The latter seems about right, or, at least, coincides with my own understanding.

But I comprehend neither the process nor the implied physics well enough to explain it any further, not without the risk of adding, due to my own conceptual errors, more confusion.

There is a 'plain English' [as it were] :) summary available.

This is probably the least nonsensical 'simple' explanation you're likely to get on it.

Cheers!