On 1/5/2025 4:46 AM, John Clark wrote:
On Sat, Jan 4, 2025 at 7:18 PM Brent Meeker <[email protected]> wrote:
/> since everything happens it's not so clear what it means that
probabilities are equal to the squared amplitude. Probability of
what? Not probability of a value happening. Probability of
finding oneself in a particular world? /
*Yes. That wasn't so unclear was it. *
/> If it's probabilistic then it must follow Born's rule by
Gleanson's theorem." But then that's assuming it's
probabilistic//not just Schroedinger's equation./
*No. If Many World is correct then ontological randomness can not
exist but epistemological randomness certainly can and certainly does.
Even in classical physics epistemological randomness exists whenever
you lack the information needed to make an exact prediction, that's
why you can't predict a coin flipor a roulette wheel . *
It's not just epistemological when it includes the whole world whether
anybody else knows it or not. QBism is actually an epistemological
interpretation which considers different wave functions for different
people depending on what they know.
*Laplace's demon, which has knowledge of all initial conditions and
has infinite computational capacity, does not need to think about
"worlds" but can just contemplate how the quantum wave function of the
entire universe evolves. Unfortunately we are not as smart or as
knowledgeable as Laplace's demon,so we need to talk about worlds. *
*For example: a box with Schrodinger's cat inside it, the environment,
and you, are all quantum objects entangled together, so there are not
3 separate wave functions but only one. After one hour there is a 50%
chance of the cat surviving, that means the quantum wave consists of
/{ (a live cat, the environment the live cat is in, and you observing
the live cat) + ( a dead cat, the environment the dead cat is in, and
you observing the dead cat) }/. After one hour you are either in the
dead cat environment or the live cat environment with a 50-50
probability, but you lack the information needed to know which one and
will only obtain it when you open the box.*
/> //...in which case why not just bite the bullet and says it's
the probability that a particular world exists.
/
*Because then you have to explain why Schrodinger's equation suddenly
stops working. *
You have to explain when the worlds split; which amounts to the same thing.
*And then you have to explain exactly what a "measurement" is and why
Schrodinger's equation**treats you very differently than any other
quantum object.*
Measurement doesn't even have to include me or anybody else. The cat
example just obfuscates the question. The measurement is done when the
detector detects the atomic decay. A cleaner version has a clock
stopped by the detection. Then it's clear that the Schroedinger
equation applied to the whole system is separating the world when the
detection is made. Exactly how this separation proceeds is somewhat
hand wavy but I can see that it will eventually make different
orthogonal worlds, only one of which we see. Carroll once joked that
non-Everettians needed to explain the disappearing worlds. I don't see
that as taking anymore explanation than he gives for them being
orthogonal. What he fails to explain is how probabilities are realized
in these worlds. As Bruce pointed out, except for 50-50 cases the
overwhelming number of worlds find QM to be empirically falsified; so
branch counting doesn't work. It appears that the Born rule adds
another axiom; it's *not* just the Schroedinger equation.
Brent
*Incidentally, the very first post sent to the Everything List was
sent by the late great Hal Finney (he was cryonically frozen in 2014
and became Alcor's 128'th patient); his message was sent on January
16, 1998 and entitled "/Infinite universe and many worlds/".*
*Infinite universe and many worlds*
<https://riceissa.github.io/everything-list-1998-2009/0000.html>
*John K Clark See what's on my new list at Extropolis
<https://groups.google.com/g/extropolis>*
fhf
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