Re: Original Sin

On Dec 14, 9:45 am, Gareth McCaughan <Gareth.McCaug...@xxxxxxxxx>
wrote:

But very few physicists these days think that observation
is fundamental to what's really going on. Instead, you
get ideas like this: "measuring the x-position" of an
electron just means allowing

I cut off your narrative in mid flow because here I would like to ask
a question. Who is doing this 'allowing' ? This 'allowing' is evidence
to me of a human observer interacting with the electron, since in the
absence of such an observer, the wavefunction would go its own merry
way and do whatever its inclined to do anyway. In the immediately
following text, 'such a way' turns out to be a choice made by the
experimenter to make a certain measurement (or if you prefer not to
use 'measurement' then 'run a certain experiment' or 'arrange the
apparatus'). So it turns out that the 'majority of physicists' haven't
removed the human observer at all, they're just playing around with
words. Or so it seems to me at any rate, do please show how my
interpretation is wrong.

This is what I meant by

| (Except in the null sense in which every scientific
| activity involves observation by human beings.)

This is an example of why I maintain the claim that 'no argument is
compelling' :-) I took it that when you said this you were indeed
referring to the null case where all physics is by definition a human
activity. But since you respond to my text above with your original
statement (which I did indeed take account of when replying to you)
then it appears that 'null sense' to you doesn't carry the same
meaning as 'null sense' to me. That's why no argument can ever be
compelling - because different people have their own meanings for the
words that are used in arguments.

Since your original illustration that I couldn't get compared QM with
classical physics, I'll demonstrate what I mean. If we speak of say,
classical Newtonian gravitation in the same phrasing as you've used
above, we obtain something like this :

'Determining the gravitational attraction between two spherical
masses just means allowing the two spheres to attract one another...'

Have you ever considered that gravity could be *prevented* by the
experimenter from acting ? I've certainly never heard it in any
formulation of classical physical theory. And if it cannot apply in
the classical sense, why introduce it in the quantum case when
according to you, there's no difference? Yet you *have* introduced the
notion of 'allowing' and now are claiming that such a notion is 'the
null case in which any scientific activity blah blah blah'.

Now, its possible that you phrased your claims imprecisely, and that
you could offer an explanation without such a form of words where the
experimenter is obviously no passive bystander. I invite you to do so.
If not, I invite you to deal with my objections rather than snipping
them out and re-stating what you had already clearly stated.

Because of course the practice of science is all about
human beings making observations, and for us to be able
to test any scientific theory we need to get out of it
some predictions about what we'll see when we make
observations. But there's nothing specific to QM here.

I agree. So here you're arguing against a straw man.

The claim Dianelos made was that "the only possible
implication of quantum mechanics is that consciousness
creates reality". If you think that this follows somehow
from the fact that when we do (experimental) science
there are conscious observers making observations,
please feel free to explain how.

I have already explained that I didn't take Dianelos' words literally
here. I don't wish to support his argument as it stands, but I'm
interested in building a case for my own version of his claim. I won't
be doing this though from the premise you state here.

So in a nutshell, this approach is saying that 'wavefunction collapse'
is actually decoherence - that it happens anyway without the need for
the human observer?

Yes.

Since this interpretation of QM was something I hadn't come across in
detail before, I did a bit of ferreting around to explore it further.
Seems from what I found it doesn't solve (inter alia) the measurement
problem - that it posits that the universe only *appears* to be
classical, there can be no certainty about a particle being anywhere
in particular, even when we're not at all interested in its momentum.
Yet experiments *do* give definitive outcomes for measurements.

Wikipedia did give me some starting points - that this approach (when
coupled with 'consistent histories') is one espoused by Roland Omnes
(amongst others). Googling for him turns up an interesting review of
his book 'The interpretation of Quantum Mechanics', written by William
Faris. I quote here from his conclusions :

~ What can we conclude from such a book?
~ Some physicists regard quantum mechanics as
~ a totally successful theoretical framework; they
~ consider any attempt to raise questions about
~ its foundations as an irritating distraction.
~ Omnès, to his credit, recognizes that the puzzles
~ are profound and that the traditional resolutions
~ do not achieve the level of clarity appropriate
~ to a completed science.
...
~ But the
~ core resolution is merely a desperate bluff.
...
~ The bluff lies in such statements as: "the
~ actuality of facts is something that need not be
~ explained by a theory," and "when one finds a
~ gap between theory and reality only at their
~ common extremities, this is not a failure but
~ the mark of an unprecedented success for quantum
~ mechanics, as compared with all the theories
~ before it."

So to me it seems that Omnes is something of a Don Cupitt in the
physics world.

Faris of course is not the only commentator to expose difficulties
with the decoherence view you posit. Henry Stapp also has similar
reservations, and in one of his papers[1] he quotes Zurek (wikipedia
notes him alongside Omnes as an exponent of the view you put forward).
Zurek's comments to me are telling [here he's reviewing the status of
various attempts to resolve QM's issues using decoherence-based
approaches], I quote:

~ The interpretation based on ideas of decoherence
~ and [environmentally induced] einselection has not
~ really been spelled out to date in any detail. I have
~ made a few half-hearted attempts in this direction,
~ but, frankly, I was hoping to postpone this task,
~ since the ultimate questions tend to involve such
~ 'anthropic' attributes of the 'observership' as
~ 'perception', 'awareness' or 'consciousness',

So, no, your approach doesn't solve any of the hard problems of QM
[with the possible exception of Schroedinger's Cat], rather it looks
the other way.

Who is the
writer of this book incidentally ?

(I assume you mean the one about QFT.) Anthony Zee.

I checked out this book, it is indeed about QFT, not QM per se. So it
would not surprise me at all that Prof. Zee doesn't comment on
difficulties of interpreting QM. If I'm wrong though, and he does,
would you care to include them for us here?

In your estimation, sure. Not in mine - I make a distinction between
building a hypothesis from evidence (the scientific method) and
stating a claim which then is subject to objections. The latter is
what I term a defense of a claim; in the former there's nothing to
defend and there are no attacks.

I'm not sure what the content of this distinction is: whether
the hypothesis is arrived at before the evidence arrives or
after, perhaps? In practice, hypotheses are formed when some
but not all of the relevant evidence is in; defending a claim
against objections is just one variety of examining the evidence
to see how well a hypothesis is supported.

Are you using 'claim' interchangeably with 'hypothesis' ? I prefer to
make a distinction - a claim would be the end result of the process of
building a hypothesis - a claim being much stronger than a hypothesis.
Thus a weak hypothesis falters and never gets built into a claim, a
claim has already withstood the evidence.

A claim is a hypothesis that someone chooses (for whatever
reason) to assert as fact or probable fact.

In which case, in the book you question, the writers don't assert any
hypothesis as fact. Therefore they make no claims. No hypothesis is
fact, its experimental results which are facts. Hypotheses are
tentative, as they explicitly point out.

'Compelling arguments' in my experience simply do not exist. What
compels people (to update their paradigms of reality) is experience,
not arguments.

Arguments are part of experience, and they can perfectly well
lead people to update their ideas of reality.

I see. I still disagree, unless by 'lead' you're saying something like
'they have an influence'.

Yes, that's what I'm saying. (In particular, for the avoidance
of doubt, when I call an argument "compelling" I don't mean
that everyone who hears it is somehow forced to agree with
its conclusion. Rather, that most reasonable and well informed
hearers would do so.)

This is fanciful poppycock. A 'reasonable hearer' does not exist in
the absence of a message is he/she is hearing. And depending on what
the content of such a message is, a hearer might respond reasonably,
equally well might not.

For an example, if the hearer is Ken and the message is something from
New Scientist in regard to a new evolutionary theory, the results are
fairly predictable.

So no doubt has been avoided here, its been compounded, even before we
move on to consider your probablistic statement about 'most' - its
totally impractical to perform an experiment to determine this.

I'm not sure where you're coming from in citing the
book's authors as saying their conclusions are tentative. Are you
saying that means they're not really sure of their conclusions?

I'm saying it suggests that they don't think that the evidence
they've presented makes their conclusions inescapable.
...
So I take it that they, like me, don't subscribe to the 'inescapable
argument' theory. Its a perceptual error to interpret that (and I'm
not claiming you are necessarily doing so, not enough evidence for
that yet) as 'they are not completely sure of their conclusions'.

It seems to me that when you go out of your way to call your
conclusions on some matter "tentative", you have to be saying
something more than that they have the same uncertainty about
them that *all* conclusions do.

That's the mistake I'm pointing out to you. That perception is
distorted, its clearly not what they mean in this context. But then,
you've not read much of the book...

Richard

[1] http://xxx.lanl.gov/PS_cache/quant-ph/pdf/0110/0110148v2.pdf
.

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