The Simple Process of Elimination

Miguel Lerma wrote:
 Thinking that things are as they appear is the most natural 
 position (so the "Earth is flat and still", "the Sun turns 
 around the Earth", etc.). Only when that assumption makes us 
 to run into contradictions we need to reevaluate it.

I'm not sure the roundness of the Earth implies that we should
reject the evidence of our senses.  Admittedly, when we talk 
about how things SEEM, we may be influenced by the connotations 
of falsehood that attach to the word in common usage ("Why seems
it so particular with thee?" "Seems, madam?  Nay, it is. I know 
not 'seems'."), but I was using it in the most neutral meaning 
of that which appears directly to our senses.  Now, we acknowledge
the disturbing possibility that things may not be as they seem,
meaning that our direct perceptions and experiences may be false;
indeed, this is the sort of notion that underlies things like
the philosophy of Parmenides, who argued that existence is
indivisible and unchangeable, and that "opinions" about 
multiplicity and change are merely artifacts of thought. 

The question is, what does the round Earth teach us about 
the plausibility of such ideas?  Does the Earth's roundness 
really suggest that our senses are unreliable?  I would say no.
Our senses tell us that the surface of the Earth is approximately
flat, at least on the scale of several miles.  Beyond that, we
have no direct knowledge (assuming we've never looked at the masts 
of ships appearing on the horizon, or made any of the other 
observations that clearly show curvature).  However, if we are 
not careful thinkers, we might be tempted to EXTRAPOLATE our 
direct knowledge of the approximate flatness of our local region, 
and imagine that this flatness extends arbitrarily far.  Would 
our subsequent discovery that the Earth is round cause us to 
challenge our direct sense perceptions?

I think not. (And when I say "I think not", I don't mean that I
don't think, I mean that I think I disagree.)  The local region 
is still as flat as it ever was.  Our sense perceptions have not 
deceived us.  Rather, our mistake was in EXTRAPOLATING our
knowledge from one regime into another where we have no direct 
experience.  This has often happenned in physics.  If and when 
we venture into another regime, we may find that some of our 
previous extrapolations are now falsified by new experiences and 
observations, but it's worth noting that, at all times, the final 
arbiter of scientific knowledge is experience and observation.  
We do not discredit the reliance on observation by invoking better 
observations.  Thus, when I say that the "no collapse" interpretation 
of quantum mechanics presents a picture that is at variance with our 
immediate observations in our local regime of experience, it is a 
mistake for you to equate my comment with some unjustified 
extrapolation of experience into a distant regime.

Of course, another option for you would be to challenge my
assertion that the MWI presents a picture at variance with our
experience, but you haven't claimed that.  Instead, you've 
argued, along with Parmenides, that things are not as they seem.  
But you can't really invoke the round Earth in support of this 
position, because you're arguing not against some unjustified 
extrapolation, but against the direct evidence of our senses, 
experiences, memories, etc., as normally apprehended.  Obviously 
this kind of argument is impossible to refute, but it also, by 
itself (i.e., with no proposed replacement arbiter) completely 
undermines our ability to apprehend the world in a scientific 
(or even a rational) way.  I can't imagine that you really want 
to rest your case on the rejection of observation and experience.


Miguel A. Lerma wrote:
 Hidden variables theories do not seem to have been very
 successful, so option 1 has little chance to success.
 ... It is rather like saying that if you try hard to find 
 something in a place and you fail repeatedly, you better 
 start considering the possibility that it is not there 
 (or perhaps it is "too hidden")

I'm not a proponent of hidden variable theories, but even I know
that your premise is flawed.  Hidden variable theories HAVE been
moderately successful, assuming "success" is defined as being able
to show conformity with observations.  Of course, if you equate
"success" with widespread acceptance within the scientific community,
then it's true that hidden-variable theories have not been very 
successful, but this doesn't help your case, because by the same 
criterion the many "Many Worlds" interpretations have likewise
been unsuccessful (as shown by all the references cited in previous 
posts, and more if you want them).  Thus, your reasoning forces us
to conclude that since the MWI has not been very successful, it is 
unlikely to BE successful in the future.  (I'd actually tend to
agree with this as a plausible meta-argument that hidden-vairables,
Copenhagen, and MWI are each unlikely to ever "sweep the field",
at least in their present forms.)
 

Miguel A. Lerma wrote:
 What I say is that the Copenhagen Interpretation is inconsistent.

I sense that your criterion of consistency is inconsistent.  The 
rap on CI is that it relies on the occurrence of "measurements" to 
shift the superpositional linear wavefunction down into the elements 
of our definite non-linear experience (observations), but it gives no 
clear definition of precisely what constitutes a "measurement", so 
it's massively ambiguous.  Now, various possiblilities can be (and 
have been) considered to remedy this, ranging from random fluctuations 
to conscious observation as the keys to collapse.  We can critique 
each of these possibilities, but the point is that CI, as it stands, 
is philosophically unsatisfactory because it fails to provide a clear
and unambiguous map from its conceptual elements to our actual 
experience.

Fair enough.  But surely this very same objection applies (even more 
so) to the many Many Worlds interpretations.  They each fail, in 
different ways, to provide a clear and unambiguous representation
of what we experience, which is, after all, the ultimate purpose of 
an interpretation.  Needless to say, it's not acceptable to claim 
that "our experiences are in there, along with a bunch of other stuff 
that does not correspond to our experiences", because that's like 
someone ordering a statue of David and you deliver a huge block of 
stone and say "It's in there."  Knowledge consists not just in the 
assertion of what is true, but in the exclusion of what is false.

Let me make one more comment on your charge of inconsistency.
You surely realize that QM has not been fully reconciled with
special relativity, let alone general relativity, and yet those
theories are integral parts of our overall understanding of the
world.  Thus, as things stand, EVERY theory is "inconsistent"
with some other part of our understanding.  That's the reason
people have looked so hard at various possible ways of reconciling 
these two basic frameworks.  Just to give an indication of the
problem, notice that the Schrodinger equation is linear, whereas 
our best understanding of gravity is essentially non-linear.  Thus, 
if you want to claim that MWI already represents a unification of 
QM with gravity, you've got some serious explaining to do.  

This gets back to your original formulation of the problem, where
you characterized the question as "classical versus quantum".  I 
called your formulation unhelpful, because it makes it look too 
easy.  You see, it's easy to discard "classical" (who needs 
"classical"?), but it's not so easy to discard non-linearity, 
because this is something we actually directly observe (or at 
least THINK we observe).


Albro Swift wrote:
 What IS controversial is your suggestion that the CI is the only
 conceivable way of reconciling the superpositional aspects of
 quantum mechanics with a single world.

Miguel A. Lerma wrote:
 Hidden variable theories are another possibility, but I ruled 
 them out because of their repeated failure.

It still seems to me that your survey of the available "options" 
is severely deficient.  You seem to think it's either hidden 
variables, Cophehagen, or one of the many Many Worlds, but as I 
mentioned previously, you've completely overlooked the realistic 
single-world options that I, for one, consider to be the most 
promising.  I'm sure others here could speak up for their own 
ideas.  

The point is that it's EXTREMELY difficult in these matters to 
make a case "by exhaustion", i.e., by saying "I've considered
ALL the options, and since none of them are right, the answer
must be the one remaining!"  That's essentially how you've
argued, saying that there are only three specific options for
understanding the universe, ruling out the first two rather 
summarily (and without the benefit of much knowledge, it seems
to me), and concluding that the third one MUST be correct, by the 
simple process of elimination!  You don't even seem to realize 
that what you call MWI is really a multitude of different 
interpretations.


Miguel A. Lerma wrote:
 I think that if you rule out hidden variables, then NCI implies 
 MWI, am I wrong? 

Yes, there are many different interpretations associated with 
Everett, De Witt, and the "Many Worlds" label.  One school of
thought, that might be called the literalists, consider that the 
world actually doubles at each quantum decision point, so (for
example) at a simple spin measurement there arise two distinct 
worlds, with spin UP measured in one and spin DOWN in the other.

You might wonder why anyone would be so silly as to approach it 
in this literal way, but it isn't totally without justification.  
In this way of looking at things, the basis selection problem (the 
one that you mentioned at the start of this thread) goes away,
because each of the newly created worlds has its own separate 
state vector that shows either spin UP or DOWN, not any super-
position.  Thus, the "split" imposes a realistic state vector at 
each measurement.  Of course, this is accomplished by essentially
incorporating something like collapse (or perhaps "resolution")
into the "splitting" operation, so this interpretation doesn't
really do away with the non-locality concerns and other problems
associated with "collapse" in the CI.  It just resolves the 
ambiguity in what constitutes a measurement by saying "everything 
is being measured all the time".  Notice that we also have no 
problem explaining how different people in the world agree on 
the results of all measurements in that world.  

However, this literal splitting approach has several obvious 
drawbacks.  For one, it doesn't assign the right probabilities to 
events, because the original state might have been such that the 
outcome was spin UP with probability 0.9 and spin DOWN with 
probability 0.1, whereas we end up with just two nearly identical
worlds, so it looks like 50/50 if we just count the number of 
possible future worlds.  In order to capture the correct 
probabilities we need some further principle that "weights" 
the UP world more than the DOWN world.  Not many people regard 
this literal splitting approach as an attractive option, because 
although it does solve some of the original problems, it fails
to address some of the most serious ones (like non-local 
splitting of worlds), and introduces lots of new ones.

So that brings us to what I assume is your preferred alternative,
the "no-collapse" interpretation (as distinct from the hyper-
collapse interpretation of the MWI literalists).  This avoids all 
the disagreeable features associated with actual "splitting" and 
generating multiple copies of the world by simply never compelling 
the state vector to conform to any particular realistic configuration, 
nor to ever evolve in a non-linear way.  For our previous example, 
the state vector would have some component in the UP direction and 
some in the DOWN... and that's all there is to it.  The "many worlds" 
here are all just IMPLICIT within the potentialities of a single all-
encompasing state vector of the universe.

But even most proponents of the no-collapse interpretation 
conceed that this can't really be quite "all there is to it".  
When we perform a spin measurement we don't find a superposition 
of UP and DOWN, we find either UP or DOWN, and that becomes the
component of our "apparent" state vector, which has thereby evolved
in a non-linear jump.  But clearly this is not the same as the 
"real" state vector, which is still showing a superposition of UP 
and DOWN for that measurement result, and always evolves linearly.
Thus, like Parmenides before us, we need to explain the difference 
between all the "apparent" state vectors that show non-linear 
behavior and the single "real" state vector that evolves linearly 
for all time.

At this point we could rehearse all the particular problems that
arise with this interpretation (basis selection, observer agreement,
probabilities, etc), but fundamentally it seems that we haven't
really made any progress here.  We began with the problem of trying 
to explain apparently nonlinear behavior with a linear law, and after 
much labor we've finally solved the problem, if we can just figure 
out this one last thing, namely, how to explain apparently non-linear 
behavior with a linear law.  Since we don't want to have wasted all 
this effort, let's just declare that there "really is no non-linear 
behavior" (shades of Zeno's "there is no motion") and we'll let 
someone else figure out why things appear to the contrary.


Albro Swift wrote
 ...you've simply shifted the entire burden onto an unspecified
 theory of consciousness.  You might just as well claim the
 entire universe is a giant Plutonium atom plus a suitable
 theory of consciousness to be defined later.

Miguel A. Lerma wrote:
 I guess you can. The difference is that MWI is not capricious, 
 it arises after removing an inconsistence in an interpretation 
 (CI) that works as long as we do not look at measurement devices 
 too closely.

The CI is no more or less "inconsistent" than any of the MWI's.
They are all about equally far from giving a philosophically
satisfactory framework for understanding the world.  The main
difference between them is the vast (or at least half-vast)
un-observable baggage carried by the MWI.  At some point you
may need to consider the possibility that the "inconsistency"
between our non-linear experiences and our linear laws cannot
simply be eliminated by adopting an interpretation that ignores
our experience.

By the way, you might be interested to know that Everett's 
thesis advisor, John Wheeler, who was an early enthusiast for 
many worlds, subsequently changed his mind.  Wheeler is not alone 
in having initially been attracted to (some version of) Everett's 
idea and then discarding it.  This seems to belie claims that the 
only people who disapprove of MWI are those who have failed to 
appreciate its simplicity.


Miguel A. Lerma wrote:
 If we knew what consciousness is and how it works we could 
 use it in our attempt to explain how our image of the world 
 fits in the best consistent interpretation we have of it 
 (which is the MWI).

Well, I think we do have some vague ideas about how our minds work 
(neurons 'n stuff), and it DOESN'T seem to fit.  You may choose to 
focus your efforts on searching for a theory of consciousness that 
fits with your preferred physics, but I'd prefer to persist awhile 
longer with the scientific method, i.e., rather than trying to bend 
our interpretations of our direct sense perceptions and experiences 
to conform to a particular theory, I'd keep looking for a theory 
that matches our experience.