Astronomers have detected the deepest note ever generated in the cosmos, a B-flat flying through space like a ripple on an invisible pond. No human will actually hear the note, because it is 57 octaves below the keys in the middle of a piano. The detection was made with NASA's Chandra X-ray Observatory and announced at a press conference today. The note strikes an important chord with astronomers, who say it may help them understand how the universe's largest structures, called galaxy clusters, evolve. The sound waves appear to be heating gas in the Perseus galaxy cluster, some 250 million...
