Why do you say the clock is not ticking before t=0? What's the difference, how do you know?
t=0 infers zero time.
Why would you call inflation of space "universe"? Why wouldn't you call "universe" that which contains the inflation and everything else we can't see?
Space and time are what evolved from the BB. The Universe at it's most basic structure, is spacetime.
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Experiments continue to show that there is no 'space' that stands apart from space-time itself...no arena in which matter, energy and gravity operate which is not affected by matter, energy and gravity. General relativity tells us that what we call space is just another feature of the gravitational field of the universe, so space and space-time can and do not exist apart from the matter and energy that creates the gravitational field. This is not speculation, but sound observation.
https://einstein.stanford.edu/content/relativity/a11332.html
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What is the difference between non existing space beyond BB, and existing vacuum within BB bubble?
Space was created at the BB. It did not exist before the BB.
In essence what that means, is that the BB happened everywhere at the same time, since everywhere [all of spacetime] was packed to within the volume of an atomic nucleus.
Depends on your definition of words and consistency of logic. If you understand "space" as logical rather than practical construct, you don't end up in a circular self-contradicting semantic like that. In other words, that space exist beyond BB is not practical possibility, but logical certainty, it is there by definition.
You are confusing what our models tell us, and the parameters in which they exist.
According to those models, nothing existed outside, although I prefer, nothing that we are able to understand.
Outside of those spheres is what we speculate on.
We should not be talking about whether "space" exist beyond BB, but matter, i.e. whether it is a pure vacuum or not. That makes sense, but talking about existence of abstract terms like "space" is a non-sense. Space must exist because it is a concept, a pure logical construct, and such abstracts should never be confused with material properties or practical reality.
We don't know all there is to know just yet.
Irrespective the evidence for the BB evolving all of space and time is overwhelmingly quite convincing.
The other great thing going for the BB, is how it fits in so logically, without any contradiction, with our other near certain models of reality, like our Particle zoo, SR, GR, Abiogenesis and Evolution.