Lightning has been flashin' around forever- and yet scientists just can't seem to figure it out. Granted, we have made progress since times of the early Greeks, who believed that lightning was a weapon of Zeus.
Fast forward centuries later to Ben Franklin's kite experiment, and lightning became less of a scary God-power trip, and more like a giant electrical current.
Recently in (2001 and 2002), scientists proved that lightning actually produces large amounts of X-rays. No one understands how lightning makes X-rays, but physicists at University of Florida and Florida Institute of Technology Engineering are on the brink of discovering the source of x-rays emitted by lightning. According to scientists heading the research, knowing the source of x-rays could one day help predict where lightning will strike.
The problem is temperature. Lightning is really really hot-The temperature of the air around a bolt of is about 54000° Fahrenheit. That's about 5-6 times hotter than the surface of the sun. Even so, lightning is still much to cold to produce the X-rays observed. But somehow they are being produced, the question is how.
Data from electric field and X-ray detectors, lead researchers to conclude that as lightning emerges from a cloud and hurdles to the ground in a series of 30 to 60 foot "steps", X-rays almost instantly shoot out just below each step.
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Thursday, July 17, 2008
When Lightning Strikes
Tuesday, July 15, 2008
Avalanches: Not All Their Cracked Up to Be
Skiers recently gained useful, (possibly life-saving) new knowledge about the causes of avalanches, thanks to a new study by physicists at the University of Edinburgh in Scotland.
According to the authors, the particular ways that snow cracks and collapses is a telltale sign of avalanche formation. Certain crack patterns can foreshadow whether or not a slab of snow will cascade down the slope in a tumbling mass of disaster, or simply collapse onto itself.
This means that contrary to popular belief, crack sizes don't necessarily increase as the slope angle decreases. Rather, snow slides can happen at any slope angle, there is no is minimum requirement.
Researchers modeled the most common type of avalanche, known as slab avalanches, where a giant chunk of
snow breaks off and meets its fate at the foot of a mountain. They found that compression, or how packed the snow is, plays a greater role in avalanche dynamics than gravity pulling down along the slope does.
By investigating the structure of snow layers, which are comprised of hollowed-out ice grains that form cavities, researchers determined that patterned cracks in the snow can spread over large areas, triggering avalanches.
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Tuesday, March 11, 2008
Bourbon Street Physicists
Hi there, physics lovers! Physics Buzz has temporarily headed south... to gorgeous
The March Meeting is primarily an opportunity for physicists to share their research with other physicists in their field. Every once in a while, it’s also a chance to reveal a major discovery that affects more fields of physics or even the world at large. One press conference focused on some of these major breakthroughs and included a talk on the creation of gold, lead and tin fullerenes. Physics Buzz recently had an article about the first team to image carbon fullerenes, better known as buckyballs, or tiny soccer-ball-like cages made of carbon atoms.
These cages don’t exist in nature, and are made up of only 60 carbon atoms each. Sculpture on that scale is very difficult; we’re talking about specifically manipulating the structure of just a few dozen atoms! Lai-Sheng Wang presented his group’s creation of cages made of lead, gold, and tin. These metals all have very different properties from carbon, and will offer new applications as the science develops. Almost before researchers found they could successfully create these cages, they were working on how to put things inside them (which the team successfully did). Putting an atom inside a cage that is made up of another type of atom can alter the cage material’s chemical properties. It also offers the possibility of using the fullerenes as atomic transports.
Some people are focused on other things when they come to the March Meeting. Here is the Editor in Chief of Physical Review, Gene Sprouse, showing off mad skills (just kidding of course. Although Gene is a very talented yo-yoer, he spends most of his time keeping the journals running strong).
Another breakthrough was the development of 3D optical lattices consisting of individual atoms, in which the atoms are far enough apart that they can be individually manipulated without disturbing their neighbors. David Weiss presented the data from Penn State. 
Imagine making small cubes out of toothpicks, held together at the joins by balls of clay. You could put a group of these together to then make a larger cube looking somewhat like a square jungle-gym. This is essentially a lattice, and scientists have found ways to put a single atom at each joint (where the balls of clay are). The atoms are then equally spaced apart, and take up a 3D space. Now that you’ve got those atoms where you want them, the objective is then to manipulate them. But the challenge thus far has been manipulating single atoms without disturbing their neighbors, which had to be very close by. The scientists were able to separate the atoms by 5 microns.
An additional press conference focused on the physics of climate change. There were no ground breaking discoveries to be reported in this field, but rather an underlying message from the six speakers: physicists must develop more qualitative and robust ideas about climate models if they can hope to make predictions about future climate trends. While scientists are, unquestionably, able to observe climate changes, they cannot yet create a system model that will determine why these changes occur, or give any indication of future trends. Quantitative methods are all but impossible to obtain because of the scale they need to be on (the entire frickin Earth!). Speakers noted that there are few, if any, sessions at physics meetings being focused primarily on climate change. There is only one session focused solely on climate change at the March Meeting, and they hope that number will increase at future meetings.
Shortly after the meeting, I’ll be posting an interview I did with Daniel Goldman about his research on animals that move on granular surfaces like sand and mud. He and his team built the sandbot to mimic this motion. The group thinks they’ve found some fundamental similarities between the way very different animals move on these surfaces (some of them moving at over 2 meters per second!!). It’s a wonderful example of how physics may answer some age-old questions posed by biologists, but also how physicists can learn fro nature’s living models. And of course, it raises new questions for both fields.
Stay tuned physicsbuzzers!! More to come!
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Saturday, October 07, 2006
Freak Waves
Q: When does three plus three equal ten?
A: When waves meet up in experiments to simulate monstrous freak waves that snap ships in half or topple oil drilling rigs.
Freak waves are rare, but satellite images and sailors' reports of waves in the open ocean rising up to tower over the surrounding surf show that they can reach the height of a twelve story building. They've caused numerous shipping disasters over the centuries, even appearing in epics of ancient mariners.
Until recently freak waves have defied physicists in search of an explanation of how they form. A study by Miguel Onorato of the University of Torino in Italy suggests we are closing in on an answer. It turns out that waves don't always obey simple math. When two waves combine, their total height is usually just the sum of the individual wave heights. When they start to get large and approach each other at just the right angle, however, they add up to more than the sum of their parts. In physics jargon, they combine nonlinearly.
Read more about it in Physical Review Focus.
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