The spacetime of the foggoid (for information about foggoid, please see Chapter 6 of the Antigravitation Engine Site) is curved; therefore the foggoid has gravitation. Due to the nature of "whole or none" of antigravitation, the curvature of foggoid is unstable; hence the gravitation of foggoid is unstable, and the gravitation of the black hole formed by foggoid is also unstable. The quasar is mainly formed by foggoid. Hence the energy and the luminosity of the quasar change greatly. According to the inflationary model of universe, space can move faster than the speed of light. Therefore the motion of the space of foggoid can be faster than the speed of light. The motion of foggoid is due to antigravitation, that is, the effect of the inertial frame dragging of the space of the foggoid. Therefore the foggoid can move faster than the speed of light. Thus the quasar can move faster than the speed of light, and so can the antigravitation engine. When the foggoid moves faster than the speed of light, a particle of the foggoid still moves according to the wave function of its own gfm (gravitational field matter) ball particle, and therefore it still has the spacetime of its gfm ball particle, that is, Hu Ning spacetime, in which the rest mass of the gfm ball particle is zero. For more information, please see the Antigravitation Engine Site (http://xczhx.nease.net/indexEnglish.htm).