Hi, I'm not a physicist, I'm 32 years old and I like physics. For the past years I've been troubled by an issue: the known thought experiment of Einstein with the train and the relativity of simultaneity notion. Now, most probably I'm wrong or I'm missing something but I think that there is a mistake with the train thought experiment. The train experiment has two equivalent versions: a) two lightning strikes hit the traincar both in the end-door and the front-door and the light goes towards the observer in the middle of the traincar. in this version, the event is simultaneous for the observer at the platform but not simultaneous for the observer in the traincar because the train is moving towards the light coming from the front of the wagon, thus it will reach the on-train observer faster. b) the observer in the middle of the traincar emits light flashes going to both directions. in this version, the event ( of light reaching the doors ) is simultaneous for the train observer and not simultaneous forthe observer at the platform. To make things simple let's take version a) of the experiment. I hereby claim ( i most probably am wrong somewhere ) that the measurement method of whether the events are simultaneous for the TRAINCAR observer is WRONG. Yes, the light beam coming from the front will reach him faster than the beam that comes from the back of the train, but he should NOT DEDUCE that the events are NOT simultaneous. The CORRECT way to measure the simultaneity would be to install TWO SYNCHRONISED clocks at both doors ( front and back ). That way when he checks the clocks he will notice that the lightnings hit both clocks at the same time. This is also a way for someone inside an inertial frame of reference ( a cubic black room with no windows, moving at a constant speed ) to measure whether or not his inertial frame of reference is moving or not: Just install 6 SYNCHRONISED clocks ( it's doable with 2 as well ) at each wall of the room: left, right, back, forth, up, down and then emit with a device a laser beam simultaneously to all 6 ( or two ) directions. Since the big-black-room-with-no-windows is moving with a constant velocity, there will be differences at the times measured at the clocks on each wall, thus he can find out the velocity of the room ( frame of reference ) in each axis. What do you say ? Andreas T.