I might be talking out of my ass a bit, but if I remember it correctly the “observer” part was about it being impossible to measure velocity and observe a location of a thing (electron, photon etc. I think) at the same point in time. I don’t think it actually had an effect on the particle, i remember there were some bad experiments where the measurement influenced the the thing because the measurement itself like taking a photo or whatever they did was enough to disturb… stuff.