Mapping the invisible universe

Bruce Elmegreen, IBM Research Division, New York, will deliver this lecture which will be followed by a panel discussion. Who could have guessed using our five natural senses that the most common form of matter in the universe is something that is totally invisible to all forms of light? It emits no light, reflects and absorbs nothing, and also emits and absorbs no sound. Neither can we detect it through any chemical or nuclear reactions no matter how hard we try. Even on the scale of the whole Earth, its presence has never been detected or felt. In fact, it contributes an amount of mass that is only three kilograms inside the Earth compared to the trillion kilograms of land, ocean, core and everything else we know. Yet over the vast distances of space, this appropriately named Dark Matter dominates normal matter by a factor of five, making it easy to detect through its gravitational pull. This talk will highlight the instruments and experiments that led to these remarkable discoveries and it will discuss the potential for new discoveries from instruments currently planned.

This lecture is part of Astronomy Day that will be hosted at Wits on the 19th of April 2012. For other events on the day, click here.