May 4, 2013

New Kind of Cosmic Flash May Reveal Birth of a Black Hole

A new kind of cosmic flash may reveal something never seen before: the birth of a black hole.

When a massive star exhausts its fuel, it collapses under its own gravity and produces a black hole, an object so dense that not even light can escape its gravitational grip. According to a new analysis by an astrophysicist at the California Institute of Technology (Caltech), just before the black hole forms, the dying star may generate a distinct burst of light that will allow astronomers to witness the birth of a new black hole for the first time.

Tony Piro, a postdoctoral scholar at Caltech, describes this signature light burst in a paper published in the May 1 issue of the Astrophysical Journal Letters. While some dying stars that result in black holes explode as gamma-ray bursts, which are among the most energetic phenomena in the universe, those cases are rare, requiring exotic circumstances, Piro explains. "We don't think most run-of-the-mill black holes are created that way." In most cases, according to one hypothesis, a dying star produces a black hole without a bang or a flash: the star would seemingly vanish from the sky -- an event dubbed an unnova. "You don't see a burst," he says. "You see a disappearance."

But, Piro hypothesizes, that may not be the case. "Maybe they're not as boring as we thought," he says.

According to well-established theory, when a massive star dies, its core collapses under its own weight. As it collapses, the protons and electrons that make up the core merge and produce neutrons. For a few seconds -- before it ultimately collapses into a black hole -- the core becomes an extremely dense object called a neutron star, which is as dense as the sun would be if squeezed into a sphere with a radius of about 10 kilometers (roughly 6 miles). This collapsing process also creates neutrinos, which are particles that zip through almost all matter at nearly the speed of light. As the neutrinos stream out from the core, they carry away a lot of energy -- representing about a tenth of the sun's mass (since energy and mass are equivalent, per E = mc2).

According to a little-known paper written in 1980 by Dmitry Nadezhin of the Alikhanov Institute for Theoretical and Experimental Physics in Russia, this rapid loss of mass means that the gravitational strength of the dying star's core would abruptly drop. When that happens, the outer gaseous layers -- mainly hydrogen -- still surrounding the core would rush outward, generating a shock wave that would hurtle through the outer layers at about 1,000 kilometers per second (more than 2 million miles per hour).

Using computer simulations, two astronomers at UC Santa Cruz, Elizabeth Lovegrove and Stan Woosley, recently found that when the shock wave strikes the outer surface of the gaseous layers, it would heat the gas at the surface, producing a glow that would shine for about a year -- a potentially promising signal of a black-hole birth. Although about a million times brighter than the sun, this glow would be relatively dim compared to other stars. "It would be hard to see, even in galaxies that are relatively close to us," says Piro.

But now Piro says he has found a more promising signal. In his new study, he examines in more detail what might happen at the moment when the shock wave hits the star's surface, and he calculates that the impact itself would make a flash 10 to 100 times brighter than the glow predicted by Lovegrove and Woosley. "That flash is going to be very bright, and it gives us the best chance for actually observing that this event occurred," Piro explains. "This is what you really want to look for."

Such a flash would be dim compared to exploding stars called supernovae, for example, but it would be luminous enough to be detectable in nearby galaxies, he says. The flash, which would shine for 3 to 10 days before fading, would be very bright in optical wavelengths -- and at its very brightest in ultraviolet wavelengths.

Piro estimates that astronomers should be able to see one of these events per year on average. Surveys that watch the skies for flashes of light like supernovae -- surveys such as the Palomar Transient Factory (PTF), led by Caltech -- are well suited to discover these unique events, he says. The intermediate Palomar Transient Factory (iPTF), which improves on the PTF and just began surveying in February, may be able to find a couple of these events per year.

Neither survey has observed any black-hole flashes as of yet, says Piro, but that does not rule out their existence. "Eventually we're going to start getting worried if we don't find these things." But for now, he says, his expectations are perfectly sound.

Read more at Science Daily

Roman Cemetery Discovered Beneath Parking Lot

Hidden beneath a parking lot in Leicester, England, archaeologists have discovered a 1,700-year-old Roman cemetery that seemed to show no religious bias.

The new discovery, found at the junction of Newarke and Oxford Streets, includes numerous burials and skeletal remains from 13 individuals, both male and female of various ages. The cemetery is estimated to date back to around A.D. 300, according to University of Leicester archaeologists who led the dig.

"We have literally only just finished the excavation and the finds are currently in the process of being cleaned and catalogued so that they can then be analyzed by the various specialists," John Thomas, archaeological project officer, told LiveScience in an email.

Paved over

Parking lots seem to be great places to look for bones these days. In February, archaeologists announced that bones excavated from underneath a parking lot in Leicester, "beyond reasonable doubt," belong to the lost and vilified English king Richard III. More recently, the skeletal remains of a medieval knight and possibly his family crypt were unearthed from beneath a parking lot in Scotland.

Previous to the new discovery, scientists had excavated burials on Newarke Street, located to the east and north of the present site where the Roman cemetery was uncovered; these burials seemed to follow Christian traditions, in which the bodies were buried in a supine position, facing east with little or no goods buried alongside them, the researchers said.

"Unusually the 13 burials found during the recent excavations, of mixed age and sex, displayed a variety of burial traditions, including east to west and north to south-oriented graves," said Thomas, "many with personal items such as finger rings, hairpins, buckles and hob-nailed shoes."

For instance, in paganlike tradition one grave was facing north-south with the body positioned on its side in a semi-fetal position. The head had been removed and placed near the feet alongside two pottery jars, likely for offerings for the journey to the afterlife, Thomas said. "This would seem to be a very pagan burial," he said.

Nearby was a Christian burial in which the individual was facing east and wearing a polished finger ring made of jet on the left hand. The design etched onto the ring, "IX," may have been an artistic design or could represent an early Christian symbol taken from the initials of Jesus Christ in Greek, known as Iota-Chi, or IX. "If so this would represent rare evidence for a personal statement of belief from this period," Thomas said in a statement.

From the mix of burial types, Thomas said it's possible "that the cemetery catered for a range of beliefs that would have been important to people living in Leicester at this time."

Studying the bones

Archaeologists also discovered a 17th-century ditch running alongside Newarke Street, something that would have been part of the town's defenses during the English Civil War.

The project is ongoing and the archaeologists and other scientists will analyze the human bones to determine age, sex and the likely cause of death, Thomas wrote.

Read more at Discovery News

May 2, 2013

Why Do Some Believe Conspiracies at All Costs?

Amidst the grief, shock and confusion that followed the Boston marathon bombings last month, efforts to explain the senseless act inevitably led to theories of conspiracy and suspicious intrigue.

The bombers themselves may have been acting against what they saw as a conspiracy. Even the mother of the two brothers who planted the bomb declared the innocence of her sons, accusing the United States government of conspiring to kill her eldest.

What is it that motivates people to latch on to conspiracy theories, often in spite of evidence to the contrary?

In some ways, it may be inherent in human nature to invest in certain beliefs at all costs, experts said, whether it’s about the health consequences of vaccines or the death of John F. Kennedy. Several basic psychological processes are at work.

For one thing, people feel better if they think they’re right, said Gary Marcus, a cognitive psychologist at New York University who wrote about conspiracy theorists for The New Yorker. In a phenomenon called “motivated reasoning,” it’s also common for people to both notice and seek out details that support their views and to reject evidence that might contradict what they want to believe.

Over time, people generally lose track of why they believe things in the first place, Marcus added, while continuing to strengthen their resolve. If there is strong emotional investment in an idea, such as the belief by a mother that she has raised a good son who would never bomb a public event, people will go to great extremes to resist evidence that their belief might be wrong.

Smokers are a classic example, Marcus said. When the Surgeon General released its first report about the dangers of cigarettes in the 1960s, non-smokers quickly agreed that smoking could cause lung-cancer. Smokers, on the other hand, were eager to point out that other things could kill you, too, that many smokers live long lives and that smoking is beneficial in other ways.

In his book “Kluge: The Haphazard Evolution of the Human Mind,” Marcus argued that the tendency for the human mind to retrieve information that confirms its thoughts is a design flaw -- making people feel good about themselves in the short term but reinforcing poor reasoning skills in the long term and ultimately leading to conflict.

“We’re pretty much all by default tending to notice things that fit with our theories,” Marcus said. “I think it’s a bug. We can’t search our memories for negatives. In a society where everyone gets a vote, when our brains work this way, it leads to gridlock.”

Conspiracy theories seem to hold particular appeal for Americans, said Robert Goldberg, a historian at the University of Utah, Salt Lake City. One reason is that we’ve been raised on a diet of Hollywood movies that are full of sabotage, double agents and convoluted plots.

At the same time, he said, the U.S. government has long invoked conspiracy to disparage its enemies, from Communist supporters to militia groups. Even Hillary Clinton talked about the vast right-wing conspiracy that was out to get her husband.

Eighty percent of Americans believe that conspiracy was involved in JFK’s death, Goldberg said. And more than a third believe that the United States either had a hand in the 9/11 attacks or stood aside when they occurred.

Only about 20 percent of Americans trust the government to do what’s right all or most of the time, according to a recent poll, he added. That decline of faith, combined with the appeal of a good story, sets people up to believe theories that involve secret plots.

Conspiracy theories also appeal when an event is especially horrible and when available explanations are plagued by ambiguity.

“Conspiracy theories give us a rationale, they give us reason to remove the randomness from what seem to be random, senseless acts,” Goldberg said. “They provide emotional sustenance and retaining power. They tell us what happened and why it happened and they point fingers at perpetrators. They give us targets that we can do something about.”

For some people, conspiracy theories are a fun way to speculate about what-ifs. But at their root, Goldberg said, suspicious hypotheses symbolize a lack of trust in an institution. Taken to an extreme, that same sentiment can motivate terrible acts like the Boston bombing.

Read more at Discovery News

Fossils Give Clue to Smell of Ancient Earth

Once life evolved to consume food, instead of harnessing energy from the sun or other chemical sources, picky eaters and gourmands soon followed. Now fossil evidence shows just what was on the menu about 1900 million years ago, and what was the favorite dish.

Like bones with bite marks leftover in a fire, a microfossil assemblage found near Lake Superior in Canada showed that tiny ancient microbes (about 1 micron in size) tended to munch on the larger sheaths (though still really small at 5 microns) of the cyanobacterium-like organism Gunflintia as opposed to the cysts of another bacterium (Huroniospora).

The Gunflintia fossils, found in their namesake Gunflint chert, showed not only perforated sheaths, but also pyritization where iron sulfide (pyrite or ‘fool’s gold’) replaced the biomaterial of the original sheath — a visible marker of a waste product from heterotrophic sulfate-reducing bacteria.

To our modern-day olfactory senses however the ancient Earth would have been a stinky place.

“In fact we’ve all experienced modern bacteria feeding in this way as that’s where that ‘rotten egg’ whiff of hydrogen sulfide comes from in a blocked drain. So, rather surprisingly, we can say that life on earth 1,900 million years ago would have smelled a lot like rotten eggs,’ said Martin Brasier of Oxford University’s Department of Earth Sciences, an author of the study published in this week’s Proceedings of the National Academy of Sciences (PNAS).

‘Whilst there is chemical evidence suggesting that this mode of feeding dates back 3,500 million years, in this study for the first time we identify how it was happening and ‘who was eating who,’ Brasier added.

Whereas plants and some bacteria that are autotrophs can obtain their energy from sunlight, heterotrophs must obtain their energy from the food they eat.

Read more at Discovery News

Our Solar System: Rare Species in Cosmic Zoo

Pulling from 20 years of research since the first discoveries of planets beyond our solar system, scientists have concluded that Earth and its sibling worlds comprise what appears to be a relatively rare breed in a diverse cosmic zoo that includes a huge variety of planet sizes, orbits and parent stars.

The most common systems contain one or more planets one to three times bigger than Earth, all orbiting much closer to their parent stars than Earth circles the sun, says astronomer Andrew Howard, with the University of Hawaii.

Large planets the size of Jupiter are much less common than worlds between the size of Earth and Neptune, none of which even appear in our solar system.

The analysis is based on nearly 900 extrasolar planets found so far, plus a few thousand other candidate worlds still under investigation.

The list, which grows almost daily, includes planets of all sizes and orbits, including a handful located in so-called “habitable zones” where the temperatures on their surfaces would be suited for liquid water. Water -- or at least some kind of liquid -- is believed to be necessary for life.

“It’s awesome that we have gone from nothing less than 20 years ago to being able to talk about planets in habitable zones and even have some planets that may be in habitable zones,” astrophysicist Sara Seager, with the Massachusetts Institute of Technology, told Discovery News.

In related research, Seager points out that with such a diverse collection of exoplanets found so far, scientists’ thinking about habitable zones may be too narrow.

“Because we’ve found so many different types of planets, we’re going to miss out on habitability if we don’t take a more broad view,” Seager said.

Ultimately, scientists want to search the atmosphere of Earth-like planets for telltale chemical signatures of oxygen and other signs of life.

Read more at Discovery News

Dead Stars Could Shine Light on Alien Life

With the list of planets beyond the solar system growing almost daily, scientists are eager to learn if any of the distant worlds actually are hosting life.

But even with a new generation of telescopes, scanning Earth-sized planets for the chemical fingerprints of life will be a time-consuming and tedious process.

First, scientists have to find planets that pass in front of their parent stars, relative to Earth’s line of sight, work that already is under way with NASA’s Kepler space telescope. Of particular interest are planets positioned the proper distance from their host stars so that, like Earth, they could have the right temperatures for liquid water on their surface. Water is believed to be necessary for life.

The trickiest step, however, will be to capture and analyze the tiny bit of starlight that passes through a transiting planet’s atmosphere for signs of oxygen and other potential biomarkers.

Two astronomers think they can better the odds by homing in on a particular type of star called white dwarfs, which are the leftover remains of dead stars that have shrunken down to about the size of Earth.

It is precisely their diminutive size that make white dwarfs an attractive target in the hunt for life beyond Earth, says Harvard University astronomer Avi Loeb.

During a transit, an Earth-sized planet in a white dwarf’s habitable zone would block out a sizable portion of its parent star’s light, if not completely occult the star. That geometry allows for a much quicker and easier scan of a planet’s atmosphere.

“If there is an atmosphere around the planet, this is a great opportunity to actually learn about the composition,” Loeb told Discovery News.

The idea of a dead star hosting planets is not as far-fetched as it may sound. Astronomers have found that at least 20 percent of white dwarf stars are littered with heavy elements and debris rings that are believed to be the shredded remains of planets.

Whether any planets could exist in a white dwarf’s habitable zone, which is about 100 times closer to the star than Earth is to the sun, has yet to be determined.

“We expect to find planets in stable orbits around white dwarfs. The tricky part is to find them in the habitable zone. Because the stars are so much smaller, the habitable zone is going to be very close in,” said astronomer Carolyn Brinkworth with the California Institute of Technology.

One way a planet might find itself in a white dwarf’s habitable zone is if it were gravitationally kicked inward by a larger planet farther away.

“Obviously, you don’t rule anything out, but I think it would take a very, very well-placed kick and luck to get something into a habitable zone. I think your chances of that are fairly slim,” Brinkworth told Discovery News.

Nevertheless, Loeb argues it’s worth a look.

“We know from the history of astronomy that whenever people tried to guess what the sky is like, they were very often wrong,” Loeb said.

Much of the groundwork for scanning suitable white dwarf stars can be done with small telescopes that exist today. Then, after NASA’s James Webb Space Telescope is in orbit, follow-up observations of prime candidates can be done in just five hours, computer models show.

Read more at Discovery News

May 1, 2013

Why Shark Embryos Eat Each Other Up in Utero

Shark embryos cannibalize their littermates in the womb, with the largest embryo eating all but one of its siblings.

Now, researchers know why: It's part of a struggle for paternity in utero, where babies of different fathers compete to be born.

The researchers, who detailed their findings today (April 30) in the journal Biology Letters, analyzed shark embryos found in sand tiger sharks (Carcharias taurus) at various stages of gestation and found that the later in pregnancy, the more likely the remaining shark embryos had just one father.

That finding suggests the cannibalism seen in these embryos is a competitive strategy by which males try to ensure their paternity.

"In some species, the struggle for paternity continues beyond the point where the female [mates with] the male," said study co-author Demian Chapman, a marine biologist at Stony Brook University of New York.


Full-grown sand tiger sharks are approximately 8.2 feet (2.5 meters) long, and mothers typically give birth to two baby sharks, each about 3.3 feet (1 m) long.

Since the 1980s, when detailed autopsies of sand tiger sharks revealed embryos in the stomachs of other embryos, researchers had known that the shark fetuses cannibalized each other in utero about five months into their nearly yearlong gestation. Legend has it that a shark embryo actually bit a researcher's hand during a dissection when the researcher reached into the uterus of the shark's mother, Chapman said.

While 12 littermates may start out the journey, all but one is devoured by the biggest in the pack. That strategy allows sand tiger sharks to have much larger babies at birth than other shark species, making the little ones relatively safe from other predators, Chapman said.

But scientists didn't know why the sharks were cannibalizing each other. One possibility is that females were mating with multiple partners and that the cannibalization helped only one father's genes remain dominant.

To find out, Chapman and his colleagues studied genetic samples from 15 pregnant female sharks that had died in nets off the coast of South Africa. (The nets were put in place to protect swimmers from deadly bites from great white sharks and bull sharks, but the nets occasionally snare and kill sand tiger sharks.)

Paternity struggle

Of those 15 female sharks, 10 of the sharks carried just two embryos, while the remaining five were in an earlier stage of gestation and had five to seven embryos in utero.

The team then used DNA analysis to determine paternity.

"It's exactly the same sort of DNA testing that you might see on Maury Povich to figure out how many dads there are," Chapman told LiveScience.

Those litters with five to seven embryos had at least two fathers (embryos from other fathers may have already disappeared), while the litters with just two sharks more often had just one father.

That suggested one embryo -- possibly the one that grew biggest first -- tended to devour embryos from other fathers over its full siblings.

"Basically, that loser father ultimately provided food for a rival male," Chapman said.

Sexual selection

It's still a mystery exactly what makes one father successful over another, said James J. Gelsleichter, a marine biologist at the University of North Florida who was not involved in the study.

"Sexual selection is very much like an evolutionary arms race, and the males and females are basically one-upping each other," Gelsleichter told LiveScience.

Read more at Discovery News

Richard III Dig May Turn Up Medieval Knight

The lost English church where the body of King Richard III was discovered may still yield more treasures, researchers say. Archaeologists at the site in Leicester are preparing to expand their dig in the hopes of opening the grave of a possible medieval knight.

Richard III's battle-scarred bones were exhumed last year from underneath a parking lot that had been covering the ruins of the medieval Grey Friars Church. Researchers found three other tombs during their search for the king, including a 600-year-old lead-lined stone coffin that may contain the body of Sir William Moton, a knight thought to have been buried at Grey Friars in 1362, more than 100 years earlier than Richard III's death in 1485.

Archaeologists hope to excavate the possible grave of Moton in July during a proposed expansion of their dig at the former Alderman Newton Grammar School, which is set to be converted into a Richard III heritage center. The researchers say the tomb will be incorporated into a visitors' center.

"This will be a great opportunity to confirm the plan of the east end of the Grey Friars church to learn more about its dating and architecture, and will give us the chance to investigate other burials known to be inside the building," archaeologist Richard Buckley, of the University of Leicester, said in a statement.

Relying on historical records, Buckley and his team started digging beneath the Leicester City Council parking lot on Aug. 25, 2012, looking for the final resting place of Richard III. They soon found the church, a 17th-century garden marked by paving stones, and then a male skeleton with a spine curved by scoliosis, a skull cleaved with a blade, and a barbed metal arrowhead lodged among the vertebrae of the upper back.

These clues led researchers to believe they had finally uncovered the body of Richard III, who ruled England from 1483 until his death in 1485 in battle during the War of the Roses. In February, researchers announced that DNA from the teeth and a bone matched with a modern descendant of the king. The body eventually will be reinterred in the Leicester Cathedral.

Read more at Discovery News

Two-Year-Old Girl Gets Stem Cell Windpipe

A two-year-old Korean-Canadian girl born without a trachea now has a new one grown from her own stem cells. The surgery makes Hannah Warren the youngest ever patient to benefit from the experimental treatment.

Before the surgery, Hannah Warren had been unable to eat, drink or swallow on her own and had spent her whole life with a breathing tube in her mouth at a hospital in Seoul, South Korea. Doctors in Seoul had told her parents that their daughter was expected to die.

But her parents found an Italian doctor based in Sweden and a U.S. pediatric surgeon at the Children’s Hospital of Illinois willing to try a new kind of procedure. By inserting a needle into her hip bone, surgeons were able to extract the girl’s own stem cells. The cells were then seeded into a plastic scaffold.

It took less than a week for the stem cells to multiply and form a new windpipe. Then surgeons at the Children’s Hospital of Illinois implanted the trachea during a nine-hour-long procedure on April 9.

The Children’s Hospital waived the cost, which was likely in the hundreds of thousands of dollars, as part of their mission as a Roman Catholic hospital and as a way to highlight stem cell therapy that doesn’t involve human embryos, Dr. Mark Holterman of the Children’s Hospital of Illinois told the AP.

So far, doctors say the stem cell-generated windpipe appears to be working. Hannah is still on a ventilator but her doctors say she will eventually be able to live at home and lead a normal life. Since the windpipe is made from Hannah’s own cells, there’s no need to suppress her immune system to avoid rejection, as during organ transplants.

“We feel like she’s reborn,” Hannah’s father, Darryl Warren, told the Associated Press.

Regenerative medicine is still in the very early stages, but doctors won approval from the Food and Drug Administration to go ahead with the procedure since Hannah had been expected to die before reaching age 6.

The Italian doctor, Paolo Macchiarini, had worked on 14 previous surgeries where patients’ own stem cells were used to create new windpipes. Doctors predict Hannah will need a new windpipe in about five years to accommodate her growing body.

Read more at Discovery News

Alien-Looking Skeleton Poses Medical Mystery

A teensy skeleton with a squashed alien-like head may have earthly origins, but the remains, found in the Atacama Desert a decade ago, do make for quite a medical mystery.

Apparently when the mummified specimen was discovered, some had suggested the possibility it was an alien that had somehow landed on Earth, though the researchers involved never suggested this otherworldly origin.

Now, DNA and other tests suggest the individual was a human and was 6 to 8 years of age when he or she died. Even so, the remains were just 6 inches (15 centimeters) long.

"While the jury is out regarding the mutations that cause the deformity, and there is a real discrepancy in how we account for the apparent age of the bones … every nucleotide I've been able to look at is human," researcher Garry Nolan, professor of microbiology and immunology at Stanford School of Medicine, told LiveScience. "I've only scratched the surface in the analysis. But there is nothing that jumps out so far as to scream 'nonhuman.'"

Analyzing the tiny human

Nolan and his colleagues analyzed the specimen in the fall of 2012 with high-resolution photography, X-rays and computed tomography scans, as well as DNA sequencing. The researchers wanted to find out whether some rare disorder could explain the anomalous skeleton -- for instance it had just 10 ribs as opposed to 12 in a healthy human -- the age the organism died, as its size suggested a preterm fetus, stillborn or a deformed child, and whether it was human or perhaps a South American nonhuman primate.

The remains also showed skull deformities and mild underdevelopment of the mid-face and jaw, the researchers found. The skull also showed signs of turricephaly, or high-head syndrome, a birth defect in which the top of the skull is cone-shaped.

The genome sequencing suggested the creature was human, though 9 percent of the genes didn't match up with the reference human genome; the mismatches may be due to various factors, including degradation, artifacts from lab preparation of the specimen or insufficient data.

The team also looked at mitochondrial DNA, or the DNA inside the cells' energy-making structures that gets passed down from mothers to offspring. The so-called allele frequency of the mitochondrial DNA suggested the individual came from the Atacama, particularly from the B2 haplotype group. A haplotype is a long segment of ancestral DNA that stays the same over several generations and can pinpoint a group who share a common ancestor way back in time. In this case the B2 haplotype is found on the west coast of South America.

The data from the mitochondrial DNA alleles point toward "the mother being an indigenous woman from the Chilean area of South America," Nolan wrote in an email.

More mystery

The jury is still out on the mutations that caused the deformities, and the researchers aren't certain how old the bones are, though they estimate the individual died at least a few decades ago. In addition, they didn't find any of the mutations commonly associated with primordial dwarfism or other forms of dwarfism. If there is a genetic basis for the deformities, it is "not apparent at this level of resolution and at this stage of the analysis," Nolan wrote in a summary of his work.

In addition, even if they found those mutations, they may not explain the anomalies seen in the skeleton. "There is no known form of dwarfism that accounts for all of the anomalies seen in this specimen," Dr. Ralph Lachman, professor emeritus, UCLA School of Medicine, and clinical professor at Stanford University, wrote in a report to Nolan.

This wouldn't be the first time alien-looking remains have been brought to the attention of science. The alienlike skulls of children were discovered in a 1,000-year-old cemetery in Mexico. Researchers who examined the skulls said they had been deliberately warped and illustrated a practice of skull deformation that was common at the time in Central America.

Read more at Discovery News

Apr 30, 2013

First Land Animals Kept Fishlike Jaws for Millions of Years

Scientists studying how early land vertebrates evolved from fishes long thought that the animals developed legs for moving around on land well before their feeding systems and dietary habits changed enough to let them eat a land-based diet, but strong evidence was lacking. Now, for the first time fossil jaw measurements by Philip Anderson at the University of Massachusetts Amherst and others have tested and statistically confirmed this lag.

"This pattern had been hypothesized previously, but not really tested. Now we've done that," Anderson says. He and his team found that the mechanical properties of tetrapod jaws did not show significant adaptations to land-based feeding until some 40 to 80 million years after the four-legged creatures initially came out of the water. Until then, tetrapod jaws were still very fish-like, even though their owners had weight-bearing limbs and the ability to walk on land. Anderson says this finding suggests tetrapods may have shown a limited variety of feeding strategies in the early phases of their evolution on land.

"What it took to really initiate evolutionary changes in the jaw system was for these animals to start eating plants," he says. For the study, published in an early online edition of the journal Integrative and Comparative Biology, Anderson and researchers Matt Friedman of the University of Oxford and Marcello Ruta of the University of Lincoln, U.K., examined images of 89 fossils of early tetrapods and their fish-like forebears. The fossils ranged in age from about 400 to 300 million years old. Anderson and his team were interested in how the jaws of these fossilized animals differed through time.

They used 10 biomechanical metrics to describe jaw differences. One of these, called mechanical advantage, measured how much force an animal can transfer to its bite. Anderson points out that while fossils can't tell you what an animal actually ate, scientists can infer potential feeding behavior from fossilized evidence of biomechanical tools like jaws. The researchers compared jaw features from the fossil record and calculated the rates at which jaws evolved.

"The basic result was that it took a while for these animals to adapt their jaws for a land-based diet," Anderson says. "They stayed essentially fish-like for a long time."

It turns out that just moving into a new environment is not always enough to trigger functional adaptations. In their paper, the authors say the results may be explained by an earlier hypothesis: A shift from gilled to lung breathing in later tetrapod groups was necessary before they could devote their jaw structure to eating plants.

Read more at Science Daily

Why People Believed Fake Bomb Detectors Worked

A man who sold bogus bomb detectors likened to dowsing rods in Iraq and elsewhere has been convicted of fraud in a British court. According to a piece in the New York Times:

A British businessman who sold the Iraqi security forces more than 6,000 fake bomb detectors based on $20 golf ball finders bought from the United States was convicted of fraud on Tuesday in Britain’s central criminal court. The businessman, James McCormick, 56, was described in court as having made more than $75 million from sales of the fake device in Iraq and Georgia, among other places, claiming they could detect bombs, drugs, currency and ivory, and track objects up to 3,280 feet below ground.

The devices were not faulty nor defective; they were completely useless. They had no working electronics in them that could detect bombs or anything else. The device has only one moving part, an antenna-like piece of metal that freely swivels, supposedly detecting explosive and other materials. McCormick sold the devices for up to $40,000 each. At least 800 of the detectors were purchased by the Iraqi government and used at checkpoints throughout the country, as well as in Mexico, Syria, Lebanon and Niger. McCormick faces up to eight years in prison.

According to the Times, “Iraqi officials reacted with fury to the news, noting a series of horrific bombings in the past six months despite the widespread use of the bomb detectors at hundreds of checkpoints in the capital. ‘This company not only caused grave and massive losses of funds, but it has caused grave and massive losses of the lives of innocent Iraqi civilians, by the hundreds and thousands, from attacks that we thought we were immune to because we have this device,’ said Ammar Tuma, a member of the Iraqi Parliament’s Security and Defense Committee.”

The Logic and Psychology of Bogus Detection

You might think that if the bomb-detecting devices were completely worthless, that would soon become clear to those people whose lives depended on them.

And you’d be wrong. The detectors were widely used in the field for years before questions were raised about their validity, and McCormick himself claimed to truly believe that his gadget worked.

How is it possible that the bogus detectors went undetected for so long? Part of the answer lies in human psychology and understanding random chance.

In security and law enforcement situations where people and devices are trying to detect things such as bombs or drugs, the task is finding the threats among the non-threats (or the signal from the noise). Bombings are relatively rare events compared to the number of non-bombings: the vast majority of people, vehicles, and items going through a security checkpoint will be innocent and harmless. The number of real threats will be a small fraction of the potential threat, perhaps 1% (or likely far less).

If one of the bogus bomb detectors falsely detects a bomb or threat, then a suspicious package or person is searched and (assuming nothing is found) allowed to go on their way — an event that routinely happens at airport security checkpoints around the world every day. If that happens (with any device, working or not) the assumption is not that the device doesn’t work, but instead that it gave off a false alarm — as real, working devices often do. Thus the bogus detector’s false positives are ignored (as long as they do not happen continuously, of course). Because bombings are relatively rare events, most of the time a non-working bomb detector will appear to be working correctly, since it didn’t detect bombs that were not there. As they say, even a broken clock is right twice a day.

What about when the device “failed”? Even after a real bomb was successfully smuggled through the checkpoint (and not detected by the non-working bomb detector) and detonated, the fact that the detector failed to find the bomb can simply be rationalized away by security officials: maybe the bomb was expertly hidden in some material that prevented the detector from working that time, or the person using the detector didn’t operate it correctly, or maybe the device simply malfunctioned, as all electronics do now and then. After all, everyone knows that no system, person, or device is 100 percent accurate or perfect all the time: Operators make errors, devices are not correctly calibrated and give off false alarms, drug-sniffing dogs make mistakes, and so on. Because there were alternative, plausible explanations for the device’s clear failures, few suspected that they did not (and could not) work at all.

Read more at Discovery News

Wrong Reality: How Our Brains Warp the World

Tom Cruise, Keira Knightly, Angelina Jolie: When viewed one at a time on a computer screen, photographs of gorgeous celebrities highlight pleasing features on generally symmetrical faces.

 But if you look at the same images side-by-side while focusing on a cross between them, something bizarre happens. The faces begin to morph, becoming bulbous and grotesque, especially when one member of a pair has a face that is structured very differently from the other.

The optical illusion, as described in a 2011 research paper and illustrated in a disturbing YouTube video, is just one example of how our senses often distort reality -- a concept illustrated in a recent Dove ad that showed how other people tend to see us as more beautiful than we see ourselves. In the video, an FBI forensic artist drew women as they described their own faces and as others described them.

Through studies of illusions like these, along with research on vision, brain science and memory, researchers are beginning to understand the limits of our ability to interpret the endless reams of input that we absorb all day long. We often see things that aren’t there and don’t see things that are.

And while many details about the relevant brain processes remain mysterious, it seems that our innate tendency to distort reality can be a useful trait.

“One way we think about perception is that it’s an interpretation of the world rather than a veridical representation of the world because it makes us function in the world,” said Kalanit Grill-Spector, a neuroscientist at Stanford University in Palo Alto, Calif. “If you were representing exactly what was hitting your eyes, it might not be optimal for your behavior.”

She offered a red tomato as an example. If you were to use a spectrometer to measure the wavelengths of light that bounce off of a tomato in different environments, the quality of the fruit’s redness would appear to be wildly different when held outside than it would in the produce aisle of the supermarket. To our eyes, however, the same tomato looks equally red in both places, and that kind of color constancy allows our brains to understand that a tomato is a tomato, no matter where it is.

In another famous illusion, an image can appear to be a duck or a rabbit, depending on which part of the picture you focus your eyes on.

“In this situation where an ambiguous stimulus is prone to multiple interpretations, your brain has to resolve it,” Grill-Spector said. “There might be competition in your brain and it might be happening all the time. If you are walking in the fog and it’s not clear what you’re seeing; you have to make an inference.”

Studying illusions can help scientists better understand how information travels from our eyes to specific areas of our brains and what goes wrong in people, who may, for example, have trouble recognizing faces.

Memory research offers similar insights. Just as it can be helpful for our brains to fill in information so that we “see” what isn’t really there, it’s adaptive for our memories to be less than perfectly accurate, said Sasha Cervantes, a human memory researcher at the University of Chicago.

“The brain requires energy to function and we couldn’t consume enough sugar to retain and filter all the information we take in on a daily basis,” Cervantes said. “It would be inefficient. It’s not necessarily the best thing for us to remember everything with perfect clarity.”

From moment to moment, our biases and feelings influence the way we perceive the present and what we decide to pay attention to or consider important, she added. Later on, we can only remember the details we noticed in the first place.

Even then, every act of remembering involves a reconstruction of what happened, which makes memories malleable. Memories also change as we hear other people’s accounts of them or as we pick certain memories to reinforce at the expense of others.

Understanding the flexibility of memories has become important in research on post-traumatic stress disorder. For people who have experienced trauma, intentionally morphing memories may be the key to recovery.

In ongoing research, Cervantes said, scientists are slowly piecing together a complicated picture of the brain regions involved in forming and reforming memories and how those regions communicate with each other.

Read more at Discovery News

There's a Mighty Maelstrom at Saturn's North Pole

The incredible vortex of spiraling clouds that churns above Saturn's north pole is seen in all its blood-red glory in this stunning image from NASA's Cassini spacecraft, released today (April 29).

Taking advantage of a new orbital trajectory that puts it high above Saturn's rings and poles, Cassini acquired the near-infrared images used to make this composite back on Nov. 27, 2012. The resulting image is false color -- our eyes aren't sensitive to those particular wavelengths of light -- but still no less amazing.

The intense coloration does serve a purpose besides being pretty. The deep-red rose colors correspond to cloud layers lower in the atmosphere, while emerald-hued clouds are higher up.

Lit by the sun at a low angle (summer is currently on its way to Saturn's northern hemisphere) the towering clouds within the vortex cast strong shadows, heightening the level of detail.

A wider-angle view of the ringed planet's pole looks like this:

"We did a double take when we saw this vortex because it looks so much like a hurricane on Earth," said Andrew Ingersoll, a Cassini imaging team member at Caltech. "But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn's hydrogen atmosphere."

Much larger than any hurricane ever seen on Earth, the storm over Saturn's north pole is 1,250 miles (2,000 kilometers) wide with wind speeds up to 330 mph (150 meters per second).

Fueled by internal heat and powerful eddies, and with no underlying land masses to affect them, winds on the rapidly-rotating Saturn can reach over 1,100 mph (1,800 km/h). And with nowhere else to go, this polar hurricane will remain at the planet's pole indefinitely... it was likely already there when Cassini arrived in 2004.

Read more at Discovery News

Apr 29, 2013

Fish Use 'Sign Language' to Help Out Hunting Buddies

Two types of fish have been shown to use gestures, or sign language, to help one another hunt. This is the first time these types of gestures have been found to occur in animals other than primates and ravens.

Both types of fish, grouper and coral trout, are known for hunting cooperatively with other kinds of animals. Whereas the grouper hunts with giant moray eels and a fish called the Napoleon wrasse, coral trout partner up with octopuses to snag prey. A study published last week in the journal Nature Communications found that the fish are able to "point" their heads toward prey, to help out their hunting buddies.

After observing the fish in the wild for many hours, the researchers found that when a prey fish escaped its hunting party, a grouper occasionally moved over the place where the fugitive prey was hiding. The grouper would then rotate its body so that its head faced downward, and it would shake its head back and forth in the direction of the potential meal, in what researchers call a "headstand" signal. Coral trout make a similar sign, the researchers found.

Grouper partner with eel and wrasse, which live in the Red Sea and have complementary hunter-prey tactics: Grouper has "burst speed" in the open water, whereas giant moray eels can crawl into small holes, and wrasse have protracting jaws that can crush coral to get at prey, according to the study. Coral trout collaborate with octopuses, which are also better at fitting into tight spaces. This latter pair lives in Australia's Great Barrier Reef.

In the study, researchers recorded grouper doing the headstand signal 34 separate times; afterward, one of the predators caught the hidden fish on five occasions.

It is, of course, difficult to determine for sure that an animal's movement is truly this type of so-called "referential gesture" (or more loosely referred to as "sign language.") The researchers wrote that the headstand qualified as such because it fulfilled all of the generally accepted components of referential gestures: It was directed toward an object, not useful for any immediate mechanical purpose, aimed at a recipient, seemingly intentional and followed by a voluntary response from the fish's partner.

Read more at Discovery News

Dinosaur Lineage Traced to Africa

Ten million years after the world's largest mass extinction, a lineage of animals thought to have led to dinosaurs took hold in Tanzania and Zambia, according to new research.

The study, published in the latest Proceedings of the National Academy of Sciences, reveals how the end-Permian mass extinction 252.3 million years ago permitted a significant reorganization of terrestrial animals living in the southern part of the supercontinent Pangea.

Out of this chaos emerged the dino predecessors, which likely ushered in the Dinosaur Age.

There were losers, such as fat lizard-looking Dicynodon, which sported a short tail and a turtle's head. It completely bit the dust after the huge extinction event, which led to the disappearance of 90 percent of all life on the planet.

On the winners' side were silesaurs, which were plant-eaters very closely related to dinosaurs.

"In Tanzania, the main silesaur that we find is called Asilisaurus kongwe," co-author Kenneth Angielczyk told Discovery News. "Asilisaurus was about the size of a medium dog, like a golden retriever, and they tended to have long thin limbs."

Yet another fossil find was Nyasasaurus parringtoni, a Labrador retriever-sized animal with a 5-foot-long tail.

"Nyasasaurus is either the oldest known dinosaur or the closest known relative of dinosaurs, but we can't completely rule out either option because the material is rather fragmentary," said Angielczyk, who is Associate Curator of Paleomammalogy at the Field Museum of Natural History.

Angielczyk and his colleagues unearthed these creatures over the course of seven fossil-hunting expeditions in Tanzania, Zambia and Antarctica. The researchers created two "snapshots" of four-legged animals about 5 million years before the mass extinction event and 10 million years after it.

The cause of the great die-off remains a mystery, with intense volcanic activity, a meteorite strike and extreme global warming all being possible candidates.

Before the extinction event, 35 percent of four-legged species were found in the majority of the areas studied, with some species having ranges that stretched 1600 miles. Ten million years after the die-off, just 7 percent of species were found in the same number of areas.

In addition to the already mentioned animals, the survivors included other archosaurs, which is a group that includes modern crocodiles, modern birds and- back in the day- dinosaurs. Cynodonts also lived through the onslaught. This group later evolved into mammals, so these were our very distant ancestors. Certain additional reptiles and amphibians survived too.

While the fossil discoveries would seem to suggest that the motherland for dinosaurs was Africa, the researchers point out that landmasses were configured very differently then. What is now Africa was part of Gondwanaland, the southern portion of Pangea.

Co-author and geologist Sterling Nesbitt of the Field Museum of Natural History explained to Discovery News that "true dinosaurs first show up about 230 million years ago from what is now Argentina. We think that dinosaurs first evolved in Gondwanaland-including Africa, South America, India, Madagascar, Australia, Antarctica."

Bruce Rubidge, a dinosaur specialist at the University of Witwatersrand, said, "The expeditions by this team of researchers to little-explored Permian and Triassic aged depositional basins in Africa and Antarctica, which form part of the supercontinent Gondwana, has greatly enhanced our understanding of the distribution of land-living vertebrates that lived more than 200 million years ago."

Rubidge continued, "The results of this research provide documentation of distribution, both in time and space, of important land living vertebrates soon after the greatest extinction event of all times and indicate how the post extinction recovery fauna evolved and became distributed around the world."

Read more at Discovery News

Dinos, Humans Out of Africa: Why There?

Turns out we humans have something in common with dinosaurs: We all trace our origins to Africa. Or at least it seems that way with the new discovery of a new early lineage of dinosaurs from Africa. But is there more to the story? Is there something special about Africa that makes it a cradle of consequential species?

Absolutely! Yes. In a way. I mean, sort of. Um…no, not really. The truth is, it depends on how you look at it.

There is definitely something very special about the old blocks of continents that have survived billions of years. They shift about the planet, form supercontinents now and again, wander off on their own, and all the while carry around in their rocks and strata many of the chapters of Earth’s history. And sometimes, as the rocks are being chipped away by erosion and tectonics, they those chapters are opened for geologists and paleontologists to read.

The chapter about African dinos, as we now see, is a very cool one. But it’s not really African, but Pangean. When the beast that would become dinos roamed the Earth, the supercontinent Pangea was still intact. An animal did not have to swim or fly to get from Africa to South America. They could walk. In fact, similar fossils found on both continents were early evidence of plate tectonics.

Something that the African section of Pangea of 240 million years ago seems to have in common with the Africa of 2 million years ago (when we evolved) is a warm climate. So that’s another thing we have in common with most dinos: we are warm-weather creatures. But then, so are flies and cockroaches and lots of other species that are arguably not very consequential.

And while we are on the matter of “consequential,” let’s get something straight. Dinosaurs existed as a large and changing group of animals that lasted for more than 100 million years. We, for all our planet-altering power, are a single species and have been around for 2 million years. Any old microbe can alter a planet (by making oxygen, for instance, as happened on early Earth). But to last 100 million years — that’s consequential.

Read more at Discovery News

Sea-Ice Brinicles As Spires of Life

What's cooler than being cool? Brine-cold.

When salt-rich water leaks out of sea ice, it sinks into the sea and can occasionally create an eerie finger of ice called a brinicle. New research explains how these strange fingers of ice form and how the salty water within sea ice could have been a prime environment in which life may have evolved.

The study, published in the American Chemical Society's journal Langmuir, suggests that brinicles form in the same way as hydrothermal vents, except in reverse. Hydrothermal vents are spiny-looking towers on the ocean bottom where boiling, chemical-rich water flows out of the seafloor.

The brinicle-forming process goes like this: When sea ice freezes in the Arctic and Antarctic, the salt and other ions in the water is excluded from the water crystals, said study author Bruno Escribano, a researcher at the Basque Center for Applied Mathematics in the Basque Country in northern Spain. This salt-heavy brine accumulates in fractures and compartments within the sea ice.

Inevitably, however, sea ice cracks, and the brine leaks out. The brine itself is colder than the freezing point of seawater, since salt-rich water freezes at lower temperatures (hence the reason people put salt on icy sidewalks in the winter, enabling the ice to remain a liquid when it's below freezing), Escribano told OurAmazingPlanet.

Since the concentration of water in the brine is lower than that in the ocean — and water moves from high to low concentrations, via osmosis — water is attracted to the brine. But the brine is so cold that the water freezes, forming a descending tube of ice, Escribano said.

Hydrothermal vents form by an analogous method: Ion-rich hot water is expelled from the seafloor and then begins to dissolve, forming a porous shell of metal extending upward. Water then rushes in, moving from high to low concentration, rupturing the membrane and causing more metal-rich water to spurt out, extending the tube and repeating the process.

Both are examples of "chemical gardens," a type of chemical process and the name of an experiment common in chemistry sets that operates along the same principles and forms tubes of crystals that make plant-like shapes, Escribano said.

Read more at Discovery News

Apr 28, 2013

Turtle Genome Analysis Sheds Light On Turtle Ancestry and Shell Evolution

From which ancestors have turtles evolved? How did they get their shell? New data provided by the Joint International Turtle Genome Consortium, led by researchers from RIKEN in Japan, BGI in China, and the Wellcome Trust Sanger Institute in the UK provides evidence that turtles are not primitive reptiles but belong to a sister group of birds and crocodiles. The work also sheds light on the evolution of the turtle's intriguing morphology and reveals that the turtle's shell evolved by recruiting genetic information encoding for the limbs.

Turtles are often described as evolutionary monsters, with a unique body plan and a shell that is considered to be one of the most intriguing structures in the animal kingdom.

"Turtles are interesting because they offer an exceptional case to understand the big evolutionary changes that occurred in vertebrate history," explains Dr. Naoki Irie, from the RIKEN Center for Developmental Biology, who led the study.

Using next-generation DNA sequencers, the researchers from 9 international institutions have decoded the genome of the green sea turtle and Chinese soft-shell turtle and studied the expression of genetic information in the developing turtle.

Their results published in Nature Genetics show that turtles are not primitive reptiles as previously thought, but are related to the group comprising birds and crocodilians, which also includes extinct dinosaurs. Based on genomic information, the researchers predict that turtles must have split from this group around 250 million years ago, during one of the largest extinction events ever to take place on this planet.

"We expect that this research will motivate further work to elucidate the possible causal connection between these events," says Dr. Irie.

The study also reveals that despite their unique anatomy, turtles follow the basic embryonic pattern during development. Rather than developing directly into a turtle-specific body shape with a shell, they first establish the vertebrates' basic body plan and then enter a turtle-specific development phase. During this late specialization phase, the group found traces of limb-related gene expression in the embryonic shell, which indicates that the turtle shell evolved by recruiting part of the genetic program used for the limbs.

"The work not only provides insight into how turtles evolved, but also gives hints as to how the vertebrate developmental programs can be changed to produce major evolutionary novelties." explains Dr. Irie.

Read more at Science Daily

Speed of Light May Not Be Constant

The speed of light is constant, or so textbooks say. But some scientists are exploring the possibility that this cosmic speed limit changes, a consequence of the nature of the vacuum of space.

The definition of the speed of light has some broader implications for fields such as cosmology and astronomy, which assume a stable velocity for light over time. For instance, the speed of light comes up when measuring the fine structure constant (alpha), which defines the strength of the electromagnetic force. And a varying light speed would change the strengths of molecular bonds and the density of nuclear matter itself.

A non-constant speed of light could mean that estimates of the size of the universe might be off. (Unfortunately, it won't necessarily mean we can travel faster than light, because the effects of physics theories such as relativity are a consequence of light's velocity).

Two papers, published in the European Physics Journal D in March, attempt to derive the speed of light from the quantum properties of space itself. Both propose somewhat different mechanisms, but the idea is that the speed of light might change as one alters assumptions about how elementary particles interact with radiation. Both treat space as something that isn't empty, but a great big soup of virtual particles that wink in and out of existence in tiny fractions of a second.

Cosmic vacuum and light speed

The first, by lead author Marcel Urban of the Université du Paris-Sud, looks at the cosmic vacuum, which is often assumed to be empty space. The laws of quantum physics, which govern subatomic particles and all things very small, say that the vacuum of space is actually full of fundamental particles like quarks, called "virtual" particles. These matter particles, which are always paired up with their appropriate antiparticle counterpart, pop into existence and almost immediately collide. When matter and antimatter particles touch, they annihilate each other.

Photons of light, as they fly through space, are captured and re-emitted by these virtual particles. Urban and his colleagues propose that the energies of these particles -- specifically the amount of charge they carry -- affect the speed of light. Since the amount of energy a particle will have at the time a photon hits it will be essentially random, the effect on how fast photons move should vary too.

As such, the amount of time the light takes to cross a given distance should vary as the square root of that distance, though the effect would be very tiny -- on the order of 0.05 femtoseconds for every square meter of vacuum. A femtosecond is a millionth of a billionth of a second. The speed of light has been measured over the last century to high precision, on the order of parts per billion, so it is pretty clear that the effect has to be small.

To find this tiny fluctuation, the researchers say, one could measure how light disperses at long distances. Some astronomical phenomena, such as gamma-ray bursts, produce pulses of radiation from far enough away that the fluctuations could be detected. The authors also propose using lasers bounced between mirrors placed about 100 yards apart, with a light beam bouncing between them multiple times, to seek those small changes.

Particle species and light speed

The second paper proposes a different mechanism, but comes to the same conclusion that light speed changes. In that case, Gerd Leuchs and Luis Sánchez-Soto, from the Max Planck Institute for the Physics of Light in Erlangen, Germany, say that the number of species of elementary particle that exist in the universe may be what makes the speed of light what it is.

Leuchs and Sanchez-Soto say that there should be, by their calculations, on the order of 100 "species" of particle that have charges. The current law governing particle physics, the Standard Model, identifies nine: the electron, muon, tauon, the six kinds of quark, photons and the W-boson.

The charges of all these particles are important to their model, because all of them have charges. A quantity called impedance depends on the sum of those charges. The impedance in turn depends on the permittivity of the vacuum, or how much it resists electric fields, as well as its permeability, or how well it supports magnetic fields. Light waves are made up of both an electric and magnetic wave, so changing those quantities (permittivity and permeability) will change the measured speed of light.

"We have calculated the permittivity and permeability of the vacuum as caused by those ephemeral virtual unstable elementary particles," Soto-Sanchez wrote in an email to LiveScience. "It turns out, however, from such a simple model one can discern that those constants contain essentially equal contributions of the different types of electrically charged particle-antiparticle pairs: both, the ones known and those so far unknown to us."

Both papers say that light interacts with virtual particle-antiparticle pairs. In Leuchs' and Sanchez-Soto's model, the impedance of the vacuum (which would speed up or slow down the speed of light) depends on the density of the particles. The impedance relates to the ratio of electric fields to magnetic fields in light; every light wave is made up of both kinds of field, and its measured value, along with the permittivity of space to magnetic fields, governs the speed of light.

Some scientists are a bit skeptical, though. Jay Wacker, a particle physicist at the SLAC National Accelerator Laboratory, said he wasn't confident about the mathematical techniques used, and that it seemed in both cases the scientists weren't applying the mathematical tools in the way that most would.

"The proper way to do this is with the Feynman diagrams," Wacker said. "It's a very interesting question (the speed of light)," he added, but the methods used in these papers are probably not sufficient to investigate it.

Read more at Discovery News