- Massive Volcanism May Have Caused Biggest Extinction Ever
- First Volcano Sighting on Saturn’s Most Earthlike Moon
- How to Test What Really Happened After the Big Bang
- Cheap DIY Camera Systems Perform Amazing Photographic Feats
Posted: 14 Dec 2010 03:24 PM PST
SAN FRANCISCO — The greatest extinction in the history of life may have been caused, in part, by ozone-depleting gases spewed in a massive volcanic eruption, a new study suggests. Geologists have found surprisingly high amounts of the elements fluorine and chlorine in Siberian lavas dating back 250 million years — when about 90 percent of marine species and 70 percent of terrestrial species went extinct.
Benjamin Black, a graduate student at MIT, and his colleagues described their theory Dec. 13 in a poster presentation at a meeting of the American Geophysical Union.
Researchers have long struggled to explain the "Great Dying" that occurred at the end of the Permian period. Some think that the extinction was a long, drawn-out affair caused by multiple factors — perhaps gradual changes in oceanic or atmospheric chemistry (SN: 5/28/05, p. 339). Others have blamed a single catastrophic event such as a belch of methane from the seafloor or an asteroid impact (SN: 2/24/01, p. 116) like the one thought to have wiped out the dinosaurs and other species 65 million years ago.
Volcanoes might be one of those calamities. In Siberia, around 250 million years ago, a series of massive volcanic eruptions spewed out lava over more than 2 million square kilometers [800,000 square miles]. Some scientists have blamed these eruptions, known as the Siberian Traps, for climatic changes that contributed to the extinction.
Black and his MIT adviser, Lindy Elkins-Tanton, have been traveling to Russia for the past few summers to test such theories in the Siberian Traps.
The rocks contain tiny blobs of once-molten material, preserved like chemical time capsules from the earliest days of the eruption. Measuring the amounts of sulfur, chlorine and fluorine in those blobs, Black found surprisingly high levels of those elements — up to 0.75 percent chlorine and 1.95 percent fluorine, by weight, in one sample. That's significantly more than the amounts found in similar deposits like the Deccan Traps in India and the Columbia River flood basalts in Washington and Oregon.
The chemicals probably weren't in the magma as it began traveling up from deep within the Earth, the team proposed, but melted into the magma as it passed through salt-rich rock before erupting on the surface.
In all, the amount of chemicals in the Siberian rocks could translate to 9 trillion tons of sulfur, 8.5 trillion tons of fluorine and 5 trillion tons of chlorine spewing into the atmosphere during the eruptions. Such elements, when pumped out by power plants, can cause acid rain locally. If the eruptions were violent enough to lift the chemicals high into the atmosphere, the team proposed, the chemicals could have damaged the ozone layer just as chlorofluorocarbons do today — helping cause or at least exacerbate the mass extinction.
Stephen Self, a volcanologist at the U.S. Nuclear Regulatory Commission in Washington, D.C., said the main question is how long the chemicals would have stayed in the atmosphere. In a 2008 Science paper, Self and his colleagues reported finding high levels of sulfur and chlorine in the Deccan Trap lavas, though not as high as Black's team reports.
"What happens to the chlorine is highly questionable," Self said. It might, for instance, react with water droplets and rain out quickly.
Black's team is now starting detailed calculations to see how high the chemicals would have gotten into the atmosphere. Regardless, the researchers reported, Siberia at least would have had one very bad time of it.
Posted: 14 Dec 2010 12:46 PM PST
SAN FRANCISCO — Three icy volcanoes line up on Saturn's moon Titan, giving some of the best evidence yet that explosive eruptions are possible on worlds beyond Earth.
The volcanic peaks and pits lie in a region called Sotra Facula on Titan's southern hemisphere. The mountains rise more than 3,000 feet into the air, and the deepest hole sinks nearly 5,000 feet below the surrounding plains, geologists announced in a press conference here at the American Geophysical Union meeting Dec. 14.
"It's a combination of features that you really can't make any way other than volcanism," said geophysicist Randolph Kirk of the U.S. Geological Survey. "That's what really has excited us: We finally have some proof that Titan is an active world."
Titan is the only body in the solar system other than Earth to have lakes, rivers, clouds, and a cycle of evaporation and mist or rainfall connecting them all. But on Titan, where temperatures hover around minus 300 degrees Fahrenheit, the flowing liquids are hydrocarbons like methane and ethane, not water.
The frigid moon is shrouded in a dense, hazy atmosphere of methane and other hydrocarbons. But astronomers think all the methane should have been broken apart by sunlight millions of years ago, suggesting that something on Titan is constantly pouring fresh methane into the atmosphere.
An icy volcano, also known as a cryovolcano, could be the methane pump scientists sought. But until now, the telltale peaks and flows indicating a volcanic eruption had been hidden.
New radar data from NASA's Cassini spacecraft has helped astronomers build a 3-D topographical map of Sotra Facula. They saw three mountains lined up in a row. The most obvious one, which the scientists dubbed the Rose, is a single peak with a bite taken out of it and a crater 5,000 feet deep to its side. A second peak, shaped like a football stadium, lies nearby, and a third is to the north.
Measurements from Cassini's spectrometer show evidence of some kind of magma flowing from the volcanoes to cover the surrounding planes, though what the magma is made of is still unclear. It could be a combination of water and ammonia, or it could be hydrocarbons similar to molten asphalt, candle wax or polyethylene, says planetary scientist Jeffrey Kargel of the University of Arizona, who was not involved in the new work.
"In my opinion, Sotra Facula is the best example of a cryovolcanic mountain on Titan and in the outer solar system," Kargel said.
If the volcanic material is water-based, it could provide a comfortable place for life to take hold, Kargel suggested.
"Volcanoes on Earth are destroyers of life," he said. "But on Titan, cryovolcanism could represent perhaps the very liquids that would form the habitat for life, and very conveniently for us, the means by which these very speculative life forms are brought to the surface and made accessible."
Video: NASA/JPL-Caltech/USGS/University of Arizona
Posted: 14 Dec 2010 10:42 AM PST
A new test that takes data from several realms of physics could explain what really happened in the first sliver of a second after the Big Bang.
Most cosmologists believe the universe burst from an extremely dense, hot state around 13.7 billion years ago, and has been expanding and cooling ever since. The universe ballooned ridiculously fast in its first moments, doubling in size thousands of times in less than a trillionth of a trillionth of a second.
"That would take a region the size of an atomic nucleus or a proton, and stretch it to a size exponentially greater than our observable universe at present," said cosmologist Paul Steinhardt of Princeton University. "Superlatives are not enough here. Incredible, remarkable, unbelievable amounts of stretching."
This idea, known as inflation, is the most popular theory for explaining why the universe looks the way it does. But so far, no one has proved it.
"At the moment it's our best theory, but it could be literally on the wrong track," said Latham Boyle, a cosmologist at the Perimeter Institute in Canada. "It's important to remember that it's not a fact."
In a paper published Dec. 6 in Physical Review Letters, Boyle and Steinhardt show how a cluster of unrelated observations could clinch the case for inflation.
"You take two completely different sets of measurements," Steinhardt said. "If those two numbers match, either that's a remarkable coincidence, or inflation was the cause. This is the new test that we're introducing."
Cosmologists dreamed up inflation in the 1980s to account for some weird coincidences that the original Big Bang theory, which assumed the universe expanded at a relatively slow, constant rate, couldn't explain. The universe looks nearly the same in every direction, even in regions so distant from each other that they shouldn't know about each other. The time for light to travel from one point to the other is longer than the age of the universe.
"Why would you expect two regions of the universe to have identical properties if they never had a chance to communicate with one another?" said Steinhardt, who was one of the original authors of inflation theory. "Before inflation, the only thing you had to say was, 'I don't know the answer, but we have to suppose it is so.'"
Inflation offered an explanation: Those two distant points in the universe started out next door to each other, but blew apart almost immediately. Later observations of the cosmic microwave background, the subtle glow of the first atoms to release light, fit closely with what cosmologists expected if inflation were true.
Those observations pushed inflation ahead of all the competing theories, but didn't rule the other theories out. Steinhardt himself is working on an alternative theory "where the Big Bang is not the beginning, but it's kind of a bounce." Other theories call on funny features of particle physics or extra dimensions.
In the new study, Boyle and Steinhardt suggest a way to show that inflation was really responsible for the universe's unlikely uniformity.
The key, they say, is to compare two different times when the universe stretched out: the extremely rapid stretching that happened during inflation, and the slower stretching that has been going on ever since.
During inflation, space expanded so quickly even light couldn't keep up. That means two particles sitting right next to each other before inflation would vanish from view once inflation began.
After inflation ended, though, light started to catch up. The universe kept expanding, but slowly enough that light could start making its way across the universe. Eventually, the light from those two particles traveled far enough for the particles to see each other again.
The amount of stretching the universe suffered from the instant those particles lost sight of each other until inflation ended should be exactly equal to the amount of stretching from the end of inflation until the particles were reunited, Boyle and Steinhardt point out. Otherwise, the particles would remain hidden from each other.
Conveniently, cosmologists can calculate the different amounts of stretching "using different bits of information that seem to have nothing to do with each other," Steinhardt said.
Knowing the amount of matter, radiation and dark energy in the universe gives a good estimate of the amount of expansion the universe has gone through since inflation ended.
"Once you know what it is in the present, you can extrapolate back to any time you like, and ask how much expansion has there been from then to now," Steinhardt said.
Observations of the cosmic microwave background plus data on gravitational waves (ripples in space-time predicted by general relativity) give a close sense of how much the universe expanded during inflation. Astronomers haven't detected gravity waves yet, but several observatories are already searching for them.
If the amounts of stretching turn out to be equal, "you declare victory," Steinhardt said. "Then you've really proven that inflation was the cause in a way that would be virtually impossible to explain by any other idea."
If they're not equal, though, that doesn't mean inflation is wrong. But all the competing theories would still be just as likely.
"If the test succeeds, it would eliminate the alternatives I've been thinking of, and seal the case," Steinhardt said. "If it fails, it's wide open."
"I think in retrospect these predictions will become very famous," said cosmologist Arthur Kosowsky of the University of Pittsburgh, who was not involved in the new work. "It's not going to shake up theoretical physics in the next year. But I think that in 20 years, if the real model of inflation comes out in this class of models that they write about, it will be looked back on as a very important contribution."
Image: A timeline of the universe, based on data from the WMAP probe. Credit: WMAP/NASA
Posted: 14 Dec 2010 04:00 AM PST
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By day, Linden Gledhill develops pharmaceuticals. After hours, he pushes the limits of high-speed, up-close and on-the-cheap digital photography.
The British native's latest science-inspired shots of insects in midflight, splattering paint droplets and butterfly wing scales are made possible by a small photographic-accessories company in Michigan. When Gledhill hits a barrier to his artistic will, he calls up Cognisys co-founder Paul DeZeeuw for help.
"Our mission is to help photographers capture what they wouldn't normally be able to, and for cheap," DeZeeuw said. Some of the equipment Cognisys sells for a few hundred dollars can cost tens of thousands of dollars from other companies. "My friend and I started this whole thing in a basement, and Linden was one of our first customers. He's been suggesting features and accessories and all sorts of things since then."
The two have already created a high-speed handheld photography rig and are joining forces on other devices to capture Gledhill's impossible shots, including a shutter system that can actuate in about 5 milliseconds from pushing the button to recording a photo. That's about 12-13 times faster than systems built into today's consumer digital cameras.
"This collaboration has opened up a whole new world for me. It's enabling me to do professional work," he said.
Despite taking on such professional work — including a recent contract to create images for Canon — Gledhill still describes himself as an amateur. His modesty runs so deep that, if you let him, he attempts to hide his engineering prowess behind soft-spoken statements about overcoming "slight" technical barriers.
But this is a man who went out to the garage and built a high-speed camera shutter from an old hard drive when his camera wasn't fast enough to capture images of flying bugs.
"My dad was an engineer, mechanical-maintenance kind of guy, so we built things together. But he was also interested in photography, and I picked up the hobby with him," Gledhill said. "Even in those days, when I was 11 or 12, we built an infrared trigger system for a camera" and a made-from-scratch telescope.
Gledhill cultivates his passions from the home he shares with his wife and three children, uploading his work (along with images of his do-it-yourself camera rigs in the living room) to Flickr.
We share some of his favorite images here, plus some of the technological magic behind their creation.
All images © Linden Gledhill.
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