>>11456024>What is outside the observable universe?You should never distinguish between the universe and the observable universe. This is a fallacy of assuming that the word "exist" means something more than "something we can measure and interact with". There is no accepted or concievable way to explore other universe, so one must be very careful when talking about their existence. It is usually just a figure of speech.
Physics operates based on a philosophy called positivism, which is operational--- in order to ask a question you should give a prescription for how it is to be answered experimentally. If you can't, it isn't part of physics, at least not yet. In this case, it doesn't seem likely that there is any operational definition to this question.
The model of the universe that one uses should be bounded by the cosmological horizon, and this horizon came from an inflating small-size deSitter horizon (this is the inflation theory). The start of inflation is shrouded in mystery for now, but any attempt to extend the concept of the universe outside the cosmological horizon is at best unobservable, and most likely incompatible with the quantum gravitational holographic principle, which asks that the spacetime have a description along the horizon boundary.
