I'll have to read that sometime. But the definition of "universe" is everything that exists... everything. So if it is expanding, then there has to be somewhere for it to expand to, which would already be a part of the universe anyway assuming it exists. For there to be boundaries, there has to be something outside those boundaries, making the universe infinite. Or maybe there's an infinite multi-verse, either way, we'll probably never know.
thats one definition of the universe, but its a problem with semantics. the universe is all we are privy to by most. for example if string theory, perhaps the leading cosmological(physics) model of the universe is correct. there are many universes or branes, each with weird properties. quantum gravity will tell us if this theory is correct. so the definition of all that exists is incorrect, because there are seperate universes or branes, which are all part of the megabrane.
multiverse, as the name implies , assumes multiple universes. therefore the universe(singular) cannot be all that exists if it's talked about in a plural sense. i would say that the universe is more so all that exists in which we can navigate and measure. due to relativity we cant access other universes, so that definition fits better in my mind.
im not sure i follow you. infinite has no boundaries. space is and infinite medium that can strecth forever, like thought for example. i cant really describe it properly, but its like imagining ripples in a pond in which you can get creating ripples which expand outwards. but your not depleting a stock amount of ripples. its infinite and can be stretched forever.
im not trying to bust your balls morrison
. im just discussing this with you. its and interesting topic.
the only problem is we cant conceptualize infinite nor eternal but yet they exist. which is mindboggling. and we all may not be thinking about then in the right way.
