Science News

Headlines

. Neutrinos faster than light?
. Aerosols affect rainfall patterns
. Dinosaurs used to migrate too
. Teenage brains change rapidly
. Lasers reveal a gem's origins 
. Did you notice a ripple in one of Saturn's rings?

Read more details about these below.

Neutrinos faster than light?
The OPERA experiment in Europe has detected neutrinos that appear to travel faster than light. Einstein's special theory of relativity says that nothing can travel faster than light in vacuum. (In water or any medium, for instance, it is possible for particles to travel faster than the speed of light in water or that medium). So this discovery is testing fundamental assumptions in physics and is a subject of inquiry and debate: if independently confirmed, it could have far-reaching implications for our understanding of physics.
Dario Autiero, who leads the OPERA team's analysis of the faster-than-light result, has stated that further scrutiny and independent tests are necessary to definitely confirm or refute the results. Independent tests by other collaborations are under way.
What is this experiment? Protons are accelerated in a beam pipe called the SPS at CERN in Geneva, Switzerland. These very fast protons hit a target and produce secondary particles, which later decay to produce neutrinos. All this happens over a kilometer of distance. But now comes the amazing part: these neutrinos travel through the Earth for another 730 km before they are detected at the Gran Sasso laboratory (LNGS) in Italy!
How is this possible? That is because neutrinos are very special particles. These are usually produced in association with particles such as electrons and muons. Neutrinos have no charge and so do not feel electromagnetic interactions. So even though they are copiously produced (in the Sun, in stars, in Earth's atmosphere, in radioactivity) they are rarely observed. In this experiment, mostly muon-type neutrinos were produced.
Since they are so weakly interacting, they can travel large distances without disturbing anything in their path. While protons, electrons and even light are absorbed quickly by Earth, the neutrinos can on average go through seven Earth diameters without interacting even once! So it is very difficult to study them. However, they have exotic properties which scientists believe would help them understand fundamental properties about the formation and nature of the Universe; hence there are several neutrino experiments around the world.
The OPERA experiment measured the speed of the neutrinos. Since speed equals distance divided by time, they had to know the distance from CERN to LNGS very precisely. They also had to know the time taken by the neutrinos (arrival or detection time at LNGS minus the production time at CERN) correctly. For the timing measurement, they used GPS (Geographic Positioning Systems). However, one clock was used to measure the production time and another the detection time (since these are in two different places, actually in two different countries!). Because of this, the clocks had to be synchronised very accurately. GPS along with atomic clocks were used to give an accuracy of 2.3 nanoseconds (one nanosecond is 1 billionth of a second, i.e., 1/1000000000 s).
But this is not enough. The GPS signal only came to the main control room. From here, it had to be routed by cables and electronics to the neutrino beam control room 8 km away! This needed the length of the cables to be found, and the delay due to this was calculated to be more than 10,000 nanonsecs. A similar delay occurred in the detection end at Gran Sasso. All this needed each element of the system to be accurately measured.
Standard GPS has only 100 ns accuracy. To improve this to the 1 ns range, OPERA researchers used a precise PolaRx2eTR GPS timing receiver which allowed measurement of the time offset between an extremely precise atomic clock and each of the satellite clocks. In addition, highly stable cesium clocks were installed both at LNGS and CERN to cross-check GPS timing and to increase its precision. The travel time (called time of flgight) was eventually measured to an accuracy of 10 nanoseconds.
Now for the distance. The detector is underground so it was not a simple matter of starting with a measuring tape at CERN and measuring the distance to the detector. While GPS was used to measure the coordinates of the source, special techniques had to be used to link the coordinates of the detector with the location just overhead overground. In fact, to connect the surface GPS location to the underground site, traffic had to be diverted on the access tunnel to the lab! Finally, when all the corrections were put into place, the researchers calculated the distance to an accuracy of 20 cm within the 730 km path!
There were further complications: individual neutrinos are not measured, but only bunches of them. Indeed, bunches of protons were measured at the source and signals for neutrinos were measured at the detector.
In the final analysis, the experimental result was that the neutrinos on the average arrived about 60 ns earlier than light could have travelled over that distance. This is a value much larger than the experimental uncertainty due to measurement, so the group is very confident of their results. The experiment was repeated recently and the result was confirmed.
Many experiments around the world are planning to modify their equipment to cross-check this measurement. In the meanwhile, theorists have been busy, trying to understand the consequences of such a dramatically new result. More than 80 papers discussing the experiment have been posted on the arXiv website for electronic preprints. Most try to explain the anomaly theoretically, while a small minority claim the experiment has problems. The view of CERN theorists was that "there was no consistent theoretical model that could accommodate the measurement."
We may have to wait at least a year for independent confirmation before we know the truth.

2. Aerosols affect rainfall patterns
If you're near a window, look up at a cloud and *really* look at it. If you look up again in a few minutes, you'll see that the cloud has changed shape and probably moved. Clouds contain cloud droplets, tiny quantities of water too small to overcome the wind and fall to the ground. Clouds also contain water molecules that condense, or concentrate, on tiny airborne particles called aerosols, forming drops of water. When drops get heavy enough, they fall as rain.
Some of these particles occur naturally and include dirt and dust. Other aerosols come from human activities and represent air pollution. Once these particles get swept up into a cloud, they start to make changes. Imagine what would happen with too many aerosols: the water molecules would condense, but not enough on any individual aerosol to make it heavy enough to cause rain.
Recent research has found a strong link between pollution and rainfall. They studied 10 years' worth of data to know how aerosols in the air affect cloud development. They learned that rainfall depended on the amount of aerosols in the clouds, as well as the type of cloud and amount of moisture. They found a link between large amounts of aerosols and extreme weather. The clouds in dry regions may hold their water longer, contributing to droughts. Clouds drifting over moist areas may lose their water more quickly, leading to severe rains. Both situations may pose severe problems for farmers.

3. Dinosaurs used to migrate too
Animals migrate to survive. Golden eagles head south for the winter, salmon swim upstream to lay eggs and locusts move on when it gets too crowded. Scientists now say that 150 million years ago, plant-eating dinosaurs called sauropods living in North America may have migrated, too. The new study suggests that these enormous animals traveled at the change of the seasons, leaving dry riverbeds in search of well-watered areas thick with plants.
The dinos' giant size kept them safe from smaller, sharp-toothed, carnivorous dinos, like Allosaurus. Scientists compared the chemicals in minerals with those in the teeth of sauropods called Camarasaurus to discover the dinosaurs' wandering ways. When animals drink water, the oxygen in that water gets incorporated into the bloodstream and eventually into tooth enamel. Oxygen comes in different forms, called isotopes. Different sources of water may contain different isotopes, so the oxygen in a mountain stream may be slightly different from the oxygen in swamp water.
Scientists compared isotopes in the dino tooth enamel with isotopes in minerals near where the teeth had been excavated. The scientists found different levels in the teeth and the minerals, which suggests the sauropods had another source of water.
So teeth tell a tale of travel!

4. Teenage brains change rapidly
In 2004, neuroscientist Cathy Price of the University College London and her colleagues tested the IQs of 33 teens who ranged in age from 12 to 16. (An IQ, or intelligence quotient, attempts to measure a person's ability to think and reason.) At the same time, the scientists took pictures of the teens' brains using MRI, or magnetic resonance imaging. An MRI produces images of the brain using radiation and a powerful magnetic field.
A few years later, in 2007 and 2008, the participants returned to the lab. Like the first time, the scientists tested the teens' IQs and used an MRI to see their brains. But when Price compared the old and new results, she was shocked. Many of the teenagers' IQs had changed dramatically over the years. One person had lost 18 IQ points; another had gained 21. Some people with high IQs on the first test had even higher IQs on the second. And some low-scoring individuals saw their scores fall even further.
When Price looked the brain scans, she discovered more surprises. The brains of teens whose scores went up on verbal IQ tests had more gray matter than before in an area called the left motor cortex, which is involved in speaking. She found other connections between increased IQ scores and gray matter, which is tissue containing brain cells.
Scientists do not understand *why* teenagers' brain scans show so many changes, but that teenage brains change so much is interesting.

5. Lasers reveal a gem's origins 
Can you look at a gem and say where it was mined? Does it come from Australia or the Congo?
Beneath the surface of a gemstone, on the tiny level of atoms and molecules, lie clues to its origin. Scientists have reported on a technique that uses lasers to unravel these clues and identify a stone's homeland.
Just as heat can turn ice into water or water into steam, energy from a laser beam can change the state of matter of a mineral. The laser changes a miniscule portion of the gemstone into plasma, a gaseous state of matter in which tiny particles called electrons separate from atoms.
The plasma, which is superhot, produces a light pattern. (The science of analyzing this kind of light pattern is called spectroscopy.) Different elements produce different patterns, but gemstones from the same area produce similar patterns. People have already collected patterns from thousands of gemstones, including more than 200 from diamonds. They can compare the light pattern from an unknown gemstone to patterns they do know and look for a match. The light pattern acts like a signature, telling the researchers the origin of the gemstone.

6. Did you notice a ripple in one of Saturn's rings?
No, you couldn't have, unless you were working on the Cassini spacecraft, which orbits Saturn and beams back information about the planet and its moons and rings. This happened when a comet plowed through Saturn's rings and blasted apart, some 600 years ago -- more than 200 years before Galileo Galilei first gazed through the telescope and mistook Saturn's legendary rings for handles or mammoth moons.
Those rings are actually vast seas of individual rocks. Just as an object creates waves when it splashes in water, the comet disturbed the rocky rings on its final flight. Patterns in Saturn's rings allow astronomers to learn about the planet's past.
Scientists found the ripples in Saturn's C ring, a faint band inside the more familiar and giant A and B rings. Over time, the ripples bunched up. They were highly regular little wiggles that rippled over hundreds of kilometers in a very specific pattern. The scientists didn't see the ripples in pictures. Instead, they found telltale disturbances in radio waves from a Cassini experiment.
Scientists found similar waves in the rings of Jupiter too. In the case of the 600-year-old ripples on Saturn, they identified two distinct wave patterns of similar sizes, which suggests that the plunging comet passed twice near the ring and never had a chance of escape the second time.
Saturn's rings are beautiful, and the study of astronomy offers plenty of drama as well.

--Compiled from several sources