The big bang theory?

the event was a punctual one, acting at a point. All expansion that we see is from the event itself and is not a response to a continuing application of force. When dealing with a point, it is meaningless to speak of inside versus outside as the thing has no "surface". Thus, the event could be viewed either as an impulse from the point or a pulling on the point from everywhere else. Just an issue of perspective, choice of point of view. We tend to look at it from the perspective of "Inside" because that is where we are now (we don't even know what "Outside" is, or would be).

In either perspective, there is the issue of what is the medium that the universe formed within, anyway, so that complicates the concept of interior versus exterior as well.

"Outside" <--- spotted the problem with your theory

O.K. so....what?