This is not the accepted model, it wouldn’t work with our current observations. There was no “outside” space before space started expanding. When the universe was smaller, it was also infinite but an infinitely dense medium with nothing outside of it. The whole universe was infinitely dense energy, there was no “outside” or “inside” to speak of, even the geometry of spacetime was infinitely distorted, so there was no “before” or “after” states for literally anything.
Time and space didn’t begin until the expansion event. At that point, if it were possible to be an observer, it would seem like suddenly everything stretched away in all directions from all points, and this allowed interactions and events to start occuring, which we mark as the passage of time.
This is not the accepted model, it wouldn’t work with our current observations. There was no “outside” space before space started expanding. When the universe was smaller, it was also infinite but an infinitely dense medium with nothing outside of it. The whole universe was infinitely dense energy, there was no “outside” or “inside” to speak of, even the geometry of spacetime was infinitely distorted, so there was no “before” or “after” states for literally anything.
Time and space didn’t begin until the expansion event. At that point, if it were possible to be an observer, it would seem like suddenly everything stretched away in all directions from all points, and this allowed interactions and events to start occuring, which we mark as the passage of time.