The Nature article and your comment reminds me of [1]: What if the hill is a perfectly symmetric hemisphere, so that every path down the hill is equally valid?

The Nature article and your comment reminds me of [1]: What if the hill is a perfectly symmetric hemisphere, so that every path down the hill is equally valid? In fact, this is precisely the shuttlecock analogy in the Nature article, even though that analogy is talking about the quantum Universe initial boundary state, as opposed to the hemisphere example in classical Newtonian mechanics. I guess the shuttlecock analogy isn’t that useful after all, since it fails to set apart quantum Universe theory from Newtonian mechanics, in that the latter can also have no boundary. [1] The Dome: A Simple Violation of Determinism in Newtonian Mechanics https://sites.pitt.edu/~jdnorton/Goodies/Dome/ https://sites.pitt.edu/~jdnorton/Goodies/Dome/ https://news.ycombinator.com/item?id=37012347 https://news.ycombinator.com/item?id=37012347