Sorry to be one of those posters that doesn't follow suit, but I have a question that has been wandering the back of my mind. A while ago now, I remember my physics teacher telling me something weird. 1 + 1 = 1 in some circumstances. He said that if a beam of light passes another beam of light traveling in parallel in the opposite direction, they will pass each other at the speed of light. Is this true? Math tells us that they will pass each other at 2c But my teacher said they would pass at c. This is a weird concept for me to grasp if it's true, so can someone verify?