On 11 Dec 2012, at 18:05, meekerdb wrote:
On 12/11/2012 6:58 AM, Bruno Marchal wrote:
On 10 Dec 2012, at 17:25, meekerdb wrote:
On 12/10/2012 2:47 AM, Bruno Marchal wrote:
On 10 Dec 2012, at 02:03, Jason Resch wrote:
On Sun, Dec 9, 2012 at 6:51 PM, meekerdb <[email protected]>
wrote:
On 12/9/2012 4:37 PM, Jason Resch wrote:
On Sun, Dec 9, 2012 at 5:40 PM, meekerdb <[email protected]>
wrote:
On 12/9/2012 12:08 PM, Jason Resch wrote:
And without a doubt the most popular interpretation of Quantum
Mechanics among
working
physicists is SUAC (Shut Up And Calculate),
That's not an interpretation at all.
Well for a more philosophical statement of it see Omnes. His
view is that once you can explain the diagonalization of the
the density matrix (either by eigenselection, dechoherence, or
just assumed per Bohr) then you have predicted probabilities.
QM is a probabilistic theory - so predicting probabilities is
all you can ask of it.
Is science just about its applications or about understanding
the world? I would argue that science would not progress so
far as it has if we thought finding the equation was the be all
and end all of science. The "shut up and calculate" mindset
can be translated as "don't ask embarrassing questions", it is
the antithesis of scientific thinking.
Student in the 1500s: Does the earth move about the sun, or do
the planets merely appear to move as if earth moved about the
sun?
Professor in the 1500s: We have all the formulas for predicting
planetary motion, so shut up and calculate!
Fortunately, Copernicus wasn't satisfied with that answer.
So what's your objection to Omnes? That the world just can't be
probabilistic? So instead there must be infinitely many
inaccessible worlds - which happen to mimic a probabilistic world.
It is fine if QM is a probabilistic theory. Where I disagree
with him is in his belief that we can never go beyond that in
our understanding of it. I am not sure how accurate this
statement is, since it is a secondary source, but http://en.wikipedia.org/wiki/Roland_Omn%C3%A8s
says: "We will never, Omnès believes, find a common sense
interpretation of quantum law itself." To me, it almost seems
as if he says it is not worth trying to find an answer. I lean
more towards David Deutsch who says science is about finding
good explanations.
Omnes is very special. His many books gives the best account and
defense of the MWI, except that in the last paragraph, or
chapter, he insist that we have to be irrational, in fine, and
select one reality. This is really cosmo-solipsism, and makes QM
indeed no more rational at all.
What's not rational about it? I think 'rational' just means
'being able to give coherent reasons'. There's a perfectly good
coherent reason for 'selecting' one reality - we experience one
reality.
But there is no reason to extrapolate from this. We experience a
flat earth, we see the Sun turning around Earth, we feel the need
of force to keep the same speed, etc.
And all those inferences were perfectly rational. The fact that
later, more comprehensive theories were found doesn't change that.
Rational is not the same as 'always right'.
OK. But I was pointing of the fact that there was a pattern in the
mistake, which consists in extrapolating from our experience. Progress
along the path Galileo, Einstein, Everett always come from a better
distinction between what is, and how it can appear to us.
Then in the search of a TOE, we need to use coherent reasons, but we
need also a coherent big picture.
I agree I tend to use "rational" is an unusually restricted sense:
going from "the earth look flat" to the "earth looks round" is
rational. Going from "the earth looks flat" to "the earth *is* round"
is irrational.
Usually when we refer to experience we are wrong
We're not wrong about the experience, although we may be wrong about
it's extrapolations.
OK. That is what I meant.
(and from this some extrapolate wrongly that we cannot mention
experience in experiment ...).
Also, we do not experience a reality. We experience something
(consciousness, mainly) and we extrapolate reality from that, and
from theories already extrapolated.
I agree. But the model of reality we build should comport with
experience. We don't experience many worlds, so a valid model must
include that.
But we do experience many worlds. We see those interference that we
can see, and without collapse, that we don't see, this is a sort of
experiencing the many worlds. Like we do experience the roundness of
the earth, through travel, media, pictures, etc. If not, we never
experience anything physical to start with. We are just more and more
conscious of the assumptions we make.
Being rational we prefer to explain the complex from the simple than
the simple from the complex. But the understanding of the simple,
itself, is already complex, and so it is the place where we have to
agree, the more explicitly, on what is simple and what is not.
Bruno
http://iridia.ulb.ac.be/~marchal/
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