TFNR - Quantum measurement
In general, a measurement is an interaction.
It is not possible to distinguish a "measurement" interaction from an "ordinary" interaction. We call measurement an interaction where the acquired information is used to characterize an Event, a Relationship, a Process, a Phenomenon or quantify a Property or physical quantity.
A quantum measurement is a measurement in which one or more quantum objects are involved: any interaction between one or more quantum objects and the Elemental Field, itself or themselves, or other quantum objects. Interaction means that Action is exchanged, that all quantum objects involved give up and acquire information. Their quantum states change, are modified by the interaction.
Even when it seems that the state of a quantum object is not modified by the interaction, by the measurement carried out, something changes.
Under certain conditions, for certain types and intensities of interaction, the overall quantum state of the quantum object can remain unchanged, but the states of part of the event points that support the object, of part of the volume of space time by time occupied by the object, change, are influenced by interaction / measurement.
These variations in the partial states (of part) of the object, as mentioned, may not be sufficient to determine a change in the overall state, but they can add to other subsequent partial variations which can ultimately produce a variation in the overall quantum state.
Links to the tables of contents of TFNR Paper
