In the movie Wandering Earth, our planet travels to another sun.

That is, it gets attached about 10000 engines fed by rocks.


Given humanity could survive it somehow, how much mass would Earth actually lose to travel say for 10 light years?


closed as unclear what you're asking by Ash, Alex2006, StephenG, Cyn, ltmauve May 12 at 17:06

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  • $\begingroup$ I feel like this belongs in a different StackExchange, such as SciFi or Movie $\endgroup$ – H Franklin May 12 at 12:53
  • $\begingroup$ @Franklin This would be off-topic on SciFi.SE, as they don't provide real-world explanations of fictional concepts. I don't know whether this would be on-topic on Movies.SE, I'd recommend asking on their meta first just to be sure. $\endgroup$ – F1Krazy May 12 at 12:57
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    $\begingroup$ Hello J.Doe. The first answer to your question addresses the question in your title rather than the question in the body of your post. Ideally, they should be the same. Could you edit your question and change either the title or the body to reflect a single question? $\endgroup$ – JBH May 12 at 14:03
  • $\begingroup$ This is not really answerable as the energy required to travel any distance is zero (while coasting) and is some unknown non-zero amounts to get up to speed and later decelerate, and the energy cost of stopping Earth's rotation (not recommended). You also have to factor in the again unknown cost of generating power to keep people alive with no Sun. What happens the Moon during this process is yet another complication. $\endgroup$ – StephenG May 12 at 16:48
  • $\begingroup$ @StephenG Good point about coasting, maybe the most natural way of modifying the question would be to ask about the energy needed for Earth to achieve escape velocity from our solar system, then decelerate symmetrically so it could get captured in a similar orbit by a Sun-sized star at rest relative to our own Sun. So you'd need to figure out the escape velocity for the Earth from the Sun, then use the rocket equation with the most efficient possible type of rocket where the exhaust velocity is equal to c, the speed of light. $\endgroup$ – Hypnosifl May 12 at 18:28

It’s not completely stupid. If we could manage to make a fusion drive that fused hydrogen to helium (which is much more difficult than the deuterium-tritium fusion that we can’t yet make work), then there would be enough energy available from the hydrogen in the oceans to accelerate the Earth to the necessary 0.2% of light speed (and decelerate at the other end). But the drive would have to be very very close to 100% efficient, or the waste heat would boil the biosphere and what was left of the oceans.

  • $\begingroup$ Still interesting to know, would it consume 1% of all oceans? 10%?.. $\endgroup$ – J. Doe May 12 at 11:16
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    $\begingroup$ This does not provide an answer to the question. To critique or request clarification from an author, leave a comment below their post. - From Review $\endgroup$ – Ash May 12 at 13:01
  • $\begingroup$ @Ash It answers the question asked in the title. The question in the body is a different question, which is unfortunately all too common. $\endgroup$ – Mike Scott May 12 at 13:49
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    $\begingroup$ When the title question conflicts with the body question it is best to ask the OP to clarify which Q should be answered. Otherwise you get this circumstance, where people need to judge whether or not you responded to the OP's intent (it appears you did not, the discrepancy notwithstanding). The help center page "How do I write a good answer" tells us that we should only answer well-asked questions for this purpose. $\endgroup$ – JBH May 12 at 14:00

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