A closer look
Fire destroys almost everything in its path, but it can't manage to accomplish the basic task of blocking light. A shadow is formed when an opaque object blocks a light source from hitting a surface. A flame, however, is a gaseous chemical reaction emitting its own photons. When you shine a stronger beam of light through a standard flame, the light passes straight through the heated gases without being blocked. Unless there's heavy, unburned soot in the flame (which would block light), the fire itself is practically transparent to other light sources.
