Showing posts with label Physical Review Letters. Show all posts
Showing posts with label Physical Review Letters. Show all posts
Friday, May 02, 2014
Has The Mystery of How The Pyramids Were Built, Been Solved?
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How ancient Egyptians constructed the pyramids is still somewhat of an archeological mystery. Everything from cranes and ramps to oil-slicked slipways to aliens (naturally) have been put forward as possible mechanisms. A group of Dutch physicists has a new hypothesis on how ancient Egyptians managed to drag the colossal stones necessary to build pyramids across the desert. The answer: wet sand.
In a study in the journal Physical Review Letters, researchers from the University of Amsterdam and FOM (the Foundation for Fundamental Research on Matter) recreated a laboratory version of the sledge on which workers hauled heavy stone, and tested how it fared in sand. They found that pulling the sledge across damp sand requires only half the force of hauling it in dry sand. Because the water droplets bind the grains of sand together, wet sand is twice as stiff as dry sand, and doesn't pile up in front of the sledge as it moves along. (A good tip for sandcastle construction, too.) . . .
Saturday, January 18, 2014
First Instance of Ball Lightning Captured on Video
Researchers in China have captured, for the first time, an instance of ball lightning, on digital video along with spectrographs. The accidental capture, detailed by the team in a paper they've had published in Physical Review Letters, offers proof that ball lightning does exist and because it was captured via spectrographs also, offers clues as to how it came to exist.
People have been reporting instances of ball lightning for as long as people have been able to communicate. But until now, because of their rarity no one has ever managed to capture one on tape—that the researchers also captured data on spectrographs only adds to the specialness of the event.
The researchers report that they were not out to capture video of ball lightning, instead, they were video-taping lightning strikes as part of a genera research effort. As they were recording, a ball lightning event occurred right in front of their camera. They report that it came into being just off the ground, travelled for about five meters before rising slightly higher and traveling for another fifteen meters before disappearing. The entire event last just over a second and a half.
More importantly, the researchers were also recording with spectrographic equipment which allowed them to discern the main elements that made up the ball. They found them to be iron, silicon and calcium, the very same main ingredients in soil. . . .
