1. Of course, measurements need not have outcomes until they are over,until a recording exists in the measuring device! So, if (i) is to be a meaningful physical requirement of a satisfactory theory of the collapse, then something is going to have to be said about what a recording is. It will be best (it will make our argument as strong and as general as possible, as the reader will presently see) to be very conservative about that: so no change in the physical state of a measuring device will be called a recording, here, unless that change is macroscopic, thermodynamic, irreversible, and visible to the unaided eye of a human experimenter.
2. Bell, J.S. (1987) Are There Quantum Jumps? in ‘Speakable and Unspeakable in Quantum Mechanics’, Cambridge University Press, Cambridge, pp. 201–212.
3. Ghirardi, G.C., Rimini, A., and Weber, T. (1986) Unified Dynamics for Microscopic and Macroscopic Systems, Phys. Rev. D34, 470.
4. Recently, a theory which leads to continuous ‘jumps’ was developed: Pearle, P. (1988) Combining Stochastic Dynamical Statevector Reduction with Spontaneous Localization,to be published in Phys. Rev. A.
5. Actually, the first thing that gets correlated to the z-spin in an arrangement like this is the momentum, or something approximating the momentum, of the measured particle; but that momentum (since the initial wave-function of the particle is taken to be reasonably well localized) quickly (before the particle hits the screen) gets translated into a position, which can then be ‘read off’ from the screen.