Question

What is the effect of presence or absence of an observer on the experiment conducted by Heisenberg ?

Answer 1

Dear student,

In particle physics, the observer effect, in general use, refers to any effect caused by the act of observation. When Heisenberg came up with the uncertainty principle, although the mathematics of the theory was accurate, his reasoning behind it, was not. Heisenberg's idea was - the position and velocity/momentum of a particle cannot be measured accurately, at the same time, because the very act of measurement of position, causes a change in the particle's momentum - because of the interaction between the measuring photon(any detecting particle) and the particle itself. But it was later found that the uncertainty was in fact, not a result of measurement, but an inherent property of the universe. i.e when you take the wave nature of a particle - if the position is well defined, the wavelength/momentum isn't and if you can measure the wavelength accurately, the position isn't well defined. So, w r t the general use of the term, there is no real connection between the uncertainty principle and the observer effect - the former being a law of the universe irrespective of measurement.
In physics, the term observer effect is more famously used to describe, the collapse of a wave function upon the act of measurement, which is a true account of quantum behavior i.e you can say, the act of measurement has localized the position of the particle.

I hope you understand .