On 10/28/2022 5:43 PM, Bruce Kellett wrote:
On Sat, Oct 29, 2022 at 11:37 AM Brent Meeker <[email protected]>
wrote:
On 10/28/2022 5:28 PM, Bruce Kellett wrote:
On Sat, Oct 29, 2022 at 10:54 AM Brent Meeker
<[email protected]> wrote:
On 10/28/2022 4:38 PM, Bruce Kellett wrote:
On Sat, Oct 29, 2022 at 10:27 AM Brent Meeker
<[email protected]> wrote:
On 10/28/2022 3:06 PM, Bruce Kellett wrote:
Simply saying that QM as traditionally formulated
considers measurement
as a special process that os irreversible, doesn't
cut it, because
measurement is then not treated in terms of the
fundamental dynamics of
the theory, it is put in in an ad hoc way.
Lots of things are put into physics in an ad hoc way.
The Born rule is a prime example -- it is just
imposed on the quantum wave function in an ad hoc way
-- it cannot be derived from the fundamental theory.
But by Gleason's theorem it's the only consistent way to
put a probability measure on Hilbert space.
Who said we need a probability measure?
Because we observe that the same initial condition results in
different later conditions, but with predictable probability
distributions.
That is what is known as an ad hoc adjustment of the theory --
anything that is required for the theory to agree with
observation. Let's face it, all of physics is ad hoc!
That is as ad hoc as anything else; besides, unitary QM does
not allow for a probabilistic interpretation.
Not if you insist that all evolution is unitary, but that's
why Born added the projection postulate to connect the
unitary evolution to observation.
But Saibal and his ilk are insisting that all physics is unitary.
That is why the addition of probability (and the Born Rule) is
just an ad hoc adjustment so that their theory agrees with
observation. Gleason's theorem does not change this fact.
It's not "ad hoc" when it's part of a theory that applies to
everything.
That is just an arbitrary stipulation.
ad hoc
ăd hŏk′, hōk′
adverb
1. For the specific purpose, case, or situation at hand and for no other.
2. On the spur of the moment.
3. For a particular purpose.
Brent
Without the projection postulate and the probability
interpretation how would we compare QM to experimental data?
We couldn't, so we would have to conclude that the theory was useless.
That is why we add ad hoc postulates.....to compare to experiment.
Bruce
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