The actual ‘state’ of a particle may be very different from our perception of it’s ‘state’.
We claim to know the ‘state’ of a particle we cannot see, and there is no guarantee our measurements are 100% precise. We say that taking the measurement alters the ‘state’ of the particle, yet we don’t know what the ‘state’ was before we took the measurement. This means that saying the ‘state’ changes when we measure it is based on a total lack of evidence.
Read “The Universe and Dr Einstein”. Free on line.
Basically we can’t really “know” anything. All we can do is build rules and models based on what we perceive.