Quantum decoherence 5.3
In the delayed choice experiment, the wave function of the system (the photons and the environment) is also in a superposition of eigenstates, not just the wave functions of the individual photons are.
All the past is there, but our present measurement “chooses” which part to see.
The chosen part must be a consistent story, according the quantum mechanics.
The chosen part is what we called “an observer”.
— Me@2018-01-22 09:35:02 PM
2011.11.20 Sunday (c) All rights reserved by ACHK