[peebeebee]

Yeah. There's such a huge difference in interplanetary life vs interstellar or even intergalactic life.

Interplanetary: easy.

Interstellar: pushing the boundaries of what's possible imho.

Intergalactic: no way.

Our closest planet (Mars) is 3 lightminutes away.

Our closest star (Proxima Centauri) is 5 lightyears away.

Our closest galactic neighbour (LMC) is 150000 lightyears away.

[giraffe_lady]

Is there even any reason to think interplanetary is easy? We have a lot of stories saying so, and we intend to do it but we don't even have a loose plan of what that would look like.

Creating a closed self-sustaining ecosystem capable of supporting large animal life & cut off from the earth's resources is not something we've been able to do even at a proof-of-concept level.

We're very confident in ourselves but idk. It's not preposterous that life is a planetary expression and that it's simply not possible to expand an instance of it beyond the planet that birthed it. We assume we aren't subject to this constraint but we haven't demonstrated it at all.

[peebeebee]

I meant for all intelligent species that could be living in our universe, I can see interplanetary life as something rather easier to achieve. You don't have to think far out of the box for this. I can imagine some solar systems having multiple liveable planets for a single lifeform, which would make it something we could even do right now. Our some transpermia on planets that now host different but communicating lifeforms that are cooperating.

[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.

[timschmidt]

Another way to look at it:

Interplanetary: chemical.

Interstellar: nuclear.

Intergalactic: antimatter / black hole.