In general relativity, what value must the density parameter (\Omega) hold for the universe's geometry to be perfectly flat?

Answer

\Omega = 1

A universe is considered flat (Euclidean) when the density parameter, $\Omega$, equals one. Geometries where $\Omega$ is greater than one are closed, and where it is less than one are open.

In general relativity, what value must the density parameter (\Omega) hold for the universe's geometry to be perfectly flat?

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