The animation above shows the observer as a grey line, who is trying to percieve a reality (a 2D circle in this case) in his 1D limited mind. The animated blue line is what he perceives. Note that the reality, the circle, is not changing in time, its radius, colour and all other properties are a part of the reality. The observed thing is very different from this, it is a blue line varying in length WITH TIME. For the observer, it remains a mystery as to what happened to the original full length of line, why and how it changes length and 'pops in and out' of his 'observed reality'.