The concept of a multiverse refers to the possibility that there may be multiple universes or regions of space-time beyond what is observable in our own universe. Different theories propose various forms of multiverse, and the nature of empty space between universes, if it exists, would depend on the specific multiverse hypothesis under consideration. Let's explore a couple of common multiverse scenarios:
Bubble Multiverse (Inflationary Multiverse): In this hypothesis, our universe is just one "bubble" within a larger "multiverse." During a phase of rapid expansion called cosmic inflation, different regions of space undergo quantum fluctuations, resulting in the formation of separate bubble universes. These bubble universes would be disconnected from each other and could be separated by vast expanses of empty space.
Many-Worlds Interpretation (Quantum Multiverse): According to the Many-Worlds Interpretation of quantum mechanics, every quantum event spawns multiple universes. These universes exist in parallel but are typically considered to coexist in the same physical space, with each universe representing a different outcome of quantum interactions. In this case, there would not necessarily be empty space between the universes as they would occupy the same physical region.
It's important to note that the multiverse is a speculative concept, and its existence has not been definitively proven or disproven. Different multiverse models propose different characteristics, and there are various ongoing debates and investigations within theoretical physics to explore the nature of the multiverse, if it exists.
Ultimately, the existence of empty space between universes in a multiverse scenario would depend on the specific multiverse model and the underlying physics that governs it, which is an area of active research and speculation.