I'm trying to visualize the relativity example given in the book. The one with 2 generals signing a treaty at ends of a train (the light in the middle goes on and they both sign when light reaches them). The observers claim that one of the generals signed first. However, the generals claim that they signed at the same time. Both are relatively correct. What if instead of signing, the train was set up with a ball on a plank pefectly balanced in the middle: 0 ------------------------------ | And instead of signing, the generals would drop a weight on their side of the plank when the light reached them. According to the generals, they would drop the weight at the same time and the ball would remain balanced. What would the stationary observers see? Thanks Edit: My "diagram" is not formatting correctly the "0" and the "|" are supposed to be in the middle of the plank "---..."