Karl Popper, the highly influential philosopher of science was unusual in that, as a philosopher, he had a large impact on science itself. He was actually listened to by physicists! He's best known, of course, for his falsifiability criterion for theories to be considered scientific, which has become de rigeur in most branches of science. He's less well known for his commentary on quantum physics and his interpretation of the mathematical formalisms of quantum physics. In his 1982 Postscript to the Logic of Scientific Discovery - Vol. 2 being Quantum Mechanics and the Schism in Physics - Popper presented the most fully developed discussion of his "propensity field interpretation" of quantum mechanics, in "thirteen theses." He poses a hard-hitting critique of the Copenhagen school of QM, arguing for a realist, particle-based, non-deterministic interpretation in which the most basic pieces of nature are indeed particles, with real positions and momenta, even if we can't know them precisely, there is no wave/particle duality, there is no "collapse of the wave function" caused by a conscious observer, and most importantly an interpretation of the Schrodinger wave equation as applying only to epistemology - what we can know abouat nature, what nature actually is - and not supporting the notion that particles are in fact waves in some instances and particles in others (or as Schrodinger believed simply waves that seem particle-like in some situations). His thirteen theses are based in large part on Alfred Lande's 1965 work, New Foundations of Quantum Mechanics. Lande was a strong proponent of the Copenhagen school until later in life becoming disillusioned with the Bohr/Heisenberg/Pauli dismissive approach to reality and causality. Here is my paraphrase of his thirteen theses: 1. Quantum mechanics concerns statistical problems about matter and energy. 2. Statistical questions demand statistical answers. 3. Because quantum mechanics provides statistical answers to statistical problems, it is a mistake to insert an “observer” into quantum mechanics as a necessary component of “wave collapse.” 4. The “great quantum muddle” results from mistaking the wave function – the statistical answers of quantum mechanics – for a physical property of the particles at issue. The wave function is a mathematical device, not a physical property. 5. Heisenberg's uncertainty formulae are not actual limits on the precision of our knowledge, they are, rather, “statistical scatter relations.” “They thereby limit the precision of certain individual predictions.” 6. The statistical answers of quantum mechanics refer to populations of particles, which do, contrary to the Copenhagen Interpretation, have a real and precise position and momentum. (We cannot know with absolute precision, however, these data for any particular particle, but this does not mean the particle itself does not actually have a defined position and momentum). 7. Heisenberg effectively admitted the truth of the previous theses but the commonly accepted Copenhagen Interpretation has for some reason maintained the contrary views for the most part. Heisenberg was, however, on final reflection, agnostic about the reality of a given particle's past history, based on retrodictive measurements: “It is a matter of personal belief whether such a calculation concerning the past history of the electron can be ascribed any physical reality or not.” 8. The mistaken Copenhagen Interpretation is closely related to the common interpretation of the calculus of probability, which mistakes certainty (or lack thereof) about our knowledge of events in the world with the certainty (or lack thereof) of certain events actually happening. The objective “propensity interpretation” of probability calculus is the best approach for quantum physics, which avoids the mistake of the common interpretation. The “propensity field” indicates the likelihood of a certain outcome of the experimental arrangement. A given experimental arrangement's propensity field is a real physical quality, though a “somewhat abstract kind of physical quality.” 9. The collapse of the wave function is not an effect unique to quantum mechanics – it is an effect common to all probability theory. There is no more to the wave collapse in QM than the “trivial principle: if our information contains the result of an experiment, then the probability of this result, relative to this information (regarded as part of the experiment's specification), will always trivially be” 100 percent. 10. The propensity interpretation of probability calculus solves the problem of the relationship between particles and their statistics, that is, between particles and the wave function, because in Popper's interpretation there is a real particle, with defined position and momentum, and the propensity field of the entire experimental arrangement (or situations outside of any actual human experiment, though human knowledge will require an experiment). 11. It is misleading to speak of wave/particle duality or of a duality of particles and propensity fields. This is the case because propensity fields are properties of a given experimental arrangement, not of the particles that are the object of study. There is, therefore, no need for an “observer” to collapse the wave function because there is no “collapse” in a physical sense. 12. The mistaken idea of wave/particle duality arose from de Broglie and Schrödinger's attempts in the 1920s to create a wave theory of the structure of particles. These attempts failed, but the wave/particle duality interpretation was mistakenly retained. 13. Both quantum physics and classical physics are indeterministic. Popper doesn't clarify this point in his paper. So my question is: who has actually heard of the Popper/Lande "propensity field" interpretation of QM and what do people think of these ideas as a more common-sense interpretation of the queer QM maths?