Don’t get too close. Astronomers are reporting that they have taken the measure of the biggest, baddest black holes yet found in the universe, abyssal yawns 10 times the size of our solar system into which billions of Suns have vanished like a guilty thought. Such holes, they say, might be the gravitational cornerstones of galaxies and clues to the fates of the violent quasars, almost supernaturally powerful explosions in the hearts of young galaxies, that dominated the early years of the universe.