Underwater 'Thunder' Could Lead to Better Sonar Sounds generated
using a thunder-like mechanism could lead to lighter, thinner
sonar projectors for advanced subs and underwater drones. The
new technology relies on carbon nanotubes, microscopic pipes
just nanometers or billionths of a meter wide that have
displayed a wide range of extraordinary mechanical, thermal and
electrical properties. For instance, they are 100 times stronger
than steel at one-sixth the weight. In 2008, scientists in China
revealed one more remarkable feature of nanotubes — sheets of
them could serve as loudspeakers. When electrical current is run
through the fabrics, the nanotubes rapidly get hot, which in
turn heats and expands the air around them to produce sound,
much like how lightning generates thunder. In light of this past
work, physicist Ali Aliev at the University of Texas at Dallas
and his colleagues wanted to see if these sheets could work as
loudspeakers underwater as well, potentially for use in sonar.
Sonar works by emitti