Mysterious "Cold Spot": Fingerprint of Largest Structure In the Universe?
astroengine writes At the furthest-most reaches of the observable universe lies one of the most enigmatic mysteries of modern cosmology: the cosmic microwave background (CMB) Cold Spot. Discovered in 2004, this strange feature etched into the primordial echo of the Big Bang has been the focus of many hypotheses — could it be the presence of another universe? Or is it just instrumental error? Now, astronomers may have acquired strong evidence as to the Cold Spot's origin and, perhaps unsurprisingly, no multiverse hypothesis is required. But it's not instrumental error either. It could be a vast "supervoid" around 1.8 billion light-years wide that is altering the characteristics of the CMB radiation traveling through it.
It is not semantically possible that the cold spot be "another universe," because the concept of there being an "other" universe is a logical contradiction.
The definition of "Universe" from Marriam-Webster: " all of space and everything in it"
Other pockets of space-time would logically be part of the "Universe."
What they mean when they say "multiverse" is exactly what the word "Universe" already means.