Editing Copenhagen interpretation (section)

=== Probabilities via the Born rule ===
{{Main|Born rule}}
The [[Born rule]] is essential to the Copenhagen interpretation.<ref>{{cite journal|last1=Bohr|first1=N.|year=1928|title=The Quantum Postulate and the Recent Development of Atomic Theory|journal=[[Nature (journal)|Nature]] |volume=121|issue=3050|pages=580–590|bibcode=1928Natur.121..580B|doi=10.1038/121580a0|doi-access=free}}, p. 586: "In this connexion [Born] succeeded in obtaining a statistical interpretation of the wave functions, allowing a calculation of the probability of the individual transition processes required by the quantum postulate."</ref> Formulated by [[Max Born]] in 1926, it gives the [[probability]] that a [[measurement in quantum mechanics|measurement of a quantum system]] will yield a given result. In its simplest form, it states that the probability density of finding a particle at a given point, when measured, is proportional to the square of the magnitude of the particle's wave function at that point.{{refn|group=note|While Born himself described his contribution as the "statistical interpretation" of the wave function,<ref>{{cite journal|last1=Born|first1=M.|author-link=Max Born|year=1955|title=Statistical interpretation of quantum mechanics|journal=[[Science (journal)|Science]] |volume=122|issue=3172|pages=675–679|bibcode=1955Sci...122..675B|doi=10.1126/science.122.3172.675|pmid=17798674}}</ref><ref>{{cite journal|quote=... the statistical interpretation, which I have first suggested and which has been formulated in the most general way by von Neumann, ...|author-link=Max Born |last=Born |first=M. |year=1953 |title=The interpretation of quantum mechanics |journal=[[British Journal for the Philosophy of Science]] |volume=4 |number=14 |pages=95–106|doi=10.1093/bjps/IV.14.95 }}</ref> the term "statistical interpretation" has also been used as a synonym for the [[ensemble interpretation]].<ref>{{cite journal|last1=Ballentine|first1=L.E.|year=1970|title=The statistical interpretation of quantum mechanics|url=http://nthur.lib.nthu.edu.tw/dspace/handle/987654321/65291|journal=[[Reviews of Modern Physics]] |volume=42|issue=4|pages=358–381|bibcode=1970RvMP...42..358B|doi=10.1103/revmodphys.42.358|s2cid=120024263 |url-access=subscription}}</ref><ref>{{cite book|author-link=Max Born |last=Born |first=M. |year=1949 |chapter=Einstein's statistical theories |title=Albert Einstein: Philosopher-Scientist |editor-first=P. A. |editor-last=Schilpp |editor-link=Paul Arthur Schilpp |publisher=Open Court |location=La Salle IL |volume=1 |pages=161–177}}</ref>}}