Yes, and that’s the source of the waste that the nitrogen cycle handles - I was pointing out that oxygen doesn’t come from within the tank in any real quantity (unless you’re VERY heavily planted and lightly stocked) but you are right, that’s another aspect that’s not closed about a fish tank.
I have an idea:
How about we send an AI to terraform a suitable planet along with a couple of human embryos. Once the flora and fauna are thriving, at least in a good-sized area, the embryos could be thawed out - naturally, it would be a male and a female.
The AI would have to educate the new humans and eventually, they would reproduce. Of course, they would have no genetic defects, so even though the first few generations would be closely related, it shouldn’t be a problem. Give it a couple of hundred years and the population would be looking pretty viable.
You gonna have the AI change diapers?
It would probably be best if the AI took a biological form rather than being a disembodied voice. Something from the animal kingdom. At least at first, that is. Later on it can pop in to give advice as whatever is convenient, such as a burning bush, talking cloud, piece of toast, or whatever.
What would be the point? Why do other planets need humans on them?
I mean, I get the biological imperative to reproduce; we want offspring to perpetuate our genes, but when it’s as disconnected as the seed ship thing - nobody back here at home benefits from it; the destination planet is just fine as it is. Seed ships aren’t even really about expansion of the human race; they’re about starting something else, somewhere else, and abandoning it to expand or not on its own.
I mean, I know that’s essentially the same with a generation ship with a continually changing population of living humans; once they’re gone, they’re disconnected from us in almost every practical sense, but a generation ship is a bit (well, exactly) like having children and grandchildren and great-grandchildren. A seed ship seems more like some sort of vandalism where we just spraypaint our DNA across the universe for the sake of it.
That’s the premise of a short story by John Scalzi I read recently.
Slow Time Between the Stars (Far Reaches, book 6) by John Scalzi.
An artificial intelligence on a star-spanning mission explores the farthest horizons of human potential—and its own purpose—in a mind-bending short story by New York Times bestselling author John Scalzi.
Equipped with the entirety of human knowledge, a sentient ship is launched on a last-ditch journey to find a new home for civilization. Trillions of miles. Tens of thousands of years. In the space between, the AI has plenty of time to think about life, the vastness of the universe, everything it was meant to do, and—with a perspective created but not limited by humans—what it should do.
The destination planet is a inert ball, it’s not fine, it exists with no purpose, no future, no past, with absolutely nothing capable of understanding the concept of its existence. It could be swallowed up by a black hole and nothing would even know it ever existed or went away.
Exactly. It doesn’t need humans on it and putting humans on it has zero benefit to us back here.
I suppose you might say that putting humans on it imbues it with purpose. Maybe, but it didn’t need purpose.
While don’t always agree with Carlin, especially on just how much damage we can do on the short-to-medium scale, your comment brought this quote to mind:
The planet will be here for a long, long, LONG time after we’re gone, and it will heal itself, it will cleanse itself, ’cause that’s what it does. It’s a self-correcting system. The air and the water will recover, the earth will be renewed. And if it’s true that plastic is not degradable, well, the planet will simply incorporate plastic into a new paradigm: the earth plus plastic. The earth doesn’t share our prejudice toward plastic. Plastic came out of the earth. The earth probably sees plastic as just another one of its children. Could be the only reason the earth allowed us to be spawned from it in the first place. It wanted plastic for itself. Didn’t know how to make it. Needed us. Could be the answer to our age-old egocentric philosophical question, “Why are we here?”
Plastic… asshole.”
― George Carlin
I’m not really talking about damage. I just don’t see the point of creating something we’ll never see. I have children of my own, but raising them was a relationship; not necessarily always rewarding, but something I started because it was something I felt I wanted to see through.
If the process of procreating was instead just to pop some unknown offspring into existence somewhere random and far away, never to be seen, I’m not sure I’d have seen the point in it.
I agree that there’s no point in doing this for real. I find the discussion interesting for the problem solving aspect, but I can’t see any way that this idea would become a reality. Humanity doesn’t care enough to spend trillions of dollars and decades in development to send a ship on a one way trip that we’ll never know anything about. And even if humanity could be united behind such an idea, it would be much more likely that we’d put that effort into making this planet more livable. If we end up trashing the planet so much that we have to leave, then that means we wouldn’t be united enough to do the work to get to another planet. But from a what-if and sci-fi aspect, the discussion is still interesting.
A serpent might be good.
Ha ha ha, that made me laugh out loud. Thanks.
The Milky Way galaxy is 100,000 ly across. Even at a crummy 0.1C* that’s 30,000 years for a gardner ship to make it’s way all the way around – no shortcuts through the center with it’s lurking massive black hole. That’s a long time in human terms but an eye-blink in cosmological terms.
It’s one of the main pillars of the Fermi Paradox.
*Not that we’ve achieved that yet.
I think you mean 300,000 years. Usually generation ships travel somewhat slower than 0.1c; more like 0.01c, to take advantage of the lower fuel requirements per gram of payload. So we are talking upwards of 3 million years; still relatively short compared to the age of the galaxy.
Note that a generation ship would require very large boosters to accelerate the initial mass, boosters which would mostly be shed in the earliest stages of the journey - these boosters would need to be rebuilt completely and refuelled before the ship could leave again - more delay.
Won’t it need as much force to decelerate upon arrival?
But the point of several of these scenarios is that “humanity” doesn’t have to be “united”. All we need is some sub-set of humanity that’s willing to do the work. And if we’re ever going to be in a position to do these sort of things, we will, of necessity, already have significant space infrastructure to do it. That infrastructure can be built for any reason, and be re-purposed by those who want to send a generation ship or a seed ship, or whatever.
Once we’re in space as a society, the add-on costs of projects like this are going to be significantly less than they would be if we were starting entirely from scratch. Probably well within the capacity of your typical megalomaniacal billionaire, religious cult, or political movement. Hell, we could probably crowd-source it, too.
If humanity moves out into the Solar System in a major way, there’s no reason to think the species won’t last a million years, or more. We’re just barely at the start of that period. Who’s to say that in the next 950,000 years, no one will have both the money and motivation to do this?
Frozen sleep could become an option.
No. The acceleration phase is much more energetic, because you have to accelerate all the fuel that gets you up to speed, plus the fuel required for the deceleration phase, which is just dead weight when you are accelerating. You would need to carry at least twice as much fuel during the acceleration phase as during the deceleration phase, and in practice considerably more. Several empty fuel tanks would be discarded after the acceleration phase, unless you can repurpose them during the flight as habitable space.
But long compared to the life of our species; or of mammalian species in general. We’ll almost certainly be somebody else long before then, if our descendents survive. The descendents of multiple generation ships would be a lot of different somebody elses.