Light Speed a Barrier? To go, the children of tomorrow may have had to discover what is believed impossible today -- how to travel faster than light. Mel Zisfein, deputy director of the national Air and Space Museum, and an aerosynamicist amoung other things, has noted a similarity between the way most people today regard "C," the speed of light, and the way many people a generation or so ago regarded "a", the speed of sound. For this publication, he sketched the illustrations which appear on the following page, and drafted the following... "Some people used to look at...