Title: Observer effect - Simple English Wikipedia, the free encyclopedia
Headings: Observer effect
Observer effect
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Use in science
Use in Information technology
Use in the social sciences
Observer bias
References

Content: A significant minority still find the equations point to an observer; John Archibald Wheeler, who probably worked more deeply on this subject than any physicist thus far, devised a graphic in which the universe was represented by a "U" with an eye on one end, turned around and viewing itself, to describe his understanding. The Heisenberg uncertainty principle is also frequently, confused with the "observer effect". The uncertainty principle actually describes how precisely we may measure the position and momentum of a particle at the same time – if we increase the precision in measuring one quantity, we are forced to lose precision in measuring the other. Thus, the uncertainty principle deals with measurement, and not observation. The idea that the Uncertainty Principle is caused by disturbance (and hence by observation) is not considered to be valid by some, although it was discussed in the early years of quantum mechanics, and is often repeated in popular treatments. There is a related issue in quantum mechanics relating to whether systems have pre-existing – prior to measurement, that is – properties corresponding to measurements that could possibly be made on them. The assumption that they do is often referred to as " realism " in the literature, although it has been argued that the word "realism" is being used in a more restricted sense than philosophical realism. A recent experiment in the realm of quantum physics has been quoted as meaning that we have to "say goodbye" to realism, although the author of the paper states only that "we would [..] have to give up certain intuitive features of realism". These experiments demonstrate a puzzling relationship between the act of measurement and the system being measured, but it is unclear if they require a conscious observer or not.