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Explanation: Scientists are melting holes in the bottom of the world. In fact, almost 100 holes melted near the South Pole  are now being used as astronomical observatories. Astronomers  with the IceCube Neutrino Observatory  lowered into each vertical lake a long string  knotted with basketball-sized light detectors. The water in each hole soon refreezes. The detectors attached to the strings are sensitive to blue light emitted in the surrounding clear ice. Such light is expected from ice collisions with high-energy neutrinos  emitted by objects or explosions out in the universe. Late last year, the last of IceCube ‘s 86 strings was lowered into the frezzing abyss, pictured above , making IceCube the largest neutrino detector yet created. Data from a preliminary experiment, AMANDA , has already been used to create the first detailed map  of the high-energy neutrino  sky. Experimental goals of the newer IceCube  include a search for cosmic sources of neutrinos, a search for neutrinos coincident with nearby supernova  and distant gamma-ray bursts , and, if lucky, a probe  of exotic physical concepts  such asunseen spatial dimensions  and faster-than-light travel .