The essense of the problem is that Photons and electrons,behaves as small participles and waves too, according the experiment.Bohrs theory was: Electron is a participle but we have to avoid every efford for detailed description of its track.The only thing we can say, its that this can be described from a ''wave-connection''(Mathematic connection) The squere of the wave-connection, is at one point the possibility to find an entity.
Well, we can say that electron is everywere, until the measure finish. After that the wave-connection collapses and the electron is a small participle with a known possition.
Austrian physic Erwin Staidinger invented an intelligible experiment for make ridiculus Bors theory. The experiment ''demants'' a vase with a cover and a radioactive substance.From there it can be a trasmission of a small particle. This particle will activate a searching machine, so nerve gas will be free. A cat is puted inside the vase(We dont know why he choosed a cat). After some time, there is 50% possibility to be transmission of the small particle. An observer, looks the vase, for see what will happens to the cat.According to Bohr, cat is not alive and also not dead, until the wave-connection of the observer abolished(when he 'll open the cover for see what happened to the cat). Many conversations happened for this experiment.
In reality, the mistake of this efford, was the wrong application of the word ''observer''. Observation doesnt need to include only one person.
In Bohrs theory, its very important the action of measure. The point that the wave-connection abolished, is the point that the small particle influenses with the searching machin and inversely. After that there is no way out for the cat.