Again there is consistency to the credible reports. The craft seem to nearly always be completely silent or to emit a low humming noise. They seem to be able to move with speed and at angles that defy the known laws of physics. Any living creature inside such a craft performing such maneuvers would surely have their organs liquefied if there not some way to overcome the effects of gravity on such moving objects. Hence one can speculate that these are projections – holographic craft perhaps – and not actual craft. Or, that the craft are used by alien civilizations that can overcome through technology and science gravitational and momentum effects. Sometimes the craft have been observed with what look to be portals and/or lights arrayed along their sides and/or underneath. Triangular craft seem to always have lights on their underside while disc and cigar-shaped craft seem to glow in sections or all over as if from within. Nearly always the craft are reported to be composed entirely of light or of a metallic substance – usually a dull matte finish or shiny. Rarely are markings reported.