Comment by tmuir | Hacker News Reader

Comment by tmuir | Hacker News Reader

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(4) - The driving force behind space exploration is the idea that Earth will eventually be made uninhabitable by climate change. However, for any planet or moon in our solar system to be a viable alternative, we're going to have to induce "climate change" there as well, but on a far larger scale that what Earth is experiencing. No other body in our solar system experiences the same range of surface temperatures as Earth, has breathable air, fertile soil, fresh water, comparable gravity, a food chain, weather patterns, or countless other things necessary for large scale sustainable human life.

Doesn't it stand to reason that in the course of developing those technologies, we'd be able to fix the Earth's comparatively minor problems long before we could transform a planet or moon. One could even argue that the advancement required would probably first arrive at asteroid defense, scalable food solutions and small scale climate control to provide more habitable land on earth for future population growth.

Perhaps exploring space is an appropriate vehicle to spur those developments, but it just doesn't seem like a plausible endgoal.

It's the only end goal that supports human life after the death of the earth.

The earth is not likely to die for billions of years. Its ability to sustain human life on a large scale is certainly at risk. What I'm saying is that the technological advances required to make even the best candidate planet a superior alternative to earth, in terms of human habitability, are an enormous superset of the those required to fix every one of the earths problems that drove us to consider a replacement planet in the first place.

This assumes we won't find a viable alternative. I really like Interstellar for this reason -- I can see us sending x ships to x planetary systems with the understanding that all but one of those ships will likely perish for a greater good.

I think the other reason we want to be on multiple planets is less about climate change, but cataclysmic shocks (asteroid impact, nuclear war, etc.) -- if we're on multiple planets, we have a greater chance of surviving a cataclysmic shock to one planet.

Your point on climate change is great, though -- you're right that if we can terraform Mars or the Moon, we have the technology to fix whatever climate issues are happening on Earth! Funny that this doesn't come up more.

The chances of finding a preexisting viable alternative actually make the prospect of developing all that technology seem trivial.

Life has evolved over hundreds of millions of years, influenced by the earths environment, which itself has been influenced by its size/gravity, proximity to the sun, axial tilt, air composition, our atmosphere, and countless other macro scale variables, many of which are random and independent of each other. Most of these quantities have exceedingly small windows that can support human life. Furthermore, the particular sequence of these variables changing over millions of years has shaped evolution.

Think of it like this: there are 68 teams in the NCAA men's basketball tournament. This makes for 9.2 quintillion possible outcomes. There are certainly many orders of magnitude more variables that have shaped the evolution of life on earth. I'm not saying only one of those permutations results in a planet suitable for humans, just that the sheer scale of how large of a cosmic accident we are makes me think we'll run out of time before we ever find another earth suitable for normal human life.

Hmm... You're just getting me thinking now: if we get sophisticated enough to travel hundreds/thousands of light years, etc... Then wouldn't it also stand to reason that we wouldn't even need to find planets, but rather can build our own artificial "microplanet"?

Curious what you think.

That's a far more difficult prediction: what technology will be developed in the next several hundred years. What sticks out as some problems with building a planet are where do you get all of the material, and how would you manage its rotational and revolutional speeds as it grew larger? Propelling a space ship seems fairly simple compared with propelling a planet.

Douglas Adams had some things to say about designing planets.

I was going to rebuff about not necessarily needing a second earth, but after re-reading your earlier comment and considering sustainability issues like oxygen and food production, you may have convinced me.

I guess I should spend more time being productive and less time considering how I could survive the heat death of the universe.

While I'd prefer avoiding a longer discussion of this myself here, my own view is that interplanatery and/or interstellar travel by lifeforms is far more likely to happen at the bacterial level than primate / mammalian.

As a mode to ensuring life proceeds, possibly. Humans: less likely.

Given the nature of a few past evolutionary bottlenecks (cyanobacteria ⇒ anaerobes, mitochondrial symbioticism, single-cell ⇒ multi-cell, this might represent a significant evolutionary acceleration on other worlds.

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