- #36
Ut-Napishtim
- 27
- 0
Here is the Einstein's thought experiment in his own words from his book cited above. In my version I ONLY have replaced mirrors with beer dispensers and made the results more obvious by sending tweets.
"Lightning has struck the rails on our railway embankment at two places A and B far distant from each other. I make the additional assertion that these two lightning flashes occurred simultaneously. We require a definition of simultaneity such that this definition supplies us with the method by means of which he [the observer Ut.] can decide by experiment whether or not both the lightning strokes occurred simultaneously.
The connecting line AB should be measured up and an observer placed at the midpoint M of the distance AB. This observer should be supplied with an arrangement (e.g. two mirrors inclined at 90o). If the observer perceives the two flashes of lightning at the same time, then they are simultaneous. There is only one [italic by Einstein Ut.]demand to be made of the definition of simultaneity, namely, that in every real case it must supply us with an empirical decision as to whether or not the conception that has to be defined is fulfilled. That my definition satisfies this demand is indisputable.
Suppose a very long train traveling along the rails with the constant velocity. People traveling in this train will use the train as a rigid reference-body (coordinate system); they regard all events in reference to the train. Then every event which takes place along the line [railway Ut.] also takes place at a particular point of the train. Also the definition of simultaneity can be given relative to the train in exactly the same way as with respect to the embankment.
Events A and B also correspond to positions A and B on the train. Let M' be the mid-point of the distance A---B on the traveling train. Just when the flashes of lightning occur, this point M' naturally coincides with the point M."
"Lightning has struck the rails on our railway embankment at two places A and B far distant from each other. I make the additional assertion that these two lightning flashes occurred simultaneously. We require a definition of simultaneity such that this definition supplies us with the method by means of which he [the observer Ut.] can decide by experiment whether or not both the lightning strokes occurred simultaneously.
The connecting line AB should be measured up and an observer placed at the midpoint M of the distance AB. This observer should be supplied with an arrangement (e.g. two mirrors inclined at 90o). If the observer perceives the two flashes of lightning at the same time, then they are simultaneous. There is only one [italic by Einstein Ut.]demand to be made of the definition of simultaneity, namely, that in every real case it must supply us with an empirical decision as to whether or not the conception that has to be defined is fulfilled. That my definition satisfies this demand is indisputable.
Suppose a very long train traveling along the rails with the constant velocity. People traveling in this train will use the train as a rigid reference-body (coordinate system); they regard all events in reference to the train. Then every event which takes place along the line [railway Ut.] also takes place at a particular point of the train. Also the definition of simultaneity can be given relative to the train in exactly the same way as with respect to the embankment.
Events A and B also correspond to positions A and B on the train. Let M' be the mid-point of the distance A---B on the traveling train. Just when the flashes of lightning occur, this point M' naturally coincides with the point M."