Are We Living in a Multiverse?

The term multiverse was first coined by William James (Philosopher, 1842 – 1910) in 1895, although his use was more about different moral possibilities than parallel universes. The scientific basis of the multiverse concept can be traced back to the study of black holes and the Big Bang Theory. The gist is that there’s much debate within the mainstream scientific community regarding multiverse theories. 

The mainstream scientific community refers to a multiverse as a collection of multiple universes coexisting simultaneously. Even Hollywood has its own take on the multiverse with Doctor Strange in the Multiverse of Madness, Everything Everywhere All at Once, and Rick and Morty, just to name a few. But there appears to be at least four prevalent multiverse theories based on Max Tegmark’s (Theoretical Physicist) multiverse taxonomy.

Level 1

The level one multiverse theory centers around the concept of an infinite universe. It suggests that due to the vastness of the universe, there must be regions so far away that they act like separate universes with potentially identical copies of themselves.

Level 2

The level two multiverse theory centers around the concepts of bubbles and eternal inflation. It suggests that different inflated bubbles (universes) break off — each with potentially different fundamental physical constants, like the strength of gravity. This would mean the physics parameters could be different even though universes may share similar structures.

Level 3

The level three multiverse theory focuses on the Many World’s Interpretation (MWI) in quantum mechanics. This was coined by Hugh Everett III (Physicist, 1930 – 1982) in his 1957 MWI doctoral thesis at Princeton. MWI suggests that every quantum possibility is realized, causing the universe to branch into a new reality for every possible quantum outcome. MWI is often associated with Erwin Schrödinger’s (Theoretical Physicist, 1887-1961) cat thought experiment whose aim was to illustrate the absurdity of applying the rules of quantum mechanics (which govern the subatomic world) to macroscopic objects (the everyday world).

Level 4

The level four multiverse theory suggests that every mathematically possible universe with any laws of physics exists, covering all possibilities beyond the scope of the lower levels.