Uncollapsing the wave function

The space quantization induced by a Stern-Gerlach experiment is normally explained by invoking the ``collapse of the wave function.'' This is a rather mysterious idea; it would be better to explain the Stern-Gerlach results without using it. We re-analyze the Stern-Gerlach experiment using path integrals. We find if we model explicitly the finite width of the beam, coherent interference within the beam itself provides the space quantization -- without need to invoke the collapse. If we insist on employing only wave functions with the space and spin parts kept forcibly disentangled, we recreate the need to invoke the collapse. The collapse-free approach makes more specific predictions about the shape and position of the scattered beams; if the interaction region has finite length, these may be testable. Pending experimental disambiguation, the chief arguments in favor of the collapse-free approach are that it is simpler and less mysterious, has no adjustable parameters, and requires the invocation of no new forces.