4 ms·
This is actually not true. Look at the following constellation: A--1--B--2--C Imagine 1 and 2 are satellites and observer B launches a rocket at both of them
by Sebb767 4y ago
This is actually not true. Look at the following constellation:
A--1--B--2--C
Imagine 1 and 2 are satellites and observer B launches a rocket at both of them at the same time. From B's perspective, both satellites explode at the same time.
A, however, will see 1 explode before 2. C, on the other hand, will see the reverse, that 2 explodes first.
There's no right ordering here, just different reference frames.
- oneshtein 4y agoIf Alice, Bob, and Charlie knows distance to satellites, then they can calculate the true timestamps of events. Alice will register explosion of satellite 1 at time Ta1 and distance Da1, satellite 2 at time Ta2 and distance Da2, and so on, then Alice will subtract time of propagation to receive true timestamps and will see that `Ta1 - Da1/c = Ta2 - Da2/c`.
- MrJohz 4y agoThe key idea is that there is no true timestamp. This is really hard to get across in simple examples, because we almost always describe the example from an objective, external viewpoint, and then start discussing how things appear from different perspectives in the example. But the supposedly "objective" viewpoint is just a different viewpoint that we've invented, it is no more accurate than either of the other ones. So yes, Alice, Bob, and Charlie can all calculate the timestamps relative to the other positions, and they could collectively decide together that one of those options will count as the "true" measuring point. But this is still a measurement decision that they have made.
- anyfoo 4y agoTrue, and any other "true" measuring point would be just as right. Hence, no simultaneity in the universe.