Some think that the universe has a shape like the sphere, only with things "raised up" by a dimension. This is called the 3-sphere model of the universe. In this model, the universe has elliptic geometry (in which the sum of the angles of a triangle is greater than 180 degrees), has positive curvature, and will have a period of expansion followed by a period of collapse ending in a big crunch. This is an example of a closed universe. In this case, the universe is finite.

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