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Existing only in theory, a vacuum is space without matter in it. The most nearly perfect vacuum exists in intergalactic space, which is estimated to contain less than one molecule per cubic meter. By comparison, air at sea level contains about 30 billion billion molecules per cubic centimeter. Several kinds of pumps have been devised for removing the molecules from a space, but even the best man-made vacuums still contain matter. What eight-legged creature can survive for days in a vacuum? Discuss
Source: The Free Dictionary