[giraffe_lady]

We can easily imagine faster than light travel but it simply isn't possible regardless. There are constraints on us other than our capacity for imagination.

We have never seen another living planet so we don't know what to expect from one. I touched on this originally but I'll be explicit now: the fact that we can't create a closed ecosystem even given a working example and diverse raw materials is a powerful indicator of our ignorance about the contours and possibilities of life.

I'm not saying it is impossible, but I'm saying any confident assertions about its possibility, much less how "easy" it is are fantasy if not pure hubris. It's quite possible that no level of advancement will allow for even merely interplanetary life.

[StanislavPetrov]

Out of the trillions of galaxies out there and the trillions more solar systems, it is very likely that at least some of them have multiple planets with habitats suitable to whatever intelligent life evolves there. In that case, an interplanetary civilization would merely require reaching the other habitable planet, not trying to change its environment.

[giraffe_lady]

> it is very likely that at least some of them have multiple planets with habitats suitable to whatever intelligent life evolves there.

This assumption is exactly what I am challenging: that there is such a thing as "general suitability" to life.

We should be open to the possibility that a living system is only compatible with the specific circumstances it emerges from. We've seen nothing to indicate either way, of course, not having seen any other life. But we should not so comfortably assume it's a transferrable process.