Stephen Hawking, the world’s leading theoretical physicist, was among a group of 16 to receive the Presidential Medal of Freedom, the highest civilian award. The medal honors those who have significantly contributed to world peace, U.S. security or other endeavors.
Pres. Barack Obama presented the award, lauding Hawking’s immense contributions in spite of his physical disability due to a neurological disorder. “From his wheelchair, he has led us on a journey to the farthest and strangest reaches of the cosmos. In so doing, he has stirred our imagination and showed us the power of the human spirit,” [Sky News], Obama said of Hawking as he placed the medal around his neck. Besides his contributions to the field of physics through his research on topics like black holes and cosmology, Hawking, 67, is also the author of the best-selling science book A Brief History of Time.
The motion of jellyfish and other sea creatures might mix the oceans just as much as the winds and tides do, according to a study published in Nature. The study’s findings provide support for a theory called Darwin drift, which was developed by Charles Galton Darwin (the grandson of the Darwin). The theory holds that a body moving through water brings along some of the wet stuff.
To test the theory of Darwin drift, researchers first modeled the motion of swimming organisms in a lab, using liquids of various viscosities, or levels of internal resistance. They found that bodies drag more liquid along with them when the liquid is thicker. This effect can be significant; in fact, when marine plankton-sized objects moved a couple of body lengths forward in the most viscous liquids, they carried with them up to four times their volume in liquid. Next the researchers monitored jellyfish as they swam through clouds of dye in a lake on the Pacific island of Palau. A trail of dye followed each animal, as Darwin’s mechanism would predict. Using a laser-equipped camera, the team then measured the dye’s movement and the stirring of suspended particles in the animal’s wake [Nature News]. The scientists found that the mechanism proposed by Galton Darwin provided for 90 percent of the mixing between the water and the dye.
Scientists now know how the iridescent green scarab beetle’s shell get its iridescent hue: A molecular arrangement that reflects light, with the reflected light’s magnetic field oriented like a corkscrew, according to a study published in Science.
The beetles don’t appear green due to pigments, which give flowers and plants their colors. Instead, they get their hue from structural color, or molecular structures that reflect light in a certain manner–the same way birds and butterflies do. Light hitting the shell is reflected by the microstructures, and these reflections create an electric field that forms a clockwise helix. Humans cannot see this property — known as left-handed circular polarization — but can see a green hue [ScienceNews]; some organisms, however, can actually see circular polarization itself. The molecular structure consists of three shapes: pentagons, hexagons, and seven-sided heptagons.
The pitter-patter of raindrops on your umbrella is caused by raindrops of all different sizes, and now physicists have a new explanation for how those raindrops form. A pair of researchers used a high-speed camera (video below the jump) to watch a single drop of water fall and change shape over the course of six-hundredths of a second, and found that the shattering of single raindrops after they leave clouds is enough to explain the wide variety of drop sizes [Science News].
Previously, the leading theory to explain the diversity of raindrops had been that raindrops grow as they gently bump into each other and coalesce. Meanwhile, more forceful collisions break other drops apart into a scattering of smaller droplets. All this action would explain the wide distribution of shapes and sizes [ScienceNOW Daily News]. But lead researcher Emmanuel Villermaux says he questioned that theory, with its supposition of frequent collisions. Real raindrops are so sparse, he said, that it is likely a drop would “fall on its own and never see its neighbours” [BBC News].
In the past century, jockeys have helped their horses race about six percent faster, thanks to a position on the horse known as the “monkey crouch.” This elevated, squatting stance minimizes the work the horse must do to propel his rider forward, according to a study published in Science.
To analyze the movement of the horse and jockey while racing, scientists attached sensors to the saddle and the jockey’s belt. They found that when a horse runs, it also moves up and down, bringing the jockey along with it. The rider can therefore weigh the horse down or, in the case of the monkey crouch, he can isolate himself from the horse’s motions, and therefore minimize his effect on the horse’s movement. When seated upright, riders act much like sandbags, weighing down the horse and incurring increased mechanical and metabolic costs. But in the crouched … position, a jockey can move relative to the horse and minimize this forward-backward and up-and-down movement [Scientific American].
The sandfish lizard appears to “swim” like a fish through sand, but how exactly the animal does it has long puzzled biophysicists. Now, a study published in Science reveals that the four-legged creature really does swim through sand like it would in water by retracting its legs and undulating its body.
To examine the lizard’s movement, researchers had to peek underground. They did this using X-ray imaging, and found that once the lizard, or skink, has dived beneath the sand, it doesn’t paddle. “When started above the surface, the animals dive into the sand within half a second. Once below the surface, they no longer use their limbs for propulsion — instead, they move forward by propagating a traveling wave down their bodies like a snake,” said study leader Daniel Goldman [LiveScience]. This movement was surprising because previous magnetic resonance imaging studies seemed to suggest that the lizards pushed themselves along using their legs.
Astronomers have caught sight of two stars that went kaboom only 2.5 billion years after our universe was created in the Big Bang, and say that ancient explosions are the oldest and most distant supernovas ever discovered. Researchers plan to use the new technique used to identify these supernovas to find other stars that blew up in the universe’s early days, which may aid our understanding of how the universe was seeded with heavy elements.
Only a few lightweight elements – hydrogen, helium, and lithium – are thought to have been created in the big bang; all others were forged over time in the nuclear furnaces of stars and in supernovae. Since the spectrum of light from a supernova reveals the chemical composition of the exploding star, observing many such explosions would allow astronomers to trace out a chemical history of the universe [New Scientist]. Heavier metals eventually gathered in the clouds of dust that surrounded young stars, and sometimes formed parts of rocky planets like Earth.
The European Space Agency’s Planck observatory has reached its operating temperature of a mere tenth of a degree above the lowest temperature theoretically possible given the laws of physics, known as absolute zero. That means it’s ready for its mission: Observing the oldest light in the universe, known as the cosmic microwave background, or CMB, to create the clearest picture yet of what the young universe looked like.
Although scientists have achieved temperatures closer than this to absolute zero in the laboratory, the spacecraft is likely the coldest object in space. Such low temperatures are necessary for Planck’s detectors to study the Cosmic Microwave Background by measuring its temperature across the sky. Over the next few weeks, mission operators will fine-tune the spacecraft’s instruments. Planck will begin to survey the sky in mid-August [SPACE.com], and the first batch of data is expected to be released next year. Planck was launched May 14 and will observe the CMB from a spot more than 930,000 miles from Earth.
Astronomers believe they’ve found something never before detected in the universe: a black hole of intermediate size. And while that may not sound thrilling to the layman, researchers are thrilled by the discovery of the so-called “Hyper-Luminous X-ray Source 1,” which is poised at the edge of galaxy ESO 243-49. Astronomers are excited because they’ve seen plenty of small black holes and large black holes, but experts had questioned whether a medium-sized variety could exist. These middleweights, at about 500 times the mass of the sun, could represent a missing link between common stellar black holes, created by the death of a single star, and the supermassive variety that can pack the mass of millions or even billions of suns [SPACE.com].
Astronomers explain that small black holes, between three and 20 times the mass of the sun, are created when big stars collapse and leave behind a gravitational pull strong enough to block nearby light rays. Researchers have speculated that super-massive black holes result from the successive fusion of many smaller black holes. But without finding evidence of a medium-size hole, it was a tough theory to prove [Wired.com]. Supermassive black holes are of particular interest because they lurk at the hearts of most galaxies, and may play an important role in galaxy formation.
Computers powered by frickin’ laser beams just came a step closer. Light-based, or photonic, computers would theoretically be much faster and smaller than the electronic computers we use today, but researchers have had a hard time putting theory into action. Now, a new study has shown that two laser beams can be harnassed to turn a single molecule into a transistor. However, the specialized conditions necessary for the trick to work mean that computer stores won’t have photonic sections anytime soon.
Conventional computers are based on transistors, which allow one electrode to control the current moving through the device and are combined to form logic gates and processors. The new component achieves the same thing, but for laser beams, not electric currents. A green laser beam is used to control the power of an orange laser beam passing through the device [New Scientist]. In the study, published in Nature, the green beam could make the orange beam either weak or strong, which is analagous to an electronic transistor turning a current on or off.
Scientists have found a way to safely store notoriously dangerous white phosphorus on the atomic scale: in a cage made of atoms that can only be unlocked by a specific molecule, according to a study published in the journal Science.Containing white phosphorus, a tetrahedral formation of phosphorus atoms, will be useful because the molecule readily reacts if it comes into contact with air.
It’s not surprising, then, that it is often used in military campaigns to create smokescreens to mask movement from the enemy, as well as an incendiary in bombs, artillery and mortars [ScienceDaily]. White phosphorus is also an essential ingredient in many plant fertilizers and weed killers, so the ability to safely transport and store the molecule would also be an asset for those industries.
Contrary to what scientists previously thought, it’s not only the power of a dog’s muscles that limits how fast the animal can accelerate; instead, it’s the need to keep those front paws on the ground and avoid doing a backflip. Although animals clearly don’t have wheels, the authors have branded this potential imbalance a quadrupedal “wheelie,” according to a study (pdf) published in the journal Biology Letters.
The ability to gain speed quickly is crucial for survival, but there’s a limit as to how rapidly an animal can accelerate. Researchers wondered whether the “wheelie” problem experienced by cars during a drag race could be a factor in four-legged animals’ ability to speed up. They came up with a simple mathematical model… to see how fast a quadruped could accelerate without tipping over backward. The model predicts that the longer the back is in relation to the legs, the less likely a dog is to flip over and the faster it can accelerate. Then the researchers tested the model by going down to the local track, London’s Walthamstow Stadium, and video-recording individual greyhounds as they burst out of the gate in time trials. The acceleration approached–but never exceeded–the limit predicted by the model [Science NOW]. That means that at low speeds, it’s the ability to keep his front end from pitching up that determines a dog’s maximum acceleration.
The sand that runs through an hourglass may look like a smooth and regular stream of particles, but if you had a big enough hourglass and a fancy enough camera, you’d see that those grains of sand behave in strange ways, not like a regular solid. In fact, the stream of grains begins to look more like a liquid as it falls, with the particles clustering together to form “droplets.”
For the study, published in Nature, researchers created a stream of tiny glass beads, each about the width of a human hair. The team dropped an $80,000 high-speed camera in free fall with the glass to capture still pictures of the same three-centimeter-long section of the grain flow [Science News], and watched as the stream separated into distinct droplets over the course of falling three feet. In another experiment, researchers examined two individual beads under an atomic force microscope, and found that the attraction between the two can be explained by an extremely weak surface tension in the beads. Previously, scientists thought grains did not display surface tension, or if they did, the effects were too small to change the flow of the particles. “But this experiment says that if we look very carefully, we find surface tension is almost zero, but it is not exactly zero” [Science News], says study coauthor Heinrich Jaeger.
Who knew this spring’s soggy weather fell under the umbrella of physics research? Scientists found that when raindrops fall faster than physics predicts, the drops have actually broken into smaller droplets, according to a study in the journal Geophysical Research Letters. And because weather services gauge rainfall based on the velocity at which droplets fall–conventional wisdom holds that large drops should hit the ground at a higher speed than do smaller droplets–these results could improve the way we predict weather.
All falling objects have a so-called terminal velocity, a speed they can’t surpass due to air resistance. Therefore, larger drops generally should fall faster because their heftier size helps them power through air resistance more easily than little drops. (In the extreme case, think of fog: water droplets so small they don’t fall at all.) But data showing small drops sometimes impact the ground at the same speed as larger ones showed this conventional wisdom was wrong, and has puzzled scientists for years. To solve the mystery, the researchers collected a shower of data using optical equipment over a period of several years. The team clocked about 64,000 raindrops falling in Mexico City. The researchers measured their sizes and velocities only in extremely calm conditions, so the wind that often accompanies rain could not skew the data. They found that some drops plummeted faster than the so-called terminal velocity for their size [ScienceNOW Daily News].
The sun has been surprisingly quiet lately, and until now astronomers couldn’t figure out why. An 11-year cycle governs solar flares and sunspots, and researchers knew that we were at the end of a cycle in a “solar minimum” or quiet period–but that somnolence has continued for an extra year beyond the point at which researchers expected sunspot activity to resume. Comments Australian astronomer Phil Wilkinson: “We have had a drought of sunspots…. This is the longest period the sun has been quiet since the start of the Space Age. Seeing the sun doing nothing is really exciting,” he said, adding it made physicists wonder how little they really understood [Sydney Morning Herald].
Now, new observations announced at a meeting of the American Astronomical Society reveal a possible explanation: “sluggish” solar jet streams 4,350 miles below the surface of the sun. Every 11 years, the sun simultaneously generates twin streams of plasma at each of its poles. Unlike the jet streams on Earth, the solar versions are magnetized and travel only toward the equator. This migration takes place very slowly–at about 10 kilometers per hour. For reasons still not understood, when the streams reach 22 degrees of latitude, north and south, they touch off a new solar cycle, and the sunspots reappear [ScienceNOW Daily News].
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Stephen Hawking, the world’s leading theoretical physicist, was among a group of 16 to receive the Presidential Medal of Freedom, the highest civilian award. The medal honors those who have significantly contributed to world peace, U.S. security or other endeavors.
Scientists now know how the iridescent green scarab 
The pitter-patter of raindrops on your umbrella is caused by raindrops of all different sizes, and now physicists have a new explanation for how those raindrops form. A pair of researchers used a high-speed camera (video below the jump) to watch a single drop of water fall and change shape over the course of six-hundredths of a second, and found that the shattering of single raindrops after they leave clouds is enough to explain the wide variety of drop sizes [
In the past century, jockeys have helped their 
The sandfish 
Astronomers have caught sight of two stars that went kaboom only 2.5 billion years after our universe was created in the 
The European Space Agency’s 
Astronomers believe they’ve found something never before detected in the universe: a 
Computers powered by frickin’ laser beams just came a step closer. Light-based, or photonic, computers would theoretically be much faster and smaller than the electronic 
Scientists have found a way to safely store notoriously dangerous white phosphorus on the atomic scale: in a cage made of atoms that can only be unlocked by a specific molecule, according to a 
Contrary to what scientists previously thought, it’s not only the power of a dog’s muscles that limits how fast the animal can accelerate; instead, it’s the need to keep those front paws on the ground and avoid doing a backflip. Although animals clearly don’t have wheels, the authors have branded this potential imbalance a quadrupedal “wheelie,” according to a 
The sand that runs through an hourglass may look like a smooth and regular stream of particles, but if you had a big enough hourglass and a fancy enough camera, you’d see that those grains of sand behave in strange ways, not like a regular solid. In fact, the stream of grains begins to look more like a liquid as it falls, with the particles clustering together to form “droplets.”
Who knew this spring’s soggy weather fell under the umbrella of physics research? Scientists found that when raindrops fall faster than physics predicts, the drops have actually broken into smaller droplets, according to a 
The 
