(Gavin Ritz, 2008.04.06. 10.04NZT)
[From Bill Powers
(2008.04.05.0937 MDT)]
Martin Taylor 2008.04.05.10.21 –
(Gavin Ritz.
2008.04.05.18.33NZT)
[Martin Taylor 2008.04.04.11.24]
(Gavin Ritz, 2008.04.04.17.52NZT)
I couldn’t have given a better
answer than Bill’s below.
But it’s not only momentum and position,
you can refigure the equation to be Energy and time, both very elusive
concepts. Hence my earlier comment why not try measure energy directly. What is
this stuff called energy. Even Feynman conceded that he doesn’t know what it is.
It’s a clever production of the mind.
What did Bohr say about the Copenhagen
Interpretation and the mind, there lies the answer?
It’s an incredible measure of a mental
process abstracted of an abstraction with an or-or logic.
By the way I don’t dispute there is
something outside ourselves, of course there is, just kick a rock and find out.
But if you don’t have receptors in what you are kicking (a rock) in this
case you may well believe it isn’t there.
The Copenhagen
Interpretation tells us it’s all a dream.
That’s a funny
interpretation of the collapse of he wavefunction, or
the decay of entanglement consequent on interactions with the rest of
the world.
Not that funny really, because all of physics is just a mental
representation.
In which case, isn’t it rather restrictive to say that it is “The
Copenhagen Interpretation” that proves it to be so? Even Plato made the
same point, didn’t he?
What you are saying sounds as though the Copenhagen
interpretation has finally provided proof that there is no external reality to
which our perceptions could possibly be related. There’s nothing at all that
produces shadows on the wall of the cave. The shadows are all there is. All is
solipsism. If you believe that, why did you write your message?
The accusation of solipsism may come from a misreading of Gavin’s (and my)
position – and possibly even your own. You have said that the uncertainty is
in the eye of the beholder, which agrees with my ideas, but this is not the
same as saying there is nothing underlying the uncertainty. In fact, I proposed
three things that you pointed out may underly uncertainty.
There is a difference between saying that all experiences are perceptions, and
saying that there is nothing outside us causing those experiences. My position,
and I believe Gavin’s, is simply that we have no way of knowing what is outside
even though we are convinced there must be something.
The Copenhagen Interpretation, on the other hand, seems to be saying that the
uncertainty we experience is simply a true representation of the nature of the
external reality. It’s not just that we are uncertain about position and
momentum because of limitations on human perception and interpretation:
instead, position and momentum, independently of us observers, are themselves
uncertain, so we should not imagine that a particle “really” has a
position and a momentum at a specific time. This kind of attitude is at the
foundations of quantum physics. The fault, dear Brutus, is not in
ourselves, but in the stars.
I can see two ways to interpret that idea. One is the obvious one – that the
proponents are naive realists, who believe that what we perceive is what
actually exists, including uncertainty. But the other way of seeing this
position is that it actually is semi-solipsistic: it says that all we can know
is what we perceive or measure and that there is no point in even
speculating about a so-called “real reality.” There is no real
reality; all that exists is our measurements and perceptions. By that
interpretation, it is not possible that position and momentum could be
completely determinate while our measurements of them are uncertain.
I believe that the latter view is actually close to what some physicists
maintain. I think I ran into this view many times as I was learning physics. It
explains why, when I asked why there is gravity, my mentors became impatient
with me and told me not to ask why. All we know is what we observe, and gravity
is one of those things. It’s not to be explained, it’s simply to be taken into
account. This, it seems to me, is the mind-set that allows quantum physics to
exist. Don’t ask why such things as entanglement or tunneling or uncertainty or
other quantum effects exist. Don’t ask for a deeper explanation. These are
simply summaries of observations, and the observations are too well-established
and replicable to doubt. These observations are the deepest explanations we
will ever find, so just accept them and go on from there.
[GAVIN:]
You don’t really believe there is actually something called
hydrogen or there is anything such as these particles.
[MARTIN]:
Why not? What counter-evidence might argue the contrary? What competing theory
provides a simpler or more precise description of our perceptions?
When you have to invoke logic, argument, and counterargument, that is the sure
sign that you are not talking about experiences. You don’t have to argue about
experiences, because you can’t even doubt that they are occurring. The hydrogen
atom is imaginary. Nobody can see or otherwise experience it. It is a
proposition which, if it really were true, would account for certain aspects of
what we can experience. We have no way of finding out if hydrogen actually
exists. All we can do is make predictions about what we would observe if it did
exist and had the properties we assign to it, and then see if those predictions
match what we experience. All we can say is that so far, we haven’t found
anything wrong with the hypothesis that hydrogen exists.
Of course that works both ways. The fact that we can’t prove the existence of
hydrogen atoms also means that we can’t disprove it. But just on the basis of
comparing our experiences with the population of entities that makes up
physics, we can say that it’s pretty unlikely that hydrogen exists in the
particular form in which we imagine it. We might have got lucky, of course, but
it would be rather foolish to assume that. In fact that would violate one of
the admonitions in science, which is that we should avoid wishful thinking.
[GAVIN]: Sure one that
works
out pretty well. Very very clever mental representation.
[MARTIN]:Yes, it is very clever. How is that relevant to proving
the mental representation cannot refer to any external reality?
That isn’t the proposition in hand. The mental representation could refer to an
external reality. Ptolemy’s proposition about the crystalline
spheres that generate epicycles could have referred to an external reality, if
there had really been crystalline spheres up there. The proposition does not
have to do with whether there COULD be an external counterpart of the mental
representation. It has to do with whether there IS an external counterpart.
Anything you imagine MIGHT correspond to something in real reality. It’s
opposite, if it has one, MIGHT equally well do the same. MIGHT and COULD don’t
prove anything except mightness and couldness. And MIGHT and COULD
automatically imply MIGHT NOT and MAYBE COULDN’T.
Modeling consists of proposing entities and structures below the level of
observation which, if they did exist with the properties we give them, would
correctly predict what we experience. That is as close as we will ever get to
“knowing” what is going on behind the scenes. From time to time some
of the things we have imagined to exist run up against phenomena contrary to
what we imagine, and then we have to knock down the mental construct and erect
a new one, as we substituted oxygen for phlogiston, or PCT for
stimulus-response theory. We can’t really ask if the new idea is right; all we can
really say is that it predicts better.
Show me how to verify that that runny stuff I drink and shave with is really
made of atoms of hydrogen and oxygen, and you will just that easily refute my
position.
Best,
Bill P.