Things that go Bloop in the Deep

If you've seen the movie The Hunt For Red October, then you receiveda primer on how sonar works. There are two kinds of sonar, active and passive. Active sonar sends out a sound wave through the water, and then measures the "bounceback" refelction of the wave. The distinctive "Ping" in submarine movies is part of the active sonar wave. Passive sonar, on the other hand, listens to sound waves being generated outside the sub, and analyzes them to give apicture of the activity in the water.

In Red October, there are two sonar operators aboard the US submarine; a veteran explaining sonar to a rookie. The vet can listen to the mish-mash of sounds and identify whales, schools of fish, and enemy submarines. He can do this because everything creates a signature sound. In the movie, the sonar system can hear the high-tech, brand-new "silent" propulsion system of the Russian submarine, but misidentifies it as a "seismic anamoly." Only the astute, experienced ears of the sonar vet hear the unmistakable mechanical rhythm of an enemy sub. The combination of sonar machines and trained human operators can listen for, analyze and idnetify thousands of different marine sounds.

But not all of them.

And that, of course, is the beginning of the interesting part for us. There are hundreds of sounds collected by sonar operators that they can not identify. By comparing these unknown sounds against known sounds, they can group everything according to th emost likely sources. This can be very important to the Navy which is always looking for unidentified mechanical or electrical sounds which might be new adversarial technology -- like brand new submarines.

One sound they have cataloged as an unknown is called "The Bloop." The sound was first picked up in 1997 by a sonar array stretched out through the open Pacific Ocean as an early warning network against missile submarines. Because subs can be rather noisy if not maintaining strict nosie disscipline, the sensitive microphones are place widely apart. And the first Bloop recording was captured on not one, but two microphone 3000 miles apart.

From comparison to known sounds, analysts can say the Bloop is of biological origin, not a machine, and not caused by geology. They know it must be huge. By process of elimination, they can even make some guesses as to what kind of animal it is not. It is probably not a whale. It is probably not a Giant Squid. Scientists don't like to make wild speculations, so they do not hazard guesses about what it is on such little evidence.

Non-scientists, on the other hand, are very willing to speculate. For them, the Bloop is evidence of Sea Monsters. In a general sense, they are probably right. Anything as big as the Bloop would be a monster, and it lives in the sea.

Bloop has been idenitifed as a sea serpent, a relic dinosaur species, giant octopi, enormous jellyfish, and even as the Great God Cthulhu finally waking from his slumber in sunken R'lyeh. Why not add the possibility of it being some shifting coil of the Midgard Serpent, or Godzilla?

All we really know from the evidence is that something huge and unknown lives in the deepest part of the ocean. It could be anything. Prehistoric species have been found in the deep ocean. For example, the megaldon shark and coelcanth. Given how little we know about the inhabitants of the deepest ocean, a "sea serpent" is still a remote possibility.

Keep this in mind when you trvel to the beach this summer; or if you volunteer for submarine duty. Do you really know what's down there?