Title: Observer effect (physics) - Wikipedia
Headings: Observer effect (physics)
Observer effect (physics)
Contents
Particle physics
Electronics
Thermodynamics
Quantum mechanics
References

Content: An especially unusual version of the observer effect occurs in quantum mechanics, as best demonstrated by the double-slit experiment. Physicists have found that even passive observation of quantum phenomena (by changing the test apparatus and passively "ruling out" all but one possibility) can actually change the measured result. Despite the "observer" in this experiment being an electronic detector—possibly due to the assumption that the word "observer" implies a person—its results have led to the popular belief that a conscious mind can directly affect reality. The need for the "observer" to be conscious is not supported by scientific research, and has been pointed out as a misconception rooted in a poor understanding of the quantum wave function ψ and the quantum measurement process, apparently being the generation of information at its most basic level that produces the effect. Contents
1 Particle physics
2 Electronics
3 Thermodynamics
4 Quantum mechanics
5 References
Particle physics
An electron is detected upon interaction with a photon; this interaction will inevitably alter the velocity and momentum of that electron. It is possible for other, less direct means of measurement to affect the electron. It is also necessary to distinguish clearly between the measured value of a quantity and the value resulting from the measurement process. In particular, a measurement of momentum is non-repeatable in short intervals of time. A formula (one-dimensional for simplicity) relating involved quantities, due to Niels Bohr (1928) is given by
| v x ′ − v x | Δ p x ≈ ℏ / Δ t , {\displaystyle |v'_ {x}-v_ {x}|\Delta p_ {x}\approx \hbar /\Delta t,}
where
Δ px is uncertainty in measured value of momentum,
Δ t is duration of measurement,
vx is velocity of particle before measurement,
v '
x is velocity of particle after measurement,
ħ is the reduced Planck constant.