Question "Length Contraction" Hello, I just finished reading special theory of relativity written by Albert Einstein himself. Even though I understand the book is only written to convey general idea it still left me with a lot of question. Einstein said that any event that occurs in one reference frame should occur in another reference frame whether simultaneously or not.(may be he didn't phrase this way) While I was thinking alot about what he said, I came up with one situation and it starts to puzzle me so much. Please, consider the question and tell me what I have misunderstood. Sorry if I speak bad English. Question There is two people namely A and B. A will be riding a train that has length L. B is standing on the ground next to the train rail devising a bomb to kill A for some reason. B makes the bomb finally and this is how the bomb works. The bomb has two switch connected to the main body. Only when the two switchs are in physical contact with the train's end point the bomb will be activated. (Bomb will not work if only one of the switch is being in contact to the one end of the train. Bomb will not work if two switchs are being contact to the train where it is not the end point of the train). So, the person B places the two switches on the rail track L meters apart knowing the train has length of L. But then he quickly realizes the length contraction of the train(Since the train will be moving with certain velocity v when it passes by him). So he calculates the new length L' that is shorter than L using special relativity and places the two swtches L' apart from each other and waits for the train to come. Now, in the view of B, the bomb should work and blow the train. But lets look at this whole set up in the view of A. For A, he will see the bomb approaching to his train with certain speed. A knows how the bomb works. He quickly sees the two switches of the bomb on the rainway and realize the length of the distances bewteen the two switchs are shorter than L(since now the length contraction will be observed by A). So A will conclude with absolute certainty that he is going to survive. So, will A survive? or will A die? is my question. Remember, the train is never accerlates respect to ground, so I don't think it is similar to that of twin paradox. And I feel somehow that this is little different than the barn paradox but can't tell how exactly they are different. Feel free to reply to this post. I am only to learn.