The problem with defining EVERYTHING as being included in one universe is that it biases the conversation. What if I want to talk about hypothetical hyper-spaces, or a spirit world, or other space-times that have not been discovered yet? I can't because the word UNIVERSE only means the billions of galaxies out there, and that's it.
Mazulu, you can talk about any thing you want - but you should define each conversation and respect the confines of that conversation.
For instance if you and your friend were stranded in the side of a back country with two flat tires on the car and no spares - it would be pointless to talk of a "quantum Fluctuation to occur that would magically restore your tires to roadworthy condition"! It is true that it could be a theoretical possibility - but it will not get you back on the road and on with your journey.
Besides, Mazulu, it is not a "problem with defining EVERYTHING as being included in one universe" - the fact of the matter is that we only have this One Single Proven To Exist Universe And Everything In It.
The ideas and "hypothetical hyper-spaces, or a spirit world, or other space-times that have not been discovered yet" that you have are still only - in point of fact - contained within this one universe.
Just imagining them or believing in them or stating them or even saying "Presto, make it so!' will not in fact cause them to manifest in this One Universe or for that matter, even in the imagined "Quantum Fluctuated Universes".
Mazulu, if this subject really means that much to you, and it appears to me that it does, you should probably do some actual research on the basics of physics at a library or on an Educational Physics Site - instead of a Forum.
After all, before Carl Sagan or Albert Einstein or Edwin Hubble were able to "blaze any new frontiers", they had to at least study and fully understand the minimum basics of their field of study.