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In about 7 Billion years our planed will be consumed by the ever-growing sun, life would have become extinct long before that. That means that in several hundred thousand years we have a deadline to either:

1) Move earth to a higher orbit to keep it from heating up
2) Move our civilization to Mars and beyond

Of course we are only beginning to understand some of the technologies which would be at work, but what do you think is the more efficient/likely solution to this issue?

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closed as not constructive by Qmechanic, David Z May 5 '12 at 14:54

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How did you exactly get "several hundred thousand years" out of the previous data such as "7 billion years"? You realize that the former is 10,000 times longer, right? ... As long as we are confined to the vicinity of the Earth, you may be sure that we will never have the energy to "move the Earth to a substantially different orbit". Bases on Mars are likely to thrive in some time but it has disadvatages. Well, among the 1) impossible and 2) hard, hard is more likely. ;-) –  Luboš Motl May 4 '12 at 19:23
    
Well, the "goldilocks zone" is actually really small. So while the earth will be habitable for bacteria and other small organisms for hundreds of millions of years, our climate is changing fast and it will become harder and harder to maintain large lifeforms. Terraforming mars is anything but difficult, especially not with technology in 100-500 years. Also, moving the earth, not difficult, NASA has proposed that before by the way of comets. –  antonpug May 4 '12 at 19:26
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You could also sheild the Earth from the expanding sun. The mass density in the gas-giant phase is very low. The big problem is when the sun dies entirely, and we will need reserves of nuclear power to keep the planet warm. With appropriate technology, we could use Jupiter's Hydrogen, or gathered heavy elements from moons. It is hard to speculate about technology 7 billion years away. –  Ron Maimon May 4 '12 at 19:30
    
Dear Antonpug, my first question was meant for you to notice a wrong factor of 10,000 in your calculation. You responded by increasing the multiplicative error to 10,000,000. Why are you talking about 100-500 year time scale here? At the beginning, you wrote very clearly and correctly that the actual issue appears on the 7-billion-year time scale so this problem has clearly nothing to do with limitations of the coming 100-500 years. –  Luboš Motl May 4 '12 at 19:34
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We will probably not be able to make "planetary transfers" in this timeframe - and we don't need to be able to do such things in the timeframe. At any rate, those long-term predictions, including the 100-year ones, are speculations. –  Luboš Motl May 4 '12 at 19:50
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1 Answer 1

These are two different problems:

1) keeping the earth alive with its fauna (us included) and flora

versus

2) preserving human civilization

If we do not blow ourselves up into a stone age at regular intervals the technology will be developed for 2, i.e. a space age a la science fiction stories, even looking for other habitable planets . There will be time enough to build Arks.

1) is less feasible, though technology might advance enough, again if we do not blow ourselves up with successive nuclear wars,to find a way. Maybe use the magma layers to heat enough mass and create a directional jet to space that will gradually propel the earth to a more distant orbit continuously compensating for the increase in heat from the red giant . As there will be thousand of years warning maybe the engineering will become feasible, like space elevators. This is really science fiction.

In any case at some point the universe will blink out and there will be no solutions.

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