Call it "n-space" instead of 'universe' perhaps?
and what separates the n-spaces... a dimension? So they're really (n-1)-spaces
And what if gravity (or mass) were a dimension, like time? Particles tend to play a "now you see them, now you don't" game, from what I understand, even appearing in more than one place within the same 'time' from what I've read [but that was YEARS ago, science may have explained that one away by now].
So if quantum events create new (if just theoretical) n-spaces, NOT having an atomic decay might have a different 'mass' dimension than 'that other universe' where the atomic decay took place.
so you're back to infinite 'n-spaces' again, even if things did not start out that way at 1.0E-33 seconds.
/me now does a shoutout for 'Noein'