Quantum mechanics is the deepest and most successful theory of physics, with incredibly accurate calculations and predictions.  However, many of the outcomes at the subatomic level defy our common intuitions about the world, as demonstrated by the famous double slit experiment where quantum interference effects contradict our explanations based on theories of classical physics.

If we are to progress and grow our knowledge in this domain, we need a good explanation for what Einstein referred to as the "spooky action at a distance" that occurs in quantum theory.  In 1957, Hugh Everett proposed the many-worlds interpretation, which invokes the idea that the physical world is a multiverse.

According to Deutsch, the many-worlds interpretation; despite its mind-bending implications, is not only the best, but the only currently viable explanation for the well-understood quantum effects that quantum theory accurately predicts and that have been repeatedly proven experimentally.

Unfortunately, most scientists have ignored the uncomfortable implications of the multiverse explanation for quantum theory, and instead opted for pragmatic instrumentalism,  an anti-scientific and anti-realist attitude that views explanations as pointless and only values calculations and successful predictions.  Meanwhile, the mysterious complexity of quantum theory has also allowed many charlatans to portray the multiverse explanation in pseudo-scientific or supernatural terms that are fanciful but false.

Until a better explanation for quantum phenomena is put forth, we need to take the multiverse interpretation and its many implications seriously.

This includes the possibility that our universe is an emergent feature of the multiverse, a unique history which seems to us a single history, but is in fact one of an unfathomably large number of divergent possible histories, each an individual channel of information flow. We know of the multiverse because of our ability to test the laws of quantum physics and the phenomena of quantum interference.

Quantum interference effects mostly take place at the subatomic level and initially involve fungible universes that have not been differentiated.  Phenomena at this level allow for the possibility of an exponentially faster form of quantum computation, which Deutsch is credited with by laying the foundations for it in his early work on quantum algorithms in the 1980's.   

The laws of motion in the multiverse are deterministic, and what we experience as apparent randomness can be explained as initially fungible instances of objects becoming differentiated.   Larger objects, like ourselves, tend to become rapidly differentiated and thus quantum effects are less noticeable on them.

Although we only experience one history, this perspective on our reality has profound implications.   In The Beginning of Infinity, Deutsch makes the startling claim that, "All fiction that does not violate the laws of physics is fact."

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