On 2/7/2020 11:00 PM, Bruce Kellett wrote:
On Sat, Feb 8, 2020 at 5:39 PM 'Brent Meeker' via Everything List
<[email protected]
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On 2/7/2020 9:54 PM, Bruce Kellett wrote:
On Sat, Feb 8, 2020 at 4:41 PM 'Brent Meeker' via Everything List
<[email protected]
<mailto:[email protected]>> wrote:
On 2/7/2020 8:14 PM, Bruce Kellett wrote:
On Sat, Feb 8, 2020 at 1:26 PM 'Brent Meeker' via Everything
List <[email protected]
<mailto:[email protected]>> wrote:
On 2/7/2020 5:57 PM, Bruce Kellett wrote:
There is nothing that picks out one particular set of
paths as preferred in the many-worlds situation.
Sure you can. For example you can pick out the set of
paths whose statistics are within some bounds of the mean.
Assuming you know what the 'mean' is absent any experiment.
The mean is estimated by the average of the experimental values.
In other words, you use the data to infer probabilities. But the
same data occur whatever the probabilities, so your backward
inference to the probabilities is meaningless.
Otherwise you are just cherry picking data to support your
arbitrary theory.
One can only get that in a stochastic one-world model.
All paths occur in a stochastic one-world model too.
No they don't. They are possible, perhaps, but they do not
necessarily occur.
They don't /necessarily/ occur. But they probabilistic occur.
It means they occur with high probability given enough instances
of the experiment. So I don't see why you attach great
significance to all possibilities occurring in MWI.
The problem here is "what constitutes enough instances of the
experiment?". In MWI, all sequences occur for ever run of several
trials. In a single-world theory, there are some sequences that will
have such a low probability that you could wait till the end of time
and never see them.
What on earth does that mean?
If the probability is very low, then the improbable sequences of
results need not occur even if you repeat the experiment 'till
the heat death of the universe. In MWI the low weight sequences
necessarily occur in every run of the experiments. Do you not see
the difference?
But the improbable sequences will occur in the same proportion in
both scenarios.
No they won't. Because we do do an infinite number of repeats of any
experiment. But all possible sequences occur on every run in the
Many-worlds scenario. That does not seem like the same proportion in
both scenarios.
Otherwise it wouldn't be a stochastic model. So it seems
that all you objections to MWI apply equally.
Get a grip, Brent.
The only difference is that some probability measure
is assumed as part of the model.
And this gives one a principled reason for ignoring the
paths that are not observed.
Why not ignore them because they are not observed? That's a
principled reason.
That is a one-world theory. And I agree that that is the way to go.
Low probability has an independent meaning in the one-world
case, so one is unlikely to observe a low probability set of
results.
One is unlikely to observe a result that is realized in only
a small fraction of the MW branches.
Why? One does not choose one's results at random from the set of
all possible results.
The theory is that which experience "you" have is determined by
making a copy of you for each result and one of them, at random,
is the "you" who has the experience. So it is effectively a random
sample from the possible results.
It is an indexical theory. The problem is that in MWI there will
always be observers who see the sequences that are improbable
according to the Born rule. This is not the case in the single-world
theory. There is no random sampling from all possibilities in the
single-world theory.
?? There's something deterministic in single-world QM? You seem to have
taken the position that MWI is not just an interpretation, but a
different theory. That some very improbable results cannot occur in SW
QM. I think you are mistaken. No matter how low a probability the Born
rule assigns to a result, that result could occur on the first trial.
In MWI there is always an observer who gets every possible set of
results. Why ignore those unfortunates who get rest inconsistent
with your pet theory?
Because they are relatively few in number and hence unlikely to be
the "you" who gets the result.
Unlikely to be you? OK, but what about the poor unfortunate who did
get the anomalous results. You choose cavalierly to ignore him . But
the fact that they might be few in number in the multiverse does not
diminish their importance to themselves, even if not to anyone else.
True. But the likelihood of being such an unfortunate is the same in
either SW or MW.
I agree that MWI fails to derive the Born rule. But I
don't agree that it is inconsistent with it, given the
version of MWI that postulates many branches...not just one
per possible outcome.
The point is that MWI is inconsistent with experience. There will
always be observers who get results inconsistent with the Born rule.
Why do you think you can't get a result inconsistent with the Born
rule in one world.
I don't think that. It is just that it is very unlikely -- of low
probability. It has probability one with MWI.
It doesn't have probability one for you, or for any other experimenter.
For any given experimenter it has the same probability as in SWI.
What do you mean by "inconsistent". The results are probabilistic
so they will have degrees of consistency and inconsistency with
the Born rule...just as there is a spread of results in MWI.
There are no probabilities in MWI. The probability of getting an
anomalous set of results for a sequence of measurements of z-spin up
for repeated measurement on x-spin up particles is calculable in
quantum mechanics. But the result is different in MWI since the
probability for any sequence whatsoever is one.
For any sequence. But not for any sequence seen by you. The tests are
assumed to be independent, indentically distrirbuted, so a sequence of
tests must have all the same statistics are as an ensemble including all
possible results, i.e. a series of experiments is ergodic.
And we cannot ensure that we are not such observers. So how can
we claim that our theory is confirmed by the data? The data are
consistent with all possible theories -- or none at all.
But it's not all or nothing. It's statistics.
So if we see anomalous results at the LHC we continue gathering data
to ascertain whether it is a real effect, or merely a statistical
anomaly. This possibility is not available in MWI (even though people
pretend that it is).
?? MWI is just an interpretation. It doesn't change the possible things
we can do.
MWI cannot explain the consistency of the statistical results we observe.
Sure it can. Any sequence of results in MWI one observes can be
observed in SWI, and with the same probability for any given observer.
Brent
Bruce
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