Hey all, I was re-reading my quantum mechanics books and I noticed that different books have different scenarios for the Einstein Train thought experiment. And I was just wondering if I understood it correctly. Scenario 1: A person inside a moving train flashes a light beam that goes in both directions. The person inside the train would see the light hit the front and back of the train at the same time (assuming they are going at a constant speed). The person outside would see the light hit the back of the train first since the light traveling towards the front has to catch up to the moving train. Scenario 2: An observer standing on a platform observes a lightning strike hitting both sides of a train at the same time. The person inside the train observes the light hitting the front of the train and then the back of the train since the light has to catch up to the back of the train. From what I understand is that the light hits at the same time if the light flash happens in the observer reference frame and that it occurs at different times if it is outside the observer reference frame. Or does it have to do with the fact that in scenario 1 that the light started in the middle of the train as oppose to scenario 2 where it occurred in both the front and the back and went towards the middle of the train. (But wouldn't the distance the light travels in both scenarios be the same? Assuming the same train length)?