Maybe all the humans crawling around the surface have something to do with it?

@Cadence that could be a good answer. Obviously most of the aliens aren't particularly fond of humans to start with since they have no problem colonizing our brains

"They're doing [the calculation in people's subconciousness] in order to find a habitable planet," aww, and not to find the actual question that is solved by the answer to life, universe, and everything?

@Vlaz well, for them, it kind of is the ultimate question of life ;)

Maybe the planet simply smells bad to them.

Remember: if you like it enough to answer you like it enough to upvote. Crass needs rep!

"'m writing a story where aliens are using humanity like a botnet to do hyper complex calculations"... didn't Douglas Adams do that? ;-)

@Matthew: He did, and the answer is obvious (42). Earth is about to be demolished to make way for a bypass

@nzaman, hah! That's super obscure, but you're right, it would technically work as an answer to this question; for political reasons (politics are hard to predict), Earth is about to be destroyed... Alternatively, they got here and a strange man with a blue box,, ah, "convinced" them they couldn't stay.

@Matthew: Can't blame him. The locals were getting upset at overgrown pepper pots wandering around, saying, "Exterminate"

"Their system of FTL travel requires nearly perfect accuracy in terms of coordinates, so they're running simulations to be absolutely certain the next planet they reach is habitable before using up expensive resources to get there." This is a bit tangential to your question, but I didn't understand the link between "FTL travel system needs precise calculations" and "FTL takes resources so we need to ensure the destination is worthwhile". Are the human-powered computations for precisely calculating the FTL jump, or for determining viability of the destination planet?

Also, Hitchhiker's Guide is not "super obscure"!

@LightnessRaceswithMonica - human calculations are for both. The precision of the coordinates is just another reason why FTL is so expensive, in addition to material resources.

They depleted their home world? OK, fine I guess. But why are they FTL jumping through the galaxy looking for a planet that might be habitable for them insted of terraforming planets or just building spin gravity habitats with the perfect environments for them? If they are truely advanced they could just do some starlifting to het resources. Or dissasable their how systems other planets once all the asteroids have been used up.

@TheDyingOfLight Maybe FTL is much easier than terraforming planets, starlifting or disassembling other planets. Or maybe the planets they could terraform or disassemble within viable distance just didn't have enough unobtainium for them. And living on spin gravity simply sucks, and you can't even look out of the window without getting dizzy and potentially barfing in your pressure suit for the 8th time this month. No thanks.

@kadu (a) Not a multi-hundred mile wrong turn, no - that would take quite the skill. (b) Still doesn't explain the connection between the two things

@LightnessRaceswithMonica (a) it needn't be hundreds of miles, if your tank is sufficiently empty, even 1 mile means pushing the car to the station. (b) if you have just enough fuel to get to where you're going, you need to get the path just right in the first try.

@LightnessRaceswithMonica I just realised that you're complaining about the reason for the calculations—to make sure the planet is habitable, rather than to jump in the right direction. Point taken.

They depleted their planet of what exactly? A civilization capable of interstellar travel has not much use of fossil fuels, and everything else they can just recycle or mine from asteroids or lifeless planets.

@vsz That's assuming that they had fossil fuels to begin with. In this case, they depleted some kind of unobtanium that was necessary to continue their way of life. What that actually is doesn't matter for my story. If you want to base an answer off of it, feel free to assume they depleted whatever you want

I find it hard to believe that a civilization with FTL capabilities and the ability to hijack the human mind into doing math for them would suborn another race for simple mathematical equations. I mean, Earth is withing a generation or two of a single computer being capable of more calculations per second than all of humanity put together, and we're nowhere near FTL capable. Why not simply build a super powerful computer and let that do the math?

@Nzall the aliens' history of computation is vastly different from ours; they developed biological computers that look an awful lot like human brains quickly after realizing how comparatively inefficient rock-based computers are. They know how to wrangle these biocomputers to be way more efficient than anything we're likely to come up with in the next millennium.

@crass_sandwich Again, why not simply grow a couple million of those brains themselves instead of suborning an entirely different species? Or are you saying that in your story, the human race hasn't existed for more than 20 years and were specifically grown to contain those brains?

@Nzall why grow brains when there's a few billion of them just lying around? It's much cheaper this way, especially since they're trying to conserve resources for their next FTL jump. Remember that these aliens don't have our best interests in mind, and that they're not perfectly rational agents to begin with - their planet is dying, the species is hanging on by a thread, they feel cornered.

@crass_sandwich There's a core problem with your general idea. It is generally A LOT better for sheer speed of calculation and efficiency to create a couple thousand or hundred thousand specialized circuits (whether biological or electronic) fully engineered to maximum efficiency than it is to suborn billions of general computing devices that additionally need to spend a significant amount of their general processing power simply on staying functional. Your idea is like turning every phone into a BTC miner just because they have a cryptographic chip on their board instead of using ASIC miners.

I think there is a bigger problem is why would anyone make a ship without the computational power to figure out its own jump. What would those aliens have done if they got here and there were no humans to hotwire?