Pongs are being used by scientists to provide a novel form of underwater location system. The problem with g p s is that radio waves don't go under water. So why is sound a better bet here? Part of it is that, as we all know, sound travels quite well under water anyway. These channels were discovered around the time of the second world war and saw some use then,. but after that it became top secret.
Demonstrations that eventually ousted the prime minister have cost lives, but the protest mood is not fading: many want every member of the storied Rajapaksa family out of government. We examine an effort to develop undersea GPS and learn why a watery sat-nav would be so useful. And why 1972 was such a formative year for music in Brazil.
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