COSMIC CHORDS

The researchers had expected to observe a cacophony of frequencies in the x-ray emission from the stars, similar to the discord produced when one presses keys randomly on a piano. Instead, they discovered that the brightness variations only occur at certain well-defined rates, "pure tones" that have been dubbed "cosmic chords", which correspond to special orbital periods for the gas going around the star. "The clockwork of the universe is much more orderly than we had dreamed," Lamb said. "The pureness of these tones makes it possible to use them to investigate how matter moves in the strongly curved space-time near these neutron stars.