What is the point of the train noise that Michael can hear in his head right after he gets the gun from the stahl in the bathroom and also while hes sitting at the table while Solozzo is talkin right before he kills them both? Is it basically suppose to show that Michael was on a train taking him far away from the family business that was now coming to a screeching halt with him now havin to kill two men for the business? Remember, he said its not personal, its just business, Sonny. Was that the point of the train or does someone else have a better explanation?