Answer to Question #198465 in Quantum Mechanics for Marisa

Question

What action causes an electron's "probability wave" to collapse into a single location?

Answer 1

There are a lot of answers already that are adamant that collapse of the wave function is "real" and undisputed. This reality is that the need for "collapse of the wave function", or some of the other measurement axioms of quantum mechanics, is still very much an open question. The subject is still debated by those active in foundations of quantum mechanics research.

To an excellent extent the projection hypothesis reproduces the results of experiments. While conceptually tricky it is undeniably a great approximation to the way nature behaves in many "measurement" scenarios. If it is wrong then we either need to show that the remaining bits of the model can reproduce this behaviour or expain it in some way or we need another axiom in its place that can reproduce the effect - but does not seem to be in such a deep conflict with the rest of the formalism (e.g. it may preserve unitarity).