Having dabbled in physics, the idea which you are speaking of was warped by a movie called the Rabbits Hole. The reason viewing a particle like in the double slit experiment changes the particle is because these particles are very sensitive to viewing instruments. In order to view something of that size, you must use another particle to bounce off of it effectively changing the quantum state of the particle. The trick is to view the particle indirectly to avoid changing said properties. Some "educational" films have effectively sensationalized this in the wrong way.