Re: Penrose's nonsense

bjflanagan <wordsmyth1@xxxxxxxxxxxxx> writes:

>Flanagan
>What if a mind/brain identity theory holds?

It doesn't; the mind and experience are subjective, while the
brain is objective. Recall that the word subjective refers to
the fact that an experience (for example) can be examined
only by the person having the experience, while the brain
is objective because anybody can examine it if they take the
time to look underneath the skull. This is in contrast to
the widespread notion that subjective simply means "bad".

The brain and the mind are different things for the
reason they they are very obviously different things.
At best you can say that there's a correspondence
of some kind between them, which isn't very strong or
very deep. You might claim, somewhat poetically, that they
are two aspects of the same underlying thing, which is
quite a shift from the original claim that there was
only one thing. Now there are three things, two of which
are "aspects" of the third. This isn't very strong or
deep either; unemployment and inflation are often
aspects of the same underlying economic trouble, but
asserting this fact is very far from claiming that
unemployment and inflation are the same thing.

In the case of the mind and the brain, the only thing which is known
about the third thing is that it is something which has the mind
and the brain as aspects. Apart from the mind and the brain, then
what we know about this thing is nothing at all except that it
is something. This is very vague, and some interpret that as mystery,
and interpret mystery as profundity.


>Here is what Chalmers, a philosopher, wrote in Sci Am:

>"The abstract notion of information, as put forward by Claude E.
>Shannon of MIT, is that a of a set of separate states with a basic
>structure of similarities and differences between them."

No it isn't; as Shannon introduced it, information had to do
with strings of symbols which were sent as messages. The amount
of information provided by a message is the logarithm of
the number of possible messages, assuming that every message
was equiprobable from the point of view of the receiver beforehand.
No "basic structure of similarities and differences" is necessary;
if I have an alphabet of 100 distinct characters, and no measure of how
similar any one is to any other, apart from merely being able to
distinguish between them, then the theory of information works just
fine - the information given by a single symbol is log(100).

>"We can think of
>a 10-bit binary code as an information state, for example. "

No we can't, because we don't know what an information state
is. We know what a 10-bit binary code is because it's a
clear and unambiguous concept. "Information state" is a term
introduced by Chalmers, although he attempts to mislead the
reader into thinking that it was Shannon who introduced it.
If Chalmers means "information", he should say "information".
By saying "information state", he invokes the idea of a "state",
which people understand to mean the condition of a thing. But
what thing is it? What is the information state a state of?
The reader has no idea; Chalmers has given the reader the idea
that, somewhere, there's a Something, associated with the
information, and the reader has no idea what it is except
that it is something.

>"Such
>information can be embodied in the physical world. This happens
>whenever they correspond to physical states (voltages, say); the
>differences between them can be transmitted along some pathway, such as
>a telephone line....
>We can also find information embodied in conscious experience. The
>pattern of color patches in a visual field, for example, can be seen as
>analogous to that of pixels covering a display screen. Intriguingly, it
>turns out that we find the same information states embodied in
>conscious experience and in underlying physical processes in the brain."

It didn't turn out; it was assumed. There are no scientists in white
coats examining "information states embodied in conscious experience".

>"The three-dimensional encoding of color spaces, for example, suggests
>that the information state in a color experience corresponds directly to
>an information state in the brain."

Why does three dimensions have anyting to do with it? Would one
dimension, or none, be any less or more suggestive? Why does
an "encoding of color spaces" suggest anything about the brain?

>"We might even regard the two states
>as distinct aspects of a single information state, which is
>simultaneously embodied in both physical processing and conscious
>experience. "

Here we find why Chalmers introduced the term "information state".
By considering the information which is (presumably) common to
the brain and the mind, and calling it an information state,
he invokes the idea of a Something which it is the state of.
We have no idea what this something is supposed to be, except
that it has something to do with the information in the
brain and the mind. The reader who confuses mystery and profundity
will be suitably impressed.

>Flanagan
>In another Sci Am article, Freeman Dyson states quite clearly that,
>from the perspective of quantum field theory (QFT) everything in the
>physical universe is a quantum field: "There is nothing else except
>these fields: the whole of the material universe is built of them."

If he states it "quite clearly" then it must surely be true.

>It follows by a ready consequence that the brain, being a part of the
>material universe, just is a collection of [quantum] fields.

Even beginning to disentangle the web of confusion here is a daunting
task. You are relying on an argument from authority (in the
form of Freeman Dyson) to establish a point ("There is nothing else except
these fields: the whole of the material universe is built of them")
which is little more than poetry, and is furthermore conditioned
of a specific "perspective" (quantum field theory).

Let me explain something about quantum field theory. It is a
collection of mathematical techniques which attempt to extend
the formalism of quantum mechanics to deal with systems
which have continuous degrees of freedom. It is not the absolute
final truth about what exists, and even when physicists
talk about this or that quantum field as though it were
a physical object, what they are in fact referring to is
a purely mathematical object - a linear operator on a Hilbert
space. You may also hear them talking about virtual or
"off-shell" particles. This kind of talk shouldn't be interpreted
as a statement that these things actually exist and form
the substrate of everything else that exists.

When Freeman Dyson says that from the perspective of quantum field
theory everything in the physical universe is a quantum field, what
he means is that the formalism of quantum field theory deals with
quantum fields and to "solve the system" in quantum field theory
means to determine the time-evolution of these fields. Similarly,
from the perspective of classical mechanics, the universe consists
of a set of coordinates q_i, and momenta, p_i. This isn't a statement
that the coordinates and momenta are what exist. It's a statement
about what mathematical objects the theory deals with.

>Hartley
>Nowadays there is debate about the practicality of building
>computational devices that exploit quantum effects. Maybe we can,
>maybe we can't. What is *quite* clear is that the human brain is
>*not* such a device. Nothing that is composed almost entirely of
>liquid water ever can be.

>Flanagan
>In a quantum universe, all effects are quantum effects, yes?

Quantum mechanics is a formalism which can be used to predict the
values of measurable quantities. An effect is called a quantum
effect if that formalism needs to be used to predict or explain
that effect. Hence not all effects are quantum effects, the Coriolis
effect being an example of a completely classical effect (explainable
using classical mechanics). The expression "quantum universe" is
poetry.

>The brain
>is mostly water and yet it clearly mediates computations. One can talk
>about "higher order" levels of the brain's organization, but the only
>level with causal efficacy is the quantum level.

There is no such thing as a "level with causal efficacy". The
brain does what it does, and we may or may not need to use
the formalism of quantum mechanics to predict what it does.
For the purpose of predicting whether a muscle will move, it
is unlikely that the formalism of quantum mechanics will be
necessary, since the Hodgkin-Huxley equations (perhaps the
most successful application of differential equations in
biology) work extremely well for characterizing the
properties of spiking neurons.

It may turn out that the quantum formalism will need to be used
somewhere if we want to predict some number to some number of decimal
places. The same is true of an internal combustion engine.

>Hartley
>That *is* a statement about the physics of the brain. If you want to
>argue with that, go ahead, but be prepared to explain how quantum
>effects can matter to a system with a *very* short coherence time and a
>*very* long interaction time.

>Flanagan
>The fractal character of neural nets and their dendritic trees might
>suggest self-similarity across spatio-temporal scales.

Are you familiar with the works of Igor and Grichka Bogdanov?

>Weyl scaling
>might obtain if, as would seem most plausible, the brain's photon
>fields are most relevant to what are called conscious processes.

>Perhaps neural form follows quantum function? Umezawa, in his nice text
>on 'Advanced Field Theory,' seems to suggest something of the kind:

>"As we have seen in preceding sections, manifestation of ordered states
>is of quantum origin. When we recall that almost all of the macroscopic
>ordered states are the result of quantum field theory, it seems natural
>to assume that macroscopic ordered states in biological systems are
>also created by a similar mechanism."

It doesn't seem natural to me. Do the "macroscopic ordered states"
he's talking about refer to superconductivity and superfluidity?
These are accounted for (at low temperatures) by QFTs, but
there's no Bose-Einstein condensation going on in biological
systems. The order that we see in biological systems is the
result of evolution. Quantum field theory is not necessary to
understand evolution.

BJ on colours:

>(4) respect the laws of projective vector geometry; and

>(5) are readily observable.

>Weyl is quite explicit regarding #4: "Thus the colors with their
>various qualities and intensities fulfill the axioms of vector geometry
>if addition is interpreted as mixing; consequently, projective geometry
>applies to the color qualities." On his analysis, it seems as though
>sounds ought to respect that geometry also:

>"Mathematics has introduced the name isomorphic representation for the
>relation which according to Helmholtz exists between objects and their
>signs. I should like to carry out the precise explanation of this
>notion between the points of the projective plane and the color
>qualities . . . the projective plane and the color continuum are
>isomorphic with one another. Every theorem which is correct in the one
>system S_1 is transferred unchanged to the other S_2."

Weyl is incorrect. What is at issue here is the set of colours which
share a given intensity. At a particular intensity, there is
one shade of grey, one bluest colour, one greenest colour and
one reddest colour. Leaving out some details, the (+++)-octant
of a three dimensional space can be identified with the
manifold of all possible colours, with the axes corresponding
to red, green and blue.

Hence the colour purple with an overall intensity, I, will lie at
a point (I/2, 0, I/2). The purples of various different brightnesses
lie along the line which you can get by substituting various different
values of I above. Since, in this sense, the hue of purple, meaning
the colour purple without regard to its shade (or brightness),
corresponds to a line going through the origin, the set of hues
is like the set of lines going through the origin, which is called
RP2 or the real projective plane. Weyl omits the fact that only
a convex section of RP2 actually corresponds to visible colours:
only positive brighnesses are possible, and so these lines
are really only half-lines. These go from the origin into the
(+++) octant and do not extend backwards past black into some kind of
anti-colour in the (---) octant.

What's the result of all this? The manifold of hues actually
has the topology of a disc. It is simply connected, unlike
RP2. This means that you can draw a circle (or rather, closed curve)
on RP2 which can't be continuously shrunk to a single point. RP2
is like a sphere, except that every point is "the same" as its
antipodal point. You can draw the closed curve on RP2 by starting
at one point and ending at the antipodal point, which is (by
construction) the same as your starting point. This curve
can't be shrunk to zero, in the same way that a circle drawn around
the hole in a torus can't be shrunk to zero. In this sense,
RP2 has a hole in it.

It would be very exciting indeed to discover that the manifold of
hues (or the manifold of colours, for that matter), had a hole like
this, as Weyl says it does, but it doesn't. Draw a circle with
different colours at different points along the circle, with the
property that the colour changes continuously around the circle,
keeping the overall brightness of the colours constant. This is a
map from the circle into the manifold of hues. To see this, note
that, for each point, theta, on the circle, S1, you have chosen a
colour, f(theta); all the intensities are the same. Hence f:S1 ->
M, where M is the manifold of hues. Now, notice that each hue
can fade to grey continuously until the entire circle is grey. To
see this, let the colour at a point, theta, at time t be given by:

f(theta,t)=(1-t/2)f(theta,0)+(t/2)f'(theta,0)

where f'(theta,0) is the complementary colour to f(theta,0). At time
1, the entire circle has, at every point, an equal mixture of
a colour with its complementary colour. That is, the entire
circle is grey and so the image of the circle on the colour
manifold is a single point. This recipe works if you want to
talk about the manifold of hues. For the manifold of colours,
where the intensity can vary around the circle, instead use the map:

f(theta,t)=(1-t)f(theta,0)

And watch the entire circle fade to black at time 1.

>Dirac, writing about the usual sorts of QM superpositions, points out
>several salient features which apply equally well to superpositions of
>colors and sounds--which would make a good kind of sense if some sort
>of identity should obtain:

>"When a state is formed by the superposition of two other states, it
>will have properties that are in some vague way intermediate between
>those of the original states and that approach more or less closely to
>those of either of them according to the greater or less 'weight'
>attached to this state in the superposition process. The new state is
>completely defined by the two original states when their relative
>weights in the superposition process are known, together with a certain
>phase difference, the exact meaning of weights and phases being
>provided in the general case by the mathematical theory."

>Dirac, 'The Principles of Quantum Mechanics,' Oxford, 1958.

Now, you want to "identify" colours with quantum states, based on
the fact that they can be added together to form mixtures. Let
me make two objections:

1. When mixing quantum states, there is a very important
phase to be taken into account: |up> + |down> is very
different from |up> - |down>. When adding colours there
is no corresponding phase.

2. Coloured light can be mixed with other coloured light
by shining both lights onto a common surface. If you want
to keep the intensity constant you can dim both lights
as you mix them. This is a way of defining "addition of colours" -
A + B means the colour that you would see if you shone
A-coloured light and B-coloured light onto the same white
screen. Or you could try using inks and lightening by adding
white. Either way, neither of these methods of adding light
are "mental", by which I mean that, if I have never played
with lights or ink, and I have never seen purple, then
showing me a picture with red in one place and blue in
another place will not reveal to me what purple looks like.
The addition has to be performed outside me.

I have seen purple, and I think it looks more like blue
or red than like green, suggesting that I may have
some kind of a built-in distance function for the
manifold of hues (or it could have come from the
fact that blue things look purple from certain
angles or in certain lights - that is, from
experience), but I don't have any ability to
add colours together in my head. All my understanding
of colour mixing comes from experience of experimenting
with coloured lights and inks.

What you want to do is say that the experience of
seeing colours is the same as a quantum state, based
on a shared additive property, but the fact is that it
is not the experiences of seeing colours which
can be added together; only the lights and inks
are added.

R.

.

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