On Many Worlds, entanglement and hidden variables
Thoughts after watching Veritasium video at youtube: Parallel Worlds Probably Exist. Here’s Why
Many-Worlds Interpretation, by Hugh Everett, says that every interaction implies an entanglement and a \textit{branching} of the universe. For example, the radioactive atom of the Schrodinger cat experiment gets entangled with the hammer, the cat and even the scientist observing the experiment, producing a \textit{really big wavefunction} for the whole reality. And this wavefunction contains the two worlds: cat alive and cat death. There is no collapse of the wavefunction: we simply live (or we can say \textit{our conciousness really is}) in one of the points of the wavefunction.
Other more real example happens when an energetic photon arrives to the special crystal that yields entangled photons (beta-barium borate crystal), the world branches in two: one in which the left photon has clockwise polarization and the other counterclockwise polarization, and another one with opposite polarizations. So we have no any \textit{spooky action at a distance}, but simply me and my college live in the same branch.
But, what if there is no any ramification inside the crystal, but instead the incoming photon is already living in an specific branch? That would imply that it keeps inside a hidden variable, and I guess that this would contradict Bell's result. So either there is a real branching after the photon enters the crystal, or the hidden variable applies even to us, since we are part of the system. I.e., we live in a world where \textit{that} incoming photon \textit{has} to split that way and the following photon in that other way, etcetera. I think that this has to do with something called superdeterminism: the only branching happened at the Big Bang, and we have no possibility of choice.
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Author of the notes: Antonio J. Pan-Collantes
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