Science with Fast

A Five hundred meter Aperture Spherical Telescope (FAST) is proposed to be built in the unique karst area of southwest China, and will act, in a sense, as a prototype for the Square Kilometer Array (SKA). It will be over twice as large as Arecibo coupled with much wider sky coverage. Large radio telescopes have a distinguished record of foundamental discoveries. The FAST will be especially effective in deep surveys for sources such as rare types of pulsars and neutral hydrogen clouds at moderately high redshifts. FAST as a VLBI station will be the hub of the most highly sensitive network. FAST will play an important role in the deep space network, and in SETI searches. We discuss some of the major science drivers here.