Three Thought Experiments Challenging the Relativity of Simultaneity and the Constancy of Light Speed

This paper presents three thought experiments based on the train-and-embankment setup. They reveal logical inconsistencies in the relativity of simultaneity and the constancy of the speed of light. Experiment 1 shows that applying relativity’s own logic to multiple lightning strikes forces global simultaneity in the train frame, contradicting the claim that simultaneity is relative. Experiment 2 demonstrates that unequal light arrival times imply unequal propagation speeds in the train frame, showing that light speed is not the same in the forward and backward directions relative to the train. Experiment 3 examines wavefront propagation from coincident sources — one moving and one stationary — and confirms that the speed of light is constant only relative to its source, not in all frames. Together, the experiments suggest that simultaneity must be absolute and that the speed of light is determined by its source, and is not the same in all reference frames.