In a flat universe, all local curvatures and local geometry are flat. In general, it can be described by Euclidean space, however there are some spatial geometries that are flat and bounded in one or more directions. This includes, in two dimensions, the cylinder, the torus, and the Möbius strip. Similar spaces in three dimensions (like the Klein bottle) exist as well. The latest measurements of the curvature of space,

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Pro: made by the European Planck space mission, show that ΩK, its value, is 0.000±0.005, which is consistent with a flat Universe

Shape and size of the universe

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made by the European Planck space mission, show that ΩK, its value, is 0.000±0.005, which is consistent with a flat Universe

Selected claim, supporting its parent

Pro claim 1, children below

made by the European Planck space mission, show that ΩK, its value, is 0.000±0.005, which is consistent with a flat Universe