The negasphere is built of negative matter. This material--or, rather, antimaterial--is in every respect the exact opposite of the everyday matter of normal space. Instead of electrons, its ultimate units are positrons--the "Dirac Holes" in an infinity of negative energy. To it a push, however violent, is a pull; a pull is a push. When negative matter strikes positive, then, there is no collision in the usual sense of the word. One electron and one positron neutralize each other and disappear; giving rise to two quanta of extremely hard radiation. Thus, when the spherical hyper-plane which was the aspect of negasphere tended to occupy the same three-dimensional space in which the loose planet already was, there was no actual collision. Instead, the materials of both simply vanished, along the surface of what should have been a contact, in a gigantically crescendo burst of pure, raw energy. The atoms and the molecules of the planet's substance disappeared; the physically incomprehensible texture of the negasphere's antimass changed into that of normal space. And all circumambient space was flooded with inconceivably lethal radiation; so intensely lethal that any being not adequately shielded from it died before he had time to realize that he was being burned. Gravitation, of course, was unaffected; and the rapid disappearance of the planet's mass set up unbalanced forces of tremendous magnitude. The hot, dense, pseudoliquid magma tended to erupt as the sphere of nothingness devoured so rapidly the planet's substance, but not a particle of it could move. Instead, it vanished. Mountains fell, crashingly. Oceans poured. Earth-cracks appeared; miles wide, tens of miles deep, hundreds of miles long. The world heaved--shuddered--disintegrated--vanished. * * * * * The shock attack upon Arisia itself, which in the Eddorian mind had been mathematically certain to succeed, was over in approximately six minutes. Kinnison, Maitland, and LaForge, fuming at their stations, had done nothing at all. The Boskonians had probably thrown everything they could; the probability was vanishingly small that that particular attack was to be or could be resumed. Nevertheless a host of Kinnison's task forces remained on guard and a detail of Arisians still scanned all nearby space. "What shall I do next, Kit?" Camilla asked. "Help Connie crack that screen?" Kit glanced at his youngest sister, who was stretched out flat, every muscle rigidly tense in an extremity of effort.