The discussion revolves around the concept of a spatially flat universe, exploring its implications and interpretations, particularly in relation to geometry and curvature. Participants examine the characteristics of both flat and closed universes, including the behavior of parallel lines and the sum of angles in triangles.
Participants express varying interpretations of spatial curvature and its implications, with no consensus reached on the characteristics of closed universes or the behavior of rods in different geometries.
The discussion includes assumptions about the nature of the universe, such as the implications of infinite length rods and the effects of cosmic expansion on geometry, which remain unresolved.
Ok. Now, in a closed universe, what would be an interpretation for its closed form, besides angles not adding to 180°?mfb said:Yes. It also means angles in triangles add up to 180 degrees.
kent davidge said:Ok. Now, in a closed universe, what would be an interpretation for its closed form, besides angles not adding to 180°?
Thanks.Jorrie said:Your straight rods will converge and cross over at some large distance in any direction.
Take note that in our presently accelerating expansion universe, even it it has a small positive spatial curvature, your rods will break long before they reach that crossover point, because they cannot extend past our Hubble radius.