Is a Multiverse Considered a Universe or Multiple Universes?

[Flustered]

If we were living in a multiverse, would the right definition be a multiverse? Or would all the universes count as one big universe and not a multiverse? My Astronomy professor said it is impossible for a multiverse to exist because it would be considered an universe.

 

[Mark M]

'Multiverse' is just a broad term that can refer to a scenario in which there are a variety of 'universes' which are casually disconnected.

It's all a matter of terminology. If you consider the universe to be the totality of everything that exists, then you wouldn't use the term multiverse. But there is no definition of 'universe' that is universally used. There can be casually disconnected spacetimes, or 'pocket universe' separated by inflating space - but at the end of the day, it depends on your terminology.

 

[mathman]

casually

should be "causally".

 

[Mark M]

should be "causally".

Thanks for the correction. I've become to reliant on spell-check for spelling...

 

[Gibby_Canes]

That is really just playing with word definition. In order to have an intellectual argument about it, you have to be able to quantify something, otherwise it is just wordplay. So if you had a mathematical definition of what constitutes an individual universe, or an area of theory that predicts other universes that are mathematically discernible from each other, than you would have ground to suppose the existence of a multiverse.