In quantum mechanics, measurement plays a fundamental role and to me, its role is usually described in a rather odd way. The Copenhagen interpretation states thus
When that device makes a measurement, the wave function of the systems is said to collapse, or irreversibly reduce to an eigenstate of the observable that is registered.
But I could not find any understanding of when is the observation happening. Does it happen when the event (such as the electron hitting the screen) happens, or when a person seeing the plate, (or when that person tells me!)
I have read about the multiverse explanation, a few explanations like the importance of consciousness etc. I understand that this is a very fundamental question, and my question is not what really happens. My question is what is wrong with the following interpretation:
The process of measurement is the development of some sort of coherence (I am afraid of using the word entanglement because I do not understand it) between the observed object and the observer. So, from the observer's perspective, the wavefunction has collapsed, without the wavefunction ever collapsing from the perspective of anyone who has not observed it.
This is not the same as the Copenhagen interpretation because there is no real collapse of the wavefunction, nor the multiverse interpretation because there is no real splitting of the universe. This interpretation also makes the "Wigner's friend" experiment intuitive to understand, and removes the distinction between the observer and the observed.
Added after the comment by Luke:
In fact, this interpretation defines measurement as the observer attaining coherence with the observed. Consciousness plays no part, and neither does the act of conducting an observation modify anything about the observed nor split the universe. Repeat measurements by the observer will yield the same result because of the coherence. Isn't this consistency the meaning of reality? This will look to the observer as a collapsed wavefunction. However, for any external agent (Mr. Wigner) who has not made the observation, there is no collapse.
I am more of a quantum mechanics enthusiast, reading mainly from popular science books on this subject. I would be glad if anyone helps me understand why this interpretation is wrong.