If our Sun was teleported away by aliens, would it be possible for people to survive? I'm assuming that humans had prior warning of this ice age (the aliens warned us first) and could drill underground.

My question is, do they have to drill below the surface, and if so, how far down would the inhabitants of the world have to drill to sustain human life? Assume this is in the future and people have very efficient laser drills (0.5 mile/sec). Also assume that in 10000 years, the Earth will reach another solar system and fall into orbit in the Goldilocks Zone (or the aliens put the Earth there), and the Earth will not crash into anything. If there is one, how would humans feed themselves/find water? Finally, how could they preserve biodiversity after the 10000 years?


closed as too broad by Frostfyre, We are Monica., Trevor, Ryan_L, Cyn says make Monica whole Aug 1 at 19:50

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ Welcome to the site. Please note that the Worldbuilding SE is dedicated to providing detailed answers to specific questions you have while developing your fictional world. To that end, we ask that you keep each question post limited to one question. You've asked five distinct questions here, sufficient for this to be closed as too broad, and a few of those fail what we call the "book test" in that they would take too long to answer sufficiently for the SE format. Feel free to take the tour and check out our site culture. $\endgroup$ – Frostfyre Aug 1 at 17:16
  • $\begingroup$ A few people can sustain themselves on thermal energy, but only a few. We don't need to drill too deep to get there, the challenge is building the whole new infrastructure underground. $\endgroup$ – Alexander Aug 1 at 17:16
  • $\begingroup$ I suppose the Ocean bottoms might stay liquid, just like some moons we know of. But the surface would be near absolute zero. $\endgroup$ – Trevor Aug 1 at 17:20
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    $\begingroup$ Also, note that the closest star to our solar system is Proxima Centauri. It takes light over 4 years to travel between here and there. If a society has the capacity to move a planet at 1/50th the speed of light, it has the technology to render all your questions trivial. $\endgroup$ – Frostfyre Aug 1 at 17:20
  • $\begingroup$ One question per post maximum, your questions can be asked in separate threads though, that's OK. When this thread gets put on hold as too broad (it will probably) you can edit it down to one question for re-opening. $\endgroup$ – We are Monica. Aug 1 at 17:29

You've got a lot of questions here, but let's start with the easy ones:

How far down would humans have to drill?

A Rapture Reminder

Depending on how they wanted to live, they wouldn't have to drill at all. Once the surface of the ocean froze over, the sea bottom would be insulated (but still freezing cold) and stay liquid for thousands of years, let alone a paltry two hundred. Deep-sea habitats, therefore, could be built and sustained indefinitely with geothermal or nuclear power sources. Farming would be strictly greenhouse-based, but you'd have plenty of energy to work with and warm them. Alternately...

Talkin' 'bout My Generation (Ship)

Again, no drilling necessary, save to mine the necessary materials - build arcologies or construct generation ships on the surface. It saves on geological engineering, and makes construction a heck of a lot faster. If you can build a self-sufficient space ship, you can build a structure on the surface to last two hundred years.

If you really want to use those neato (and terrifyingly fast!) laser drills, creating your own geothermal heat pipes would be a snap at half a mile a second.

In either case, light would be electrically generated, and water would be easy to find. (In the first case, not finding water would be the challenge!)

Preserving biodiversity would likely be a combination of advances in biology (allowing for in-vitro gestation, not just fertilization) and genetic engineering (to reintroduce heterozygosity when a lot of life will just have died).

Expansion is similarly easy - build more structures.

If you're really desperate to put people underground, at about a kilometre down things are a balmy 25 degrees, and that's not going to change just 'cause the sun switched off. That'll work just fine, and it'll only take you a second and a quarter to get there with those laser cannon... I mean drills.


As was pointed out in the comments to the main question, 200 years is a really, really short time for Earth to reach another star system, let alone slotting perfectly into the Goldilocks zone, so I'm assuming the same interstellar Thieves' Guild that stole our sun drops by two centuries later to try and undo the damage by teleporting Earth to an appropriate address.

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    $\begingroup$ One thing to consider is that if I am growing all my produce from artificial light sources, that will reduce the depth because those lamps get hot fast. There's a picture out there of a house taken moments prior to Canadian Mounties raiding it for being an illegal grow house. They were tipped off because the lights used heated the roof so much, it became the only house in the picture without snow on top of it following a recent storm. $\endgroup$ – hszmv Aug 1 at 17:36
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    $\begingroup$ That's true - in fact, one of the major issues with an underground civilization would be heat dissipation; rock's a great insulator. It would make sense to build somewhat higher-up, where things are cooler, and just drill down to run heat pipes for power and heating. That said, if they have half-mile-a-second lasers, I'm betting they have pretty efficient LED arrays too, so heating from plant growth would probably not be the major contributor. $\endgroup$ – jdunlop Aug 1 at 17:38
  • $\begingroup$ You could probably just have chimneys to the surface to exchange the air. There will probably be ventilation systems too. $\endgroup$ – Trevor Aug 1 at 17:43
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    $\begingroup$ @jdunlop: Not only is rock a great insulator, but given the above scenario, the ubiquitous ice on top of the rock is also a great insulator (this is the whole reason igloos are even a thing. They're very warm on the inside.) $\endgroup$ – hszmv Aug 1 at 17:43
  • $\begingroup$ @TrevorD - Not really. Without the sun, surface temperatures would drop to -100 degrees in about a year, and oxygen liquifies at -118. A short while into the multiple-century bunkering, Earth wouldn't have air to exchange. $\endgroup$ – jdunlop Aug 1 at 17:48

Regarding biodiversity, one thing they could do is something like this: Svalbard Global Seed Vault. This is a huge vault of seeds that is kept on ice in Spitsbergen, Norway. They've been doing this for more than 30 years so they have learned some things about keeping seeds viable over long term storage.

They could take lessons from this vault. They could collect every possible kind and variety of seed and store them someplace convenient and far from volcanoes and such. Probably you can, with a few centuries of technological advance from today, safely get seeds down to liquid Helium temperatures and then return them safely. Probably you can do the same with embryos of large numbers of species, though bringing an embryo whale to term without a mother whale is harder than planting some seeds.

They would also need to be thinking about cultures of very many different micro organisms. From amoeba to yeast there are lots of species that won't fare well through a 100-century cryogenic level freeze. Some of them might survive a few centuries of freezing. But many would likely die off. Some will be OK if carefully preserved in liquid Helium. Others will need to be kept alive in active cultures. That turns out to have a good side because it means you have an excuse to keep making beer and cheese and some other things.


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