WASHINGTON (Reuters) - Reckless pulsars -- spinning searchlights in space -- might tear themselves apart if they whirled too fast, but ripples in the cosmic fabric first predicted by Albert Einstein may set a celestial speed limit. That limit is still extremely high, about 760 revolutions per second, astronomers said on Wednesday. But scientists figure some of the fastest pulsars could technically go two or three times that speed. Unfortunately, they would inevitably disintegrate if they did. What stops them is the phenomenon predicted by Einstein's theory of relativity -- the rippling of the fabric of space and time. Known...