Obviously I have to learn how to start a topic, but I believed that in a scientific forum, what matters is the idea, not the presentation. I'll try harder this time. Since every scientist knows very well the ladder paradox, I believe I won't be wrong, by missing something in the set. --- A third simultaneous event is introduced in the ladder paradox, by attaching a rod to each door, which are welded perpendicularly on the inside of the doors, in a way that both rods touch when the doors are simultaneously closed (the small added red lines on the graphics) (The rods are not on the way of the ladder, and can be placed in a way not to touch the floor.) The single event "touching of the rods" verifies that both doors are closed simultaneously. touch - simultaneity no_touch - no_simultaneity In the same time as a single event it must be present in both frames of reference. As seen on the left graphic (garage frame of reference with shorter ladder), the rods touch in the frame of the garage, when the doors are closed. As an event, it should be present in the ladder frame of reference, but it is not. Here is the process of the long ladder passing through the garage as presented in Wikipedia: The first event is the front of the ladder approaching the exit door of the garage. The door closes, and then opens again to let the front of the ladder pass through. At a later time, the back of the ladder passes through the entrance door, which closes and then opens. See the images bellow for reference.