Segunda-feira 23 Mai 2011, 7h:34

This may be old news to some of you. To me, it’s a discovery as recent as it is thrilling.

In the 1960s, the US Navy set up a vast array of hydrophones in the world’s oceans in order to detect the movements of Soviet submarines. This network of underwater microphones was known as SOSUS, or Sound Surveillance System. The network is still in use, although these days, with the cold war behind us, it is being used for scientific purposes, like detecting seismic activity in the ocean floors, as well as monitoring biological events, such as whale migration. Scientists at the US National Oceanic and Atmospheric Administration (NOAA) analyze the sounds collected from the hydrophone system. Needless to say, these guys are experts in identifying marine sounds – everything from different types of ships, via underwater volcanoes and earthquakes, to marine animals down to species level.

However… in 1997, the hydrophone array in the Equatorial Pacific Ocean registered something that nobody could identify: an ultra-low frequency and extremely powerful underwater sound. The sound was detected several times. The experts at NOAA were sure that it was not man-made; the audio profile indicated that it was biological in origin. But the Bloop, as the sound was named, did not match the signature of any known sea animal. In addition, it was several times louder than the loudest known animal, the blue whale. Calculations suggested that if the sound originated from a sea creature, it had to be something enormous. The origin of the Bloop is still unknown.

On March 1st, 1999, another stunning detection was made in the same area. This sound, which was named Julia, was different from the Bloop but carried the same signature of biological origin. Julia was loud enough to be heard over the entire Equatorial Pacific Ocean autonomous hydrophone array. It lasted for about 15 seconds, and was never heard again. Its origin remains unknown.

Over the years, the hydrophones have picked up a number of sounds of unknown origin, but for most of these (the Slow Down, the Upsweep, the Train, and the Whistle) there are plausible explanations, like friction of ice against landmass in the Antarctic. With the Bloop and Julia, however, there are no such explanations.

What is the Bloop? What is Julia? Something caused these noises, but what? This mystery appeals to me on so many different levels: the cryptozoology enthusiast in me is thrilled by the possibility of an unknown seamonster lurking in the Pacific, the science fiction fan in me envisions a fantastic film based on this, and the sound nerd in me immediately wants to incorporate the recordings of Julia and the Bloop into a piece of music – that would truly be the music of the unknown.

I love the fact that we can’t explain everything, that there are still a few white spots on the map. I love the mystery, the unknown. There is something out there, and it is making sounds for us to hear. The very thought sends chills of pleasure down my spine.

Listen to the Bloop, Julia, the Slowdown and other unidentified sounds here:
http://www.pmel.noaa.gov/vents/acoustics/sounds_mystery.html

Read CNN’s report on the events here:
http://edition.cnn.com/2002/TECH/science/06/13/bloop/index.html