[ExI] Everett worlds

Giulio Prisco giulio at gmail.com
Mon Aug 17 08:37:03 UTC 2020

On Sun, Aug 16, 2020 at 1:03 PM John Clark via extropy-chat
<extropy-chat at lists.extropy.org> wrote:

> The great advantage of Everett's Quantum interpretation is the simplicity of its assumptions, it says everything including conscious observers obey the exact same laws of physics and evolve according to the purely deterministic Schrodinger wave equation, all other quantum interpretations stick in a whole bunch of additional ifs, buts and howevers at that point. If some of the worlds allowed by Schrodinger are real and others are not then additional rules and assumptions would be needed and that simplicity would be destroyed. And there is no reason needed to stick in those additional assumptions to explain experimental results. Somebody said Everett is cheap with assumptions but expensive in universes, maybe so but I think an idea that starts with simplicity but produces great complexity is a sign of a good theory, Darwin's theory would be an example. You should always get more out of a theory than you put in or it has no point.

I admit that this is what gives Everett's interpretation its unique
sober elegance. I have always been an Everett fan.

One counterpoint is: Everett assumes that quantum mechanics as we know
it today is the final word. But I would be surprised if a theory
developed by us monkeys in the 20th and 21st century turns out to be
the final word. Perhaps there is something more to be found, and
perhaps that something will open the door to free will.

I suspect that (as Dirac and others hoped) quantum physics will be
"explained" by some new nonlocal theory with strongly chaotic
dynamics, which will link unpredictability in-practice with
uncomputability in-principle.

In the meantime, Everett worlds are currently understood as a
classical approximation to one underlying quantum world. Decoherence
theory shows that interference terms become small and therefore
quantum amplitudes become *almost* classical probabilities, but isn't
*almost* an important caveat? What is the role of residual
interference terms?

I'm currently re-reading David Deutsch's two books and related papers.
Also Sean Carrol's last book Something Deeply Hidden. Then I'm
studying David Wallace's The Emergent Multiverse (more technical but
VERY clear and good). Then I plan to study decoherent/consistent
history theories.

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