|MadSci Network: Earth Sciences|
"What if" questions are very difficult, especially ones that imagine unusual situations like this. In a "what if" question, we imagine that one thing changes, and everything else stays pretty much the same. But sometimes that is just not possible. Some other things have to change, and there are different ways that that might happen. There is one very sure part to the answer to your question. It would not be very long (in geological terms) before the Earth got back to being a flattened spherical shape again. It would probably only be a matter of centuries at the most. And it would be an unrecognizable Earth, that would perhaps have more in common with the very early stages of the Earth's formation than the Earth that we know. So here is an answer to one interpretation of your question. What if a powerful and evil wizard were to come along tomorrow and change the Earth from a spherical shape into a cube? We will assume that all of the Laws of Physics were not tampered with beyond what was necessary to make this happen. Immediately, catastrophic things would start to happen. The force of gravity would really get into gear. The corners of the new Earth would be like huge mountains. First of all, the waters from the oceans that finished up near the corners of the cube would find themselves 8860 km from the centre of the Earth. All of the ocean water would immediately rush towards the centre of the nearest face of the cube where it would only be 5200 km from the Earth's centre. This would produce huge tidal waves, quite a lot of frictional heating of the oceans, and evaporation of ocean water. Secondly, the air of the atmosphere would also flow from the corners down to the centres of the faces of the cubes. Major wind storms would result, and the region near the edges and corners of the cube would be left without any air at all. Thirdly, the molten rock under the crust of the Earth would also flow away from the edges and corners towards the centres of the faces. This would create a vacuum under the thin solid crustal rock at the corners and edges, and a huge pressure under the crust near the face centres. Initially there would be earthquakes and volcanic eruptions to relieve this pressure, but very soon the heat generated by the frictional forces would boil off the rest of the oceans, and melt the surface rocks. Soon the whole of the outer part of the Earth would become liquid, and freely flow until it was again in the shape of a flattened ball. It is quite likely that almost the whole of the atmosphere, including the water vapour from the oceans would be lost into outer space. There would be no living things or recognizable weather systems to worry about! Ward, I'm sorry, because I have a feeling that this was not the sort of discussion you were hoping for, but unfortunately that is the sort of way that nature works. There are very good and unchangeable reasons that the only shape large planets can be is flattened spheres.
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