4. The bloop
During the cold war, the US government littered the world’s oceans with an array of underwater microphones, or hydrophones, to detect submarines. The hydrophones are still working, and have picked up some worrying noises. One sounded like it might have been made by an animal, but analysis of the acoustics revealed that the animal would have had to be far bigger than the biggest whale. The US National Oceanic and Atmospheric Administration call this unexplained sound “The Bloop” . There are hundreds of unexplained noises from the ocean, it turns out. If you go down to the depths today, be sure of a big surprise.
5. Axis of evil
The universe is meant to be “isotropic”, which means it looks pretty much the same whichever way you are facing. Unfortunately, the cosmic microwave background radiation [http://en.wikipedia.org/wiki/Cosmic_microwave_background_radiation], which fills all of space, didn’t get the memo. Its hot and cold spots are meant to be randomly distributed, but there seems to be a pattern that could be used to give the universe a “this way” and “that way” characteristic, just as a piece of wood has a grain. This is bad because we don’t yet have the mathematical skill to deal with a universe where one direction is different to another. No wonder cosmologists refer to this cosmic alignment as the “axis of evil”.