The idea that our universe may be just one among many out there has intrigued modern cosmologists for some time. But it looks like this “multiverse” concept might actually have appeared, albeit unintentionally, back in the Middle Ages.
When scientists analyzed a 13th-century Latin text and applied modern mathematics to it, they found hints that the English philosopher who wrote it in 1225 was already toying with concepts similar to the multiverse.
via How a Medieval Philosopher Dreamed Up the ‘Multiverse’ | Space.com.
Another article about Robert Grosseteste and his views of the universe. I’m a history buff and I find the history of science to be fascinating, if for no other reason than allowing me to put modern scientific theories in perspective.
Although Grosseteste’s description of the origin of the cosmos is not accurate and not based on modern physics, his theory makes sense, and — when one accepts Grosseteste’s initial assertions — it is “a logical argument that a modern physicist would be proud of,” Bower added.
“Personally, it reminds me that in future centuries, a new generation of physicists will look back at how we understand the universe today, and think, ‘How could they not see that?'” Bower said. “Modern cosmology is a grasping towards a more complete understanding of creation, but we do not yet see the full picture.”
Grosseteste’s view of the universe was wrong, not because he wasn’t a clear logical thinker, but because he lacked the telescope and knowledge of all the observations that have been made since its invention. To me, this is something to always bear in mind when evaluating modern theories, particularly when they’re about phenomena beyond our current ability to observe or detect.
SelfAwarePatterns 
I’m not sure about branching quantum multiverses and MUTs, but one thing that seems clear to me is that if a universe can be created once, then probably an indefinite number of similar universes can (and would) be created, unless there’s some reason why it’s a one-time-only event.
of course, if space and time are created as part of the universe, then the idea of a creation “event” is meaningless,
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I would say that if one universe can exist, then there’s no reason to suppose it should be unique. We don’t need to think in terms of events to make the inference in your first paragraph.
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Unless there was a reason. With our current knowledge we can’t say what is possible,.
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I think that’s the rub. We can extrapolate from what our current observations tell us, but the further out we do that, the larger the risk that new observations will upset it.
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Absolutely. But there’s no reason right now to suppose there is a reason why it should be unique. Essentially the same point you’re making with reference to creation events.
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As Wittgenstein said,
🙂
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How does the second follow from the first?
If we understand “universe” as “everything that exists” then there must be a single universe. If there exists another one it must be a part of “everything”.
If one universe can exist, then… Quite honestly, nothing seems to follow from this fact.
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I’m with you there agrudinsky. But there could be sub-universes. The word ‘universe’ can be used in two different ways.
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