4 ms·
>For example: Civilization A achieved space flight x time units (whatever time units, such as Planck time unit) after Big Bang, and civilization B achieved spac
by VladRussian2 13y ago
>For example: Civilization A achieved space flight x time units (whatever time units, such as Planck time unit) after Big Bang, and civilization B achieved space flight y time units after Big Bang?
as long as special relativity is applicable, for space-like separated events A and B, there exist frames of reference such that A is at x time units after Big Bang and B is at y in one frame of reference, and A is at y and B is at x in the other frame, ie. in reversed order.
- Cookingboy 13y agoYes, but for any such reference frame if you know the distance between the observer and A and B, then after observing both A and B you can still deduct the true chronological order. But I get the parent's point now, for our purpose of observation there is no point figuring out this "true chronological" order anyway since a civilization could have achieved space flight 100,000 years after Big Bang but is at a distance so far away from us that the information may NEVER reach us due to universe expanding.