On 1/8/2025 4:11 AM, Quentin Anciaux wrote:
Brent,
The core of my argument is that in a single-world framework, the
ensemble of possibilities described by Schrödinger’s equation is only
conceptual. If only one history is realized, then those
"possibilities" don’t exist in any meaningful way—they’re theoretical
abstractions. In the absence of an actual ensemble from which a
selection occurs, the notion of randomness is a metaphor, not a mechanism.
In the many-worlds framework, every possibility is realized, so the
"selection" is an emergent phenomenon from within the structure of the
totality. In the single-world view, however, there’s no actual
ensemble. Probabilities merely describe the likelihood of the one
realized outcome, but there’s no underlying framework where those
possibilities are instantiated. Randomness then becomes a label for
the lack of explanation rather than a true process.
To say "the single history simply is" and call that random doesn’t
resolve the issue—it just restates it. Without an ensemble that exists
ontologically (even probabilistically), the idea of selection
collapses because there’s nothing to select from. The photon emission
you mentioned is described by probabilities in QM, but those
probabilities don’t correspond to real, alternate outcomes in a
single-world framework. The realized outcome is the only one that
exists, and all other "possibilities" are simply unrealized ideas.
In contrast, in the many-worlds interpretation, the photon’s emission
in one state is one thread of the total structure, and alternate
emissions exist along other threads. This gives explanatory power to
the probabilities, as they correspond to real structures within the
ensemble.
But small probabilities explain why things */don't/* exist.
Regarding your point that probabilities lose meaning in MWI because
all possibilities are realized—that’s not the case. Probabilities in
MWI are understood as the measure of the branching structure relative
to the observer's perspective. They still hold meaning because they
reflect the structure of the multiverse, not a singular outcome.
What about the one's for which P=0, you could as well say that reflect
the structure of the multiverse. Will you make an ensemble of them?
The single-world view still strikes me as incoherent because it leans
on the language of probability and possibility but denies their actual
realization. Without an ensemble, it’s hard to see what randomness
truly means.
In every other application of probability theory (and for years I headed
the Reliability Division at Pt. Mugu) the ensemble is only notional. It
is a the set of possibilities without assuming that they exist, in which
case they would be actualities. With an ensemble of which every member
exists, randomness becomes incoherent.
Brent
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To view this discussion visit
https://groups.google.com/d/msgid/everything-list/207aada7-2a8d-4c9e-8490-a25f23eff83a%40gmail.com.
