Think Multiverses Aren't Real? These Theories May Change Your Mind

https://www.forbes.com/sites/quora/2017/08/11/think-multiverses-arent-real-these-theories-may-change-your-mind/#65c2dc1f6507

Think Multiverses Aren't Real? These Theories May Change Your ...

www.forbes.com/sites/quora/2017/08/11/think-multiverses-arent-real-these-theories-may-change-your-mind/2

文章认为，由于如下原因，四种层次的多重宇宙（multiverse）可能是真实的：

Metric expansion of space — The universe is thought to be governed by cosmic inflation. The universe went through a period of exponential expansion from 10-36 to 10-32 seconds after the Big Bang, called the inflationary period. After this period the universe continued to expand, but at a less rapid rate. However, it’s accelerating in its expansion and will continue to do so. As the universe keeps expanding, the observable universe will keep getting smaller as more objects go beyond the so-called Hubble sphere. This is the sphere of observation—beyond which galaxies recede from the observer faster than light—for a given observer in the universe. As the observable universe is estimated to be 93 billion light-years in diameter, observers who are more than 46.5 billion light-years beyond this diameter will never be able to get any information from our observable universe, nor we from them. For all intents and purposes those island Hubble spheres are separate universes. Even if our universe is infinite, the ergodic hypothesis states that it must must contain Hubble volumes much like our own. This is a level I multiverse.

Eternal inflation — In chaotic inflation theory, inflation could be going on forever, called eternal inflation. With different inflationary regions, some regions expand faster than others, and so you get distinct regions of space. As such, so-called pocket universes emerge. This is a level II multiverse.

Many-worlds interpretation — Everett’s many-worlds interpretation of quantum mechanics indicates that every quantum possibility inherent to the quantum wave function becomes a real possibility in some reality. As such, a construct of parallel universes emerges. This is a level III multiverse.

Ultimate Ensemble — The mathematical universe hypothesis. This theory posits that all computable mathematical structures must have a reality somewhere. This is a level IV multiverse.