When I first heard the idea of multiple universes, I was super excited to consider the possibilities. Imagine entangled universes where our antimatter counterpart could perform some action that would affect our actions here on Earth! Or even a parallel universe where dark energy/matter occupy roughly 30% of the universe’s mass, and one where antimatter dominates. The possibilities are certainly endless.
Of course, this is difficult to determine because we are uncertain of the scope of our own universe. More interestingly, since different universes imply separate space-times, we wouldn’t be able to communicate across different universes. But perhaps we could! This paper presents an interesting theory- collapsed black holes lead to wormholes connecting universes. These black holes could have formed during post Big Bang inflation; as inflation was very rapid and could have led to high space-time strains, tears in the continuum could have lead to singularities or black holes. Thus multiverses could exist in the black hole connection- this could also potentially be an explanation for the information paradox in black holes. (This problem is essentially that as particles near a black hole, some particulate matter is ejected as Hawking radiation, and information is lost during this process). Perhaps the information goes towards another universe altogether?
The theory sounds great, but how on Earth (or Mars, or Jupiter, even?) could you prove this? One would have to analyze the energy signatures near a black hole- both going into and out of the black hole. The energy trace on the cosmic microwave background (to be discussed soon!) could potentially reveal the nature of formation of early black holes. And who knows? Captain Kirk might also be found somewhere on this map in a Where’s Waldo-type quest.