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.