Photon Seemingly Travels Faster Than Light
According to Albert Einstein’s theory of special relativity, nothing can exceed the speed of light. It’s impossible. As matter speeds up, it gains mass. The more mass it has, the more energy is required to keep the object accelerating. Once it hits the speed of light, the mass is infinite, and thus, the required energy to keep it accelerating would be infinite, as well.
“There is no experiment that has contradicted special relativity,” states Donald Schneider, professor of astronomy and astrophysics at Penn State. “We have accelerated sub-atomic particles to well over 99 percent of the speed of light, but not equal or exceeding the speed of light.”
However, an experiment by scientists at the Joint Quantum Institute have sped up photons faster than the speed of light by launching them through strategically-placed stacks of material. Or, created the illusion of it, at least.
Researchers placed 30 dielectric (electrically insulating) layers of material, one in front of the other, each 80 nanometers apart. The layers alternated between high (H) or low (L) refractive indices, which caused the light to bend or reflect in varying amounts. When a photon passes through these layers, it has a chance of either being reflected or passing through. When it passes through, it passes through all of the layers in 12.84 femtoseconds (quadrillionths of a second). When the researchers added another H layer, the photon reduced its transit time to about 5.34 fs, so that they seemed to emerge through the stack at faster-than-light speeds.
However, this behavior is easily explained by the wave properties of light. As a photon passes through each layer, it creates a remaining wave, and these waves interfere with one another, combining to give the illusion of photons traveling faster than the speed of light. I’m not exactly sure how that works, but it’s still awesome. (::reminds self to get a degree in Quantum Physics::)
A similar thing occurs when photons pass through water. Water is denser than empty space and thus, photons are slowed to three-fourths of their original speed. In a nuclear reactor, photons flying off of radioactive rods also appear to exceed the speed of light. This is a process called the Cherenkov Effect. I don’t understand how this works, either, but it does make the water glow a neat, eerie blue color, and so this too, is awesome.
Wormholes, tachyons and warp drives are staples of science fiction, and it looks like they won’t become a part of reality anytime soon. But at least we can mimic faster than light travel effectively, and that’s half the battle.
Source: Science Daily
Take a Pill, Stop Being Hungry
Leptin is a hormone that essentially tells our brain when we’re no longer hungry. A group of researchers at the Universite de Montreal are developing a pill that harnesses this protein and hope to start animal testing it in 2010.
In previous studies, mice deprived of leptin did not know when to stop eating, becoming morbidly obese (amusing images of cantaloupe-shaped mice rolling around their cage like soccer balls fill my head).
Post-doctoral student, Phillipe Cammisotto, is developing a pill that would harness the appetite-suppressing abilities of leptin.
“Taken orally, such a pill would provide obese people with the sensation of being full,” states Dr. Cammisotto. “They would eat less and in turn lose weight.”
Morbidly obese people sometimes have a deprivation of leptin within their system – deprived of the hormonal signal that they are full, they are literally always hungry. When administered recombinant human leptin, only the most obese subjects showed a significant weight loss, so a pill-administered leptin agent may not be as effective for those just wanting to lose a couple of pounds.
Source: Science Daily
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Algal Blooms Responsible for Mass Extinctions?
When you think of mass extinctions, you think of a catastrophic event: meteorites slamming into the Earth, hurling hunks of rocks and clouds of suffocating dust; volcanic eruptions that block out the sun with the massive amounts of ash expelled into the air. However, you don’t think of algae, the seemingly innocuous seaweed, being able to significantly contribute to a mass extinction. However, recent research is showing that algae may have played a significant role in all five mass extinctions.
Algae blooms occur fairly regularly in the ocean. When large numbers of algae come together, they discolor the surrounding waters and outcompete, poison or asphyxiate any other life forms dwelling there. A particularly nasty form of alga, Heterosigma akashiwo, caused the death of 260 tons of farmed Atlantic Salmon in 2007. Algae come in a number of different forms: dinoflagellates, the producers of red tides, cyanobacteria (though reclassified as bacteria, it is sometimes still considered algae because it causes an algal bloom), and euglenids, the cause of green algal blooms.
Geologist James Castle from Clemson University and John Rodgers, an environmental toxicologist, wanted to see if algal blooms were as harmful millions of years ago as they are today. An investigation of current research showed that rock formations had increased populations of cyanobacteria called “microbial mats,” during four out of the five mass extinctions. A comparison of the structures of modern cyanobacteria with ancient cyanobacteria found that the species has not changed very much over the years.
“Since they’ve changed very little in their structure, and they make toxins today, we propose that they did so in the past,” states Castle.
However, algal blooms were probably not the sole agents responsible for mass extinctions. Instead, they provided a “kill mechanism,” a way for environmental change to contribute to increased deaths.
“The toxins tend to become stronger and released when there’s something that stresses the algae, [such as] a change in salinity of the water, a change in temperature,” explains Castle. “There could have been an impact or volcanic eruption, and that may have stressed the algae, [and] by changing the conditions, they released toxins that kill the organism.”
However, some scientists don’t agree with Castle’s and Rodger’s hypothesis, claiming that the microbial mats were formed after the extinctions had already occurred.
“In all cases, the microbial sediments post-date the extinction, so it seems unlikely that they were the actual cause,” said Matthew E. Clapham, a marine paleoecologist at the University of California, Santa Cruz. “Although many extinctions do share common causes, I don’t know that it’s really as good of an idea to try and explain all things by just one cause like this.”
Though it is possible that algal bloom may have played a role in prolonging recovery from extinctions, or added additional stress to species during an extinction period, it’s unlikely that they were the major cause of an extinction.
“Because cyanobacteria have been around for most of the history of life on Earth, it’s virtually certain that there were times in the past when there were local die-offs due to cyannobacterial toxins,” states Clapham. “But to demonstrate that it was a global event, or something significant enough, I’m not sure that’s likely.”
Frederick Rich, a geologist at Georgia Southern University poses the question: “Who knows what the causes were, or might be, for a species’ extinction? It is all, and is absolutely, and without equivocation, speculation to decide how something or someone died.”
Thanks for the lead, Labyrinth!
Source: Live Science
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Dino Rocks Red Mohawk, Red and White Tail Feathers
For all the progress paleontologists have made in reconstructing the look and feel of a dinosaur, there’s still one thing that they’ve been unsure of – what color was its skin? Fossils are mainly collections of mineralized bones – no signs of color or pigmentation typically survive millions of years worth of fossilization. Very few fossils are found with preserved skin or preserved feathers. But a team of British and Chinese scientists have gotten lucky. For the first time ever, they’ve have found a way to unlock the color patterns of some of the first feathery dinosaurs.
The dinosaur is called Sinosauropteryx, and it has a red mohawk, with a red and white striped tail. When the fossil was unearthed in China, Mike Benton, a researcher on the project, found that they shared something else in common with birds, besides their tail feathers. Inside a preserved feather were structures called melanosomes, which provide the color pigments in current bird feathers. The color of the feather depends on the shape of the melanosome: “A ginger-haired person would have more spherical melanosomes, and a black-haired or grey-haired person would have more of a sausage-shaped structure,” stated Benton.
The team found both spherical and sausage-shaped melanosomes in the ancient feathers, which mean that they would have grey and red stripes. These elaborately-colored feathers were likely used in courtship displays, similar to how colorful modern day birds use their feathers.
Source: Discover
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Published: Feb 1, 2010 05:30 pm