# Multiverse Quantity

LightningInAJar
TL;DR Summary
How many universes might there be?
If there was a multiverse composed of many universes how many would there be? As many as could be possible or a number fewer than that? And if fewer, what limits the number of possible universes?

Staff Emeritus
2022 Award
Name a serious (professionally discussed) model/theory/hypothesis that involves a multiverse first. Unfortunately the answer will probably depend greatly on which one you're asking about.

Here's a classification scheme for some of the various multiverse hypotheses that might help:
https://en.wikipedia.org/wiki/Multiverse#Classification_schemes

After skimming the list I'd say most if not all of them involve an infinite number of universes.

Demystifier
Homework Helper
Gold Member
2022 Award
Summary:: How many universes might there be?

If there was a multiverse composed of many universes how many would there be? As many as could be possible or a number fewer than that? And if fewer, what limits the number of possible universes?
To have a multiverse you probably need at least two universes.

Staff Emeritus
If there was a multiverse composed of many universes how many would there be? ?
In the spirit of @PeroK's answer, I'll see his "at least two" and raise to "all of them"

Hornbein
In the spirit of @PeroK's answer, I'll see his "at least two" and raise to "all of them"
I'll up that to uncountable infinity. The question is, what is the truth of the continuum hypothesis? Is there an uncountable infinity smaller than the continuum?

Gold Member
Nowadays they don't like the word Universe so they changed it to Multiverse.

As if that changed something in our understanding.

Quarker
The multiverse idea seems to have come about as an explanation for the “fine tuning” problem, why so many constants are “just right” for the physical universe to exist. But the idea that universes can evolve from one another is still pure speculation. Explaining how a handful of particle types, with certain properties and rules of interaction, arose to form the complex structures of the universe, is still a work in progress.

PeroK
andresB
To have a multiverse you probably need at least two universes.
Somebody needs to postulate a fractional multiverse hypotheses. It probably would be as solid as all of the other options.

MathematicalPhysicist
diogenesNY
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