# What is Many world: Definition and 12 Discussions

The many-worlds interpretation (MWI) is an interpretation of quantum mechanics that asserts that the universal wavefunction is objectively real, and that there is no wavefunction collapse. This implies that all possible outcomes of quantum measurements are physically realized in some "world" or universe. In contrast to some other interpretations, such as the Copenhagen interpretation, the evolution of reality as a whole in MWI is rigidly deterministic. Many-worlds is also called the relative state formulation or the Everett interpretation, after physicist Hugh Everett, who first proposed it in 1957. Bryce DeWitt popularized the formulation and named it many-worlds in the 1960s and 1970s.In many-worlds, the subjective appearance of wavefunction collapse is explained by the mechanism of quantum decoherence. Decoherence approaches to interpreting quantum theory have been widely explored and developed since the 1970s, and have become quite popular. MWI is now considered a mainstream interpretation along with the other decoherence interpretations, collapse theories (including the Copenhagen interpretation), and hidden variable theories such as Bohmian mechanics.
The many-worlds interpretation implies that there are very many universes, perhaps infinitely many. It is one of many multiverse hypotheses in physics and philosophy. MWI views time as a many-branched tree, wherein every possible quantum outcome is realised. This is intended to resolve some paradoxes of quantum theory, such as the EPR paradox and Schrödinger's cat, since every possible outcome of a quantum event exists in its own universe.

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1. ### I Question on number of generated worlds in many world interpretation

Hello. I am curious to learn many world interpretation. In collapse of state 3/5 |0>+ 4/5 |1> to |0> or |1>, it jumps to |0> with probability 9/25 or to |1> with probability 16/25. In many world interpretation I assume 9 worlds of |0> and 16 worlds of |1> so total 25 (or its multiple)...
2. ### A Wavefunction of the Universe considering all possible boundaries?

The Hawking-Hartle no boundary condition is well known. The authors considered a many worlds/histories model considering a sum over all compact euclidean metrics. But are there any models or theories that consider a sum over all possible metrics or boundaries? And finally, if all possible...
3. ### A Question on many world interpretation of Quantum Theory

Every second the universe branches into 5000 universes and each of those 5000 universes branches into 5000 more after one more second. Now, consider an 80 year old person, he has lived close to 80*365*24*60*60 seconds, which is 2.5 Billion seconds. So, in his life time, universe has branched...
4. ### I Probabilty of many world viewing.

I believe that anything is possible. If technology became so advanced, that it was suddenly possible to peer into any of the other worlds (in the infinite number of many worlds suggested by MWI) and see what was happening. What do you think we would see? What technology would be needed? What...
5. ### Many World Interpretation and Personal Choice

So I've heard of the many worlds interpretation - something about any event that could have happened in the past, really did happen in some parallel universe. What I want to know is - how does this translate into personal choice? Like, say I am considering some decision. Tonight for dinner I...
6. ### Books on Interpretations of Quantum Mechanics

What are some good textbooks dealing with various Interpretations of Quantum Mechanics? I am not asking for popular science books. I have a book called 'Understanding Quantum Mechanics' by Ronald Omens on the consistent histories approach and I am looking for something like that.
7. ### Copenhegen interpretation or Many World Interpretation?

Can there be an experiment (even a thought experiment), which could settle the debate CI vs MWI? Now a days many scientists seem to favour MWI. I find it interesting because it perhaps allows time travel (the possibility of an observer going back to his/her own past) while avoiding the...
8. ### Is QM truly random and many world theory

Hi everybody, i didn't wanted to create two separate threads so merged them into one. i got confused watching Brian Green explaining QM on one of his shows. He compared distribution in double slit experiments with throwing a ball on a roulette. He said that casino doesn't have to know...
9. ### Do you think this theory/website REALLY prove Many World Interpretation of QM?

Hello all, On one forum I found this link: http://oyhus.no/QM_explaining_many-worlds.html claiming to demonstrate correctness of Many Wordls interpretation of QM. On the one hand - seems like well presented arguments. On the other hand: it claimes to be discovered in 1990,and it seems...
10. ### Many world interpretation on large scale

can many world interpretation be valid for large scale collapses that brings out a single reality?
11. ### Schrödinger's cat and many world interpretations

In the Schrödinger cat's experiment if the observer decide not to interact with cat directly by opening the box but rather by bringing the interaction of Geiger counter and radioactive substance to see if the cat's alive then why the de-coherence will occur?
12. ### Divine proportion in many world theory

ok...im 14...so i am not expecting anything at all out of this theory...i just wanted to play around with it and see where it could go... okay my idea first needs an understanding of the divine proportion in the gowth of trees...many of you probably already know this...but just in case...tree...