[1][2] This is often the result of utilising instruments that, by necessity, alter the state of what they measure in some manner.
This effect can be found in many domains of physics, but can usually be reduced to insignificance by using different instruments or observation techniques.
A notable example of the observer effect occurs in quantum mechanics, as demonstrated by the double-slit experiment.
Physicists have found that observation of quantum phenomena by a detector or an instrument can change the measured results of this experiment.
Despite the "observer effect" in the double-slit experiment being caused by the presence of an electronic detector, the experiment's results have been interpreted by some to suggest that a conscious mind can directly affect reality.
A formula (one-dimensional for simplicity) relating involved quantities, due to Niels Bohr (1928) is given by