Measuring a moving train - I
As seen by 2 conductors at ends of the train. A flash of light at the middle of the train (measured by rulers on the train) defines “same time” at the two ends:
- Each conductor observes that he is at the position of the telegraph poles at the instant the light arrives.
- Each conductor sets off another flash that illuminates each pole exactly when the first light flash arrives
- Two observers on the ground at the positions of the poles agree:
- Each conductor set off a flash as he passed the respective pole.
- But do they agree that the two flashes were at the same time???