Imagine a long straight train that is not moving. (Relative to the ground) Each individual boxcar on the train is exactly the same length, which is 100 km. All the boxcars are numerically numbered starting at the front. (Example 1,2,3,4,5…) There are two observers, Chuck and Sam. Chuck is standing at the front of the train (in front of boxcar #1) and is at rest compared to the train. Sam is next to Chuck, but Sam is in a craft that can instantly accelerate to 150,000 km/sec and can instantly stop. If Sam instantly accelerates to 150,000 km/sec and travels for exactly one second (according to Sam) in the direction of the train (Example 1,2,3,4,5…), what number boxcar will Sam stop at? I am pretty sure (tell me if I’m wrong) that Special Relativity says that passing a 100 km long boxcar at the speed of 150,000 km/sec would cause Sam to measure the boxcar to only be 86 km long due to length contraction. This would mean that Sam should pass 1744 - 86km long boxcars in one second, which means Sam will stop on boxcar # 1744. I am not a believer of SR, but I would like the opinions of people who have a deeper understanding of SR than myself. I believe Sam will stop at #1500 and any change in the length of the boxcars will be due to error, but that is for another discussion. I would like to know which boxcar you think Sam will stop at and the perspective of both Sam and Chuck.