Comment by mlyle

> I’ve never understood how this battle could possibly persist, considering that planes can fly upside-down.

That's orthogonal. Planes flying upside down still have air flowing faster over the new "top" of the wing than the bottom.

Though, a common misunderstanding is that air must be taking the same "time" to go over the top and the bottom. This is not true.

You can build a pretty good mental model of flight with either simplified mechanism, but you end up underestimating performance by a fair bit.