The matter is quantum mechanics. Quantum mechanics is a kind of very wired theory. A quantum particle has no trajectory. Or, which is strangely the same - such particle moves all possible ways, as shown in the figure from David Deutsh famous paper on quantum computations.
A particle, say an electron or a photon (as at the figure) travels all possible ways and is even able to collide with itself and thus not to pass.
This is an unexact, an easy-to-view-and-conceive formulation of what quantum theory constitutes.
David Deutsh, a distinguished theorist from Oxford University, says that he believse that actually many worlds exist, and the particles that move all paths actually move in different Universes. This is what he calls Multiverse.
Multiverse is not a very new idea, it was first proposed by physicist Hew Everette. First it was referred to as "many-worlds interpretation of quantum theory".
Multiverse, or many-worlds is a brilliant idea, I think. But why not to move from general words to construction of quantitative theory of Multiverse? I asked David Deutsh some simple questions on fundamental difficulties Multiverse interpretation meets, but he ignored.
I believe that Multiverse is in true what I propose. The references are available. To work, Multiverse must use hidden time. Hidden time concept is true Multiverse. I invite Prof. Deutsch and anyone else to discuss hidden time
Hidden time concept
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My report at ICCE\11 conference, 2004
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Fundamental time detecting procedure
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Discussing quantum superposition and David Deutsch's quantum computation thru hidden time viewpoint
soon