Editing Copenhagen interpretation (section)

=== Schrödinger's cat ===
{{main|Schrödinger's cat}}
This [[thought experiment]] highlights the implications that accepting uncertainty at the microscopic level has on macroscopic objects.  A cat is put in a sealed box, with its life or death made dependent on the state of a subatomic particle.<ref name="omnes" />{{Rp|page=91}} Thus a description of the cat during the course of the experiment—having been entangled with the state of a subatomic particle—becomes a "blur" of "living and dead cat."  But this cannot be accurate because it implies the cat is actually both dead and alive until the box is opened to check on it. But the cat, if it survives, will only remember being alive.  Schrödinger resists "so naively accepting as valid a 'blurred model' for representing reality."<ref>{{Cite journal|last=Trimmer|first=John D.|date=1980|title=The Present Situation in Quantum Mechanics: A Translation of Schrödinger's "Cat Paradox" Paper|journal=[[Proceedings of the American Philosophical Society]]|volume=124|issue=5|pages=323–338|issn=0003-049X}}</ref> ''How can the cat be both alive and dead?''

In Copenhagen-type views, the wave function reflects our knowledge of the system. The wave function <math>(|\text{dead}\rangle + |\text{alive}\rangle)/\sqrt 2</math> means that, once the cat is observed, there is a 50% chance it will be dead, and 50% chance it will be alive.<ref name=":2">{{cite book| first=Asher |last=Peres |author-link=Asher Peres |title=Quantum Theory: Concepts and Methods |title-link=Quantum Theory: Concepts and Methods |pages=373–374 |year=1993 |publisher=[[Kluwer]] |isbn=0-7923-2549-4 |oclc=28854083}}</ref> (Some versions of the Copenhagen interpretation reject the idea that a wave function can be assigned to a physical system that meets the everyday definition of "cat"; in this view, the correct quantum-mechanical description of the cat-and-particle system must include a [[superselection rule]].<ref name=":7" />{{Rp|page=51}})