🚀 go-pugleaf

Hi folks,

Have been recovering from a severe case of bronchitis (bordering on pneumonia
apparently).  My my... ya'll've been lively on wave interpretation lately!

SOME SNIPES AT MWI

I was amazed to see several apparently totally serious statements about
MWI such as "many bizarre worlds are predicted, too!" (not a direct quote).

Hmmm...  call me old fashioned, but I always thought "predicted" means
"there is some way, even if it is very difficult, to verify its existence."

If there is any mechanism whatsoever for getting a single bloomin' idea for
a REAL prediction out of MWI, I'd love to hear about it.  (Is there?  Maybe
I honestly *have* missed something.  Dr. Baez?)

I sometimes wonder whether one factor in why Dr. Bell (a very great man in my
opinion) did not receive a Nobel prize before his untimely death was simply
because he refused to get caught up in abstractions that have no physical
meaning.  How dull.  How bland.  How un-front-coverish.  How spectacularly
successful at finding a genuine, bona-fide *testable* prediction of a truly
strange implication of QM.  Ironic, is it not, that a fellow who thought
very little of his own rather considerable musings in quantum cosmology was
nonetheless able to out-predict the showier front-cover QM cosmologies that
riveted the imagination of pop physics?

Again my question to MWI advocates:  Does MWI say *anything* at all that has
the courtesy of being testable in *any* conceivable fashion?  If not, how can
you seriously claim the MWI to have any meaning?

One last note:  Yeah, "intermediate versions of MWI..."  Follow them up
rigorously and I stick with my postion that what you will find is going to
end up looking an awful lot like a fancy pilot wave model.

...

In article <Joe.0039@twistor.dialix> Joe@twistor.dialix
(Joe Katnic) writes:

> It appears that there is some argument as to where QM effects, I.E. so
> called wave function collapse, and wave function interference, stops as
> you move on up the scale from atoms to chairs etc.
>
> If you consider the photon two slit experiment.  Simply increase the size
> of one of the slits. At some point the interference pattern will cease.
  ...
> Would this not limit the nature of the QM effects and suggest that
> the CAT is alive or dead (not both in some Quantum State) but that
> the decaying radioactive material can be in a set of Quantum states.

QM/CLASSICAL BOUNDARIES

I think Dr. Baez has already stated in nicely in some other article.  The
prediction of QM and the evidence to date both say "no!"  There is no
*fundamental* reason why very large objects cannot do the same sort of
strange things that electrons do.  I've never heard of anyone finding
a shred of experimental evidence that there is such a boundary.  Indeed,
large-scale quantum effects found in fairly recent experiments such as
"quantum vortices" in rotating cylinders of superfluids tend to argue the
in the other direction.  If you set it up carefully enough, it really does
seem to be the case that QM applies to large objects, also.

INFORMATION TRACES AND QM/CLASSICAL BOUNDARIES

The lack of, say, interference effects between very large bodies, is usually
explained away in terms of the extremely small wavelengths of their wave-
functions.  That explanation is happens to be incorrect, or at least rather
seriously incomplete, and it is one of the very few places where Dr. Feynman
made any sort of conceptual error in his physics lectures series.  Dr. Feynman
stated in passing in Volume III that the reason that large objects such as
bullets don't interfere when passing through slits is that their momentum
frequencies are so high as to make such interference effects very, very small.

Poppycock.  They don't interfere first and foremost because each bullet
leaves so many kinds of "information traces" that is flatly inconceivable
that it could do anything BUT behave classically.  Even though Dr. Feynman
strongly makes the point that electron self-interference effects disappear
if there is *any* potentially detectable trace of information as to which
slit an electron passed through, he never discusses the same issue for the
bullet example.

A KNOWN BULLET IS A CLASSICAL BULLET

A bullet *must* behave classically because it is absolutely riddled with
information-depositing effects.  Photons aplenty bounce helter-skelter from
it, air molecules are rudely and crudely knocked aside, and any slit against
which it might bounce will be seriously damaged by the impact of the bullet.
Not until all of these QM-killing, information-depositing effects are
eliminated is it even worth mentioning the QM wavelength of the bullet.

AN UNKNOWN BULLET IS A QM BULLET

BUT if you eliminate all those information-depositing events, you will have
to be much more careful about ignoring QM effects.  If you take that same
bullet and find for it an uncanny whole in the universe, a gap of many light
years in which absolutely *nothing* but the bullet itself is allowed to pass
(no atoms, no photons of any wavelength, no particles of any kind at all)
then questions about the nature of its wavefunction will become much more
meaningful.  Even if it was lanched with unimaginable classical precision and
targeted with utter precision, the bullet's trajectory will grow increasingly
imprecise as it travels, due not to classical uncertainty but to the very
slow expansion of its wavefunction.

DETECTING A QM BULLET

Until the bullet wavefunction touches something -- and that "something"
could be as insubstantial as a single photon -- it will remain a super-
position of many possible bullet trajectories or histories.  A genuine
large-scale QM object.

A bacterium riding within the bullet would know nothing of this.  It would
continue to see the same-old "bullet interior" it always saw.  To it the
bullet would in no way seem ghostly or abstract.  Indeed, it would only be
the external world that would seem like an abstraction, since the bacterium
would be unable to receive any information whatsoever about that world
without immediately become a classical object.

And when the bullet did finally "hit" an object that reconnected it with
the rest of the universe, there would be no jerk or collapse or anything
of the sort.  Instead, both sides would simply observer that "Ah!  so THIS
is where your trajectory took you!  You're a bit off course!"  Just exactly
as if it had been that way all along, with absolutely no trace of all those
other alternative paths left over.  Both the bacterium and the observer are
relieved to see that QM had no real effect other than to whack the course
off a bit.  Right?

SELF-INTERFERENCE IN A QM BULLET

Well, not quite.  Set it up again, except that this time you put up a very
dark sheet with two holes in it -- holes separated by less than the distance
across the main part of the bullet wavefunction -- and something odd begins
to happen.

Most bullets will "rejoin" the universe at large by going ker-splat against
the dark sheet.  But a few that do not touch or graze the sheet in any
fashion will make it through.  And a very, very careful observer will find
a incredibly fine-scale structure to how those bullets finally land.  There
will be unimaginably thin lines where the center of the bullet never lands,
and adjacent lines where it does land.  In other words, wave interference
lines -- very, very small ones, but quite real.  And with them comes the
highly uncomfortable implication that they are formed by a wave that passes
through *both* of the dark holes -- leaving the smart little bacterium
passenger to ponder out loud, "I did WHAT?"

REAL QM BULLETS?

Could such an experiment (sans smarty E. Coli) actually be done?  With much
smaller objects, more in the range of *extremely* small dust particles, the
answer is probably yes -- but it wouldn't be easy!  Without careful removal
of information-forming processes, the experiment would be ruined before it
began.  If you take into account that gravity itself could be a significant
information-forming process, you can get some idea of how hard it might be!

MEA CULPA

By the way, all of the above bullet self-interference analysis is my own.  I
don't know of any book that goes about it in quite this fashion, particularly
in the emphasis on elimination of information-forming processes.  If anyone
has seen such a discussion anywhere, I'd be greatful to hear about it.

				Cheers,
				Terry Bollinger