Hacker News Reader

Comment by chii | Hacker News Reader

why can humans not expand interplanetarily? Then, inter-stellarly, then finally, inter-galactically?

Because that's still science fiction. We have enough ressources to sustain current population/economic system for a few decades, a century at most (i'm thinking gas, rare earth, phosphore, etc). It's been 50 years since we got to the moon and we're still stuck on low-orbit earth. Even getting to Mars is still very very hard. Do you think we'll be technologically ready to colonize an earth-like planet by the end of this century?

While we can't rule it out fure sure, it would be crazy to bet on that possibility.

I’d argue not that we’re ‘stuck’ here on Earth (just) because it’s hard, but because there’s been no major incentive to do otherwise for decades.

The original incentives for the space race were political during the Cold War - rockets, satellites, then landing on the moon. Since then, NASA has mostly stagnated without a clear vision to deliver. Likewise (until recently) the major aerospace providers were happy just doing well enough to make some dollars from their lobbying and ‘cost-plus’ contracts.

The only game-changer is SpaceX, set up to deliver the vision of a slightly eccentric multi-millionaire (now billionaire, of course). But I’d argue that SpaceX isn’t doing anything so revolutionary that it couldn’t have been done earlier by various others (including NASA itself) if they’d had the right vision and incentives. Sad, really - all of that money, time, effort, and human potential effectively wasted.

Because of interplanetary transportation costs, due to physically unavoidable planetary gravity wells, the existence of other inhabited planets has essentially zero effect on the prosperity of the average Earth inhabitant. There is physically no way to build the space equivalent of cheap maritime shipping.

Even if we successfully build a space elevator and putting stuff on orbit becomes relatively free, we would still need to build a 100% sustainable spaceship. Or a completely game-changing technology like teleportation, and there's no proof such thing is practically possible.

It seems to me that's an achievable goal... if everyone throws risk aversion/mitigation out of the window.

No rules about nuclear power on ships, no worrying about contamination on other planets, laissez-faire attitude about risks that come with space launches/travel and fully automated control of rockets/spaceships, massive investment in life support systems and AI, etc.

>we would still need to build a 100% sustainable spaceship

Yet for the purpose of this article, or at least discussion, people are acting like the Earth is.

We can, we just need to not burn out our resources and single planetary home before then.

If humans can expand inter-galactically, then it likely it would have happened already by some other species, given the size and age of our galaxy. But since we're not part of some prior alien galactic empire, it's probably not feasible. And we would also be able to see the energy output from other galactic civilizations nearby. But we see nothing. Not from Andromeda, not from anywhere in our local cluster.

>If humans can expand inter-galactically, then it likely it would have happened already by some other species, given the size and age of our galaxy.

That's only true if we assume the chance of life arising is relatively high. It could actually be incredibly massively low, and we wouldn't notice, because we're observing from a position of extreme selection bias. I.e. probability(intelligentLifeInUniverse given weAreObservingIt) = 1.0.

> And we would also be able to see the energy output from other galactic civilizations nearby

or they are utilizing an energy source so efficient that no leaks happen (that we can observe).

Reply on news.ycombinator.com