Maybe they couldn't imagine space travel ever being possible?
"Vatican Holds Conference on Extraterrestrial Life":
* https://www.universetoday.com/44713/vatican-holds-conference...
* https://phys.org/news/2009-11-vatican-extra-terrestrial-life...
* https://www.ncronline.org/news/vatican-discusses-extraterres...
See also the book Would You Baptize an Extraterrestrial?, co-authored by the director of the Vatican Observatory (Br. Guy Consolmagno, SJ):
* https://www.penguinrandomhouse.com/books/228109/would-you-ba...
I think there's many ways to think about this.
First, the place where Christ was supposed to have been born is "special". Clearly he (or god) chose to be born in some continent and not another. Now multiply to... how many planets are there in the universe? What's the chance that Earth in particular was a special planet to be born in?
Second, I think the tale of Christianity is meant to be both unique and universal. It's not "this is the shape it happens to have taken in our world", it's meant to be "this is the shape it universally takes" (e.g. "love one another [...]", what if aliens are biologically incapable of love? What if they are a hive mind? Etc). The lessons are meant to be for the cosmos. This excludes all other worlds, or at the very least it'd require a fundamental revision of what Christianity means.
Third, look at the time frames. How long did it take from Christ being born to natives in other continents being "saved"? Very little given the time life (not even human life) has existed on Earth. So if we're going with the "missionary" hypothesis, i.e. that people of Earth are supposed to evangelize to aliens all over the universe, how long is this going to take? Is this even technologically possible before the universe ends? Does this mean some aliens are doomed no matter what, because they live so far from us they'll never get to hear about Jesus?
I'm an atheist but I can see some sort of religion being created that encompasses all of the universe. It would have to be different to Christianity though. I think this is why these thinkers thought the "multiple worlds" hypothesis was at odds with their religion.
Some discussion:
> When asked how aliens could be redeemed, [Vatican Observatory head] Father Funes referred to the Gospel parable of the lost sheep. Aliens, he speculated, could already be redeemed because they could have remained in full friendship with God, while the human race “could be precisely the lost sheep, the sinners that need the shepherd.”
> But what if they were sinners like us? Father Funes replied that just as Jesus is believed to have come to save mankind, so he was sure that they, “in some way, would have the chance to enjoy God’s mercy.”
[…]
> The question has also been debated within the Church since the Middle Ages and was discussed by Christian apologist C.S. Lewis, whose fictional “Space Trilogy” featured extraterrestrial beings.
I have to say I disagree though, or rather, I find Funes unconvincing (hey, a fellow Argentine!). First, it's just his personal opinion and not that of the Vatican or any official dogma, and I have no doubt individual Christians can still believe regardless of whatever happens in the cosmos. I think the "Enlightenment" perspective from the article is more about deeply thinking about the consequences and whether the idea of the Christian god is compatible with intelligent life in multiple planets.
I think Funes' line of thought is a bit of hand waving, and essentially an "I choose to believe regardless". For example:
> Aliens, he speculated, could already be redeemed because they could have remained in full friendship with God, while the human race “could be precisely the lost sheep, the sinners that need the shepherd.”
Well, yes... but the story of the original sin and humans needing redemption, us being "lost sheep", Christ dying "for our sins", etc, are all fundamental to Christianity. They are not an "accident", they ARE the religion. If you remove this aspect (e.g. because hypothetical aliens don't need redemption) then it turns into something entirely different. You cannot excise this from Christianity and still have it remain the same religion at a fundamental level.
Also, this humanizes aliens too much. What if the alien lifeform is a highly intelligent hive mind comprised of cannibalistic entities with no notion of the self (as we understand it)? Are they "already saved"? Or should they be redeemed? And how, exactly?
This is still an Earth- and human-centered point of view. I believe this is what all those philosophers considered at odds with the sentience on multiple worlds hypothesis.
I can see a different religion still being compatible with multiple worlds, but not Christianity.
From her example it's no large leap to say that other rational animals might also have been saved precisely by being prevented from falling. Still Mary would retain the special privilege of being the Mother of God. But there is plenty of room in the hierarchy of being for other unfallen men below her.
As for hive minds and such, once we identify a will in the action of any set of material, that set of material should be recognized as a single person. The field of metaphysics will no doubt help us find the right times to apply the words "rational", "animal", "man", "human", etc. to any new and strange physical configurations we discover. The key will be finding the boundary between one single will and another, whether or not that corresponds to what we would call a "stable" "physical" boundary.
Particularly I don't think referring to a "notion of the self" helps the search for these things, since the Christian view is not that any animal's "notion of self" generates its intelligence, but that God Himself infuses intelligence where He wills, and any creature's "notion of self" at one time or another is merely a result, not the cause, of its intelligence—and I even think it's possible to have either one without the other.
If you've got the time and interest, check out Dr. Paul Thigpen's book Extraterrestrial Intelligence and the Catholic Faith, a fantastic overview of the debate over extraterrestrial life in the context of Christian history. The author's thesis is that the existence or nonexistence of extraterrestrial life—in any of a multitude of forms—poses no threat to the Christian, and particularly Catholic, faith.
Space travel between worlds is SF.
A manned mission to Mars is entirely feasible with current technology. In fact I'd argue it'd have been feasible with 1980s technology, it was simply costly. If we (we as in humankind) wanted, we could have a base on Mars for some time now.
Who is to say what our capabilities will be in 50 years? In 100 years?
A manned mission to another solar system is going to be very-very difficult, we'd need generational space ship/habitats. Note that difficult is not the same as impossible. Such a ship could be feasibly constructed with modern day technology, but it would be enormously costly so there was no motivation to do it.
I'd agree with your point that a mission to another galaxy is basically unimaginable with technology we can realistically theorize about today. We'd need extremely exotic physics which are unlikely to be doable ever.
Probes aren't space travel for humans.
> A manned mission to Mars is entirely feasible with current technology.
As no manned missions to Mars have ever proven this conjecture, it is still entirely speculation on your part.
> A manned mission to another solar system is going to be very-very difficult, we'd need generational space ship/habitats. Note that difficult is not the same as impossible.
No, it is impossible. Humans cannot survive in space that long. Never have, currently can't, and there's no precedent to assume it ever becomes possible. Pure speculation on your part.
But we do have manned missions to other celestial bodies, and we have sent and landed probes on Mars. I'm confused as to how a manned mission to Mars is "entirely speculation".
>no precedent to assume it ever becomes possible
This isn't a qualifier for what is possible. We knew it was possible to go to the moon before there was precedent. If anything, you calling it impossible is pure speculation. OP is right, difficult is not the same as impossible.
But based on what I know, I don't see any reason to believe a manned mission to Mars is impossible with current technology.
Do you have specific reasons we can't, or examples of technological gaps?
- One year enduring radiation sickness.
- various strategies to block incoming cosmic rays: https://en.m.wikipedia.org/wiki/Effects_of_ionizing_radiatio.... In particular, hydrogen-rich plastics.
Fans of space colonization are encouraged to read: a City on Mars by Weinersmiths, https://www.acityonmars.com/
I don't have any doubts that at some point humanity will find a way to do interstellar travel. Though I doubt it will happen in our lifetime
Heck, my own house is an unsustainable habitat that requires constant resupply.
Science fiction often becomes reality. There are companies, governments, and NGOs working on extraterrestrial habitation as we discuss this. While it will be expensive and make many rather unhappy, it will likely happen… assuming that humankind doesn’t annihilate itself first.