The edge of the known universe" is that where there are no more star or galaxy formations?
I believe that would be an area where time has some weird effects, because time is a function of space (as I understand it). There would be no space, there.
But it’s also hard to say whether such an edge even needs to exist. The universe expands everywhere all at once, not from an “edge.” It’s making more space everywhere. Like bread expanding in the oven.
Or could some objects be so far away, there aren't enough light particles left traveling those vast distances to be seen?
That’s the “observable universe” and totally exists.