Re: Original Sin

On Dec 13, 3:53 am, Gareth McCaughan <Gareth.McCaug...@xxxxxxxxx>
wrote:
[snip]

Well, e.g., I have on my shelves a very nice book called
"Quantum field theory in a nutshell", and its description
of the physics doesn't involve human observation anywhere,
and this is pretty typical these days.

That's quite alright. It's not quantum theory that involves human
observation, but the ontological implications of quantum theory that
do so. I suppose most textbooks today do not find it relevant to
discuss these implications, especially considering that they are
paradoxical.
[snip]

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 it to interact with the
rest of the world in such a way that the Wavefunction Of
The Universe afterwards tends to look like a linear
combination of components each of which involves one
particular "x-position" of the electron in combination
with one particular configuration of the rest of the
world. Operations that don't have that sort of property
just don't get called "measurements", and that's all
the mystery there is to measurements and collapsing
wavefunctions and all that stuff.

Well, the fact remains that according to scientific naturalism science
describes objective reality, what quantum mechanics describes is the
wavefunction with a non-zero amplitude in virtually all points of
physical space, but what we see when we look around is a concrete and
sharply delineated world, no matter whether we measure big things or
tiny elementary particles. So, as the objective world produces the
phenomenal world of our experience, if scientific naturalism is true
then somewhere a collapse of the wavefunction into the concrete
phenomenal reality we observe must have taken place.[1] Von Neumann
studied the question of where exactly that collapse of the
wavefunction takes place and found that it can take place anywhere
between the measured thing itself and the observer's perception. Now
you suggest that the collapse takes place when a particle decoheres by
getting entangled with its environment. First of all this hypothesis
is arbitrary as there is nothing in quantum theory or in quantum
observations that implies that this is what in fact happens. Indeed
one can equally well suggest that a decohered particle is still in a
state of superposition, i.e. that it still exists as an uncollapsed
wave. So, for example, consider a double slit experiment in which some
device measures through which slit a photon passes through. When that
happens the photon decoheres and the interference pattern disappears
but the photon may still exist in a left-slit / right-slit superposed
state until such time that a conscious observer actually looks at the
result of the measurement thus collapsing the photon's wavefunction.
[2] Now I know that that's not the ontological model you suggest, and
I agree that what you suggest is 1) possible and 2) makes away with
the observer-dependence of the wavefunction collapse. Indeed Nick
Herbert in his book "Quantum Reality" distinguishes between two types
of observer-created reality, and calls the case where the conscious
observer collapses the wavefunction the second kind. But most claims
for an observer-created reality concern acts of the first kind, namely
when the observer decides which of a quantum systems dynamic
attributes to measure. Nevertheless, let me here defend the existence
of the second kind of observer-created reality, using an argument
known since von Neumann's research into this matter in the early
1930's: All other places in the so-called von Neumann chain where
collapse can take place are well understood physical processes and
it's unlikely that something as momentous as the wavefunction collapse
and the fixing of a quantum system's dynamic attributes would happen
there. The only place in that chain we don't quite understand is at
its very edge where conscious experience is generated, so it is
reasonable to hypothesize that that's where the collapse of the wave
function takes place.[3] Indeed some modern researchers such as Henry
Stapp and Roger Penrose believe that there is a deep connection
between the wavefunction collapse and consciousness (but disagree
about which way the effect goes :-)

In any case the above is *not* where I most disagree with what you
write, for what you write gives the impression that the paradoxes of
the ontological implications of quantum mechanics that were found to
be so perplexing to its founders have later been solved and that
that's why so few physicists today discuss such questions. I think
that is a gross misrepresentation of the facts. After all it's not
like the two physics professors who in 2005 published "Quantum Enigma:
Physics Encounters Consciousness" were unaware of the content of your
book "Quantum field theory in a nutshell". Nor is it plausible to
believe that Nick Herbert and David Mermin who extensively wrote about
the paradoxes of quantum mechanics in the 1980s were unaware that the
solution had already been found. Not to mention Eugene Wigner, or
Henry Stapp who is doing research today.[4] So the fact that today
many quantum physicists or many textbooks about quantum physics simply
ignore these paradoxes only evidences that many of those who are aware
of the ontological implications of quantum theory have given up trying
to solve them, and, of course, many physicists are not aware of the
problem in the first place. I bet such problems are hardly taught at
physics departments. And why should they? They are philosophical
problems which whether solved or not hardly make a difference in
either theoretical or applied physics.

[1] There are some other possibilities, such as that it's not the
wavefunction that collapses but rather the observer and the universe
around them that explodes - but we can for the moment overlook such
exotic possibilities.

[2] In the case of Schodinger's cat, if you put a camera inside the
box to record what's happening then the camera too will remain in a
superposed state of "dead cat recorded" / "live cat recorded" until a
conscious observer actually looks to see what's happened.

[3] In this context there is an interesting and wildly speculative
idea to explain the apparent fine-tuning of the physical constants
within naturalism's paradigm: (The following may or may not reflect
John Wheeler's idea.) Consider a generalized version of the
wavefunction of the universe in which the values of the fundamental
constants are also in a state of superposition. As there is no
conscious being around the wavefunction evolves without any collapse
to a very highly complex superposed state. Now in one of these states
a physical configuration appears that produces consciousness, which
then at its first conscious experience immediately collapses the
universal wavefunction thus fixing the values of the fundamental
constants as well as the values of the various physical facts (such as
the position of the galaxy where that first conscious physical system
evolved). And, voila, we have a concrete physical universe with the
physical constants as well as physical facts (that by themselves would
appear to be a very lucky coincidence) optimized for the evolution of
consciousness. Incidentally the above hypothesis has an interesting
implication, namely that our universe is not only one of the rare ones
in which consciousness could have evolved, but it is strictly
optimized for consciousness in the sense that it is the earliest
possible universe in which consciousness can evolve. That implication
by the way may turn out to be testable.

[4] Perhaps one possible way out of the paradox is for the naturalist
to reconsider the meaning of scientific knowledge: Perhaps science is
not about reality, but about what can possibly be known about reality.
So the collapse of the wavefunction does not refer to some event that
takes place in objective reality, but rather refers to the collapse of
our subjective ignorance about the values of a model of objective
reality. Unfortunately this view does not jingle very well with such
experiments as Wheeler's "delayed choice experiment": As long as it
makes sense to speak about the path of a photon in the physical
universe Wheeler's delayed choice experiment brings us back to square
one. The only clean way out is to consider that science is about what
can be known about our observation of reality - exactly as idealism
has it.

Well, perhaps not quite all. The question arises: how
come the universe mostly looks classical to us? Which
turns out to mean: how come so many of the things we
do with electrons behave in that sort of way? When we
do the famous two-slit experiment, why don't we see
a whole interference pattern of detection for *each*
electron or photon that goes through the slits?

Well, what would that mean? It would mean that the
interference effect "persists" right the way up to
the macroscopic level at which our brains and bodies
mostly operate. But there's too much noise for that
to be so: too much messy environmental interaction.
An individual photon may be (trivially) coherent
and therefore able to interfere with itself, but
the rest of the world isn't, and the result is that
those interference effects mostly go away just as
interference effects mostly go away when you use
incoherent white light instead of single photons
or coherent monochromatic light from a laser.

The concept of "interference" is a contingent property of the
wavefunction, correct? I don't think that it's meaningful to ask why
we can't see it, because the wavefunction is not supposed to be
visible. But by seeing the marks that photons leave on a light-
sensitive film we can deduce whether these photons' wavefunction had
that particular property or not, or conversely our computation of the
wavefunction based on the experimental configuration allows us to make
statistical predictions about where the photons will leave a mark. The
first kind of observer-created reality refers to the fact that our
decision about what to see *radically affects* what we shall deduce,
as if our choice about what to watch had the power to affect reality
(in the case of the delayed choice experiments to affect reality
millions of years ago). Even more weird ontological implications
result from so-called "delayed choice quantum eraser" experiments.
Again: all these are not problems for quantum mechanics but on the
contrary demonstrate the truth of its predictions and cement our
confidence in it. They are problems for a particular understanding
about objective reality, namely those ontologies that posit that
scientific concepts and models refer to objective reality (whether
exhaustively or not), such as the ontology of scientific naturalism,
or the ontology of traditional theism.
.