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17 April 2014 12:48 pm ,
Vol. 344 ,
Officials last week revealed that the U.S. contribution to ITER could cost $3.9 billion by 2034—roughly four times the...
An experimental hepatitis B drug that looked safe in animal trials tragically killed five of 15 patients in 1993. Now,...
Using the two high-quality genomes that exist for Neandertals and Denisovans, researchers find clues to gene activity...
A new report from the Intergovernmental Panel on Climate Change (IPCC) concludes that humanity has done little to slow...
Astronomers have discovered an Earth-sized planet in the habitable zone of a red dwarf—a star cooler than the sun—500...
Three years ago, Jennifer Francis of Rutgers University proposed that a warming Arctic was altering the behavior of the...
- 17 April 2014 12:48 pm , Vol. 344 , #6181
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Bouncing Sand That Made Waves
30 November 1998 8:00 pm
Today is the birthday of Ernst Chladni, a German physicist born in 1756 who helped found the science of acoustics. Chladni, who was a lawyer and music lover as well as a scientist, began studying sound waves in 1786 and worked out mathematical formulas to describe how they travel. His most famous experiment demonstrated that when a thin plate of metal covered with fine sand vibrates, the jiggling sand grains collect along so-called nodal lines--regions where the waves do not bend the plate. These patterns are now called Chladni's figures. He also measured the changes in pitch that occur when an organ pipe is filled with gases other than air, thus showing that the frequency of a sound wave varies according to the molecular composition of the gas through which it passes.
[Source: Roy Porter, Ed., The Biographical Dictionary of Scientists (Oxford University Press, ed. 2, 1994).]