Consider the wave-function representing single electrons
(1) α|1>a + β|1>b ,
with both |α|2 < 1 and |β|2 < 1. On the path of the wave-packet |a> is set a detector A.
The question is what causes the reaction of the detector, i.e. a recording or staying silent? A couple of possibilities are considered here:
1) The detector reacts only to the electron charge, the amplitude of probability α has no influence on the detector response.
2) The detector reacts with certainty to the electron charge, only when |α|2 = 1. Since |α|2 < 1, sometimes the sensitive material in the detector feels the charge, and sometimes nothing happens in the material.
3) It allways happens that a few atoms of the material feel the charge, and an entanglement appears involving them, e.g.
(2) α|1>a |1e>A1 |1e>A2 |1e>A3 . . . + β|1>b |10>A1 |10>A2 |10>A3 . . .
where |1e>Aj means that the atom no j is excited (eventually split into am ion-electron pair), and |10>Aj means that the atom no j is in the ground state.
But the continuation from the state (2) on, i.e. whether a (macroscopic) avalance would develop, depends on the intensity |α|2. Here is a substitute of the "collapse" postulate: since |α|2 < 1 the avalanche does not develop compulsorily. If |α|2 is great, the process intensifies often to an avalanche, but if |α|2 is small the avalanche happens rarely. How many times appears the avalanche is proportional to |α|2.
Which one of these possibilities seem the most plausible? Or, does somebody have another idea?