On Parallel Universe, Multiverse and Many Worlds Interpretation

One of the movies that stormed my senses so hard was the one with Jet Li entitled "The One"(the other perhaps is "Star Gate") that talks about him being an officer of a multiverse authority agency that polices interdimensional travel via wormhole, seeking to hunt down all variations of himself in alternate universes. But now, there are many of these multiverse science fiction stories being made, motion picture or comic books-wise. 

But where did this "Parallel Universe" and "Many-Worlds-Interpretation" concept come into existence in a scientific context? While other laws of the universe like General Relativity, particularly one that involves gravity, are predictive and deterministic(in other words, if we knew the positions and momenta of all the particles, and had infinite computational power, the properties of any particle an arbitrary amount of time into the future can be predicted), one can't say the same for Quantum Mechanics.  For example, in a Uranium nucleus, you very well know that it will decay after a given amount of time if you get a large enough sample of Uranium, however predicting properties of the larger ensemble is different than doing so for an individual particles and that there is also no way you can predict what any one particular particle will do. The same quantum weirdness and indeterminism turns up in other system. And that is just a Uranium atom, there are at least 10 to the 90th particles in our observable universe. So how many times did that one particle experience a quantum interaction with another? How many times did its position or momentum change? How many times did one particular quantum possibility happen for that particle, and hence, not the other possibilities? The answer is staggering. Each time a nuclear reaction takes place inside a star(something that happens maybe 10 to the 20th times each second in our Sun alone), a huge number of particles experience a quantum interaction. And if just one of these interactions had a different outcome, our Universe would be in a different quantum state than the one it’s actually in. 

In quantum mechanics, a particle’s property is defined by a wavefunction, and that function changes over time. While measurable data is a real thing and wavefunction is another, in our understanding of Many Worlds Theory, the wavefunction is definitely real, and so every time a “quantum decision” can be made, every quantum possibility happens somewhere, and what we experience in our universe is simply a path being chosen by one of these plurality of quantum possibilities. And if we want to be strictly mathematical about it, the cosmic inflation(10 to the negative 30th seconds) could have also produced 10 to the 10th to the 90th more or less worth of identical space, time and matter for it to happen. 

However the many-worlds-interpretation doesn’t require that Parallel Universes are real. The Parallel Universes are, in a conservative view, is simply just a visualization of what the wavefunction creates.

But there are some physicists who are putting together the huge amount of universe-spacetime created via eternal inflation and the many-worlds-interpretation model/effort to argue that Parallel Universes are real, and that for every "quantum realization" that occurs in our universe, there exists a real Parallel Universe where everything that ever occurred in our universe occurred also over there, except for that one difference.

And that difference is that in this another universe, I am an emperor. Or a rock star. Or perhaps I am the one who fused General Relativity with Quantum Mechanics and came up with one equation to all known laws of the universe. I am the one who read the mind of god.