Why are electromagentic waves not visible itself but visible if they are reflected by an object ? Assuming a source of light emitting photons. This waves are not visible in the dark. If they end up on a surface of any object which "reflects" the light we start to see the object. What happens at the object, that we can see the light or the object which is kind of the same electromagnetic wave emitted by the source? Is the "reflected light" still an electromagnetic wave? How can we locate, where the reflected light comes from? Even if the light travels "straight" or takes the way of the shortest time, it could still be closer or far away. How do we now, how far the object is? Would the same object, whichs distance is shorter to us send out the same light or information?