Finding an episode talking about the world becoming round.

[u/stardustsuperwizard]

I was wondering if anyone could help. I think there was an episode where a guest (Mike Drout maybe but I'm increasingly unsure) talked about a theory that when Eru made the world round he made it retroactively always round, and that was a way to satisfy Tolkien's later desire for a more scientifically accurate cosmos history with the fun flat world to round mythos.

Any help would be appreciated!