If we (in this post) use “universe” to mean the one instance we’re in, and “multiverse” to mean all of them collectively, then yes, words like “before”, “after”, and “north” are all local to our universe. You’re spot-on there.
But that immediately raises the issue that once we can prove the existence of the multiverse, and we can identify at least one member of it other than ourselves, we will need broadly analogous terms to describe the relationship(s) between the Us and the Other(s).
There may be direction-like or time-like (speaking informally, not in the GR sense of “timelike”) or polarity-like or chirality-like or dimension-like differences and similarities between Us & the Other(s). And between the various Other(s). Whatever the differences are, we’ll have to coin a term for the axis of them and terms for the directionality of them.
But if our universe is just one bubble, and there are other bubbles out there that we are not in direct contact with, what is the framework for the larger whole that encompasses all those bubbles? It apparently isn’t “length, width, and height” because those are limited to our universe as well. Right?
And if the bubbles weren’t all get spawned in the same event, then it is very likely there were bubbles spawned before our bubble just like after our bubble, in whatever context of “before” and “after” you wish to define. Just because it is in a different coordinate system doesn’t mean there isn’t a framework of before and after within that system.
It depends on the framework in which the bubbles are defined. In an eternal inflation multiverse, for instance (which actually has some fairly strong circumstantial evidence in its favor), our concepts of “dimension” (whether space or time) map over relatively well to the surrounding plenum.
The cosmological singularity in big bang theory is an example of geodesic incompleteness, which is a pathology in the structure of spacetime. Now one way to interpret this is that the pathology in spacetime is a direct representation of reality, but it seems pretty natural to interpret the pathology as a breakdown of the theory too, in which case it seems fairly natural to assume we can extend time back beyond the big bang.
Sure, so if we define our universe with 4 dimensions–x, y and z for space and t for time, then mathematically it’s easy to just keep on adding new axes that are orthogonal to x, y, z and t. So we could call the distances between our Universe and some other Universes q, r, and m or whatever.
The problem with defining these relations is that we have no evidence for the physical existence of other universes, let alone some method of investigating the differences between them. But in any case, another universe wouldn’t be north of our universe, or left of our universe, or before our universe. But you’re right that it might help us to envision some relations as analogous in certain ways to time or spatial coordinates. Or maybe some other analogy would be more helpful, like our universe is cinnamon and theirs is chocolate and another is strawberry.
The multiverse has come to mean that but it’s actually a misnomer. By definition “the universe” should encompass everything (i.e. all possible realities), and each individual reality should be referred to as a multiverse. But generally the terms are flipped and we talk about a universe within the multiverse.
The universe came first, and it meant everything. And then we described things like universal laws, laws that describe the behavior of the universe.
Then we posited other things like our universe that had different laws. They are not within our universe, but are analogous to it. Thus, they are other universes. Therefore, the collective set of universes is the multiverse.
We could have extended the word “universe” and tried to create a new word for the local bubble in which we live versus the other bubbles that might have different laws. Call it the sub-verse or something. But that’s not what happened.
But the universe means literally the thing there is only one of. So by definition if there is more than one of it, it’s not a universe. That’s why the term multiverse originally coined, to describe these other things that look like universes, but aren’t (as there are more than one of them, that collectively make up the universe). But over time the term was use incorrectly (to describe the collective thing, not the individual facets) and that incorrect use stuck.
Can’t find a cite, or remember who the scientist was who coined the term, but I believe it’s covered in one of the popular books on the subject (Maybe In Search of the Multiverse ?)
Thinking about it. It may have been Hugh Everett, who first proposed the Many Worlds Interpretation of quantum physics. Incidentally he’s also the father of Mark Everett the lead singer of the Eels (and may have also invented the term Mutually Assured Destruction while working at RAND, but that work is still classified).
What about “In the beginning God created the heavens and the earth”? I thought the heavens is the universe… are you saying that there was an eternal universe and then God put galaxies, etc, in it? (if theism is true)
