text: which scientist was attributed to stating that no one can actually observe something without effecting it? i cannot remember which scientist proclaimed that the act of observation of an event actually would effect the outcome of that event and therefore no one can actually observe an event in its pure form. does anyone know who this scientist was? it was heisenburg.  the heisenburg uncertainly principle is  (change in position).(change in momentum) is always greater than half of plancks constant over pi.  this comes from the quantum phenomenon that you cannot know a particles position and momentum at the same time.  to observe something you have to see it with photons,but when the photons reflect from the particles you are observing they impart a change in momentum and change its position!