popper-logic-scientific-discovery

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some structural components of a theory of experience
photon], a kind of physical action (a reduction of wave packets) is
exerted from the place where the reflected half of the wave packet is
found upon another place—as distant as we choose—where the other
half of the packet just happens to be’; a description to which he adds:
‘this physical action is one which spreads with super-luminal velocity.’
This is unhelpful since our original probabilities, αP k(β) and αP k(β - ),
remain equal to 1 2. All that has happened is the choice of a new reference
class—β or β - , instead of α—a choice strongly suggested to us by
the result of the experiment, i.e. by the information k εβ or k εβ - ,
respectively. Saying of the logical consequences of this choice (or, perhaps,
of the logical consequences of this information) that they ‘spread
with super-luminal velocity’ is about as helpful as saying that twice two
turns with super-luminal velocity into four. A further remark of Heisenberg’s,
to the effect that this kind of propagation of a physical action
cannot be used to transmit signals, though true, hardly improves matters.
The fate of this imaginary experiment is a reminder of the urgent
need to distinguish and to define the statistical and the formally singular
probability concepts. It also shows that the problem of interpretation
to which quantum theory has given rise can only be approached by way
of a logical analysis of the interpretation of probability statements.
77 DECISIVE EXPERIMENTS**
I have now carried out the first two parts of my programme outlined in
the introduction preceding section 73. I have shown (1) that the
corpuscle. If we assume that the wave is, as a matter of principle, related to an aggregate
of equal but mutually independent bodies, the paradoxical conclusion vanishes.’
*Einstein adopted in some of his last papers a similar interpretation: cf. the note ** below.
** The imaginary experiment described in the present section, pp. 238 to 242, is
based on a mistake. (See also notes *3 and *4, below.) The mistake was first noted by von
Weizsäcker (Naturwissenschaften 22, 1934, p. 807); by Heisenberg (in letters), and by
Einstein in a letter here reprinted in appendix *xii. I therefore have withdrawn this
experiment; yet I do not any longer regard it as ‘decisive’. Not only are my arguments
down to p. 238 unaffected, but we can also replace my invalid experiment by the famous
imaginary experiment described by A. Einstein, B. Podolsky, and N. Rosen, Physical Review
47, pp. 777–780. Niels Bohr’s reply to this experiment seems to me to shift the problem:
see appendix *ix below, and also my paper ‘Quantum Mechanics Without “The
Observer”’, in Quantum Theory and Reality, edited by Mario Bunge, 1967, pp. 7–44.