But what’s “the other side of that space”?
Well, as I said, it was garbled, but I took it that he(?) was trying to contrast the idea of space itself expanding, and something expanding into a space: trying to express what he took to be the absurdity of something (space) expanding, but not expanding into some sort of pre-existent space (the ‘other side’ outside of ‘space’ that physicists tell him does not exist).
It seemed to almost make sense to me, anyway.
What is the effect of the appearance of a region of an even more vacuumy vacuum that would result in the destruction of the universe as we know it?
In other words, what takes the role marked by the ‘X’ in the following:
Appearance of truer vacuum ----> X ----> the destruction of the universe.
Is the relevant effect crudely analogous to air rushing in to fill a low pressure region?
X would be the expansion of the bubble of “true vacuum”. Or maybe you’re wondering why the true vacuum destroys the universe - well, it doesn’t destroy it per se, but the laws of physics would be different in it. Since life depends very much on the current physics laws, and the new “true vacuum” would have other laws that may not even sustain chemistry, much less life - you see how that would be a problem for us.