First of all, I find it charming how you think that flat earthers are knowledgeable. Thats really cute. But its beside the point. If the sun behaved in the way that is explained in the Wiki, in the way you people believe it does, there would never be night. Ever. If you continue to read, please pay attention now, because this is the explanation. Light is a form of radiation, emitted as a photon, a speeding, mass-less particle that bounces off of any surface, whether the surface is a wall or an atom. If the earth were flat, there would be no sunset, even if the sun is a "spotlight" as you claim it to be. When light is emitted, it bounces off of anything; liquids, solids and gasses all reflect light, which our eyes perceive as color. Imagine holding a powerful flashlight and pointing it to the floor. If you do this, you will be able to see the beam, while the entire room lights up because the light is reflected by the air molecules into the surrounding space. The same thing would happen with the earth if it was flat. The light from the sun would bounce off of air molecules and light up every other place on earth.