> Of course, if that someone else is very close to you (say, living in the same solar system), you'll reach the same limits as visiting your own past. But visi

> Of course, if that someone else is very close to you (say, living in the same solar system), you'll reach the same limits as visiting your own past. But visiting the past of someone from another galaxy is simply a matter of getting in a rocket and getting there. If you move very fast, you'll reach their "past", if you move slow you'll reach their "future", taking any arbitrary point as their "present". To me, that's just moving myself in space, not in time. (but I'm pointing this out because perhaps embedded here is some understanding of space-time I've not got yet). > For example, it's in principle perfectly possible for someone from another galaxy who lives for 100 years from their own point of view to visit the time of Jesus, and then to visit us today and tell us what they saw happen. But it's not possible as far as we know for someone from Earth to do so (or even for someone who lived on Pluto). Also, it's not possible for that same someone to do the opposite - if they visit us today, they can't then visit the time of Jesus and send him a message from us. Your example's tickling some imagination/understanding... thanks.