From: Lee Corbin (lcorbin@tsoft.com)
Date: Thu Sep 12 2002 - 20:23:10 MDT
Thanks to Serafino for the outstanding essay (below). I will
attempt a summary of the main points.
1. Born was himself forced to a more "realist" position.
2. Pauli was uncomfortable with the CI and submitted a
precursor to MWI.
3. Heisenberg believed that a certain "action" was propagated
at a velocity greater than that of light.
4. Bohr has to somehow be seen as a *realist*, despite what
one might at first think.
5. Bohr's complementarity principle is not as strong as
he supposed it to be: the complementarity is "smooth",
definitely not yes/no, particle/wave.
I hope that I have not done violence to what you have written :-)
In addition, I would say
A. Very few of these or other physicists would be comfortable
describing their own beliefs as constituting a "subjectivist"
position.
Should we regard knowledge as subjective? I can see arguments
both ways. On the one hand, if you have looked at the flipped
coin and I have not, then what you know is *about* the coin,
and so your knowledge is *not* subjective. On the other hand,
the only difference is what is in our heads, and so is not an
objective difference (hence subjective).
Lee
> -----Original Message-----
> From: owner-extropians@extropy.org
> [mailto:owner-extropians@extropy.org]On Behalf Of scerir
> Sent: Thursday, September 12, 2002 12:48 AM
> To: extropians@extropy.org
> Subject: Re: Postmodernists have nothing useful to contribute
> (was:Americaneducation)
>
>
> Lee Corbin wrote:
> > > Perhaps, but would you say more about why you suppose the Copenhagen
> > > view to be subjective, especially in its historical context? ...
>
> ' The question of whether the waves are something "real" or a function
> to describe and predict phenomena in a convenient way is a matter of
> taste. I personally like to regard a probability wave, even in 3N-dimensional
> space, as a real thing, certainly as more than a tool for mathematical
> calculations ... Quite generally, how could we rely on probability
> predictions if by this notion we do not refer to something real and
> objective? '
> Max Born, 'Natural Philosophy of Cause and Chance',
> p. 107, Dover publ., 1964.
>
> I must say that the early interpretation by Born was less "realist".
> But interference experiments with "single" photons (just one particle
> in the apparatus) showed very soon that the "statistical" nature
> of randomness has nothing to do with ensembles of particles.
> So he was forced to a more "realist" position.
>
> Btw the so called Born's rule is nothing more than the extrapolation
> of old concepts: Einstein's 1909 phantom field and Bohr-Kramers-
> Slater (BKS) ghost field.
>
> H. Kragh (in 'Dirac: a Scientific Biography', Cambridge U.P., 1990)
> describes a 1927 discussion between Dirac, Born and Heisenberg
> about what actually gives rise to the "collapse". For Born and Dirac it
> is the Nature who makes the choice of measurement result. Heisenberg
> maintained that behind the collapse, the choice of which branch of the
> wavefunction would be followed, was the observer itself. Like von
> Neumann, London and Bauer, Wigner, etc.
>
> Heisenberg changed opinion later, and developed his "later interpretation"
> in terms of "potentia", which is close to Popper's interpretation in terms
> of "propensities".
>
> The original term, for "collapse", was "reduction of the probability packet",
> sometimes also "reduction of wave packet", and the concept (according
> to Born) is due to Heisenberg (circa 1926). Heisenberg and Born
> at that time were puzzled because waves were spreading, in space, but
> the same waves became particles, (i.e. drops in the Wilson
> chamber).
>
> Interesting to note that Pauli did not like the "reduction" and he was thinking,
> at that time, about a sort of 'many dimensions' interpretation, a sort
> of MWI ante litteram, nothing new under the sun!.
>
> Heisenberg wrote about the "collapse":
> " In relation to these considerations, one other idealized experiment
> (due to Einstein) may be considered. We imagine a photon which is
> represented by a wave packet built up out of Maxwell waves.
> It will thus have a certain spatial extension and also a certain range of
> frequency. By reflection at a semi-transparent mirror, it is possible
> to decompose it into two parts, a reflected and a transmitted packet.
> There is then a definite probability for finding the photon either in
> one part or in the other part of the divided wave packet. After
> a sufficient time the two parts will be separated by any distance
> desired; now if an experiment yields the result that the photon is, say,
> in the reflected part of the packet, then the probability of finding the
> photon in the other part of the the packet immediately becomes zero.
> The experiment at the position of the reflected packet thus exerts
> a kind of action (reduction of the wave packet) at the distant point
> occupied by the transmitted packet, and one sees that this action is
> propagated with a velocity greater than that of light. However, it
> is also obvious that this kind of action can never be utilized for the
> transmission of signals so that it is not in conflict with the postulates
> of the theory of relativity." [The Physical Principles of the Quantum
> Theory, W. Heisenberg (University of Chicago Press, Chicago, 1930),
> reprinted by Dover Publications, p. 39.]
>
> According to Folse (Bohr's major expert) even Bohr was a "realist".
> But, imo, his "reality" concept was a bit "blown up" (or Eintein's was
> too "restricted" as Bohr once said).
>
> Actually even Bohr's complementarity principle (which is not as
> strong as he supposed to be - Zurek, Wootters, Noyer showed
> that the complementarity is "smooth", definitely it is not a yes/no,
> particle/wave, localization/superposition situation) has, perhaps,
> a bit of "realism" in it.
>
> < [Bohr] ... attached reality, i.e. reality as it was defined by
> him, to those aspects that could be directly observed in certain
> limiting circumstances by direct macroscopic observation.
> And, of course, in the case of radiation it is clear that direct
> observation in the limiting case of small values of
> h nu / K T
> gives the usual classical wave description of Hertz and
> Maxwell. As to the photon or the light quantum concept,
> introduced by Einstein, Bohr regarded it as a useful but
> an "auxiliary" concept, one which he later called symbolical,
> meaning thereby that it was not an aspect of the radiation
> phenomena which could be directly observed as such ...
> Bohr always made this distinction between the two aspects
> of radiation.>
>
> Thus the photon is the expression for the exchange
> of energy and momentum between matter and radiation.
>
> < For matter, the aspect which is in correspondence
> with classical observation is the particle aspect, of course;
> whereas the wave aspect is a symbolical one .... >
>
> [Rosenfeld, 1973, p. 252, p.260, Reidel publ., "The Wave-Particle
> Dilemma", in Mehra (editor) "The Physicist's Conception of Nature"]
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