm challenging in this paper. There are limits, and that's why we don't have a trillion species. But those limits can change."

Alroy crunched marine fossil data in the Paleobiology Database, which gathers specimen records from nearly 100,000 fossil collections around the world. He used a statistical adjustment method designed to reduce the skewing influences of paleontological circumstance — the greater chances of finding young fossils rather than old, the ease of studying some types of rock rather than others.

Historical species diversity among marine animals of Cambrian, Paleozoic and Modern origin.

The analysis, published September 2 in Science, produced what Alroy considers to be the most accurate reflection of extinction dynamics to date. And while his data supported the notion that each group's diversity eventually hits a limit, he didn't find Sepkoski's correlation between pre-mass-extinction diversity rates and post-extinction success. Each mass extinction event seemed to change the rules. Past didn't indicate future.

In an accompanying commentary, paleontologist Charles Marshall of the University of California, Berkeley noted that Alroy's statistical methods still need review by the paleobiology community. The Paleobiological Database, for all its thoroughness, might also be incomplete in as-yet-unappreciated ways. "There will be no immediate consensus on the details of the pattern of diversity," he wrote. But "the pieces are falling into place."

Enough pieces have come together for Alroy to speculate on his findings' implication for the future, given that Earth is now experiencing another mass extinction. Starting with extinctions of large land animals more than 50,000 years ago that continued as modern humans proliferated around the globe, and picking up pace in the Agricultural and Industrial ages, current extinction rates are far beyond levels capable of unraveling entire food webs in coming centuries. Ecologists estimate that between 50 and 90 percent of all species are doomed without profound changes in human resource use.

In the past, many evolutionary biologists thought life would eventually recover its present composition, said Alroy. In 100 million years or so, the same general creatures would again roam the Earth. "But that isn't in the data," he said.

Instead Alroy's analysis suggests that the future is inherently unpredictable, that what comes next can't be extrapolated from what is measured now, no more than a mid-Cretaceous observer could have guessed that a few tiny rodents would someday occupy every ecological niche then ruled by reptiles.

"The current mass extinction is not going to simply put things out of whack for a while, and then things will go back to where we started, or would have gone anyway," said Alroy. Mass extinction "changes the rules of evolution."

Images: 1) A fossil skull of Dunkleosteus, an apex predator fish that lived between 380 million and 360 million years ago, and had what is believed to be history's most powerful bite./Michael LaBarbera, courtesy of The Field Museum. 2) Graph of species diversity among marine animals of Cambrian, Paleozoic and Modern origin./Science.

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Citations: "The Shifting Balance of Diversity Among Major Marine Animal Groups." By J. Alroy. Science, Vol. 329 No. 5996, September 3, 2010.

"Marine Biodiversity Dynamics over Deep Time." By Charles R. Marshall. Science, Vol. 329 No. 5996, September 3, 2010.

Brandon Keim's Twitter stream and reportorial outtakes; Wired Science on Twitter. Brandon is currently working on a book about ecological tipping points.

String Theory Finally Does Something Useful

Posted: 02 Sep 2010 10:50 AM PDT

String theory has finally made a prediction that can be tested with experiments — but in a completely unexpected realm of physics.

The theory has long been touted as the best hope for a unified "theory of everything," bringing together the physics of the vanishingly small and the mindbendingly large. But it has also been criticized and even ridiculed for failing to make any predictions that could be checked experimentally. It's not just that we don't have big enough particle accelerators or powerful enough computers; string theory's most vocal critics charge that no experiment could even be imagined that would prove it right or wrong, making the whole theory effectively useless.

Now, physicists at Imperial College London and Stanford University have found a way to make string theory useful, not for a theory of everything, but for quantum entanglement.

"We can use string theory to solve problems in a different area of physics," said theoretical physicist Michael Duff of Imperial College London. "In that context it's actually useful: We can make statements which you could in principle check by experiment." Duff and his colleagues describe their findings in a paper in Physical Review Letters September 2.

String theory suggests that matter can be broken down beyond electrons and quarks into tiny loops of vibrating strings. Those strings move and vibrate at different frequencies, giving particles distinctive properties like mass and charge. This strange idea could unite all the fundamental forces, explain the origins of fundamental particles and connect Einstein's general relativity to quantum mechanics. But to do so, the theory requires six extra dimensions of space and time curled up inside the four that we're used to.

To understand how these extra dimensions could hide from view, imagine a tightrope walker on a wire between two high buildings. To the tightrope walker, the wire is a one-dimensional line. But to a colony of ants crawling around the wire, the rope has a second dimension: its thickness. In the same way that the tightrope walker sees one dimension where the ants see two, we could see just three dimensions of space while strings see nine or ten.

Unfortunately, there's no way to know if this picture is real. But although string theorists can't test the big idea, they can use this vision of the world to describe natural phenomena like black holes.

Four years ago, while listening to a talk at a conference in Tasmania, Duff realized the mathematical description string theorists use for black holes was identical to the mathematical description of certain quantum systems, called quantum bits or qubits.

Qubits form the backbone of quantum information theory, which could lead to things like ultrafast computers and absolutely secure communication. Two or more qubits can sometimes be intimately connected in a quantum state called entanglement. When two qubits are entangled, changing one's state influences the state of the other, even when they're physically far apart.

"As I listened to his talk, I realized the kind of math he was using to describe qubit entanglement was very similar to mathematics I had been using some years before to describe black holes in string theory," Duff said. When he looked into it, the mathematical formulation of three entangled qubits turned out to be exactly the same as the description of a certain class of black holes.

In the new study, Duff and his colleagues push the similarity one step further. They used the mathematics of stringy black holes to compute a new way to describe four entangled qubits, an open question in quantum information theory.

"We made statements that weren't previously known using string theory techniques," Duff said. "Whether the result is some fundamental principle or some quirk of mathematics, we don't know, but it is useful for making statements about quantum entanglement."

What's more, these statements are precise and experimentally provable, unlike previous suggestions for ways to test string theory, Duff says.

"So in a way, there's bad news and good news in our paper," he said. "The bad news is, we're not describing the theory of everything. The good news is, we're making a very exact statement which is either right or wrong. There's no in between."

Duff emphasized that this is only a test of string theory as it relates to quantum entanglement, not as a description of the fundamental physics of the universe. The battle over string theory as a theory of everything rages on.

"Already I can imagine enemies sharpening their knives," Duff said.

And they are. A chorus of supporters and critics, including Nobel laureate and string theory skeptic Sheldon Glashow and string theorists John Schwarz of Caltech, James Gates of the University of Maryland, and Juan Maldacena and Edward Witten of the Institute for Advanced Study in Princeton agree that Duff's argument is "not a way to test string theory" and has nothing to do with a theory of everything.

Mathematician Peter Woit of Columbia University, author of the blog Not Even Wrong, thinks even claiming that the new paper is a test of quantum entanglement is going too far.

"Honestly, I think this is completely outrageous," he said. Even if the math is the same, he says, testing the quantum entangled system would only tell you how well you understand the math.

"The fact that the same mathematical structure appears in a quantum mechanical problem and some model of black holes isn't even slightly surprising," he said. "It doesn't mean that one is a test of the other."

Witten takes a more optimistic view of the theory's chances, pointing out that the mathematics of string theory have turned out to be coincidentally useful in other areas of physics before.

"In general, this kind of work shows that string theory is useful, and in fact by now it has been useful in many different ways," Witten said in an email to Wired.com.

"One might surmise that a physics theory that has proved to be useful in so many different areas of physics and math is probably on the right track," he added. "But that is another question."

Via Universe Today
Image: Entangled string. Flickr/Whatknot

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Sunday, 5 September 2010

Johnald's Fantastical Daily Link Splurge

Johnald's Fantastical Daily Link Splurge

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