Some notes on Chapter 1: Presenting the Enigma
Many students starting a course using QE will know essentially nothing of quantum mechanics. More than a few will have been mislead by the purveyors of quantum pseudo-science. (But occasionally physics grad students attend parts of our conceptual physics course since we discuss material not in standard quantum courses.)
We ask students to read QE’s first page (p. 3) three times! And in our introductory remarks in class we emphasize that every quantum demonstration we describe is completely undisputed. We warn that the implications of the demonstrations can seem unbelievable, and their meaning is controversial. In this sense, Richard Feynman said, “Nobody understands quantum mechanics.” But, remarkably, one can come to the point beyond which nobody understands without any previous physics background.
We talk right away of the attitude of most physicists toward the weirdness of quantum mechanics, the quantum enigma,or what in physics is called “the measurement problem.” At the point where the problem encounters the mystery of consciousness, most physicists stop. Consciousness is beyond the normal boundary of the physics discipline. But it’s OK to explore beyond that boundary. (Some students might want to skim Chap. 15, “The Mystery of Consciousness” even at this point.)
We don’t describe the measurement problem in Chapter 1 because it can raise more questions than we want to address in writing at this point. But it works to encourage some discussion right away and assure students that the rest of the course focuses on the enigma.
So, in a few non-technical words, understandable to students even at this entry stage: what is the measurement problem? First, what the measurement problem is not:
It’s not a problem with the quantum theory. The theory is logically consistent.
It’s not a problem with the experimental quantum results. They turn out just the way the theory predicts.
The measurement problem, the quantum enigma, is that the actual physical world would have been different had you chosen to do a different experiment. Thus by your choice you create a physical situation. You therefore create a history. (See Jordan quote, p. 103.) (Regarding “history,” see that point in our discussion of Schrodinger’s cat, p. 119.) (This hard to believe, to say the least).
Bohr with the Copenhagen interpretation had physics evading this weirdness by arguing that physics need not consider the results of choices not actually made (see p. 104)
While this stance works, and is the way we deal with measurement problem for all practical purposes, it amounts to what the philosophers call the denial of “counterfactual definiteness.” Such a denial implies a completely deterministic world–going beyond a mere denial of the usual idea of free will. John Bell called this stance more mind boggling than the problem it was intended to resolve.
The epigraph to this chapter quotes a colleague saying that presenting this material, although correct, is the intellectual equivalent of allowing children to play with loaded guns. Our response is that we teach gun safety: the method of science. It’s the way one should decide on the acceptance of a hypothesis as reliable science. (See Chapter 4, and the remarks on Chapter 4 on these website pages.)
The nature of the quantum enigma will become clearer to students as the course progresses. The enigma is displayed in QE , but the book does not pretend to resolve this mystery physics has revealed, which has been called “the skeleton in our closet.”