User talk:2A01:C50F:9000:E00:6900:3B90:7B72:2E07

Observer in quantum mechanics
This is what I found from Glenn Research Centre - grc.nasa.gov

In order for the observers to learn about the system, they must cause at least one quantum of "information" (energy, momentum, spin, or what-have-you) to pass from themselves through the boundary. The quantum of information is absorbed by the system (or it might be reflected back) and the system is thereby perturbed. Because it has undergone a perturbation, it causes another quantum of information to pass back through the boundary to the observer. The "observation" is the observer's subjective response to receiving this information. In a simple diagram, the situation looks like this:

right arrow O | S leftarrow

where O and S represent the observer and the system, the vertical line represents the interaction boundary, and the arrows represent the information exchanged in the act of observation.

In this scheme, no observation can be made without first perturbing the system. The observation is never one of the system "at rest," but of the system perturbed.