Following the recent study on the emergent Friedmann equation from the expansion of cosmic space for a flat universe, we apply this method to a nonflat universe, and modify the evolution equation to lead to the Friedmann equation. In order to maintain the same form with the original evolution equation, we have to define the time-dependent Planck length, which shows that the spatial curvature of $k=0$ and $k=1$ is preferable to $k=-1$ since the Planck length of the nonflat open universe is divergent. Finally, we discuss its physical consequences.

• Received 1 June 2013

DOI:https://doi.org/10.1103/PhysRevD.88.067303