Re: The edge is nothing more than a ripple in the pond
A ripple on the earths surface (or a balloon) travels it's entire distance, and has no other ripples "outside".
The flatness of the universe or it's curvature is partly responsible for our current observations and conclusions. We do currently observer it to be flat like a pond though (through 3 dimensional space however), as you say.
Though my confidence is on information theory, and the entirety of "universe" being the observable one, including our observed quantum probabilities. No magic alternate universe, time travel or other side of that ripple. Sorry.