In my story, humans are testing AIs by placing them inside of a simulated universe and seeing how their society evolves. However, to save on processing power, the scientists have reduced the size of their world and upped the density to ensure an earth-like gravity and atmosphere. The rest of the solar system isn't being simulated in detail, and the sim will shut down as soon as it takes up too much processing power (basically once the AIs develop space travel and advanced computers).

Given that my world is only about 2-million square km in surface-area (2,500 km in circumference), and is mostly land, how will it affect seasons and climates? It seems like it wouldn't have icy "poles" or hot "tropics" because, while they all get different levels of sunlight, they're so close together that the heat would circulate and mostly even things out. Or does the lack of large oceans prevent this?

My objective is to make this simulated planet as earth-like as possible, but I'm not sure about the optimal planet-size for this. In theory I could "cheat" and have the simulation simply decree that certain biomes exist, but that might tip the AIs off that they're living in a simulation. Are there any other "realistic" scientific levers I can pull to make this work?

Finally, are there any other pitfalls in having a tiny earth-like planet that I'm not thinking of? Thanks!

Edit: OK, you've all convinced me to just run a plain old "flat earth" sim and hack the rest. This makes everything easier. It does mean the AIs will eventually have to explain their weird laws of physics, but that could itself be interesting. That also means this post is moot. Thanks for the input!

  • $\begingroup$ A planet that small implies certain things such as not as many civilizations developing at the same time, etc. Some technologies will never be developed or refined, because there will simply be no pressing need (think faster ships, or advanced communications). If you want to simulate the Earth ... then simulate the Earth. As things stand the first aggressive population to "evolve" on the planet will simply take the whole thing over, then probably stagnate as it faces no outside enemy, or changing force acting on it. $\endgroup$ – AndreiROM Oct 19 '17 at 16:42
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    $\begingroup$ Planets core would cool way to quickly and would like not produce a magnetosphere capable of protecting its atmosphere. $\endgroup$ – anon Oct 19 '17 at 16:44
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    $\begingroup$ Are the Moon and Sun also being simulated, and are they also being reduced in size? What about the other planets and objects in the Solar System? $\endgroup$ – HDE 226868 Oct 19 '17 at 16:45
  • $\begingroup$ Why would they simulate a smaller world instead of just plugging in value from our world on a smaller scale? Why is the size of the earth even simulated at all if you are looking at AI development? The thing you'd need to simulate is how the AI interacts with objects that the AI would do. The affect of the weather on a smaller planet would have zero effect on the simulation to look at the effect of the AIs. You'd be better off hard coding all the things that doesn't really matter and make the world as Earth like as possible. $\endgroup$ – A. C. A. C. Oct 19 '17 at 17:12
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    $\begingroup$ You can't scale a world like this as physical laws are non-linear. Take gravity - scale the size by half and you need to balance that by adjusting mass and hence density. Likewise the atmosphere and hence weather and climate. The list of things that won't scale properly is endless. $\endgroup$ – StephenG Oct 19 '17 at 17:15