[extropy-chat] Scientific standards of evidence

[Mitchell Porter]

Eliezer:

>>There is no rational necessity for such dogmatism, especially when (i)
>>today's standard-issue laws of physics already contain a mechanism for
>>nonlocal correlation,
>
>(Disagree; Everett.)

The key consideration is that Bell's inequality (and many
similar constraints that exist under classical local causality)
can be violated, because of entanglement. In terms of
Julian Barbour's timeless picture, this means that spacelike
conditional probabilities can be super-correlated. So if you
are an idealized Barbourian model builder trying to guess
the Hamiltonian and the quantum state of the universe
(and your own position within it), and you come across
super-correlation data, you do have the option of
interpreting it as data about physics, rather than as data
about the reliability of an information source.

I'll try to be more specific. Suppose you have a remarkable
correlation between two complex material systems
reported. Most of the skeptical options boil down to a
search for faulty classical information channels. But we do
also have the option of looking for quantum information
at work, either in isolation (e.g. Bell correlations) or in
conjunction with classical processes (e.g. quantum
teleportation). So one can ask: what sort of joint quantum
state could have produced the reported correlation, and
how likely is it that the two systems really were in such a
state to begin with?

Our understanding of the dynamics of entanglement -
its ups and downs, its movement with respect to the
world of localized observables - is still very primitive.
Most physicists *presume* that it plays no visible role in
the everyday macroscopic world, because they have a
heuristic which says "Many degrees of freedom + finite
temperatures => decoherence." But if you look at what's
coming out of quantum information theory, you'll find all
sorts of tricky possibilities: decoherence-free subspaces,
entanglement echoes, noise-induced entanglement,
entanglement production in quantum phase transitions...
We have to face it: even if we already know the Hamiltonian
of our energy scale (the Standard Model), we are still
hugely ignorant when it comes to understanding what
it predicts, especially in the domain of many-body quantum
effects. We have yet to fully acquire the relevant concepts,
let alone apply them to the data.

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