PeterWB

I was not aware that there were multiple versions of the Copenhagen Interpretation. The maths makes me wonder if it might be possible to design an experiment to test when the superposition ends. Maybe a variation on the Bell's Theorem experiment, where entangled particles in a superposition are measured, then a second measurement is made before the first result is seen by the experimenter (This assumes that a new superposition is not created automatically after the first measurement). If the second measurement showed that there was still a superposition, this would support the intelligent observer version of CI. If not, maybe science writers will eventually stop asking "Can the universe exist without a human observer" (not that we can observe the universe - all we can observe are photons and cosmic rays).

Schrödinger objected to the Copenhagen Interpretation's definition of his wave function as the probability of an electron, or other quantum object, being in a particular position or state, and that it was in all positions/states at the same time until measured/observed, when the function collapsed to a single definite position/state. Unfortunately he could not come up with an alternative "physical" interpretation of what the wave function represented, and he also missed the biggest flaw in the Copenhagen Interpretation(CI): - The CI is based on a Classical (i.e. pre quantum) definition of an observer as a Human being. Quantum Mechanics was born out of subatomic physics, where electrons and protons, etc, are so small that they they are not "seeable" in the way we understand this. The only way to "see" an atom, electron, photon, etc, is to "bounce another particle off it", i.e. have it interact with another quantum object so that information is exchanged. e.g. a photon being absorbed by a dye molecule in a light sensitive cell in the retina of our eye (the photons energy changes the shape of the molecule, revealing a enzyme site which starts the process of triggering a neurone, etc, etc, which eventually leads to sight.). Thus a quantum observation or measurment does not involve a human being, but instead is an interaction which changes the state of the thing being observed ( even if the interaction occurs in the retina of our eye, rather than in a camera or piece of laboratory equipment). Therefore it is not the involvement of a human observer which changes the state of the observed particle as claimed by CI. This points to a second flaw in the Copenhagen Interpretation - There can be multiple human observers of a single measurement/observation, which can occur at different times. This is illustrated by Baryon's post where the first human observer was also in a box and subject to being "observed" by a second human observer.