Getting on dark matter´s wavelength

Dark matter, the most abundant form of matter in the universe, is invisible and intangible. But that doesn´t keep Leslie Rosenberg from seeing it nearly everywhere he looks. Like most physicists, he finds ample evidence of it written on the sky. It´s there in the swirling of galaxies, the aftermath of cosmic collisions, and the vast, weblike scaffolding that the universe´s luminous matter seems to hang upon. /spl moddot/ It´s also, he hopes, near at hand. Dark matter almost certainly sweeps through Earth like water through cheesecloth. But Rosenberg, a professor at the University of Washington, in Seattle, thinks he might have just the thing to coax it out of hiding. Tucked into the concrete floor of a large warehouselike laboratory at the edge of campus, the Axion Dark Matter eXperiment (ADMX) contains the world´s most sensitive radio receiver in its frequency range. Its builders are fond of boasting that if the detector were placed on Mars, it could pick up a cellphone signal sent from Earth, assuming there were no interference.