The Mysteries of the Quantum World

Readers who have read this far are probably confused. Normally
this is not a good situation to be in at the start of the last chapter
of a book. Here, however, it could mean that we have at least
learned something: the quantum world is very strange. Certain
experimentally observed phenomena contradict any simple picture
of an external reality. Although such phenomena are correctly
predicted by quantum theory, this theory does not explain how they
occur, nor does it resolve the contradictions.
What else ought we to have learned? We have seen, again on the
basis of experiment, that a local picture of reality is false. In other
words, the assumption that what happens in a given region of space
is not affected by what happens in another, sufficiently distant,
region is contrary to observation.
Nothing else is certain. We have met questions which appear to
have several possible answers. None of these answers, however, are
convincing. Indeed, it is probably closer to the truth to say that all
are, to our minds, equally implausible. The quantum world teaches
us that our present ways of thinking are inadequate.
I have tried to give a quick survey of the questions and their
possible answers in tables 6.1 and 6.2 The first of these tables
presents the problem purely in terms of the potential barrier experiment
introduced in 81.3. No reference is made here to quantum
theory or its concepts.