[Comevius]

It's important to be realistic. We are not an interstellar species, we build infrastructure for cars and we can't even afford the maintenance bill on it.

Even in space we could not afford an exponential growth. You would want to pace yourself before you can afford to reach other stars, then other galaxies. Eventually there will be nowhere to run.

[raxxorrax]

> Eventually there will be nowhere to run.

Even a tiny fraction of our galaxy is large enough that you can run your entire lifetime and then some. That is also part of the problem...

[zpeti]

> Eventually there will be nowhere to run.

You do realise there are probably more habitable planets than there are human beings right now? You seem to have no concept of how big the universe is.

I'm not saying we are going to populate the entire universe at any point, but your statement here is just ridiculous.

[coldtea]

>You do realise there are probably more habitable planets than there are human beings right now?

Which is neither here, nor there. Speed of light, and around thousands of required technologies missing, many of those huge leaps over what's available today, make their existance (assuming we even knew where they are) moot.

And even if they were known what? You'll carry 8-10 billion people there for trips taking 10s or 100s of years with light speed? Or we're talking about some "generation ship" with some handful of humanity selected for it?

And how would that help the rest?

We haven't send a man out of LEO for 50 years, might as well forget those "habitable planets".

[squiggleblaz]

> You do realise there are probably more habitable planets than there are human beings right now?

I don't realise that, for one. It certainly isn't part of the shared knowledge or common sense, so I don't think the way you have expressed yourself is fair.

I thought we had only discovered a relatively small number of planets, most of which were relatively large gas giant types, and that claims to large numbers were based on speculation. That knowledge could be very much out of date by now. What is the current state of knowledge?

What is the definition of a habitable planet? If it's just "an earth-size planet that is so close to a stable star", I don't think it's really fair to call that habitable. If there's no life on the planet already, it would be a great deal of effort to make it ready for human habitation, wouldn't it? There will be rock but no soil, so we need to start with simple life forms for a long time before we can get human food to grow. Is there any reason to suppose that a lifeless planet would have a breathable atmosphere? Or if the planet is Venusian or in a snowball phase, we probably couldn't do much on a useful timescale. Again, I don't actually know what the state of knowledge in that field is, so I'm betraying my ignorance rather than trying some kind of "gotcha".

If we only need one planet at a time, I guess it's okay. But if we're talking about exponential growth, then we will need an exponential number of planets. We will "use up" the second one much faster than the first, and the third much faster than the second, and we'll probably need the fifth when we're starting the fourth and so on. There will come a time when we either need to slow down, or the difference between some technical and practical definition of "habitable planet" becomes relevant.

[Comevius]

https://en.wikipedia.org/wiki/Exponential_growth

Even with a constant entropy production rate there would be nowhere to run eventually. The Universe is a closed system.

So you would always want to be thermodynamically efficient, which appears to also produce lifelike behavior. "Any system built to have nonzero memory has to be predictive to operate at maximal energetic efficiency."

https://arxiv.org/abs/1203.3271